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2 NDT technologies for use in QA programs. These terms are defined as follows for NCHRP Project 10-65: Effectiveness of NDT Technology--Ability or capability of the technology and device to detect changes in unbound materials or HMA mixtures that affect the performance and design life of flexible pavements and HMA overlays. Practicality of NDT Technology--Capability of the technology and device to collect and interpret data on a real-time basis to assist project construction personnel (QC/QA) in making accurate decisions in controlling and accepting the final product. Integration of Structural Design, Mixture Design, and Quality Assurance The approach taken for this project was to use fundamental properties that are needed for both mixture and structural design for both control and acceptance of flexible pavements and HMA overlays. Figure 1 illustrates this integration or systems approach. The material or layer properties were grouped into three areas--volumetric, structural, and functional--and the NDT technologies were evaluated for their ability to estimate these properties accurately. Using the same mixture properties for accepting the pavement layer that were used for structural and mix- ture design allows the agency to more precisely estimate the impact that deficient materials and pavement layers have on performance. The material tests that are needed for structural and mixture design using the newer procedures are listed in Table 1. Two structural properties that are needed to predict the performance of flexible pavements and HMA overlays are modulus and thickness. These are called "quality characteristics," and they are defined in Transportation Research Circular E-C037 as "That characteristic of a unit or product that is actually measured to determine conformance with a given requirement. When the quality characteristic is measured for acceptance purposes, it is an acceptance quality characteristic (AQC)." Products The final deliverables for NCHRP Project 10-65 were divided into three volumes. Volume 1 is the procedural manual for implementing the NDT methods for QA application. It is included herein as Appendix B. It contains some of the examples for application of the modulus values for controlling and accepting flexible pavements. Volume 2 is the standard NCHRP final report. Part 3 of Volume 2 is the main body of NCHRP Report 626. Volume 3 includes the appendices for the other two volumes. It is not published herein. The appendices in Volume 3 also include the data generated from this project. The complete three volumes are presented in NCHRP Web-Only Document 133. NDT Devices Included in the Field Evaluation A large number of NDT technologies and devices have been used for pavement evaluation and forensic studies. Table 2 summarizes the technologies and methods that have been used to mea- sure different properties and features of flexible pavements. As tabulated, GPR has been used for estimating many more volumetric properties and features than any other NDT technology, while the deflection and ultrasonic-based technologies have been used more for estimating structural properties and features. To narrow the list of NDT devices that have potential for QA application, several highway agencies were contacted to collect information on their practices and experiences. Research

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3 Site Features & Inputs: Select Strategy: Trial Structural Design, Climate cross-sections for NCHRP Project 1- Traffic pavement structural 37A design or rehabilitation. Foundation Complete structural design using mixture specifications; Select structural properties to minimize distress. Material selection & Material certification; Source Specifications: approval. Aggregate, Asphalt Binder, Additives, etc. Volumetric Mixture Perform torture test(s) (APA, Design; Superpave Hamburg, etc.) or Dynamic modulus, Gyratory Compactor fracture, permanent deformation tests, etc.; NCHRP Project 9-19. Feedback from monitoring Mix Design Tests, QA Tests; pavement NCHRP Project 9-33 NCHRP Project performance, 10-65 NCHRP Project 9-30 Prepare specimens Confirmation over range of Adjustment of Perform NDT QA tests volumetric conditions. volumetric on laboratory test mixture design. specimens. Confirmation of structural design assumptions & Select final mixture Select/Establish QA criteria performance design & measure for measuring quality; expectations E* master curve. determine seismic design modulus. PRS, NCHRP Field Verification of Calibrate NDT QA tests; Project 9- Mixture Design control strips, NCHRP 22 Project 10-65. Pavement Management: Monitoring projects Agency Acceptance Plan & Functional, Structural, Specifications Volumetric Properties & Surface Contractor Quality Control Plan Distress. Figure 1. Example flow chart for the systems approach for specifying, designing, and placing quality HMA mixtures. reports of several agencies were also reviewed. These agencies include Arizona, California, Connecticut, Florida, Georgia, Illinois, Maryland, New Hampshire, Minnesota, Mississippi, Missouri, Nevada, Ohio, Oklahoma, Pennsylvania, Texas, Virginia, Washington, and Wisconsin Departments of Transportation (DOTs), the Federal Aviation Administration (FAA), Federal Highway Administration (FHWA), Eastern Federal Lands Division, Central Federal Lands Division, U.S. Air Force, U.S. Army Corps of Engineers Engineer Research and Development Center, Loughborogh University, Nottingham Trent University, Transport Research Laboratory

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4 Table 1. Summary of material and layer properties used for design and acceptance of flexible pavements and HMA overlays. Property Needed for: Pavement Layer Material-Layer Property Structural Mixture Acceptance Design Design Density Air Voids at Construction Yes Yes Voids in Mineral Aggregate Yes Yes Effective Asphalt Binder Content Yes Yes Voids Filled with Asphalt Yes HMA Layers; Gradation Yes Yes Dense-Graded Asphalt Binder Properties Yes Yes Mixtures IDT Strength and Creep Compliance Yes Yes Dynamic Modulus Yes Yes Flow Time or Flow Number Yes Smoothness, Initial Yes Density Yes Yes Water Content Yes Yes Unbound Layers; Gradation Yes Yes Dense Graded Minus 200 Material Yes Yes Granular Base, Plasticity Index (Atterberg Limits) Yes Yes Embankment Soils Resilient Modulus Yes Yes CBR or R-Value Yes Yes Strength DCP; Penetration Rate Yes IDT Indirect Tensile CBR California Bearing Ratio DCP Dynamic Cone Penetrometer (formerly known as the Transport and Road Research Laboratory [TRRL]) University of Illinois, University of Mississippi, Louisiana State University, Worcester Polytechnic Institute, and Texas Transportation Institute. Some of the equipment manufacturers and suppliers were also con- tacted to obtain specific information and data on the different NDT devices and technologies. The manufacturers contacted include Olson Engineering; Blackhawk; Geophysical Survey Systems; Inc. (GSSI); TransTech Systems, Inc.; Dynatest; Carl Bro, and others. The following list identifies the factors used to evaluate specific NDT devices that have rea- sonable success of being included in a QA program: Accuracy and precision of the test equipment and protocols in measuring a specific material property--one of the difficulties of this category is defining the target value of some properties for nonlinear and viscoelastic materials. The accuracy and precision of the technology is also tied to the data interpretation procedures. Data collection guidelines and interpretation procedures--this category examines whether there are generalized guidelines and procedures available for performing the tests and analyzing the data to estimate the material properties and/or features. Availability of standardized test procedures (test protocols)--this category verifies if there is a test standard available for use in collecting NDT data to estimate the required material prop- erties and features. Data collection--production rate of the NDT equipment in collecting the data. Data interpretation--time and ancillary equipment/software required to analyze and interpret the data for estimating the specific layer property. Cost of the equipment--this category considers the initial cost of the test equipment, addi- tional software and hardware requirements necessary to perform the test, and the operational and maintenance costs, including calibration.

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5 Table 2. NDT methods used to measure properties and features of flexible pavements in place. NDT Technologies and Methods Type of Property or Feature Unbound Aggregate Base HMA Layers and Soil Layers GPR GPR Density Non-Nuclear Gauges; PQI, Non-Nuclear Gauges; PaveTracker EDG, Purdue TDR GPR Air Voids or GPR Infrared Tomography Percent Roller-Mounted Density Acoustic Emissions Compaction Devices Roller-Mounted Density Devices Volumetric GPR Fluids Content GPR Non-Nuclear Gauges; EDG, Purdue TDR GPR Gradation; Infrared Tomography NA Segregation ROSAN Voids in Mineral GPR (Proprietary Method) NA Aggregate GPR Ultrasonic; Impact Echo, SPA, GPR Thickness SASW Ultrasonic; SASW, SPA Magnetic Tomography Impact/Penetration; DCP, Clegg Hammer Ultrasonic; DSPA, SPA, Ultrasonic; PSPA, SASW SASW Structural Modulus; Dynamic Deflection-Based; FWD, LWD, Deflection-Based; FWD, or Resilient Roller-Mounted Response LWD Systems; Asphalt Manager Steady-State Vibratory; GeoGauge Roller-Mounted Response Systems Ultrasonic; SASW, Impulse Bond/Adhesion Response NA Between Lifts Infrared Tomography Profilograph, Profilometer, Profile; IRI NA Inertial Profilers Functional Noise Noise Trailers NA Friction CT Meter, ROSAN NA SPA Seismic Pavement Analyzer PSPA Portable Seismic Pavement Analyzer SASW Spectral Analysis of Surface Waves LWD Light Weight Deflectometer ROSAN - ROad Surface ANalyzer EDG Electrical Density Gauge TDR Time Domain Reflectometry DSPA Dirt Seismic Pavement Analyzer PQI Pavement Quality Indicator DCP Dynamic Cone Penetrometer CT Circular Texture FWD Falling Weight Deflectometer Complexity of the equipment or personnel training requirements. Ability of the test method and procedure to quantify the material properties needed for QA, mixture design, and structural design (see Figure 1). In other words, is the NDT test result applicable to mixture and structural design? Relationship between the test result and other traditional and advanced tests used in mixture design and structural design.

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6 NDT Devices Included in the Field Evaluation The following list contains, in no particular order, the NDT technologies and devices that were selected for use in the field study: Deflection Based Technologies--The FWD and LWD were selected because of the large number of devices that are being used in the United States and the large database that has been created under the FHWA Long Term Pavement Performance (LTPP) program. The LWD was used to evaluate individual layers, especially unbound layers, while the FWD was used to evaluate the entire pavement structure at completion to ensure that the flexible pavement structure or HMA overlay met the overall strength requirements used in the structural design process. Deflection measuring devices are readily available within most agencies for immedi- ate use in QA. Dynamic Cone Penetrometer--The DCP was selected because of its current use in QA oper- ations in selected agencies and its ability to estimate the in-place strength of unbound layers and materials. In addition, the DCP does not require extensive support software for evaluating the test results. DCP equipment is being manufactured and marketed by various organizations, making it readily available. Ground Penetrating Radar--GPR was selected because of its current use in pavement foren- sic and evaluation studies for rehabilitation design and for estimating both the thickness and air voids of pavement layers. If proven successful, this will be one of the more important devices used for acceptance of the final product by agencies, assuming that the interpretation of the data can become more readily available on a commercial basis. The GPR air-coupled antenna was used successfully within the FHWA-LTPP program to measure the layer thickness within many of the 500-ft test sections. Seismic Pavement Analyzer--Both the PSPA and DSPA were selected because they provide a measure of the layer modulus and can be used to test both thin and thick layers during and shortly after placement. This technology can also be used in the laboratory to test both HMA and unbound materials compacted to various conditions (e.g., different water contents for unbound materials and soils or temperature and asphalt content for HMA to evaluate the effect of fluids and temperature). GeoGauge--The GeoGauge has had mixed results in testing unbound pavement layers in the past. It was selected for this study because it is simple to use and provides a measure of the resilient modulus of unbound pavement layers and embankment soils and can be used to test typical lift thicknesses. Non-Nuclear Electric Gauges; Non-Roller-Mounted Devices--Non-nuclear density gauges have a definite advantage over the nuclear devices simply from a safety standpoint. These gauges have been used on many projects but with varying results. They were selected for the current study because the devices have been significantly improved since their previous eval- uations. Moreover, many agencies are allowing their use by contractors for QC, and some agencies are beginning to use the contractor QC results for acceptance. They also represent the baseline comparison to the results from the nuclear gauges for measuring density for use in acceptance procedures. Thus, non-nuclear density gauges that provide location-specific results were selected for evaluation under this study. The gauges selected for initial use were the PQI and PaveTracker for HMA mixtures, while the EDG was selected for unbound materials. NDT Devices Excluded from the Field Evaluation The following list contains NDT technologies and devices that were excluded from the field evaluation study. It also contains explanations for the exclusion.