Inspection Guidelines for Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods (2017)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

C-1 Testing Procedures A p p e n d i x C

C-2 TP00 TESTING PROCEDURE LIBRARY NDE Method Code Testing Procedures Template TPXX Ground Penetrating Radar (GPR) TP01 Infrared Thermography (IRT) TP02 Electrical Capacitance Tomography (ECT) TP03 Magnetic Flux Leakage (MFL) TP04 Magnetic Main Flux Method – Permanent Magnet (MMFM – Permanent) TP05 Magnetic Main Flux Method – Solenoid (MMFM – Solenoid) TP06 Impact Echo (IE) TP07 Ultrasonic Tomography (UST) TP08 Ultrasonic Echo (USE) TP09 Sonic/Ultrasonic Pulse Velocity (S/UPV) TP10 Low Frequency Ultrasound (LFUT) TP11 Sounding TP12 Electrochemical Impedance Spectroscopy (EIS) TP13 Combination: GPR/USE TP14 Combination: GPR/IE TP15 Combination: MFL/Sounding TP16 Combination: MFL/IE TP17 Combination: IRT/USE TP18 Visual Methods TP19 X-Ray Radiography TP20

C-3 TPXX INSERT NAME OF NDE TECHNOLOGY Introduction Scope: The scope briefly introduces the method, describes the physical measurements used, and any further information that differentiates categories of method application. As an example, the ultrasonic tomography testing procedure may describe the different ultrasonic techniques commonly used, such as pitch-catch, through-transmission, or indirect-transmission methods. Terminology: This section describes typical language used for the method, including terminology for the physics behind the method and language specific to the device, testing techniques, and data interpretation. Example: Dielectric constant. Different constants for different materials enable the GPR method to detect subsurface layers. The dielectric constant for water is 81, air is 1, and typical construction materials may vary from around 4-9. Significance and Use: This section briefly introduces the most common use of the method within bridge inspections. It is not meant to limit application of the method, but provide an understanding of typical usage. Capabilities and Limitations: Perhaps one of the most important components of the testing procedures, this section allows the end user to determine whether or not the most optimal method chosen by the metrics is actually suitable for the specific inspection application. As the metrics were scored using defined typical conditions, the following categories are discussed to explain the technology’s capabilities and limitations in light of different physical parameters that may exist. In some instances, the user will have to determine through these limitations if any of the ranked methods are actually suitable for a particular inspection. Depending on the weights of the categories, one significant low rating for a category can make some methods score well below other methods that are not at all suitable for a given application. The following physical parameters are discussed for each NDE technology. Capability of identifying defects: This describes the capability of the NDE method to detect strand and grout defects in the internal metal and nonmetal ducts, external metal and nonmetal ducts, and the anchorage regions. Duct location: This describes the ability for inspection of internal, external, and/or anchorage systems. Duct type: This describes the applicability for metal and/or nonmetal duct inspection. Effect of concrete cover: This describes the effect of varying concrete cover for the

C-4 TPXX INSERT NAME OF NDE TECHNOLOGY technology. Effect of layered ducts: This describes the performance of the technology when attempting to inspect ducts behind other ducts (i.e., ducts laying side by side wherein inspection of the farthest duct requires penetration through a nearer duct or group of ducts). Effect of reinforcement congestion: This describes the effect of reinforcement congestion on technology performance. Closer spacing of reinforcement will negatively affect certain methods. Accessibility requirements: This describes the required accessibility of the method for external, internal, and/or anchorage regions. Some methods require very little accessibility, while others require a great deal of free space in order to operate. Safety Requirements: This section describes any special safety requirements for the particular NDE method. Referenced Documents: This section provides any sources used in the Testing Procedures, as well as any resource that should be consulted or that can provide additional insight for the testing. This may include typical user manuals, ASTM standards, relevant specifications, reports in which the technology was used for similar testing, etc. Example: 1. ASTM D6432 (2011). "Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation." ASTM International, West Conshohocken, PA, 18. 2. GSSI (2006). "GSSI Handbook For RADAR Inspection of Concrete." http://www.geophysical.com/Documentation/Manuals/MN72367D1%20Concrete%20Handb ook.pdf, Geophysical Survey Systems Inc., New Hampshire. Procedure Data Collected This section provides a list of the actual data collected for the technology. As an example, some methods use time-of-flight measurements, some use intensity variation within a testing frame, etc. Example: Amplitude of received EM signals vs time (traces).

C-5 TPXX INSERT NAME OF NDE TECHNOLOGY Apparatus: This section describes all necessary equipment needed for testing. Some of the items in this list may vary with manufacturer. Example: GPR antenna Data Acquisition System (DAQ) Process Description/Data Collection Principle: This section describes the principles and processes behind the technology use, explaining in further detail the items within the “Data Collected” section. Photo: This section provides helpful photos of device operation and/or typical results. Data Collection Procedure: This step-by-step procedure follows the generic example below for each method. This procedure is recommended for any NDE testing. This procedure should be followed in addition to the user manual for the method. Example: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris.

C-6 TPXX INSERT NAME OF NDE TECHNOLOGY Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end time, start and end location and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: This section describes the typical criteria used for data validation and includes any necessary procedures for obtaining such validation. Data Analysis and Evaluation of Results: This section describes the typical process of analyzing, interpreting, or calculating the results of the method. This section also describes the level of training typically required for data analysis. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Specifically, this section instructs the user to record the appropriate subdivisions of testing the specific bridge component. As an example, this may be segments within segmental bridge construction with appropriately marked starting and ending spans and identified cardinal directions for scanning. Final Report: A final report describing the test and visual representation of results are to be given to the owner of the structure or file manager.

C-7 TPXX INSERT NAME OF NDE TECHNOLOGY Necessary Information for Data Collection This component of the testing procedures provides a list of all of the essential data necessary to document for each inspection. Presented in a table, the headings for each form of data require the user to document the description of the data, the units used and format requirements, and all used values and related accuracy. # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (X,Y) 10 Longitudinal Origin Location (X,Z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Center Frequency 24 Bandwidth 25 26 27 28 29 30 31 32 33

C-8 TPXX INSERT NAME OF NDE TECHNOLOGY RAW DATA 34 Time Stamp 35 Data Acquisition System 36 Antenna Model 37 Gain 38 Range 39 Word Size 40 Pulse Repetition Rate 41 Samples/Scan 42 Scans/Second 43 Spatial Mode 44 Distance Units 45 Scans/Unit 46 Vertical Filters 47 Vertical Filter Values 48 Horizontal Filters 49 Horizontal Filter Values 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

C-9 TPXX INSERT NAME OF NDE TECHNOLOGY CONDITIONED DATA 74 Data File 75 ASCII File 76 CSV File 77 Scan # 78 Longitudinal Location 79 Transverse Location 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113

C-10 TP01 GROUND PENETRATING RADAR Introduction Scope: Ground penetrating radar (GPR) is a widely used quantitative scanning tool that sends discrete electromagnetic (EM) pulses into a structure and captures the reflections from subsurface layer interfaces (Figure C-1). GPR uses EM waves and therefore obeys the laws governing their reflection and transmission in layered media. At each interface within a structure, a part of the incident energy will be reflected and a part will be transmitted with a particular magnitude and phase. The reflection parameters depend on the dielectric constant of the material on either side of the interface. The depth of penetration is limited by the system’s power, the medium’s electrical conductivity, and the antenna’s central frequency. GPR antennas can emit EM pulses of different frequencies. The choice of frequency depends on the required depth of penetration and depth resolution. In general, lower frequency antennas (~10-500 MHz) have a better resolution at deeper depths (penetration greater than 50 ft in some materials). Higher frequency antennas (~500-3000 MHz) show better details of reflectors close to the surface, but do not penetrate as deep (approximately 24 in. in some materials). The choice of antenna is therefore task-dependent, and must be made from the user’s experience and availability of other NDT methods. Two types of GPR systems are typically used in structural investigations: air-coupled (AC) systems and ground-coupled (GC) systems. The air-coupled systems are high speed (up to 55 mph in some applications) and operation involves moving an antenna along the surface at approximately 10-20 in. from the surface. GC systems are typically fit on a rolling mechanism and moved at lower speeds (approximately 3 mph) with near contact to the ground. Terminology: Dielectric constant: The different constants for different materials enable the method to detect subsurface layers. The dielectric constant for water is 81, air is 1, and typical construction materials vary from around 4-9. AC GPR: Air-coupled ground penetrating radar. GC GPR: Ground-coupled ground penetrating radar. Radargram: This is a plot (line scan) of the series of amplitude vs. time signals along the line of testing. Trace: This is an amplitude vs. time plot at a specific location. Reflector: These are objects with different electrical conductivity than the surrounding medium causing EM reflections that are captured by the antenna. These show up as hyperbolic curves in the radargram, with the apex of the curve representing the location of the object. DMI: Distance measurement indicator.

C-11 TP01 GROUND PENETRATING RADAR Significance and Use: The GPR method is best used to measure the depth of subsurface layer interfaces. Since EM signals are highly reflected by metallic objects, this method can typically locate materials such as reinforcement, embedded beams, dowels, pipes, etc. within the penetration limit. The changes in surface dielectric are highly influenced by the presence of water, therefore monitoring the surface dielectric has capabilities of detecting locations of moisture-related deterioration. Interpretation of GPR radargrams may require a high level of experience and education about the method. Capabilities and Limitations: Capability of identifying defects: GPR cannot detect strand defects in external HDPE ducts. It can detect voids in external HDPE ducts with moderate accuracy, however cannot quantify the volume of the void. It can also detect compromised grout, and water infiltration defects in external HDPE ducts with low accuracy. GPR cannot detect strand or grout defects in external metal ducts, within the internal metal or plastic ducts, or the anchorage zones. However, GPR can be used to locate internal metal and plastic ducts. Duct location: While acceptable predominantly for internal ducts (testing on a concrete surface), with a proper setup, GPR may be used to identify voids within external ducts. Duct type: If it is desirable to detect conditions within the duct, GPR is only applicable to nonmetallic ducts. However, if it is desirable to locate the internal ducts itself, then GPR is applicable to both metal and nonmetal ducts. Effect of concrete cover: The effect of concrete cover is dependent on the scanning frequency. For high frequencies (~500-3000 MHz) penetration depth can typically exceed 24 in. Effect of layered ducts: GPR is unable to even locate the far duct due to the large reflections from the steel strands in the near duct. Effect of reinforcement congestion: The presence of steel highly reflects the electromagnetic waves, thereby strongly affecting GPR’s capability of locating ducts, especially in the anchorage regions. Accessibility requirements: The area required for GPR scanning is device dependent. For GC GPR inspection, it is required that the wheels of the device be in physical contact with the structure to ensure turning of the wheels which also acts as a distance meter. The creation of a 3D image requires either a 2 ft × 2 ft or 2 ft × 4 ft manually accessible testing surface. However, these requirements could vary if an AC GPR device is used. Testing within the anchorage region typically does not provide useful information due to the large volume of the highly reflective reinforcement cage present in the anchorage zones.

C-12 TP01 GROUND PENETRATING RADAR Referenced Documents: 1. ASTM D6432 (2011). Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation. ASTM International, West Conshohocken, PA, 18. 2. GSSI (2006). GSSI Handbook For RADAR Inspection of Concrete. http://www.geophysical.com/Documentation/Manuals/MN72367D1%20Concrete%20Ha ndbook.pdf, Geophysical Survey Systems Inc., ed. New Hampshire. 3. Scullion, T., Lau, C., and Chen, Y. (1992). Implementation of the Texas Ground Penetrating Radar System. Texas Transportation Institute, College Station, Texas, 102. 4. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, S., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H., Yuan, D., Shokouhi, P., and Saarenketo, T. (2014). Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings. SHRP 2 Final Report S2-R06(G)-RW, Strategic Highway Research Program 2, Washington, DC. Procedure Data Collected: Amplitude of received EM signals vs time (traces). Radargrams (series of traces along a distance). Apparatus: StructureScan Mini HR GPR unit, or any other appropriate unit selected for the scan. User manual of the device. Compatible memory card with sufficient storage capacity. Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems).

C-13 TP01 GROUND PENETRATING RADAR Process Description/Data Collection Principle: A marking system or other form of data collection management is used to perform testing and relate findings to the physical structure. In order to use GPR for gathering data from internal tendons that are embedded within concrete, it is necessary to make grids on the surface of concrete. The size of the grids may depend on the resolution of the information that is required. Grids that were 2 in. × 2 in. (50 mm × 50 mm) were made on the webs, flanges, deviators, and anchorage zones of the specimens. The GPR unit was then calibrated and used to scan the specimens along the grids in both the horizontal and vertical directions. As the GPR unit is used to scan along the grid lines, the antenna transmits and receives the electromagnetic waves. The distance measurement indicator that is combined with the wheels of the device records the distance measurements as the wheels roll when the GPR device is guided along the grid lines. The information that is recorded from each scan line is stored as a separate file. The file contains information regarding both the received electromagnetic signals and the distance measurements which are later used during post-processing. GPR may also be used to scan external tendons if a proper setup is established such that the GPR antenna remains close to the surface of the external tendon at a constant distance, and the wheels of the unit roll as the measurements are made to make distance measurements. GPR may be used to scan only nonmetallic ducts, as scans from metallic ducts do not give any discernable information from within the ducts due to the high reflectivity from the surface of the metal ducts. GPR tests are used to detect concrete cover, as well as location and depth (within reflector and depth limitations) for reinforcement, structural components, conduits, cables, prestressing steel, PT ducts, voids, honeycombing, surface layers, member thickness, and other anomalies.

C-14 TP01 GROUND PENETRATING RADAR Photo: Figure C-1: GPR antenna sends and receives EM pulses after reflection from subsurface interfaces (left); GPR trace of signal amplitude vs time (right) (from FHWA 1992). Figure C-2: Typical GPR radargram showing surface top, two layers of rebar, and member thickness (from GSSI).

C-15 TP01 GROUND PENETRATING RADAR (a) StructureScan Mini HR GPR unit used to scan along the grids in the girder wall. (b) Temporary wooden supports for using GPR unit for MTE of stay cable specimens and external tendons. Figure C-3. Test equipment and setup for GPR. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris.

C-16 TP01 GROUND PENETRATING RADAR Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate GPR unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. Step 12 – If necessary for free span inspection, construct or assemble a setup to ensure the device wheels will rotate as the device advances along the tendon. Temporary wooden supports were used in this research. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end location and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and interpretation of results should be performed by experienced and educated personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. An appropriate software such as RADAN may be used for the analysis and interpretation of data. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified.

C-17 TP01 GROUND PENETRATING RADAR Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-18 TP01 GROUND PENETRATING RADAR Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (x, y) 10 Longitudinal Origin Location (x, z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Center Frequency 24 Bandwidth 25 26 27 28 29 30 31 32 33 34 35 36 37 38

C-19 TP01 GROUND PENETRATING RADAR RAW DATA 39 Time Stamp 40 Data Acquisition System 41 Antenna Model 42 Gain 43 Range 44 Word Size 45 Pulse repetition rate 46 Samples/scan 47 Scans/second 48 Spatial Mode 49 Distance Units 50 Scans/Unit 51 Vertical Filters 52 Vertical Filter Values 53 Horizontal Filters 54 Horizontal Filter Values 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79

C-20 TP01 GROUND PENETRATING RADAR CONDITIONED DATA 80 Date File 81 ASCII File 82 Scan # 83 Longitudinal Location 84 Transverse Location 85 Target 86 Depth 87 Amplitude 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116

C-21 TP02 INFRARED THERMOGRAPHY Introduction Scope: Infrared thermography is an imaging technique that translates thermal energy emissions that escape the surface under inspection to a temperature map. The images produced give information concerning the observed temperature gradients. This is extremely convenient for NDE as delamination and voids act as thermal barriers for heat released from concrete. However, it can be difficult to perform this testing as IRT devices are highly dependent on ambient temperature conditions. Optimal results are obtained during the time of day when the temperature changes most rapidly. IRT has continued to develop over the past few decades, becoming a highly useful device well known for its capability of detecting superficial flaws in concrete structures. Its use varies from being fixed on a vehicle for 360-degree tunnel inspections to handheld cameras (Wimsatt et al. 2014). IRT devices can be categorized as either active or passive systems. Passive infrared systems are contactless technologies that rely on the heat of the sun and different times of the day when the surroundings are either warming or cooling to provide temperature gradients for thermal inspection. Active infrared systems differ from passive systems only in the application of the heat source. In active IRT, a heater is introduced to warm the structure in a localized area and in a controlled environment. It is important to note that IRT technologies only provide images of surface energy emission; they do not provide any information regarding the depth of defects. Pollock et al. (2008) used this technology in both field and laboratory investigations. As in passive IRT, they determined active IRT could very successfully and consistently locate air voids, but only in plastic ducts in thin specimens (no greater than 8-in. thick and 2-in. cover). The voided area had to be directly between the heat source and the steel strands to be effectively identified. Furthermore, they noted that it is more productive to place the heat source on the opposite side of the test specimen from where the thermal images will be collected to capture through-heating effects. Field evaluations, similar to passive IRT, were not successful at locating ducts in a 12-in. specimen (unknown cover), even after five hours of heating. Terminology: Thermal resolution: Refers to the fine details and clarity of the image. Represents the number of pixels per unit area, more pixels means greater temperature measurement accuracy particularly for small objects. Thermal sensitivity: The minimum change in temperature that the camera sensor can detect. Higher sensitivity means more temperature variation may be observed within a narrow band of temperatures. Detector: Different IRT systems use different detectors. Typical handheld units use uncooled microbolometer types. Optical lenses: Common IRT lenses are 88.9 mm (7°), 41.3 mm (15°), 24.6 mm (25°), 13.1 mm (45°), and 6.5 mm (80°). These detail the full angle of detection available for particular lenses.

C-22 TP02 INFRARED THERMOGRAPHY Significance and Use: Passive IRT may be used successfully to locate air voids and water infiltration in external nonmetallic ducts. However, it is not possible to differentiate the difference between the air voids and water infiltration defects. When it comes to internal tendons, the depth at which the internal ducts are located plays an important role in determining if the defects in the internal ducts may be detected or not. In the present investigation, the internal ducts were located approximately at a depth of about 4 in. from the surface of the concrete. At this depth, IRT was unable to locate any of the grout defects within the internal ducts. Interpretation of IRT images may require a low to moderate level of experience and education about the method. Capabilities and Limitations: Capability of identifying defects: IRT cannot locate strand defects in external HDPE ducts. IRT has high accuracy in locating void and water infiltration defects, and low accuracy in detecting compromised grout in external HDPE ducts, however it cannot differentiate between these defects. It is also possible to make rough estimates on the size of the void and water infiltration defects. IRT does not detect strand or grout defects in external metal ducts, and also does not locate internal metal or plastic ducts if they are buried deep within concrete, let alone identify defects. While IRT cannot be used to locate defects within the ducts embedded in the anchorage zones, it can detect the void and water infiltration defects in the end caps of the anchorage regions with moderate to high accuracy. As in the case of external HDPE ducts, IRT cannot differentiate between void and water infiltration defects, and it is also possible to make rough estimates on the size of these defects in the end caps. Duct location: IRT is mainly applicable to external ducts. Applicability of IRT to internal ducts largely depends on the depth within concrete at which the ducts are located. Duct type: Applicable only to nonmetallic ducts. Effect of concrete cover: The effect of concrete cover has a significant effect for investigating and even locating internal ducts. Effect of layered ducts: Investigation of layered ducts is not possible with IRT. Effect of reinforcement congestion: It is expected that surrounding reinforcement will strongly affect any investigation using IRT. Accessibility requirements: The only requirement for IRT is the ability for the infrared camera to have a good field of view of the subject being inspected. It is also important to avoid any uneven heating in the region under investigation. Referenced Documents: 1. ASTM E1934 (1999). Standard Guide for Examining Electrical and Mechanical Equipment with Infrared Thermography. ASTM International, West Conshohocken, PA. 2. ASTM E2582 (2007). Standard Practice for Infrared Flash Thermography of Composite

C-23 TP02 INFRARED THERMOGRAPHY Panels and Repair Patches Used in Aerospace Applications. ASTM International, West Conshohocken, PA, 6. 3. FLIR (2014). User`s Manual, Flir T6XX Series. https://www.instrumart.com/assets/FLIR- T620-T640-Manual.pdf, FLIR Systems Inc., Wilsonville, OR. 4. Pollock, D. G., Dupuis, K. J., Lacour, B., and Olsen, K. R. (2008). Detection of Voids in Prestressed Concrete Bridges Using Thermal Imaging and Ground-Penetrating Radar. Washington State Transportation Center, Washington State University, Pullman, WA, 77. 5. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, S., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H., Yuan, D., Shokouhi, P., and Saarenketo, T. (2014). "Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings." SHRP 2 Final Report S2-R06(G)-RW, Strategic Highway Research Program 2, Washington, D.C. Procedure Data Collected: Thermal images Apparatus: Infrared camera. User manual of the device. Heat source (if using active approach). Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: While performing IRT inspection of the external tendons of the girder specimen, care was taken to consider accessibility restrictions that would be encountered in an in-service bridge. Owing to this reason, infrared images were taken in small segments and analyzed. In addition, owing to the length of the girder specimen and limited accessibility from the outside of the specimen, the infrared images for the internal tendons within the web and the flanges of the specimen were taken as separate sections and then combined during post-processing. While taking sections of images, care was taken to keep the temperature scale at a constant range to enable combining the

C-24 TP02 INFRARED THERMOGRAPHY images. IR images of the end cap regions were also taken to assess the condition of the grout in the end caps. A marking system was used to perform testing and relate findings to the physical structure. IRT tests were able to detect air voids and water infiltration in external ducts and in the end cap region, whereas this method was unable to detect any defects in the internal tendons. Photo: Figure C-4. FLIR T640 Infrared Camera. Figure C-5. Sample infrared image of external tendons. Figure C-6. Sample infrared image of end caps in anchorage zone. T20 T16 T18

C-25 TP02 INFRARED THERMOGRAPHY Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Note that any activity from removing debris may leave heat signature due to material removal. Handprints especially can remain for extended periods of time. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and image the selected area, making sure to note start and end location and other relevant data. Step 2 – Continue to image selected locations or paths until all areas are imaged, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes.

C-26 TP02 INFRARED THERMOGRAPHY Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and educated personnel. Care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-27 TP02 INFRARED THERMOGRAPHY Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of inspection 5 Start Time 6 End Time 7 Transverse Origin Location (x, y) 8 Longitudinal Origin Location (x, z) 9 Transverse Sampling Spacing 10 Longitudinal Sampling Spacing 11 Temperature 12 Device 13 Manufacturer 14 Data Acquisition System 15 System Model 16 System Serial Number 17 Sensor Name 18 Sensor Model 19 Sensor Serial Number 20 Spectral Range 21 Detector Type 22 Detector Pitch 23 Resolution 24 Frame Rate 25 Time Constant 26 Standard Temperature Range 27 Accuracy 28 Lens used 29 Zoom 30 Fusion 31 Operating Temperature Range 32 33 34 35 36 37 38

C-28 TP02 INFRARED THERMOGRAPHY RAW DATA 39 Time Stamp 40 Data Acquisition System 41 Antenna Model 42 Gain 43 Range 44 Word Size 45 Pulse repetition rate 46 Samples/scan 47 Scans/second 48 Spatial Mode 49 Distance Units 50 Scans/Unit 51 Vertical Filters 52 Vertical Filter Values 53 Horizontal Filters 54 Horizontal Filter Values 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 74 75 76 77 78 79

C-29 TP02 INFRARED THERMOGRAPHY CONDITIONED DATA 80 Date File 81 ASCII File 82 Scan # 83 Longitudinal Location 84 Transverse Location 85 Target 86 Depth 87 Amplitude 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 108 109 110 111 112 113 114 115 116

C-30 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY Introduction Scope: ECT obtains capacitance data from multi-electrode sensors that surround an external duct and by several thousands of iterations and an appropriate numerical technique for image reconstruction develops permittivity images of internal cross-sections. Little work has been performed for PT inspection, but these images can show the existence of air pockets in oil flow in other applications. ECT is one of the most promising tomography techniques because it is safe, has a fast response rate, and is relatively inexpensive. Although the resolution of section images is low and a method is required to accurately solve the inverse problem, optimized data processing enables the image to be enhanced. Terminology: Permittivity distribution: The permittivity distribution is the imaging of relative material permittivity within the cross-section. Note that this is the typical “image” shown by ECT. Inverse problem: This problem is encountered when trying to determine the permittivity distribution from the measured capacitance. Issues arise due to the nonlinear and ill- conditioned relationship between the two sets of data. Significance and Use: ECT has been used to reconstruct cross-sectional images of oil flow inside nonconductive pipelines. Related capacitance testing methods were applied in detecting voids in HDPE duct. The investigators attached a pair of electrodes on a small HDPE duct that included one strand and obtained successful results for identifying both air and water-filled voids in ducts. However, the ECT design is complicated when it comes to obtaining successful estimation; careful design and thorough verification are required. Electrical capacitance tomography was used in the investigation of grout defects, air voids, and water infiltration in external nonmetallic tendons. The method shows great potential for rapid, safe, and inexpensive investigation for voids, compromised grout, and water infiltration. However, the disadvantages are that the resolution can be inadequate. This technique should be further developed, particularly with optimized data processing and a new sensor configuration and design. Interpretation of ECT reconstruction images may require a high level of experience and education about the method.

C-31 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY Capabilities and Limitations: Capability of identifying defects: ECT cannot locate strand defects in external HDPE ducts. While this method has moderate accuracy in detecting voids in external HDPE ducts, it has low accuracy in detecting water infiltration and compromised grout in external HDPE ducts. Duct location: ECT is applicable for external ducts. Duct type: ECT is applicable to HDPE ducts. Accessibility requirements: ECT requires moderate accessibility around the external ducts (less than 12 in. radial clearance from center of duct). Referenced Documents: 1. Iaquinta, J. Contribution of Capacitance Probes for Nondestructive Inspection of External Post-Tensioned Ducts. Proc., 16th World Conference on NDT, Session: Civil Structures, Citeseer. 2. Ortiz-Aleman, C., and Martin, R. (2005a). Inversion of Electrical Capacitance Tomography Data by Simulated Annealing: Application to Real Two-Phase Gas-Oil Flow Imaging. Flow Measurement and Instrumentation, 16(2-3), 157-162. 3. Ortiz-Aleman, C., and Martin, R. (2005b). Two-Phase Oil–Gas Pipe Flow Imaging by Simulated Annealing. Journal of Geophysics and Engineering, 2(1), 32. Procedure Data Collected Capacitance measurements from every sensor pair surrounding the duct. Permittivity distribution reconstruction. Apparatus: Sensor array. User manual for the device. Data Acquisition System (DAQ). Computer with appropriate reconstruction software. Appropriate power source/charged batteries. Appropriate connecting cables. DMI attached to rolling systems. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or

C-32 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY pre-made grid systems). Process Description/Data Collection Principle: It is expected that ECT tests will be able to detect voids, water infiltration, and compromised grout defects. The equipment is calibrated using a duct with known grout defects, air voids, and water infiltration defect. The sensor head is then moved along the length of the external tendons, and any void or water anomaly is directly indicated on the computer screen. Cross-sectional slices of the section shows the type of fault and their relative sizes. The location of the defects may be physically measured or obtained from the distance meter attached to the device. After performing the appropriate manufacturer’s calibration, the sensor array is moved along the inspected area. An attached DMI records distance traveled for post-analysis. The array receives and transmits data at a selected scan rate/density. Photo: Figure C-7. Schematic of ECT.

C-33 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY (a) ECT sensor head installed on external tendon. No faults Red indicates moisture (water/bleeding grout) Blue indicates air void (b) Image code for results from ECT. Figure C-8. Details of ECT.

C-34 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (radial section of interest, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all duct surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference such as landscape paint or grease markers. Step 10 – Calibrate ECT unit as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end location and other relevant data. Step 2 – Continue to scan selected lines or paths until the length of the external ducts are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager.

C-35 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-36 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (x, y) 10 Longitudinal Origin Location (x, z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Center Frequency 24 Bandwidth 25 Sensor Voltage 26 27 28 29 30 31 32 33 34 35 36 37 38

C-37 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY RAW DATA 39 Time Stamp 40 Data Acquisition System 41 Sensor Model 42 Gain 43 Range 44 Word Size 45 Pulse Repetition Rate 46 Samples/Scan 47 Scans/Second 48 Spatial Mode 49 Distance Units 50 Scans/Unit 51 Vertical Filters 52 Vertical Filter Values 53 Horizontal Filters 54 Horizontal Filter Values 55 Position Of Reading (X,Y) 56 Electrical Reading 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78

C-38 TP03 ELECTRICAL CAPACITANCE TOMOGRAPHY CONDITIONED DATA 79 Data File 80 ASCII File 81 Csv File 82 Scan # 83 Longitudinal Location 84 Transverse Location 85 Target 86 Depth 87 Amplitude 88 Applied Thresholds 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117

C-39 TP04 MAGNETIC FLUX LEAKAGE Introduction Scope: Magnetic methods such as the magnetic flux leakage (MFL) are very promising techniques in the NDE field for locating steel section loss due to corrosion, strand/wire pitting, or breakage. Two setups may be used for detecting defects in strands in external post-tensioning systems. In the first application a strong permanent magnet may be directly used on the external post-tensioning system to magnetize the ferrous material (steel). This induces flux paths in the material between the two poles. Where section loss is present, the magnetic field in the material “leaks” from its typical path of least resistance. A magnetic field detector (comprised of Hall-effect sensors) between the poles of the magnet is sensitive to this change in magnetic field and indicates the leak. A more accurate application of the method is the annular coil method, where a copper wire is wound around the external duct, and the permanent magnet is used to magnetize the system. While typically requiring more time, the annular coil method is used to make precise measurements regarding loss in metallic area in the tendons. In a thorough review of NDE methods for PT tendons and stay cables for FDOT, DaSilva et al. (2009) noted that active MFL was primarily useful for scanning specimens where large areas of corrosion are present while residual MFL was better at determining small areas of corrosion. DaSilva et al. list the MFL technique as one of the most promising NDE methods for PT tendon and stay cable evaluation. Terminology: Hall-effect sensors: These sensors produce output voltages in response to a change in the magnetic field. Trace: This is an amplitude vs. time plot at a specific location. DMI: Distance measurement indicator. Significance and Use: MFL is one of the very few methods that is available for detecting loss in metallic area in the external post-tensioning and stay cable systems. MFL is capable of consistently identifying loss in metallic area greater than five percent. The method is also capable of giving an estimate on the loss in metallic area. In cases where there is limited clearance around the tendon to be able to install the full-head of the magnetic device, half-head of the permanent magnet may be used to detect loss in metallic area with sufficient degree of accuracy. Interpretation of MFL charts may require a high level of experience and education about the method.

C-40 TP04 MAGNETIC FLUX LEAKAGE Capabilities and Limitations: Capability of identifying defects: MFL can locate strand defects in both metal and nonmetal external ducts with moderate to high accuracy, however it cannot differentiate between corrosion, section loss, and breakage. It consistently locates corrosion, section loss, and breakage with a loss in metallic area greater than five percent. However, in some cases loss in metallic area as low as one percent may also be detected. It can be used to estimate the loss of metallic area, although these estimates may not have high accuracy. MFL cannot detect grout defects in ducts. The effects from the magnetization of the metallic end pipe embedded within the anchorage zone, which is also called “end effect,” can make the interpretation of results challenging. Duct location: Applicable mostly to external ducts. Duct type: Applicable to both metal and nonmetal ducts. Accessibility requirements: For the investigation of external ducts, a clearance of approximately 12 in. radius is required from the center of the duct. Referenced Documents: 1. ASTM E570 (2009). Standard Practice for Flux Leakage Examination of Ferromagnetic Steel Tubular Products. ASTM International, West Conshohocken, PA, 7. 2. ASTM E1571 (2011). Standard Practice for Electromagnetic Examination of Ferromagnetic Steel Wire Rope. ASTM International, West Conshohocken, PA, 6. 3. DaSilva, M., Javidi, S., Yakel, A., and Azizinamini, A. (2009). "Nondestructive Method to Detect Corrosion of Steel Elements in Concrete." Nebraska Dept. of Roads Research Reports, Paper 81, Lincoln, NE, 193p. 4. Scheel, H., and Hillemeier, B. (2003). Location of Prestressing Steel Fractures in Concrete. Journal of Materials in Civil Engineering, 15(3), 228-234. Procedure Data Collected: Amplitude of received voltage signals vs location (traces) Flux charts (series of traces along a specified distance) Apparatus: Signal conditioning console. Sensor head.

C-41 TP04 MAGNETIC FLUX LEAKAGE User manual for the device. Data Acquisition System (DAQ). Chart recorder, paper. Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. DMI attached to rolling systems. Copper wire. Half pipes. Process Description/Data Collection Principle: A calibration wire whose area is approximately 1% of the total metallic cross-sectional area of the tendon is used for calibration, to enable post-processing the data. After calibration, the sensor head is guided at a steady pace along the length of the external duct. The attached DMI records distance traveled, thus recording the location of the flux leakage with respect to the start position. This information is essential for post-analysis, and determining the location of the defect.

C-42 TP04 MAGNETIC FLUX LEAKAGE Photo: (a) Full-head. (b) Half-head. (c) Half-head with annular coil. (d) USB signal console connected to laptop. Figure C-9. Various possible experimental setups for sensor head, and half-head with annular coil. Figure C-10. Sample results from inspection using MFL.

C-43 TP04 MAGNETIC FLUX LEAKAGE Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection. Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all the external tendon surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected duct, making sure to note start and end locations and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the

C-44 TP04 MAGNETIC FLUX LEAKAGE inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and educated personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-45 TP04 MAGNETIC FLUX LEAKAGE Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of inspection 5 Start Time 6 End Time 7 Transverse Origin Location (x, y) 8 Longitudinal Origin Location (x, z) 9 Transverse Sampling Spacing 10 Longitudinal Sampling Spacing 11 Temperature 12 Device 13 Manufacturer 14 Data Acquisition System 15 System Model 16 System Serial Number 17 Sensor Name 18 Sensor Model 19 Sensor Serial Number 20 Pulse length 21 Center Frequency 22 Bandwidth 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

C-46 TP04 MAGNETIC FLUX LEAKAGE RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Sensor Model 41 Gain 42 Range 43 Word Size 44 Pulse repetition rate 45 Samples/scan 46 Scans/second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-47 TP04 MAGNETIC FLUX LEAKAGE CONDITIONED DATA 78 Date File 79 ASCII File 80 Scan # 81 Longitudinal Location 82 Transverse Location 83 Target 84 Depth 85 Amplitude 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114

C-48 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET Introduction Scope: Magnetic methods such as the magnetic main flux method (MMFM) method are promising techniques in the NDE field for locating steel section loss due to corrosion, strand/wire pitting, or breakage. Two setups may be used for detecting defects in strands in external post-tensioning systems. In the first application a magnetizer installed on the sensor head is guided along the free span of the ducts. The controller unit gathers the data and this data is transmitted to a personal laptop. The permanent magnet type measurements gives the signal search coil measurements (direct signal from the search coil) and the magnetic flux (integrated signal of the search coil). Since the integrated signal of the search coil correlates with cross-sectional area of the cable, any valleys in these signals indicate a loss in cross-sectional area. The permanent magnet also gives measurements from the Hall-Effect sensors, which detect the MFL that supplements the detection of defects. Terminology: Hall-effect sensors: These sensors produce output voltages in response to a change in the magnetic field. Trace: This is an amplitude vs. time plot at a specific location. DMI: Distance measurement indicator. Significance and Use: MMFM-permanent measurements are useful in detecting loss in metallic area in the external post-tensioning and stay cable systems. MMFM-permanent magnet is capable of consistently identifying loss in metallic area greater than 5%, while loss in metallic area as low as 1.5% was also detected on few occasions. The method is also capable of giving an estimate on the loss in metallic area. Interpretation of MMFM charts may require a high level of experience and education about the method. Capabilities and Limitations: Capability of identifying defects: MMFM-permanent magnet can locate the strand defects in both metal and nonmetal external ducts with moderate to high accuracy. However, it cannot differentiate between corrosion, section loss, and breakage. MMFM-permanent magnet consistently locates corrosion, section loss, and breakage with a loss in metallic area greater than five percent. However, in some cases loss in metallic area as low as 1.5% may also be detected. MMFM-permanent magnet inspection can be used to obtain estimates in the loss of metallic area, although these estimates may not be accurate. MMFM-permanent magnet does not detect grout defects in ducts.

C-49 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET Duct location: Applicable to external ducts. Duct type: Applicable to both metal and nonmetal ducts. Accessibility requirements: For the investigation of external ducts, a clearance of approximately 12 in. radius is required from the center of the duct. Referenced Documents: 1. ASTM E570 (2009). Standard Practice for Flux Leakage Examination of Ferromagnetic Steel Tubular Products. ASTM International, West Conshohocken, PA, 7. 2. ASTM E1571 (2011). Standard Practice for Electromagnetic Examination of Ferromagnetic Steel Wire Rope. ASTM International, West Conshohocken, PA, 6. 3. DaSilva, M., Javidi, S., Yakel, A., and Azizinamini, A. (2009). Nondestructive Method to Detect Corrosion of Steel Elements in Concrete. Nebraska Dept. of Roads Research Reports, Paper 81, Lincoln, NE, 193p. 4. Scheel, H., and Hillemeier, B. (2003). Location of Prestressing Steel Fractures in Concrete. Journal of Materials in Civil Engineering, 15(3), 228-234. Procedure Data Collected: Amplitude of received voltage signals vs location (traces). Flux charts (series of traces along a specified distance). Apparatus: Signal conditioning console. Sensor head. User manual for the device. Data Acquisition System (DAQ). Chart recorder, paper. Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. DMI attached to rolling systems. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or

C-50 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET pre-made grid systems). Process Description/Data Collection Principle: The permanent magnet sensor head is guided at a steady pace along the length of the external duct. The attached DMI records distance traveled, thus recording the location where search coil measurements are made. This information is essential for post-analysis, and determining the location of the defect. Photo: (a) Sensor head installed on the external tendon. (b) Magnetizer installed on the sensor head. (c) Controller unit. (d) Inspector performing inspection with permanent magnet. Figure C-11. Components and test setup for MMFM using permanent magnet.

C-51 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection. Step 5 – Enter span under inspection and ensure that appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all the external tendon surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected duct, making sure to note start and end locations and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions.

C-52 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and educated personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-53 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of inspection 5 Start Time 6 End Time 7 Transverse Origin Location (X,Y) 8 Longitudinal Origin Location 9 Transverse Sampling Spacing 10 Longitudinal Sampling Spacing 11 Temperature 12 Device 13 Manufacturer 14 Data Acquisition System 15 System Model 16 System Serial Number 17 Sensor Name 18 Sensor Model 19 Sensor Serial Number 20 Pulse length 21 Center Frequency 22 Bandwidth 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

C-54 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Sensor Model 41 Gain 42 Range 43 Word Size 44 Pulse repetition rate 45 Samples/scan 46 Scans/second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-55 TP05 MAGNETIC MAIN FLUX METHOD–PERMANENT MAGNET CONDITIONED DATA 78 Date File 79 ASCII File 80 Scan # 81 Longitudinal Location 82 Transverse Location 83 Target 84 Depth 85 Amplitude 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115

C-56 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID Introduction Scope: Magnetic methods such as the magnetic main flux method-solenoid (MMFM-Solenoid) are promising techniques in the NDE field for locating steel section loss due to corrosion, strand/wire pitting, or breakage This setup uses solenoid measurements to identify and quantify the loss of metallic area in external ducts. This method takes additional time to setup the equipment before taking the measurements. Electric current is passed through the wire that is wound around a drum that encases the tendon. This is then guided along the length of the free span of the external ducts of the PT girder and the stay cable specimens. The controller unit gathers the data and this data is transmitted to a personal laptop. These measurements, known as the scan measurements locate the metal defects in the external ducts. In regions of interest the solenoid may be held stationary at that location and point measurements may be made to quantify the defects in the tendons. Terminology: Trace: This is an amplitude vs. time plot at a specific location. DMI: Distance measurement indicator. Significance and Use: MMFM-solenoid measurements are useful in detecting loss in metallic area in the external post- tensioning and stay cable systems. MMFM-solenoid is capable of consistently identifying loss in metallic area greater than 5%, while loss in metallic area as low as 2% was also detected on few occasions. The method is also capable of giving an estimate on the loss in metallic area. Interpretation of MMFM-solenoid data may require a high level of experience and education about the method. Capabilities and Limitations: Capability of identifying defects: MMFM-solenoid can locate the strand defects in both metal and nonmetal external ducts with moderate to high accuracy. However, it cannot differentiate between corrosion, section loss, and breakage. MMFM-solenoid consistently locates corrosion, section loss, and breakage with a loss in metallic area greater than 5%. However, in some cases loss in metallic area as low as 1.5% may also be detected. MMFM-solenoid inspection can be used to obtain estimates in the loss of metallic area, although these estimates may not be accurate. MMFM-solenoid does not detect grout defects in ducts. Duct location: Applicable to external ducts. Duct type: Applicable for both metal and nonmetal ducts. Accessibility requirements: For the investigation of external ducts, a clearance of

C-57 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID approximately 12 in. radius is required from the center of the duct. Referenced Documents: 1. ASTM E570 (2009). Standard Practice for Flux Leakage Examination of Ferromagnetic Steel Tubular Products. ASTM International, West Conshohocken, PA, 7. 2. ASTM E1571 (2011). Standard Practice for Electromagnetic Examination of Ferromagnetic Steel Wire Rope. ASTM International, West Conshohocken, PA, 6. 3. DaSilva, M., Javidi, S., Yakel, A., and Azizinamini, A. (2009). "Nondestructive Method to Detect Corrosion of Steel Elements in Concrete." Nebraska Dept. of Roads Research Reports, Paper 81, Lincoln, NE, 193p. 4. Scheel, H., and Hillemeier, B. (2003). Location of Prestressing Steel Fractures in Concrete. Journal of Materials in Civil Engineering, 15(3), 228-234. Procedure Data Collected: Amplitude of received voltage signals vs location (traces). Flux charts (series of traces along a specified distance). Apparatus: Signal conditioning console. Sensor head. User manual for the device. Data Acquisition System (DAQ). Chart recorder, paper. Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. DMI attached to rolling systems. Electrical cables for solenoid measurements. Drums to wrap the cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems).

C-58 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID Process Description/Data Collection Principle: The solenoid measurements are made by moving the solenoid connected to the DMI is guided along the external duct to make scan measurements, and in regions of interest point measurements may also be made. This information is essential for post-analysis, and determining the location of the defect. Photo: (a) Coil wound around the stay cable specimen and attached to distance meter. (b) Data acquisition system. Figure C-12. Setup for MMFM using solenoid measurements. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection.

C-59 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all the external tendon surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected duct, making sure to note start and end locations and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and educated personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel.

C-60 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-61 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of inspection 5 Start Time 6 End Time 7 Transverse Origin Location (x, y) 8 Longitudinal Origin Location (x, z) 9 Transverse Sampling Spacing 10 Longitudinal Sampling Spacing 11 Temperature 12 Device 13 Manufacturer 14 Data Acquisition System 15 System Model 16 System Serial Number 17 Sensor Name 18 Sensor Model 19 Sensor Serial Number 20 Pulse length 21 Center Frequency 22 Bandwidth 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

C-62 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Sensor Model 41 Gain 42 Range 43 Word Size 44 Pulse repetition rate 45 Samples/scan 46 Scans/second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 74 75 76

C-63 TP06 MAGNETIC MAIN FLUX METHOD–SOLENOID CONDITIONED DATA 77 Date File 78 ASCII File 79 Scan # 80 Longitudinal Location 81 Transverse Location 82 Target 83 Depth 84 Amplitude 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114

C-64 TP07 IMPACT ECHO Introduction Scope: The impact echo (IE) method involves hitting the concrete surface with a small impactor or impulse hammer and identifying the reflected wave energy with a displacement or accelerometer receiver mounted on the surface near the impact point. The reflections of the stress wave from internal defects, material interfaces, or other anomalies are captured by transducers on the testing surface. Because the impact generates a high energy pulse and can penetrate deep into the concrete, the IE method is particularly promising for identifying defects in concrete structures. It produces a better signal to noise ratio than other ultrasonic techniques because of its low attenuation in composite materials such as concrete. Terminology: Longitudinal waves: P-waves cause the material to oscillate in a direction in line with wave propagation. Rayleigh waves: R-waves are surface waves that travel in elliptical paths along the surface of a solid material. Transducers: Transducers turn mechanical deformations into a voltage and vice versa. They are used to transmit and receive short duration mechanical waves. A-scan: This scan shows amplitude of the received wave vs time. Significance and Use: IE may be used to detect air voids, water infiltration, and compromised grout defects in internal and external tendons. For internal tendons, IE has been reported to not detect voids well when the diameter of the ducts is small and the concrete cover is large. In the present investigation, the internal ducts were located approximately at a depth of about 4 in. from the surface of the concrete. IE results were not promising in terms of locating air voids or water infiltration defects. Testing can be slow and challenging in the evaluation of anchorage zones or areas of complex geometries. In the case of external ducts, IE data were analyzed by integrating the energy under the time domain signal. This approach gave very reliable results for detecting the location of grout defects. Interpretation of IE response spectra may require a high level of experience and education about the method. Capabilities and Limitations: Capability of identifying defects: IE cannot locate strand defects in internal or external ducts. IE can locate voids and water infiltration in internal metal ducts with moderate accuracy, and compromised grout and water infiltration in internal nonmetal ducts with low to moderate accuracy. IE can also locate compromised grout, voids, and water infiltration in external

C-65 TP07 IMPACT ECHO HDPE ducts with moderate accuracy. While IE can make rough estimates on the size of the defects, there may be large errors. Duct location: Applicable to both internal and external ducts. Duct type: Applicable to both metal and nonmetal ducts. Effect of concrete cover: The effect of concrete cover is dependent on the impact. Very thick concrete cover may prevent successful measurement. Effect of layered ducts: Layered ducts do not yield meaningful results due to the large reflections from the near duct. Effect of reinforcement congestion: Presence of steel highly reflects acoustic waves, thereby negatively affecting an investigation using IE. Accessibility requirements: For nonautomated scanning systems, accessibility required is typically a 2 ft × 2 ft area. The area required for an automated scanning systems is dependent on the system. Testing within the anchorage region is generally not possible using IE due to the physical structure of the region and the highly reflective metal used in the anchorages. Referenced Documents: 1. ASTM C1383 (2015). "Standard Test Method for Measuring the P-Wave Speed and the Thickness of Concrete Plates Using the Impact Echo Method." ASTM International, West Conshohocken, PA, 11. 2. Impact Echo (2005). Impact Echo User’s Manual. http://www.impact- echo.com/_resources/Impact-Echo-Manual.pdf, L. Impact Echo Instruments, ed.Ithaca, New York. 3. Sansalone, M., and Streett, W. (1997). Nondestructive Evaluation of Concrete and Masonry. Ithaca, NY: Bullbrier Press. 4. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, S., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H., Yuan, D., Shokouhi, P., and Saarenketo, T. (2014). Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings. SHRP 2 Final Report S2-R06(G)-RW, Strategic Highway Research Program 2, Washington, D.C. Procedure Data Collected: Amplitude of received signals vs time (traces). Frequency spectrum.

C-66 TP07 IMPACT ECHO Apparatus: Transducer unit. User manual for the device. Appropriate impact source. Data Acquisition System (DAQ). Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: A grid system with appropriate spacing along the region of interest is essential in making the IE measurements. The spacing of the grids is dependent on the desired resolution of the scan measurements. The marking system is used to perform testing and relate findings to the physical structure. IE tests are used to detect concrete cover, as well as location and depth (within reflector and depth limitations) for some structural components, conduits, cables, PT ducts, voids, member thickness, and other anomalies. In the present study, an IE unit with automated impactor and four wheels was used. Rolling system increase the testing speed considerably. After performing the appropriate manufacturer’s calibration, the transducer unit is moved vertically at 6 in. spacing. The unit receives and transmits data at a selected frequency and time duration.

C-67 TP07 IMPACT ECHO Photo: Figure C-13. IE transducer sends and receives stress pulses after reflection from subsurface interfaces. A resulting waveform and frequency response spectrum (http://www.impact-echo.com/). (a) Underside view of IE scanner. (b) Data Acquisition PC. Figure C-14. IE testing equipment. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures.

C-68 TP07 IMPACT ECHO PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density, and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end location and other relevant data. The impact device and sensor should make direct contact with the surface being tested, therefore care must be taken to avoid erroneous signals as a result of exposed aggregate or surface voids. Deliberate attention must be paid to ensuring the data collected in both the time domain and the frequency domain during scanning is consistent with expected values for the material. Also, within approximately 100 ft of the IE testing, there should not be any work that could produce frequencies in the same range of interest, such as chain dragging, coring, hammer sounding, or impact drilling. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager.

C-69 TP07 IMPACT ECHO Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Analysis of the collected data will nonexclusively include signal clipping and conditioning and visualization of the frequency response for data interpretation via data mapping. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-70 TP07 IMPACT ECHO Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (x, y) 10 Longitudinal Origin Location (x, z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Pulse Period 24 Center Frequency 25 Bandwidth 26 Source Sensor Spacing 27 28 29 30 31 32 33 34 35 36 37

C-71 TP07 IMPACT ECHO RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Antenna Model 41 Gain 42 Range 43 Word Size 44 Pulse repetition rate 45 Samples/scan 46 Scans/second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-72 TP07 IMPACT ECHO CONDITIONED DATA 78 Data File 79 ASCII File 80 Csv File 81 Scan # 82 Longitudinal Location 83 Transverse Location 84 Target 85 Depth 86 Amplitude 87 Time History (Voltage Array) 88 Frequency Response of Measured Raw Data at All Test Locations 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114

C-73 TP08 ULTRASONIC TOMOGRAPHY Introduction Scope: The ultrasonic tomography (UST) uses acoustic waves over 20 kHz. The principle of operation is the same regardless of the type of UST system: a sensor or group of sensors emits a stress pulse (typically a P- or S-wave) into the specimen. As the waves propagate, areas with changes of impedance reflect portions of the wave, and these reflections are captured by sensors. Through time-of-flight measurements and frequency/amplitude characteristics, defects and/or discontinuities can be determined. Ultrasonic techniques have shown a promising future for detecting and locating internal defects in concrete structures, including concrete thickness, internal duct locations, material layers, reinforcement presence, elastic modulus, cracks, voids, and delamination. The UST technique described here uses a linear array of dry-point-contact transducers that generate shear waves at a center frequency of 55 kHz. Terminology: Shear waves: S-waves cause the material to oscillate in a direction perpendicular to the direction of propagation and cannot travel through air or water. DPC transducers: Dry-point-contact transducers do not require coupling agent like conventional UST. A-scan: This scan shows amplitude of the received wave vs time. B-scan: This two dimensional scan is a SAFT reconstruction image that shows width of scan vs depth of scan (profile or elevation view). C-scan: This two dimensional scan is a SAFT reconstruction image that shows width of scan vs length of scan (plan view). D-scan: This two dimensional scan is a SAFT reconstruction image that shows width of scan vs depth of scan (profile or elevation view perpendicular to the B-scan). Significance and Use: The UST method is best used to measure the depth of subsurface layer interfaces. Since shear waves are highly reflected by air or water, this method can typically easily locate such anomalies such as delamination, cracking, member thickness, and voids. Additionally, any material with an impedance mismatch compared to the tested media will cause reflections. This means UST can be used to locate and detect reinforcement, embedded beams, dowels, pipes, etc. within the penetration limit. However, the system is mostly unable to detect anomalies within the internal ducts. Additional limitations of the system include the inability to test non-flat surfaces, to determine the specific type of anomaly located, and depth limitations associated with the scanning frequency. Interpretation of UST scans may require a high level of experience and education.

C-74 TP08 ULTRASONIC TOMOGRAPHY Capabilities and Limitations: Capability of identifying defects: UST did not locate strand or grout defects in internal metal or nonmetal ducts or in the anchorage regions. UST can locate internal ducts when the scanning is done perpendicular to the length of the ducts. Because of the configuration of the device, it is not useful in detecting defects in external ducts. Duct location: Linear array UST testing is limited to testing on smooth concrete surfaces, and therefore applicable to internal ducts. Duct type: As long as sufficient bonding between the duct lining and surrounding grout is maintained (no shrinkage cracks or air gaps present), this method is applicable to any duct type. Metal ducts do tend to reflect acoustic waves more than nonmetal, therefore inspection within metal ducts may not be possible. Effect of concrete cover: UST device perform better when the concrete cover is between two to 12 in. Deeper cover may be acceptable provided there is no heavy reinforcement congestion. Effect of layered ducts: Ducts behind other ducts cannot be discerned using UST. Effect of reinforcement congestion: Surrounding reinforcement strongly affects investigation using UST, since the presence of steel highly reflects acoustic waves. This makes any object directly beneath the reinforcement undiscernible and areas between reinforcement visible. Densely spaced reinforcement will limit investigation beyond the location of the reinforcement bars. Accessibility requirements: An accessible area of about 2 ft × 2 ft or larger is required depending on scanning increments. Testing within the anchorage regions generally does not provide useful information due to the large amount of reflective steel used in the anchorages. Referenced Documents: 1. ACSYS (2014). Ultrasonic Low-Frequency Tomograph, A1040 MIRA, Operation Manual. http://www.acsys.ru/eng/production/detail/a1040-mira/, Acustic Control Systems, ed., Acoustic Control Systems Ltd., Moscow, Russia, 35p. 2. ASTM C597 (2016). Standard Test Method for Pulse Velocity Through Concrete1. ASTM International, West Conshohocken, PA, 4p. 3. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, S., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H., Yuan, D., Shokouhi, P., and Saarenketo, T. (2014). Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings. SHRP 2 Final Report S2-R06(G)-RW, Strategic Highway Research Program 2, Washington, D.C.

C-75 TP08 ULTRASONIC TOMOGRAPHY Procedure Data Collected and Management Procedures: Time-of-Flight (TOF) measurements for transmitted and received acoustic signals. Amplitude of received acoustic signals. Wave speed measurements. Apparatus: Transducer matrix. User manual for the device. Data Acquisition System (DAQ). Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: Grids are made on the surface of the concrete to scan the internal ducts. The grid spacing is determined by the desired resolution of the scanning results. Typically, grids that are spaced at 2 in. × 2 in. (50 mm × 50mm) is used for scanning of webs with the internal ducts. However, if it is decided that only locations around the ducts are to be scanned, then the ducts have to be located using other NDE techniques, such as GPR. The inspector also has to make the determination on how much the grids should extend beyond the location of the ducts, based on the configuration of the device, the orientation of the scans, and the precision of results required. For the scanning of external tendons using pulse-echo technique, the spacing of the measurements shall be determined based on the level of detail that is required from the measurements. A marking system or other form of data collection management is used to perform testing and relate findings to the physical structure. UST tests are used to detect concrete cover, as well as location and depth (within reflector and depth limitations) for reinforcement, structural components, conduits, cables, prestressing steel, PT ducts, voids, honeycombing, surface layers, member thickness, and other anomalies. After performing the appropriate manufacturer’s calibration (typically involving wave speed calculation), the transducer matrix is moved along the inspected area and transmits/receives data at discrete locations. An attached DMI (if appropriate) records distance traveled for post-analysis.

C-76 TP08 ULTRASONIC TOMOGRAPHY Photo: Figure C-15. UST device on inspection element showing B-, C-, and D-scans (Wimsatt et al., 2014). Figure C-16. Typical UST scan showing B-, C-, and D-scans per Figure C-15 (Wimsatt et al., 2014). x y z B-scan C-scan D-scan

C-77 TP08 ULTRASONIC TOMOGRAPHY Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (grid spacing, average wave velocity etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate UST unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end location and other relevant data. Deliberate attention should be paid to ensuring that the displayed dispersion curves and other data are what is to be expected based on the known properties of the materials being tested. Also, within approximately 100 ft of the ultrasonic tomography testing, there should not be any work that could produce frequencies in the same range of interest, such as chain dragging, coring, hammer sounding, impact drilling, or electric generator use. This frequency interference could pose problems in isolating the data by decreasing the signal to noise ratio. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report.

C-78 TP08 ULTRASONIC TOMOGRAPHY Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-79 TP08 ULTRASONIC TOMOGRAPHY Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (X,Y) 10 Longitudinal Origin Location (X,Y) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Center Frequency 24 Bandwidth 25 Pulse Delay 26 Wave Speed 27 Analog Gain 28 Color Gain 29 Period 30 Time Corrected Gain 31 Measured Wave Speed 32 Manual Wave Speed 33 Horizontal Scanning Step 34 Vertical Scanning Step 35 Pulse Delay 36 Wave Speed 37 Analog Gain

C-80 TP08 ULTRASONIC TOMOGRAPHY RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Antenna Model 41 Gain 42 Range 43 Word Size 44 Pulse Repetition Rate 45 Samples/Scan 46 Scans/Second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-81 TP08 ULTRASONIC TOMOGRAPHY CONDITIONED DATA 78 Data File 79 ASCII File 80 CSV File 81 Scan # 82 Longitudinal Location 83 Transverse Location 84 Target 85 Depth 86 Amplitude 87 Time Histories 88 Calculated Modulus Values 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114

C-82 TP09 ULTRASONIC ECHO Introduction Scope: The principle of this operation is similar to the UST system: a sensor or group of sensors emits a stress pulse (typically a P- or S-wave) into the specimen, which mechanically excites the structural elements in the inaudible ultrasonic range. As the waves propagate, areas with changes of impedance reflect portions of the wave, and these reflections are captured by sensors. Reflections occur at interfaces with metal (e.g., reinforcement, tendon duct) and with air (back- wall, air-filled void). Through TOF measurements and frequency/amplitude characteristics, defects and/or discontinuities can be determined. USE techniques have shown promising future for detecting and locating internal defects in concrete structures, including concrete thickness, internal duct locations, material layers, reinforcement presence, elastic modulus, cracks, voids, and delamination. The USE technique described here uses a linear array of dry-point-contact transducers that generate shear waves at a center frequency of 55 kHz. Terminology: Shear waves: S-waves cause the material to oscillate in a direction perpendicular to the direction of propagation and cannot travel through air or water. DPC transducers: Dry-point-contact transducers do not require coupling agent like conventional ultrasonic transducers. SAFT algorithm: Synthetic Aperture Focusing Technique is an algorithm developed to reconstruct TOF measurements into B-, C-, and D-scans for imaging. A-scan: This scan shows amplitude of the received wave vs time. B-scan: This two dimensional scan is a SAFT reconstruction image that shows width of scan vs depth of scan (profile or elevation view). C-scan: This two dimensional scan is a SAFT reconstruction image that shows width of scan vs length of scan (plan view). D-scan: This two dimensional scan is a SAFT reconstruction image that shows width of scan vs depth of scan (profile or elevation view perpendicular to the B-scan). Significance and Use: The USE method is best used to measure the depth of subsurface layer interfaces. Since shear waves are highly reflected by air or water, this method can typically easily locate such anomalies such as delamination, cracking, member thickness, and voids. Additionally, any material with an impedance mismatch compared to the tested media will cause reflections. This means USE can be used to locate and detect reinforcement, embedded beams, dowels, pipes, etc. within the penetration limit. However, the system is mostly unable to detect anomalies within the internal

C-83 TP09 ULTRASONIC ECHO ducts. Additional limitations of the system include the inability to test non-flat surfaces, to determine the specific type of anomaly located, and depth limitations associated with the scanning frequency. Interpretation of UST scans may require a high level of experience and education with this method. Capabilities and Limitations: Capability of identifying defects: USE can locate grout defects in internal nonmetal and metal ducts with low to moderate accuracy. USE does not detect strand defects in internal ducts. This method has low accuracy in detecting voids and water infiltration in anchorage regions. Duct location: Applicable to internal ducts. Duct type: As long as sufficient bonding between the duct lining and surrounding grout is maintained (no shrinkage cracks or air gaps present), this method is applicable to both metal and nonmetal internal ducts. However, it requires calibration based on the duct material. Effect of concrete cover: USE devices perform better when the concrete cover is between 2 to 12 in. Deeper cover may be acceptable provided there is no heavy reinforcement congestion. Effect of layered ducts: Ducts behind other ducts cannot be discerned using USE. Effect of reinforcement congestion: Surrounding reinforcement will strongly affect investigation since the presence of steel highly reflects acoustic waves. This makes any object directly beneath the reinforcement undiscernible and areas in between reinforcement visible. Densely spaced reinforcement will limit investigation beyond the location of the reinforcement bars. Accessibility requirements: The automated scanner with dual probe transducers require approximately 3 ft × 3 ft clearance around the inspected region. Testing within the anchorage regions generally does not provide useful information due to the large amount of reflective steel used in the anchorages. Referenced Documents: 1. ACSYS (2014). Ultrasonic Low-Frequency Tomograph, A1040 MIRA, Operation Manual. http://www.acsys.ru/eng/production/detail/a1040-mira/, Acoustic Control Systems, ed., Acoustic Control Systems Ltd., Moscow, Russia, 35p. 2. ASTM C597 (2016). Standard Test Method for Pulse Velocity Through Concrete1. ASTM International, West Conshohocken, PA, 4p. 3. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, S., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H., Yuan, D., Shokouhi, P., and Saarenketo, T. (2014). Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings. SHRP 2 Final Report S2-R06(G)-RW, Strategic Highway Research Program 2, Washington, D.C.

C-84 TP09 ULTRASONIC ECHO Procedure Data Collected and Management Procedures: TOF measurements for transmitted and received acoustic signals. Amplitude of received acoustic signals. Wave speed measurements. Apparatus: Point contact transducers. User manual for the device. Data Acquisition System (DAQ). Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: An automated scanner, which moves a dual probe made from point contact transducers over the surface was utilized for scanning the PT girder walls. The system does not require any grids. The device automatically moves the probes at about 1 in. (25 mm) increments in both vertical and horizontal directions. A marking system or other form of data collection management is used to perform testing and relate findings to the physical structure. USE tests are used to detect concrete cover, as well as location and depth (within reflector and depth limitations) for reinforcement, structural components, conduits, cables, prestressing steel, PT ducts, voids, honeycombing, surface layers, member thickness, and other anomalies. After performing the appropriate manufacturer’s calibration (typically involving wave speed calculation), the transducer matrix is moved along the inspected area and transmits/receives data at discrete locations. An attached DMI (if appropriate) records distance traveled for post-analysis.

C-85 TP09 ULTRASONIC ECHO Photo: Figure C-17. USE device with automated dual probe scanner. Figure C-18. Typical USE point contact transducer. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (scan spacing, average wave velocity etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data

C-86 TP09 ULTRASONIC ECHO Collection.” Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate USE unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end location and other relevant data. Deliberate attention should be paid to ensure that the displayed dispersion curves and other data are what is to be expected based on the known properties of the materials being tested. Also, within approximately 100 ft of the ultrasonic tomography testing, there should not be any work that could produce frequencies in the same range of interest, such as chain dragging, coring, hammer sounding, impact drilling, or electric generator use. This frequency interference could pose problems in isolating the data by decreasing the signal to noise ratio. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All calculations or interpretation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel.

C-87 TP09 ULTRASONIC ECHO Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-88 TP09 ULTRASONIC ECHO Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (x, y) 10 Longitudinal Origin Location (x, z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Center Frequency 24 Bandwidth 25 Pulse Delay 26 Wave Speed 27 Analog Gain 28 Color Gain 29 Period 30 Time Corrected Gain 31 Measured Wave Speed 32 Manual Wave Speed 33 Horizontal Scanning Step 34 Vertical Scanning Step 35 Pulse Delay 36 Wave Speed 37 Analog Gain

C-89 TP09 ULTRASONIC ECHO RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Antenna Model 41 Gain 42 Range 43 Word Size 44 Pulse Repetition Rate 45 Samples/Scan 46 Scans/Second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 78 79

C-90 TP09 ULTRASONIC ECHO CONDITIONED DATA 80 Data File 81 ASCII File 82 CSV File 83 Scan # 84 Longitudinal Location 85 Transverse Location 86 Target 87 Depth 88 Amplitude 89 Time Histories 90 Calculated Modulus Values 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118

C-91 TP10 SONIC/ULTRASONIC PULSE VELOCITY Introduction Scope: This test is designed to identify any voids, cracks, and delamination in concrete using UPV method. The underlying principle consists of measuring the time-of-arrival of compressional waves, which are generated by sources with resonant frequencies ranging from 50 to 150 kHz. Comparatively higher velocity is obtained when concrete quality is good in terms of density, uniformity, homogeneity, etc. Ultrasonic pulse velocity (UPV) has shown a promising future for detecting and locating internal defects in concrete structures including, honeycombs, voids, and delamination. UPV technique described here uses a contact transducer with ultrasonic couplant between transducer and tested concrete on the receiver side of the specimen. The source sends around 50 kHz compression waves from the other side of the specimen. 0.1 kg impulse hammer can be used as a higher frequency source for thick specimens up to 20 ft. UPV is considered a Tier 2 inspection method. Terminology: Compression waves: They are also called longitudinal waves. Compressional waves cause the material to oscillate in the same direction as the propagation of the wave. In longitudinal waves, the displacement of the medium is parallel to the propagation of the wave. Transducers: Wet-point-contact transducers require couplant between transducer and the specimen. Compressional Wave Velocity: Is calculated as the ratio of the width of the structure to the time in microsecond for the ultrasonic pulse to travel through the width. Significance and Use: The UPV method is best used to identify and map voids, honeycomb, cracks, delamination, and other damage in concrete, wood, masonry, stone, ceramics, and metal materials. UPV tests are also performed to predict strength of early age concrete. The limitations of the system include the inability to test regions that do not have access on both sides, and depth limitations associated with the scanning frequency. Interpretation of UPV scans may require a high level of experience and education with this method. Capabilities and Limitations: Capability of identifying defects: SPV-UPV does not detect strand or grout defects within the ducts in the anchorage regions. Duct location: Applicable to internal ducts as long as there is access from both sides of the structure.

C-92 TP10 SONIC/ULTRASONIC PULSE VELOCITY Duct type: This method is applicable to both metal and nonmetal internal ducts. Effect of concrete cover: Typical concrete cover is not an issue for SPV-UPV inspection. Effect of layered ducts: Ducts behind other ducts can be discerned using UPV. The position of the two transducers can be varied such that direct, semi-direct, and indirect tests can be performed, which aids in mapping out the volume of the defect. Figure C-19 shows different transducer configurations for mapping volume. Effect of reinforcement congestion: Surrounding reinforcement will strongly affect any investigation since the presence of steel highly reflects acoustic waves. This makes any object directly beneath the reinforcement undiscernible and areas in between reinforcement visible. Densely spaced reinforcement will therefore hide any investigation beyond the bars’ location. Accessibility requirements: For UPV devices, the area required for scanning is about 12 in. on both sides of the structure. UPV technique can be used for anchorage defects. Conventional UPV testing requires access to two surfaces, preferably two parallel surfaces such as the top and bottom surfaces of a slab or the inside and outside surfaces of a wall. However, this test can be performed using the indirect methods, which does not require access to two surfaces (Figure C-19). Effect of Large Voids: The compressional wave velocity in areas with defects is slower than in areas with sound concrete, and the signal amplitude is often lower. For structural members containing large voids, signal transmission may be completely lost. In some defect areas, such as honeycombs, the compressional wave velocity may almost be the same as in sound areas, but distortion of the signal (filtering of high frequencies) may be used as an indication of a honeycomb defect. Referenced Documents: 1. ACI 228.2R-13 (2013). Report on Nondestructive Test Methods for Evaluation of Concrete in Structures. A. C. 228, ed., American Concrete Institute, Farmington Hills, MI, 4. 2. ASTM C597 (2016). Standard Test Method for Pulse Velocity Through Concrete. ASTM International, West Conshohocken, PA, 4p. 3. ASTM E494 (2015). Standard Practice for Measuring Ultrasonic Velocity in Materials. ASTM International, West Conshohocken, PA, 14p. 4. Wimsatt, A., White, J., Leung, C., Scullion, T., Hurlebaus, S., Zollinger, D., Grasley, Z., Nazarian, S., Azari, H., Yuan, D., Shokouhi, P., and Saarenketo, T. (2014). Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings. SHRP 2 Final Report S2-R06(G)-RW, Strategic Highway Research Program 2, Washington, D.C.

C-93 TP10 SONIC/ULTRASONIC PULSE VELOCITY Procedure Data Collected: Note that all data is to be collected, analyzed, and reported in accordance with the data management plan and QA/QC plan [4 and 7]. Measurements for transmitted and received acoustic signals. Frequency and amplitude of received signals. Apparatus: Source and Receiver Transducer. User manual for the device. Data Acquisition System (DAQ). Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: A marking system or other form of data collection management is used to perform testing and relate findings to the physical structure. UPV tests are used to detect location and depth (within reflector and depth limitations) for reinforcement, conduits, cables, prestressing steel, PT ducts, voids, honeycombing, and member thickness. After performing the appropriate manufacturer’s calibration (typically a reference bar that is provided to check the instrument zero), couplant is applied to the transducers which is then pressed on to the surface of the material. The testing mesh is drawn on both sides of the specimen. For each test point the receiver is held at a constant point while the source (or impact hammer) is moved to different spots on the other side of the specimen. This is done to be able to receive the signals at different angles and create a better map of the defects. For each impact the received signal data and impact data is recorded by the software for post-analysis.

C-94 TP10 SONIC/ULTRASONIC PULSE VELOCITY Photo: Figure C-19. Various configuration of UPV testing transducer for volume mapping. Figure C-20. Typical UPV scan for the anchorage region.

C-95 TP10 SONIC/ULTRASONIC PULSE VELOCITY Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate UPV unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end time and location and other relevant data. There should not be any work on the tested specimen that could produce frequencies in the same range of interest, such as chain dragging, coring, hammer sounding, impact drilling, or electric generator use. This frequency interference could pose problems in isolating the data by decreasing the signal to noise ratio. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager.

C-96 TP10 SONIC/ULTRASONIC PULSE VELOCITY Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-97 TP10 SONIC/ULTRASONIC PULSE VELOCITY Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (X,Y) 10 Longitudinal Origin Location (X,Z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 Pulse Length 23 Center Frequency 24 Bandwidth 25 Pulse Delay 26 Wave Speed 27 Analog Gain 28 Color Gain 29 Period 30 Time Corrected Gain 31 Measured Wave Speed 32 Manual Wave Speed 33 Horizontal Scanning Step 34 Vertical Scanning Step 35 Pulse Delay 36 Wave Speed 37 Analog Gain

C-98 TP10 SONIC/ULTRASONIC PULSE VELOCITY RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Antenna Model 41 Gain 42 Range 43 Word Size 44 Pulse Repetition Rate 45 Samples/Scan 46 Scans/Second 47 Spatial Mode 48 Distance Units 49 Scans/Unit 50 Vertical Filters 51 Vertical Filter Values 52 Horizontal Filters 53 Horizontal Filter Values 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-99 TP10 SONIC/ULTRASONIC PULSE VELOCITY CONDITIONED DATA 78 Data File 79 ASCII File 80 CSV File 81 Scan # 82 Longitudinal Location 83 Transverse Location 84 Target 85 Depth 86 Amplitude 87 Time Histories 88 Calculated Modulus Values 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116

C-100 TP11 LOW FREQUENCY ULTRASOUND Introduction Scope: The low frequency ultrasound (LFUT) system was designed to generate and receive low frequency ultrasonic waves in a pitch-catch fashion which propagate across the cross-section. LFUT uses very low frequency ultrasound to extend the penetration capability of conventional ultrasonic testing. The working principle of operation is the same as conventional UST systems: a sensor or group of sensors emits a stress pulse (typically a P- or S-wave) into the specimen. As the waves propagate, areas with changes of impedance reflect portions of the wave, and these reflections are captured by sensors. Through TOF measurements and frequency/amplitude characteristics, defects and/or discontinuities can be determined. The LFUT technique described here uses contact transducers with ultrasonic couplant between transducers and the tested medium. The type of signal generally recommended is a modified tone burst. Terminology: Modified tone burst signal: This signal modulates a standard tone burst with a Gaussian function, the transducer is excited more gently and over a narrower band. This reduces unwanted frequencies in the signal. It also permits the use of a wide band transducer as a sender. This makes studying a range of frequencies easier. Gaussian modulated cosine: User defined pulser wave type that excites the transducer over a narrow band. Significance and Use: The LFUT method is best used to assess the condition of the grout injected into the protective ducts. Since the generated ultrasonic waves are highly reflected by air or water, this method can typically easily locate anomalies such as delamination, cracking, member thickness, and voids. The system used has a scanning head that could be motorized with a rotational encoder to provide axial position information (Figure C-21). The motorized system has limitation when the material surface is not perfectly smooth due to plugs and clamps silicone etc. However the transducers can be detached from the setup and used manually as shown in Figure C-22. Interpretation of LFUT scans may require a high level of experience and education with this method. Capabilities and Limitations: Capability of identifying defects: LFUT detects grout defects in external HDPE ducts with low to moderate accuracy. However, LFUT does not provide an estimate for the size of the grout defects. LFUT cannot detect strand defects. This method also does not detect defects in external metal ducts.

C-101 TP11 LOW FREQUENCY ULTRASOUND Duct location: Applicable for external ducts. Duct type: Applicable for external HDPE ducts. Accessibility requirements: For the investigation of external ducts, LFUT needs physical access for the placement of the transducers on the ducts and the transducers need approximately 6 in. clearance. Referenced Documents: 1. ACI 228.2R-13 (2013). Report on Nondestructive Test Methods for Evaluation of Concrete in Structures. A. C. 228, ed., American Concrete Institute, Farmington Hills, MI, 4 p. 2. ASTM E494 (2015). Standard Practice for Measuring Ultrasonic Velocity in Materials. ASTM International, West Conshohocken, PA, 14 p. Procedure Data Collected: TOF measurements for transmitted and received acoustic signals. Amplitude of received acoustic signals. Wave speed measurements. Apparatus: Transducer and receiver. User manual for the device. Data Acquisition System (DAQ). Computer with appropriate software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: A marking system or other form of data collection management is used to perform testing and relate findings to the physical structure. LFUT tests are used to detect compromised grout in PT ducts, voids, honeycombing, or water infiltration. After performing the appropriate manufacturer’s calibration with known defects (e.g., duct sections with soft grout, duct sections full of water, duct sections with voids, etc.), the transducers are moved along the inspected duct and transmits/receives data at discrete locations.

C-102 TP11 LOW FREQUENCY ULTRASOUND The DAQ system collects the data. A designated test PC with appropriate software analyzes the raw data for immediate preprocessed waveform images and records the data for post-processing. Photo: Figure C-21. Motorized system for LFUT testing. Figure C-22. Manually operated LFUT testing.

C-103 TP11 LOW FREQUENCY ULTRASOUND Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section “Necessary Information for Data Collection.” Keep this data updated for each span/section under inspection, noting any significant changes during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate LFUT unit (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end time and location and other relevant data. Also, within approximately 100 ft of the LFUT testing, there should not be any work that could produce frequencies in the same range of interest, such as chain dragging, coring, hammer sounding, impact drilling, or electric generator use. This frequency interference could pose problems in isolating the data by decreasing the signal to noise ratio. Step 2 – Continue to scan selected lines or paths until all ducts are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under “Reporting” section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager.

C-104 TP11 LOW FREQUENCY ULTRASOUND Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). And this data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structures start and/or end locations.

C-105 TP11 LOW FREQUENCY ULTRASOUND Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Origin Location (X,Z) 10 Sampling Spacing 11 Temperature 12 Device 13 Manufacturer 14 Data Acquisition System 15 System Model 16 System Serial Number 17 Sensor Name 18 Sensor Model 19 Sensor Serial Number 20 Bandwidth 21 Wave Speed 22 Time Corrected Gain 23 Measured Wave Speed 24 Manual Wave Speed 25 Horizontal Scanning Step 26 Vertical Scanning Step 27 Pulse Delay 28 Wave Speed 29 Analog Gain 30 31 32 33 34 35 36 37

C-106 TP11 LOW FREQUENCY ULTRASOUND RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Gain 41 Range 42 Word Size 43 Pulse Repetition Rate 44 Samples/Scan 45 Scans/Second 46 Spatial Mode 47 Distance Units 48 Scans/Unit 49 Vertical Filters 50 Vertical Filter Values 51 Horizontal Filters 52 Horizontal Filter Values 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-107 TP11 LOW FREQUENCY ULTRASOUND CONDITIONED DATA 78 Data File 79 ASCII File 80 CSV File 81 Scan # 82 Longitudinal Location 83 Transverse Location 84 Target 85 Depth 86 Amplitude 87 Time Histories 88 Calculated Modulus Values 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115

C-108 TP12 SOUNDING Introduction Scope: For the inspection of external PT ducts, a sounding inspection is generally performed to identify the existence of voids in ducts. In the regular inspection of PT bridges, the sounding inspection is executed by tapping an impactor or coin. At locations of the tendons where there exists “irregular sounding,” and inspectors document tendons for further inspection using borescope [1 and 4]. Although the sounding inspection might contain errors, it is easy to execute in the field and is a relatively rapid method for detecting voids in ducts. Also, this inspection is particularly effective in the field because it can be applied without a power supply, and does not require a well-trained inspector to conduct the inspection. Terminology: Impactor: Any object with a blunt edge used for tapping duct walls. Significance and Use: Sounding is an inspection technique that is easy to be implemented for the inspection of external post-tensioning and stay cable systems. It is capable of detecting air voids and water infiltration defects within the external ducts, as these defects produce a different sound when tapped compared to locations filled with grout. However, it may be difficult to differentiate between the two types of defects, and also to identify small defects. The effectiveness of the sounding method was assessed in an external tendon mock-up specimen using transparent acrylic ducts [2 and 3]. After blindly applying the sounding method, it was then compared with the visual inspection through the transparent ducts (Figure C-23). The sounding inspection method had difficulty in identifying tiny void and required experience for the assessment, but it was capable of identifying relatively large voids, which may be a cause of corrosion. Thus, the sounding method can be a promising tool to identify voids in the field. In the future it may be prudent to develop a new technique to use a microphone to record the sound and then further analyze it to detect defects in external ducts. Interpretation of sounding by ear may require a low level of experience but can be highly subjective. Capabilities and Limitations: Capability of identifying defects: Sounding cannot locate strand defects in external ducts. It can detect void and water infiltration defects in external ducts with high accuracy, although application of sounding inspection on metal ducts could be slightly more challenging compared to HDPE ducts. Sounding inspection cannot differentiate between void and water infiltration defects. While sounding cannot be used to identify strand and grout defects in the internal tendons, and anchorage regions, it can be used to detect voids, compromised grout, and water infiltration defects within the end caps of the anchorage

C-109 TP12 SOUNDING regions with high accuracy. Duct location: Applicable for external ducts. Duct type: Acceptable for both metal and nonmetal external ducts. Accessibility requirements: Sounding requires physical access to allow manual tapping on the external ducts. Referenced Documents: 1. Corven, J. (2001). Mid Bay Bridge Post-Tensioning Evaluation. Final Report, Florida Department of Transportation, Florida. 2. Im, S. B., and Hurlebaus, S. (2012). Non-Destructive Testing Methods to Identify Voids in External Post-Tensioned Tendons. KSCE Journal of Civil Engineering, 16(3), 388-397. 3. Im, S. B., Hurlebaus, S., and Trejo, D. (2010). Inspection of Voids in External Post- Tensioned Tendons. Transportation Research Record: Journal of the Transportation Research Board, No. 2172, Transportation Research Board of the National Academies, Washington, DC 115-122. 4. Trejo, D., Im, S. B., Pillai, R. G., Hueste, M. B. D., Gardoni, P., Hurlebaus, S., and Gamble, M. (2009). Effect of Voids in Grouted Post-Tensioned Concrete Bridge Construction: Inspection and Repair Manual for External Tendons in Segmental, Post-Tensioned Bridges. Texas Transportation Institute, Texas A&M University System, Product 0-4588-2. Procedure Data Collected: Void image mapping (Figure C-23). Apparatus: Impactor. Image maps. Process Description/Data Collection Principle: A map of the various locations of the duct has to be created to record the findings from the sounding technique. The use of a void image mapping is strongly encouraged. The intervals at which the tappings are performed depends on the resolution required from the sounding map. Tappings should also be done along the circumference of the duct to detect any defects along the sides or the bottom of the duct.

C-110 TP12 SOUNDING Photo: Figure C-23. Void image of external ducts (Im et al. 2010; Im and Hurlebaus 2012). Data Collection Procedure: All manufacturer’s manuals (for automated sounding methods) and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference.

C-111 TP12 SOUNDING DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and sound the selected area, making sure to note start and end time and location and other relevant data. Step 2 – Continue to sound selected lines or paths until all areas are sounded, being diligent to record the anomalous areas according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). This data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. System software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-112 TP12 SOUNDING Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (x, y) 10 Longitudinal Origin Location (x, z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Humidity 15 Type of Impactor 16 Any Automated Data Collection Specifications 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

C-113 TP12 SOUNDING RAW DATA (only for automated versions) 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

C-114 TP12 SOUNDING CONDITIONED DATA (only for automated versions) 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115

C-115 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY Introduction Scope: EIS is an experimental technique in which sinusoidal modulation of an input signal is used to obtain the transfer function for an electrochemical system. In its usual application, the modulated input is potential, the measured response is current, and the transfer function is represented as an impedance. The impedance is obtained at different modulation frequencies, thus invoking the term spectroscopy. Through use of system-specific models, the impedance response can be interpreted in terms of kinetic and transport parameters. Addition of an external potential affects the dynamics of chemical reactions leading to nonlinear electrochemical dynamics at the interface. Characterizing the changes at a surface under specific system parameters can be interpreted to gain information about the condition of the corroded interface. Terminology: Dielectric spectroscopy: Measures dielectric and electric properties of a medium as a function of frequency. Impedance: The measure of the resistance that a circuit presents to a current when a voltage is applied. Significance and Use: When used to study electrochemical systems, EIS can give accurate kinetic and mechanistic information using a variety of techniques and output formats. For this reason, EIS is becoming a powerful tool in the study of corrosion, semiconductors, batteries, electroplating, and electro- organic synthesis. EIS is a very sensitive technique and must be used with great care. It is not always well understood. EIS are very often difficult to understand by non-specialists and mathematical developments of equations connecting the impedance with the physico-chemical parameters are complicated. It should be emphasized that EIS cannot give all the answers. It is an effective technique when used together with other methods. Capabilities and Limitations: Capability of identifying defects: EIS inspection can identify corrosion in external HDPE ducts with moderate accuracy. EIS cannot detect grout defects. Duct location: EIS is applicable for external ducts. Duct type: It can be used with external HDPE or other nonconductive ducts. Accessibility requirements: EIS requires physical access to the duct being inspected, and the ability to drill small holes into the external duct.

C-116 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY As EIS inspection generates detailed information, sophisticated approaches are required to interpret the data and extract meaningful results. Referenced Documents: 1. Barsoukov, E., and Macdonald, J. R. (2005). Impedance Spectroscopy: Theory, Experiment, and Applications, John Wiley & Sons. 2. Orazem, M. E., and Tribollet, B. (2008). "An Integrated Approach to Electrochemical Impedance Spectroscopy." Electrochimica Acta, 53(25), 7360-7366. 3. Orazem, M. E., and Tribollet, B. (2011). Electrochemical Impedance Spectroscopy, John Wiley & Sons. Procedure Data Collected: EIS measurements from all four electrodes attached to the duct. Voltage response obtained from the potentiostat. Apparatus: Potentiostat for running EIS. User manual for the device. Computer with appropriate analysis software. Appropriate power source/charged batteries. Appropriate connecting cables. Appropriate drilling tool to open about 1/2 in. diameter holes. Appropriate marking system. Process Description/Data Collection Principle: A marking system or other form of data collection management is used to perform testing and relate findings to the physical structure. EIS tests are hopeful to detect corrosion in the strands. After drilling the four electrode holes, the electrodes were placed into the holes such that they touch the grout surface. Two electrodes providing the excitation voltage (input) and the other two recording the impedance response. Figure C-24 shows a picture of a typical EIS testing of a duct.

C-117 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY Photo: Figure C-24. EIS testing of an external PT duct. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (radial section of interest, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all duct surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference such as landscape paint or grease markers. Step 10 – Calibrate EIS unit (if required) as specified in the manufacturer’s manual.

C-118 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area, making sure to note start and end time and location and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). This data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results: All analysis and evaluation of results should be performed by experienced and qualified personnel. Analysis software often makes data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-119 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (X,Y) 10 Longitudinal Origin Location (X,Z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Sensor Name 20 Sensor Model 21 Sensor Serial Number 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

C-120 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY RAW DATA 38 Time Stamp 39 Data Acquisition System 40 Sensor Model 41 Gain 42 Range 43 Word Size 44 Samples/Scan 45 Scans/Second 46 Spatial Mode 47 Distance Units 48 Scans/Unit 49 Vertical Filters 50 Vertical Filter Values 51 Horizontal Filters 52 Horizontal Filter Values 53 Position of Reading 54 Impedance Reading 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

C-121 TP13 ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY CONDITIONED DATA 78 Data File 79 ASCII File 80 CSV File 81 Scan # 82 Longitudinal Location 83 Transverse Location 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116

C-122 TP14 COMBINATION: GPR/USE Introduction Scope: When available, a combination of methods should always be considered to optimize the strength of individual methods. This particular combination considers GPR and ultrasonic echo (USE) for internal ducts. Terminology: See terminology from Testing Procedures TP01 and TP09 for GPR and USE, respectively. Significance and Use: USE by itself is a slow NDE technique for the inspection of large areas, whereas GPR by itself does not collect enough detailed information. A combination of GPR and USE methods may be best used to measure the depth of subsurface layer interfaces such as voids. When combined, GPR and USE can provide faster evaluation than the methods used alone. GPR can be used to highlight potential areas of interest which can then be followed up with the USE method for a more detailed inspection. Interpretation of individual technology inspection results may require a high level of experience and education about the method(s). Capabilities and Limitations: This particular combination only considers internal ducts. For additional capabilities and limitations refer to TP01 for GPR and TP09 for USE. Referenced Documents: See referenced documents from Testing Procedures TP01 and TP09 for GPR and USE, respectively. Procedure Data Collected: For GPR, see TP01. For USE, see TP09. Apparatus: For GPR, see TP01. For USE, see TP09.

C-123 TP14 COMBINATION: GPR/USE Process Description/Data Collection Principle: If applying the methods individually and comparing results, see Testing Procedures TP01 and TP09 for GPR and USE, respectively. Photos: See photos from TP01 and TP09 for GPR and USE. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate units (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area with first method (typically GPR), making sure to note start and end time and location and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection.

C-124 TP14 COMBINATION: GPR/USE OPTION 1: Step 3 – Use the appropriate testing lines or paths and scan the selected area with second method (typically USE), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. OPTION 2: Step 3 – Use the first method results to isolate areas of interest. Then use appropriate testing lines or paths and scan the selected area with second method (typically USE), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: See Testing Procedures TP01 and TP09 for GPR and USE, respectively. Data Analysis and Evaluation See Testing Procedures TP01 and TP09 for GPR and USE, respectively. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-125 TP14 COMBINATION: GPR/USE Necessary Information for Data Collection See Testing Procedures TP01 and TP09 for GPR and USE, respectively.

C-126 TP15 COMBINATION: GPR/IE Introduction Scope: When available, a combination of methods should always be considered to optimize the strength of individual methods. This particular combination considers GPR and IE for internal ducts. Terminology: See terminology from Testing Procedures TP01 and TP07 for GPR and IE, respectively. Significance and Use: IE by itself is a slow NDE technique for the inspection of large areas, whereas GPR by itself does not collect detailed enough information. A combination of GPR and IE methods may be used to measure the depth of shallow subsurface layer interfaces. When combined, GPR and IE can be used for a fast and detailed evaluation of the area of interest. GPR can be used to identify potential areas of interest, and IE can then be used to follow-up on these areas for a more detailed inspection. Interpretation of individual technology inspection results may require a high level of experience and education about the method(s). Capabilities and Limitations: This particular combination only considers internal ducts. For additional capabilities and limitations refer to TP01 for GPR and TP07 for IE. Referenced Documents: See referenced documents from Testing Procedures TP01 and TP07 for GPR and IE, respectively. Procedure Data Collected: For GPR, see TP01. For IE, see TP07. Apparatus: For GPR, see TP01. For IE, see TP07.

C-127 TP15 COMBINATION: GPR/IE Process Description/Data Collection Principle: If applying the methods individually and comparing results, see Testing Procedures TP01 and TP07 for GPR and IE, respectively. Photos: See photos from TP01 and TP07 for GPR and IE, respectively. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate units (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area with first method (typically GPR), making sure to note start and end time and location and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection.

C-128 TP15 COMBINATION: GPR/IE OPTION 1: Step 3 – Use the appropriate testing lines or paths and scan the selected area with second method (typically IE), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. OPTION 2: Step 3 – Use the first method results to isolate areas of interest. Then use appropriate testing lines or paths and scan the selected area with second method (typically IE), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under “Preparation” as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: See Testing Procedures TP01 and TP07 for GPR and IE, respectively. Data Analysis and Evaluation of Results See Testing Procedures TP01 and TP07 for GPR and IE, respectively. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-129 TP15 COMBINATION: GPR/IE Necessary Information for Data Collection See Testing Procedures TP01 and TP07 for GPR and IE, respectively.

C-130 TP16 COMBINATION: MFL/SOUNDING Introduction Scope: When available, a combination of methods should always be considered to optimize the strength of individual methods. This particular combination considers MFL and sounding for external ducts. Terminology: See terminology from Testing Procedures TP04 and TP12 for MFL and Sounding, respectively. Significance and Use: MFL is best used to detect strand defects such as corrosion, breakage, and section loss. While sounding cannot identify strand defects, sounding can isolate voided regions accurately and at low costs. In most cases, primary tendon corrosion, breakage, and section loss conditions occur where there are voided conditions. The void locations identified by the sounding technique can then be inspected for strand defects using MFL. MFL technique can prove to be quite expensive for scanning large lengths of tendons. The combination of sounding and MFL can likely reduce the overall inspection cost. While interpretation of sounding is quite simple, MFL inspection may require a high level of experience and education about the method. Capabilities and Limitations: This particular combination only considers external ducts. For additional capabilities and limitations refer to TP04 for MFL and TP12 for sounding. Referenced Documents: Se referenced documents from Testing Procedures TP04 and TP12 for MFL and Sounding, respectively. Procedure Data Collected: For MFL, see TP04. For sounding, see TP12. Apparatus: For MFL, see TP04. For sounding, see TP12.

C-131 TP16 COMBINATION: MFL/SOUNDING Process Description/Data Collection Principle: If applying the methods individually and comparing results, see Testing Procedures TP04 and TP12 for MFL and sounding, respectively. Photos: See photos from TP04 and TP12 for MFL and sounding, respectively. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate units (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and cover the selected area with first method (typically sounding), making sure to note start and end time and location and other relevant data. Step 2 – Continue to cover selected lines or paths until all areas are covered, being diligent to name the saved data according to testing location if using automated data collection software. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection.

C-132 TP16 COMBINATION: MFL/SOUNDING OPTION 1: Step 3 – Use the appropriate testing lines or paths and scan the selected area with second method (typically MFL), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. OPTION 2: Step 3 – Use the first method results to isolate areas of interest. Then use appropriate testing lines or paths and scan the selected area with second method (typically MFL), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: See Testing Procedures TP04 and TP12 for MFL and sounding, respectively. Data Analysis and Evaluation of Results See Testing Procedures TP04 and TP12 for MFL and sounding, respectively. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-133 TP16 COMBINATION: MFL/SOUNDING Necessary Information for Data Collection See Testing Procedures TP04 and TP12 for MFL and sounding, respectively.

C-134 TP17 COMBINATION: MFL/IE Introduction Scope: When available, a combination of methods should always be considered so as to optimize the strength of individual methods. This particular combination considers MFL and IE for external ducts. Terminology: See terminology from Testing Procedures TP04 and TP07 for MFL and IE, respectively. Significance and Use: IE is used as a high speed method to localize potential grout or void conditions. While IE cannot identify strand defect, IE can isolate voided and water infiltration regions accurately and at low costs. In most cases, primary strand defects such as corrosion, breakage, and section loss conditions occur where there are voided conditions. The location of void and water infiltration defects isolated by IE inspection can then be inspected using MFL to detect strand defects. Thereby, a combination of MFL and IE methods may be used to more quickly identify regions of grout defects and strand defects. However, the interpretation of the individual technology inspection results require a high level of experience and education about the method(s). Capabilities and Limitations: This particular combination only considers external ducts. For additional capabilities and limitations refer to TP04 for MFL and TP07 for IE. Referenced Documents: See referenced documents from Testing Procedures TP04 and TP07 for MFL and IE, respectively. Procedure Data Collected: For MFL, see TP04. For IE, see TP07. Apparatus: For MFL, see TP04. For IE, see TP07.

C-135 TP17 COMBINATION: MFL/IE Process Description/Data Collection Principle: If applying the methods individually and comparing results, see Testing Procedures TP04 and TP07 for MFL and IE, respectively. Photos: See photos from Testing Procedures TP04 and TP07 for MFL and IE, respectively. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate units (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and cover the selected area with first method (typically IE), making sure to note start and end time and location and other relevant data. Step 2 – Continue to cover selected lines or paths until all areas are covered, being diligent to name the saved data according to testing location if using automated data collection software. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection.

C-136 TP17 COMBINATION: MFL/IE OPTION 1: Step 3 – Use the appropriate testing lines or paths and scan the selected area with second method (typically MFL), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. OPTION 2: Step 3 – Use the first method results to isolate areas of interest. Then use appropriate testing lines or paths and scan the selected area with second method (typically MFL), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: See Testing Procedures TP04 and TP07 for MFL and IE, respectively. Data Analysis Procedures: See Testing Procedures TP04 and TP07 for MFL and IE, respectively. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-137 TP17 COMBINATION: MFL/IE Necessary Information for Data Collection See Testing Procedures TP04 and TP07 for MFL and IE, respectively.

C-138 TP18 COMBINATION: IRT/USE Introduction Scope: When available, a combination of methods should always be considered so as to optimize the strength of individual methods. This particular combination considers infrared thermography (IRT) and ultrasonic tomography (USE) for internal ducts. Terminology: See terminology from Testing Procedures TP02 and TP09 for IRT and USE, respectively. Significance and Use: USE is a time-consuming method and too slow for the inspection of large areas. However, IRT could be effective in locating void defects in ducts that are embedded within shallow concrete. In this case, IRT can be used to locate the regions of interest, and USE can be used to perform a detailed inspection of this region. However, IRT typically does not identify defects in the internal ducts, if the ducts are embedded deep within the concrete, and in this case this combination would not offer any additional advantage. While interpretation of results from IRT are straightforward, interpretation of USE inspection results may require a high level of experience and education about the method Capabilities and Limitations: This particular combination only considers internal, nonmetal, shallow (less than 2 in. concrete cover) ducts. For additional capabilities and limitations refer to TP02 for IRT and TP09 for USE. Referenced Documents: See referenced documents from Testing Procedures TP02 and TP09 for IRT and USE, respectively. Procedure Data Collected and Management Procedures: For IRT, see TP02. For USE, see TP09. Apparatus: For IRT, see TP02. For USE, see TP09.

C-139 TP18 COMBINATION: IRT/USE Process Description/Data Collection Principle: If applying the methods individually and comparing results, see Testing Procedures TP02 and TP09 for IRT and USE, respectively. Photos: See photos from TP02 and TP09 for IRT and USE, respectively. Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (central frequency, desired coupling, scan density and rate, testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference. Step 10 – Calibrate units (if required) as specified in the manufacturer’s manual. Step 11 – (RECOMMENDED) Create a sample file to ensure proper working order of all system components. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and scan the selected area with first method (typically IRT), making sure to note start and end time and location and other relevant data. Step 2 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection.

C-140 TP18 COMBINATION: IRT/USE OPTION 1: Step 3 – Use the appropriate testing lines or paths and scan the selected area with second method (typically USE), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. OPTION 2: Step 3 – Use the first method results to isolate areas of interest. Then use appropriate testing lines or paths and scan the selected area with second method (typically USE), making sure to note start and end time and location and other relevant data. Step 4 – Continue to scan selected lines or paths until all areas are scanned, being diligent to name the saved data according to testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: See Testing Procedures TP02 and TP09 for IRT and USE, respectively. Data Analysis Procedures: See Testing Procedures TP02 and TP09 for IRT and USE, respectively. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-141 TP18 COMBINATION: IRT/USE Necessary Information for Data Collection See Testing Procedures TP02 and TP09 for IRT and USE, respectively.

C-142 TP19 VISUAL METHODS Introduction Scope: VT of external PT ducts and stay cable ducts is often the first step during inspection. This type of testing can be used to quickly identify areas of major deterioration that warrant immediate attention and further, more detailed evaluation (Figure C-25). Although very useful for external PT and stay cable ducts, VT of internal PT ducts is more difficult. For all applications, a borescope and/or videoscope can greatly aid visual inspection by providing a means to inspect the interior of the duct or conduct VT of hard to reach areas. In these cases, a borescope and/or videoscope can also be carried out to further inspect an area already identified by the use of another NDE method. Terminology: Borescope. A tubular optical device with an eyepiece on one end and a lens on the other end. Videoscope. An optical device capable of recording video. Significance and Use: VT methods can be a method of preliminary bridge inspection, exceedingly applicable to external PT ducts and stay cable ducts. VT can serve to identify deterioration of the ducts, possibly indicating locations where water and atmospheric gases have been able to infiltrate in to the interior of the duct. A borescope and/or videoscope can be used to inspect regions not visible without technological assistance. Capabilities and Limitations: Capability of identifying defects: VT can be used as a preliminary method to detect flaws in the external ducts, and for signs of flaws in internal tendons on the surface of the structure. VT is very effective in investigating the end caps of the anchorage regions, provided the end caps can be removed. VT can also provide good quantitative estimate about the defect. However, VT is usually limited by the lack of accessibility to the inspection area. An investigation using borescope needs access to insert the camera of the equipment into the region of interest. Provided there is sufficient access, this method can detect grout defects in both internal and external metal and nonmetal ducts with high accuracy. Borescope can also be used to inspect anchorage zones through the grout ports. Large strand defects and corrosion can be detected by VT, while identifying smaller defects could be challenging. Duct location: VT is mainly applicable to external ducts. However, borescope is applicable to both internal and external ducts. Duct type: Applicable to both metal and nonmetal ducts.

C-143 TP19 VISUAL METHODS Effect of concrete cover: Concrete cover is not an issue to the borescope inspection itself, but can cause a hindrance in accessing internal tendons. Effect of layered ducts: Layered duct can cause accessibility issues for borescope investigation, but is not an issue for the inspection itself. Effect of reinforcement congestion: Can cause accessibility issues for borescope investigation, but is not a hindrance to the inspection technique itself. Accessibility requirements: VT requires physical access to the duct being inspected. Borescope and/or videoscope devices require accessibility into the ducts of the internal and external tendons. Referenced Documents: 1. Trejo, D., S. B. Im, R. G. Pillai, M. B. D. Hueste, P. Gardoni, S. Hurlebaus and M. Gamble. 2009. Effect of Voids in Grouted Post-Tensioned Concrete Bridge Construction: Inspection and Repair Manual for External Tendons in Segmental, Post-Tensioned Bridges, Texas Transportation Institute, Texas A&M University System. Procedure Data Collected: Video files (if used). Photos (if used). Written assessment of visual inspection. Apparatus: Camera. User manual for the device. Borescope. Videoscope. Process Description/Data Collection Principle: A marking system is used to perform testing and relate findings to the physical structure. A marking system can be used to correlate structure locations to photos and/or video.

C-144 TP19 VISUAL METHODS Photo: Figure C-25. Broken duct and exposed strands evident during VT (Trejo et al. 2009). (a) Access hole for inspection. (b) Olympus IPLEX borescope device. Figure C-26. Setup for inspection using borescope.

C-145 TP19 VISUAL METHODS Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all devices. Step 4 – Determine appropriate parameters for the type of inspection required (testing paths, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris in order to be able to visually inspect. Step 9 – Use appropriate marking system for reference. Mark tendons with designated numbers and mark tendons with measured segments along the full length of each tendon. Step 10 – Record all information on the location of anchorage zones and deviator blocks and measure diaphragm thickness in order to estimate the depth of the tendon(s) embedded in concrete. Locate survey stations every foot from the end of the diaphragm to the first deviator block for external PT ducts. DATA COLLECTION: Step 1 – Use the appropriate testing lines or paths and conduct VT of the selected area, making sure to note start and end time and location and other relevant data. Step 2 – Continue to test selected lines or paths until all areas have undergone VT, being diligent to correspond photos and/or videos to the specified testing location. After each area is tested, repeat Steps 4-11 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager.

C-146 TP19 VISUAL METHODS Criteria for Data Validation: If available, all ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). This data can be used for calibration and validation purposes. Most of the time it is unlikely to have ground truth data for an inspected bridge. In that case the inspector should use his/her own mock-specimen for any necessary calibration of the equipment or validation of the accuracy of the device for detecting specific conditions. Data Analysis and Evaluation of Results All analysis and evaluation of results should be performed by experienced and qualified personnel. Detailed records should be kept on locations that warrant further inspection. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and any regions of significant deterioration are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-147 TP19 VISUAL METHODS Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (X,Y) 10 Longitudinal Origin Location (X,Z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Devices Used 15 Manufacturer 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

C-148 TP20 X-RAY RADIOGRAPHY Introduction Scope: Radiography in general is a technique that assesses images of an object by projecting high energy beams of electromagnetic radiation (typically x-rays or gamma-rays). X-rays (the most common type of radiography NDE methods) are typically produced by a linear accelerator (LINAC), a cyclic particle accelerator, or an X-ray generator. When film is used to inspect the object, this technique is called X-ray Radiography. X-rays can be used with multiple scan angles and computer processing and reconstruction techniques to display two dimensional images of a three dimensional object, in which case the technique is generally called computed tomography (CT). Terminology: LINAC: A typical power source for x-ray generation, the linear accelerator. Film: The “older” version of developing film uses photographic film sheets sensitive to x-ray particles. This use requires manual development. More modern films are digital which allows for on-site development within minutes of testing. Attenuation: The scattering of x-rays due to material composition. X-ray use is limited by the particular device’s power which governs attenuation. Dosimeter: A device that measures exposure to radiation. Significance and Use: Although highly expensive and potentially a significant health hazard, x-ray scans can be used to penetrate both steel and concrete within limitations. Typical usages for bridge tendon inspection can locate inclusions, voids, and broken and cut strands within shallow internal ducts and most external duct applications. It should be noted that x-ray radiography only provides images of internal composition; therefore it does not provide any information regarding the depth of defects. Interpretation of radiographic film may require a high level of experience and education about the method. Capabilities and Limitations: Duct location: Applicable for both internal and external ducts; however, concrete cover and surrounding reinforcement may severely limit penetration for internal ducts. Penetration is highly device dependent. Duct type: Applicable for both HDPE and metal ducts. Effect of concrete cover: X-rays may penetrate some small amount of concrete cover, but full penetration capabilities is highly device dependent. Effect of layered ducts: Layered effects have not been documented. Effect of reinforcement congestion: X-rays may penetrate mild steel congestion, but multiple layers will mask tendon inspection. Accessibility requirements: Radiography generally requires significant accessibility, including both sides of test object. During testing, a marked-off radius is required to maintain health and safety due to radiation exposure.

C-149 TP20 X-RAY RADIOGRAPHY Safety Requirements: All safety requirements from the manufacturer’s manuals and procedures should be strictly adhered to in addition to the following safety precautions: Equipment should be used by fully qualified and trained personnel only. Equipment is NOT approved for use in areas where hazardous gases may be present. Normal operating procedures shall be written and available to all analytical x-ray equipment workers. Note that these procedures also need to address possible emergencies. Establish appropriate perimeter per specific radiography device. Note all safety warnings on device. No operation involving the removal or alteration of shielding materials, tube housing, shutter, collimators, or beam stops shall be performed until it has been determined that the beam is off and will remain off until safe conditions have been restored. Always power down unit when not in use. Referenced Documents: 1. ASTM E94 – 04, Standard Guide for Radiographic Examination 2. ASTM E1030 – 05, Standard Test Method for Radiographic Examination of Metallic Castings 3. ASTM E1254 – 13, Standard Guide for Storage of Radiographs and Unexposed Industrial Radiographic Films 4. Harris, D. 2003. Test and Assessment of NDT Methods for Post-Tensioning Systems in Segmental Balanced Cantilever Concrete Bridges. Florida Department of Transportation Central Structures Office. 5. Mariscotti, M. and F. Jalinoos. 2008. Gamma-Ray Imaging for Void and Corrosion Assessment in PT Girders. NDE/NDT for Highways and Bridges - Structural Materials Technology (SMT).

C-150 TP20 X-RAY RADIOGRAPHY Procedure Data Collected Images depicting intensity of x-rays captured on film. Apparatus: Specified x-ray tube. Specified x-ray generator. Accessories (as needed per device, e.g. lead figures, lead screens). Appropriate film and film processing equipment (e.g., gloves, vinyl holders, filing envelopes). Dark room (if manual film development is used). Dosimeter. Densitometer. Safety apparel. Warning rope. Appropriate marking system (landscaping paint, permanent markers, welder’s soapstone, or pre-made grid systems). Process Description/Data Collection Principle: The x-ray source is focused on the testing location and appropriate film collection is placed on the other side of the specimen under consideration. Using a remote control, the generator emits x-rays for the required exposure time. A marking system or other form of data collection management is used to relate findings to the physical structure. Radiographs are collected for each testing location and can be related to the structure by marking systems (usually lead markers) attached to the structure.

C-151 TP20 X-RAY RADIOGRAPHY Photo: Data Collection Procedure: All manufacturer’s manuals and procedures should be strictly adhered to in addition to the following data collection procedures. PREPARATION: Step 1 – Collect bridge structure files. Step 2 – Gather all required apparatuses named above. Step 3 – Ensure proper working order of all system components. Step 4 – Determine appropriate parameters for the type of inspection required (testing locations, exposure time, power requirements, etc.). Step 5 – Enter span under inspection and ensure appropriate marking system is in place. Step 6 – At a minimum, record all data specified in the section Necessary Information for Data Collection. Keep this data updated for each span/section under inspection, noting any significant Figure C-27. Application of CT to internal PT ducts. Note the dark lines indicating voids of various size [5].

C-152 TP20 X-RAY RADIOGRAPHY changes (particularly in temperature or humidity) during testing. Step 7 – Perform preliminary walk-through of testing site, noting any damage indicators. Step 8 – Once a specific site is chosen for testing, ensure all surfaces are clean and free of debris. Step 9 – Use appropriate marking system for reference such as landscape paint or grease markers in addition to those required by the x-ray unit (lead markers). Step 10 – Calibrate unit (if required) as specified in the manufacturer’s manual. DATA COLLECTION: Step 1 – Collect film for the selected area, making sure to note location and other relevant data. Step 2 – Store all film as directed by the user manual for the specific technique used. Step 3 – Continue to scan all areas marked for inspection, being diligent to name the film/files according to testing location. After each area is tested, repeat Steps 4-10 under Preparation as necessary before additional continuing data collection. DATA REPORTING: Step 1 – Follow guidelines under Reporting section below in creating an inspection report. Step 2 – Submit completed inspection report to inspection program manager. Criteria for Data Validation: Ground truth data is typically collected by using the lead markers visible in each radiograph at areas of interest with the marking system. All ground truth data should be properly recorded (precise location, photos, ambient temperature, humidity, etc.). Note: For the NCHRP Project 14-28 mock-up specimens located at Texas A&M Transportation Institute, no ground truth data collection is allowed. Data Analysis Procedures: All film interpretation should be performed by experienced and qualified personnel. System software for digital radiographs often make data interpretation easier, but care should be taken that interpretation is overseen by properly qualified personnel. Note that all data is to be collected, analyzed, and reported in accordance with the data management plan. Reporting Subdivision of the Structure for Inspection & Recordkeeping: Investigators should always record the appropriate subdivisions of the structure for analysis, recordkeeping, and future tests. Every testing location should be clearly identified. Final Report: All final reports describing the test and visual representation of results are to be given to the owner of the structure or file manager. All key features noted from the investigation should be clearly identified and labeled with respect to the structure’s start and/or end locations.

C-153 TP20 X-RAY RADIOGRAPHY Necessary Information for Data Collection # Description Units/format Values/Accuracy GENERAL 1 State, City, Location 2 Structure Name 3 Personnel Performing Inspection 4 Date of Inspection 5 Start Time 6 End Time 7 Start Location 8 End Location 9 Transverse Origin Location (X,Y) 10 Longitudinal Origin Location (X,Z) 11 Transverse Sampling Spacing 12 Longitudinal Sampling Spacing 13 Temperature 14 Device 15 Manufacturer 16 Data Acquisition System 17 System Model 18 System Serial Number 19 Source/Generator Name 20 Source/Generator Model 21 Source/Generator Serial Number 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

C-154 TP20 X-RAY RADIOGRAPHY RAW DATA 40 Time Stamp 41 Data Acquisition System 42 Film Collection System 43 Gain 44 Range 45 Word Size 46 Pulse Repetition Rate 47 Samples/Scan 48 Scans/Second 49 Spatial Mode 50 Distance Units 51 Scans/Unit 52 Vertical Filters 53 Vertical Filter Values 54 Horizontal Filters 55 Horizontal Filter Values 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

C-155 TP20 X-RAY RADIOGRAPHY CONDITIONED DATA 81 Data File 82 ASCII File 83 CSV File 84 Scan # 85 Longitudinal Location 86 Transverse Location 87 Target 88 Depth 89 Amplitude 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119