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315 a p p e N D I x U Introduction A survey of several concrete slabs constructed by the Texas A&M Transportation Institute (TTI) was carried out with a portable seismic property analyzer (PSPA) within the frame- work of the second Strategic Highway Research Program (SHRP 2) Renewal Project R06G. Eleven concrete slabs and 13 shotcrete slabs were involved in this study. The dimensions of the slabs and defects are more optimized toward the applica- tion of ground-penetrating radar (GPR). The concrete slabs were evaluated on November 9 and 10, 2011, and the shotcrete slabs were assessed on November 10 and 11, 2011. The scope of this University of Texas at El Paso study was to evaluate the performance of the PSPA in locating defects inside concrete. The PSPA used in the study was developed primarily for test- ing pavement sections. As part of this study, the PSPA was mod- ified to be more user-friendly for implementation in tunnels. A second set of tests were carried out on January 28 through 31, 2013, to test the viability of the new version on some of the slabs tested previously with the traditional PSPA. Given the desire of SHRP 2 to develop user-friendly devices, the results presented here are as reported by the PSPA in the current state without further advanced analy- ses using an experienced expert analyst. The lessons learned are being incorporated in the new version of the PSPA under development. Description of pSpa and testing Methods The PSPA is a portable device that can perform two simultane- ous tests: impact echo (IE) and ultrasonic surface wave (USW). The traditional PSPA is a box containing a solenoid-type impact hammer and two high frequency accelerometers (Figure U.1a). All controls and data acquisition are in a com- puter connected to the box. The two receivers allow the calcula- tion of the Vp using the USW method. The test at a single point is simple and takes less than 30 s. The impact duration (contact time) is about 60 µs and the data acquisition system has a sam- pling frequency of 390 kHz. The advantage of combining the two methods in a single device is that once the test is performed, the variations in the modulus (an indication of the quality of concrete) and return resonance frequency (an indication of the full thickness or depth of delamination) of a slab can be assessed concurrently. As shown in Figure U.1b, the PSPA has been redesigned to make it more user-friendly and compact for tunnel work. The new PSPA is self-contained as it does not need an external per- sonal computer to collect data. The waveforms collected in the field are stored in a removable flash memory. The new PSPA is also lighter compared with the traditional PSPA (8 lb versus 16 lb). Data collection with the new PSPA is a two-hand operation, which can accommodate the curvature within the tunnel more easily. Data acquisition with the new PSPA is on average two to three times faster than the traditional one. The new PSPA is also equipped with three receivers to better opti- mize the data collection for the combined IE/USW methods. The receivers are spaced at -3 in., 3 in., and 9 in. from the source. The power source for the device is six AAA batteries in a container that can be carried on the operatorâs belt. Impact Echo Method The IE method is one of the most commonly used non- destructive testing (NDT) methods in detecting delamination in concrete (Carino et al. 1986). This method is based on strik- ing a plate-like object such as a tunnel lining with an impactor that generates stress waves at frequencies up to 20 kHz to 30 kHz and collecting signals with a receiver (Figure U.2a). By using a fast Fourier transform (FFT) algorithm, the recorded time domain signal is converted into a frequency domain function (amplitude spectrum), and the peak fre- quency is monitored. For an intact point on a slab or an intact portion of a slab, the thickness (h) is then determined Portable Seismic Property Analyzer Slab Tests
316 (a) IE method (b) USW method Source: Gucunski and Maher 1998. 1000 1200 1400 1600 1800 2000 2200 2400 0.05 0.1 0.15 0.2 D e pt h, m Phase Velocity, m/s Intact Severe delamination Intact Condition Shallow Severe Delamination Deep Onset of Delamination h 1 2 Figure U.2. Schematic illustration of test methods. (b)(a) Figure U.1. Portable seismic property analyzer. from the compression wave velocity (Vp) and the return frequency ( f ) as shown in Equation U.1: 2 (U.1)h V f p = α where a is about 0.96 for concrete slabs. For a deep and relatively small delaminated location in a concrete slab, the return frequency may shift to a higher fre- quency corresponding to the depth of the delamination. As shown in Figure U.2a, a shallow or a deep but extensive and severe delaminated area is usually manifested by a low peak frequency, indicating that little or no energy propagates toward
317 the bottom of the deck and a flexural mode dominates the fre- quency response. In this case, Equation U.1 is not applicable to measure the depth of delamination because it is influenced by several factors. Ultrasonic Surface Waves Method The USW method is used to estimate the average velocity of propagation of surface waves in a medium on the basis of the time at which different types of energy arrive at each sensor (Figure U.2b). The velocity of propagation, VR, is typically determined by dividing the distance between two receivers, DX, by the difference in the arrival time of a specific wave, Dt. Knowing the wave velocity, the modulus can be determined from shear modulus, G, through Poissonâs ratio (ν) by using Equation U.2: 2 1 (U.2)E G( )= + ν Shear modulus can be determined from shear wave velocity, VS, by using Equation U.3: (U.3)2G g VS= γ The modulus from surface wave velocity, VR, first converted to shear wave velocity can be determined by Equation U.4: 1.13 â 0.16 (U.4)V VS R ( )= ν In the USW method, the variation in velocity with wave- length is measured to generate a so-called dispersion curve. For a uniform or intact concrete slab, the dispersion curve shows more or less a constant velocity within the wave- lengths not greater than the thickness of the slab. When a delamination or void is present in a concrete slab or the concrete has deteriorated, the average surface wave velocity (or modulus) becomes less than the actual one because of interference caused by the defect. In this case, the velocity or modulus obtained may be called an apparent velocity or modulus. Description of Slabs An overall view of the test slabs is shown in Figure U.3, and their characteristics are summarized in Table U.1. Two sets of slabs were tested in this study. Each slab was 6 ft by 6 ft. The first set of specimens included six intact concrete slabs with thicknesses of 12 in., 15 in., 18 in., and 24 in., and three defective 15-in.-thick slabs with embedded 1-ft by 1-ft delaminated zones in the cen- ter of the slabs. The last three slabs contained defects at depths of 1 in., 2 in., and 3 in. from the top surface. Two other concrete Figure U.3. Overall view of TTI slabs. slabs in this set were 15 in. thick with embedded air voids and water voids at a depth of 8 in. The second set of slabs was shotcrete slabs that included four intact slabs with thicknesses of 4 in., 6 in., 8 in., and 12 in. and five 12-in.-thick delaminated slabs. The 1-ft by 1-ft delaminated areas were embedded at the center of each slab at depths of 1 in., 2 in., 3 in., 4 in., and 8 in. from the top surface. Four other shot- crete slabs contained air voids and water voids with different sizes at different depths. Data Collection process The testing schemes of different slabs are shown in Figure U.4. Every intact slab was assessed through 11 testing lines equally spaced at 4-in. intervals. On each line, 11 points were tested at every 4 in. Therefore, 121 data points were collected for each intact slab (Figure U.4a). A similar scheme was used for the defective slabs except that data were collected at 143 points, as shown in Figure U.4b. Each test slab took about 1 h to test and about 30 min to interpret and develop the contour maps. All slabs were investigated using the traditional PSPA in 2011. At each point, the PSPA source was placed on the grid point. The near and far receiver spacing from the source were 4 in. and 10 in., respectively. For reporting the USW results, the coordinate was shifted 7 in. (half the distance between the two receivers and the source). For the IE results, the coordinate was shifted 2 in. (half the distance between the source and Receiver 1). Some of the slabs, as indicated in Table U.1, were assessed again in 2013 with the new PSPA. Similarly, the PSPA source was placed on the test point. Based on the source and receivers spacing, the coor- dinate was shifted 6 in. for reporting USW results and 1.5 in. for IE results.
318 test results The USW and IE results from different concrete and shotcrete slabs are presented and compared in this section. A detailed description of the data reduction process was provided in a companion report related to testing in actual tunnels in Colo- rado and Virginia (see Appendix P). As such, they are not repeated here. Intact Concrete Slabs Figure U.5 contains the traditional PSPA results from Slab 1. Figure U.5a is a picture of the slab on the day of testing. The slab was visually uniform with a smooth finish. The acquired waveforms from the two PSPA receivers at the center point of the slabs are shown in Figure U.5b. Because of the size of the Table U.1. Characteristics of TTI Slabs Slab Information Thickness (in.) Type of Defect Size of Defect (ft by ft) Depth of Defect (in.) Tested with Traditional PSPA (2011) Tested with New PSPA (2013) Concrete Slab 1 12 Intact NA NA Yes Yes Slab 2 18 Intact NA NA Yes Yes Slab 3 12 Intact NA NA Yes Yes Slab 4 24 Intact NA NA Yes Yes Slab 5 24 Intact NA NA Yes No Slab 6 15 Intact NA NA Yes Yes Slab 7 15 Delamination 12 by 12 2 Yes Yes Slab 8 15 Delamination 12 by 12 3 Yes Yes Slab 9 15 Delamination 12 by 12 1 Yes No Slab 10 15 Air void 12 by 12 8 Yes Yes Slab 11 15 Water void 12 by 12 8 Yes Yes Shotcrete Slab 1 4 Intact NA NA Yes No Slab 2 6 Intact NA NA Yes Yes Slab 3 8 Intact NA NA Yes Yes Slab 4 12 Air void 121â8 by 9¾, 17¼ by 14¾a 7.5 Yes No Slab 5 12 Water void 11 by 10½, 15¾ by 14½a 7.5 Yes No Slab 6 12 Air void 12¼ by 12, 14¾ by 171â8a 3 Yes Yes Slab 7 12 Water void 10½ by 10½, 15½ by 14¼a 3 Yes No Slab 8 12 Delamination 12 by 12 8 Yes Yes Slab 9 12 Delamination 12 by 12 4 Yes Yes Slab 10 12 Delamination 12 by 12 3 Yes No Slab 11 12 Delamination 12 by 12 2 Yes Yes Slab 12 12 Delamination 12 by 12 1 Yes No Slab 13 12 Intact NA NA Yes Yes Note: NA = not available. a The first set of numbers indicates the void, and the second set indicates the bag that encapsulates the void. (a) (b) Figure U.4. Testing schemes of different slabs.
319 (a) Slab 1 (b) Waveform obtained from PSPA at center point (c) Average modulus from USW (d) Dominant frequency from IE 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 Time(s) Ac ce le ra tio n (m /s 2) 1st Receiver 2nd Receiver Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Apparent M oduli (ksi) Dom inant Frequency (Hz) (e) USW B-Scan along centerline (f) IE Spectral B-Scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Apparent M oduli (ksi) Norm alized Am plitude Figure U.5. Contour maps of acquired results from traditional PSPA for concrete Slab 1 (12-in.-thick intact slab).
320 specimens, reflections from the vertical boundaries are appar- ent in the later portions of the signals. The PSPA software con- tains appropriate filters to minimize the effect of these reflections as long as the PSPA is located an adequate distance from the boundary. Because the IE and USW methods used in this study are point inspection methods, contour maps are more useful for visualizing the results than individual evaluations. The contour map of the variations in the average modulus (from a depth of 2 in. to nominal thickness of the slab) from the USW tests is shown in Figure U.5c. The slab exhibited a fairly uniform mod- ulus. The mean average modulus of the slab was 6,400 ksi with a standard deviation of about 375 ksi. Similarly, the contour map of the dominant return frequency from the IE method, as shown in Figure U.5d, was also uniform. In addition to the planar contour maps, the USW and IE line scans (B-scans) along the centerline are also shown in Figure U.5. The USW B-scan (Figure U.5e) is in the form of variation in modulus with wavelength, which can qualitatively be viewed as a scaled varia- tion of modulus with depth. In this case, the variation in modu- lus with depth is small. The spectral B-scan of the IE results (Figure U.5f) is in the form of variation of normalized ampli- tude with frequency. Throughout the width of the slab, a fre- quency of about 7.7 kHz (manifested as a red band) corresponds to the 12-in. thickness of the slab. The thickness reported from IE tests was 11.9 in. with a standard deviation of 0.8 in. Figure U.6 shows the same results from the new PSPA on Slab 1. Unlike in 2011, the slab contained some micro cracks. Figure U.6a again shows the slab on test day. The time records from the new PSPA are similar or slightly higher quality than those from the traditional PSPA (Figure U.6b). The planar con- tour maps of the variations in the average modulus from the USW method and the dominant return frequency from the IE method are shown in Figures U.6c and U.6d, respectively. The mean average modulus of the slab was 4,590 ksi with a standard deviation of about 560 ksi. The average modulus from 2011 is greater than that from 2013. Aside from material degradation manifested as micro cracks, the reasons for such differences are under investigation. The higher standard deviation can be attributed to the new micro cracks observed in the slab. The average dominant return frequency is around 7.3 kHz through the entire slab, which is similar to the dominant frequency observed in 2011. A minor defect in the slab manifested in the IE planar contour map in Figure U.5d between -2 in. and +2 in. of the centerline manifests itself more prominently in the USW and IE B-scans of Figures U.6e and U.6f, respectively. Slab 2 was an 18-in.-thick intact slab and contained two cracks. Figure U.7 compares the severity of the cracks in two years of testing. Compared with 2011, the cracks had pro- gressed significantly by 2013. The traditional and new PSPA results from Slab 2 are shown in Figures U.8 and U.9, respec- tively. The interaction between the cracks and seismic wave propagation is rather complex. When the sourceâreceiver array is parallel to the crack, the USW modulus variation and the IE response spectrum are marginally affected in the cur- rent software. When the crack is between the source and the first receiver, the USW modulus is typically greater than nor- mal because of the travel path of the wave. Similarly, when the crack is between the two sensors, the reported USW modulus is lower than normal. To maintain the regularity of the testing program, we chose to carry out the tests on a rigid grid and not adjust the location of the sensors to avoid the cracks. As reflected in Figure U.8c, the PSPA sensors crossed the cracks at only a few points. For example, at a coordinate of -4 in. in Figure U.8e, the crack is propagating deep within the slab. The mean of the obtained average modulus with the traditional PSPA of this slab was about 5,980 ksi with a standard deviation of about 533 ksi. The IE thickness was about 16.3 in.; but as shown in Figure U.8f, the return frequency was very consistent, and with one core, the thickness could be readily calibrated to the actual thickness. The mean average modulus from the new PSPA (Figure U.9a) is around 5,130 ksi with a standard deviation of about 586 ksi. The dominant frequency peak is uniform in Figure U.9b. The average dominant frequency is around 4.9 kHz; therefore, the slab thickness estimates were similar to the previous results. Slab 3 (Figure U.10) was supposed to be similar to Slab 1. The average modulus was about 5,997 ksi with a standard deviation of about 750 ksi. The average thickness was about 11.4 in. Slab 3 was placed on a steel plate with a 1-ft by 1-ft hole in 2012 (Figure U.11a). The objective was to identify the NDT methods that could detect the hole. The USW and IE results in Figures U.11b and U.11c demonstrate an intact slab, and the hole in the steel plate could not be detected as antici- pated. The mean average modulus of 5,500 ksi with a standard deviation of 622 ksi was obtained. The average IE dominant frequency of around 7.6 kHz is quite similar to those measured by the traditional PSPA. Slabs 4 and 5 were each 24-in. thick. The IE method as con- figured in the traditional PSPA cannot detect thickness in excess of 18 in. Thus, detection of slab thickness was not pos- sible for these two slabs, as reflected in Figures U.12 and U.13. However, the quality of the concrete, except in isolated points, was high with mean average moduli of 5,900 ksi. Slab 4 was also tested with the new PSPA and the results are shown in Figure U.14. The mean average modulus dropped to 4,560 ksi. Similar to the traditional PSPA, with the sourceâreceiver con- figuration of the new PSPA the detection of the bottom of the slab was not feasible. Finally, with the traditional PSPA, the 15-in.-thick intact slab 6 yielded an average modulus of 6,220 ksi (Figure U.15c) with a thickness of 14.2 in. (Figure U.15). The new PSPA gave an average modulus of 5,230 ksi for Slab 6 (Figure U.16a). The average dominant frequency measured with the new
321 (b) Waveform obtained from PSPA at center point (c) Average modulus from USW (d) Dominant frequency from IE (a) Slab 1 0 0.5 1 1.5 2 2.5 3 3.5 4 x 10-3 -6 -4 -2 0 2 4 x 10 -3 Time (s) Ac ce le ra tio n (m /s 2) Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Apparent M oduli (ksi) Dom inant Frequency (Hz) (e) USW B-scan along centerline (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) De pt h (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Fr eq ue nc y (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Apparent M oduli (ksi) Norm alized Am plitude Figure U.6. Contour maps of acquired results from new PSPA for concrete Slab 1 (12-in.-thick intact slab).
322 PSPA was close to that measured with the traditional PSPA (Figure U.16b). Delaminated Concrete Slabs Slab 7 (Figure U.17a) was similar to Slab 6, with a delamina- tion embedded at a depth of 2 in. from the top surface. A comparison of the time records in Figures U.15b and U.17b clearly demonstrates the differences in the time records from an intact area and a delaminated area. With a few days of experience, the operator can readily detect the delamination by simply looking at the time signals. The delaminated area is clearly detectable in both the USW and IE results from the traditional PSPA in Figures U.17c through U.17f. The USW and IE results acquired with the new PSPA (Figure U.18) pro- vide similar delamination maps. However, the IE results from the new PSPA in Figure U.18b provide a clearer indication of the delaminated area. The same statements can be made for the traditional PSPA results from Slab 8 (Figure U.19) with delaminated zones at nominal depths of 3 in. By comparing the amplitudes of the waveforms in Figures U.17b and U.19b, one can roughly esti- mate that the delamination in Slab 7 is shallower than the one in Slab 8. The delamination in Slab 8 is readily approximated in both the USW results and IE results from the traditional PSPA in Figures U.19c and U.19d. Slab 8 was also investigated with the new PSPA. Similar to the traditional PSPA results, the new PSPA is able to detect the delamination through USW and IE contour maps (Figure U.20). In the design of the PSPA, the assumption has been that a 1-in.-deep delamination can be readily detected by tapping, and a device may not be needed during field testing. Slab 9 (Figure U.21a) was only tested by the traditional PSPA. One unexpected result was observed: the presence of the 1-in.- deep delamination was obvious from the amplitude of time records in Figure U.21b and the USW results in Figure U.21c but was not reflected in the IE interpretation in Figure U.21d. This simply occurred because of the high-pass filters applied to the IE results. The vibration frequency was so low that it was eliminated from the signal. Concrete Slabs with Voids Slabs 10 and 11 (Figures U.22 through U.26) contained voids at a depth of 8 in. from the surface of the specimens. As reflected in Figure U.22, slab 10 contained several surficial cracks. Comparing Figures U.22a and U22.b, these cracks progressed between 2011 and 2013. The cracks are reflected in the USW results from the traditional and new PSPAs (Fig- ures U.23c and U.24a). The progression of the vertical crack during the 2-year period can be observed in the USW map in (a) Slab view in 2011 (b) Slab view in 2013 Figure U.7. Crack progression on Slab 2 in a two-year period: (a) in 2011 and (b) in 2013.
323 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Time (s) Ac ce ler at io n (m /s2 ) 1st Receiver 2nd Receiver Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Apparent M oduli (ksi) Dom inant Frequency (Hz) (a) Slab 2 (b) Waveform obtained from PSPA at center point (c) Average modulus from USW (d) Dominant frequency from IE (e) USW B-scan along centerline (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Fr eq ue nc y (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Apparent M oduli (ksi) Norm alized Am plitude Figure U.8. Contour maps of acquired results from traditional PSPA for concrete Slab 2 (18-in.-thick intact slab).
324 (a) Average modulus from USW (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.9. Contour maps of acquired results from new PSPA for concrete Slab 2 (18-in.-thick intact slab). Figure U.10. Contour maps of acquired results from traditional PSPA for concrete Slab 3 (12-in.-thick intact slab). (Continued on next page.) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 Ac ce le ra tio n (m /s 2) Time(s) 1st Receiver 2nd Receiver Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Apparent M oduli (ksi) Dom inant Frequency (Hz) (a) Slab 3 (b) Waveform obtained from PSPA at center point (c) Average modulus from USW (d) Dominant frequency from IE
325 0.04 1st Receiver (e) USW B-scan along centerline (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Fr eq ue nc y (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Apparent M oduli (ksi) N orm alized Am plitude Figure U.10. (Continued.) (a) Slab 3 on steel plate (b) Average modulus from USW (c) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.11. Contour maps of acquired results from new PSPA for concrete Slab 3 (12-in.-thick intact slab).
326 (a) Slab 4 (b) Waveform obtained from PSPA at center point 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Ac ce le ra tio n (m /s 2) Time(s) 1st Receiver 2nd Receiver Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Apparent M oduli (ksi) Dom inant Frequency (Hz) (c) Average modulus from USW (d) Dominant frequency from IE (e) USW B-scan along centerline (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Distance from Center (in) Fr eq ue nc y (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Apparent M oduli (ksi) Norm alized Am plitude Figure U.12. Contour maps of acquired results from traditional PSPA for concrete Slab 4 (24-in.-thick intact slab).
327 (b) Waveform obtained from PSPA at center point (c) Average modulus from USW (d) Dominant frequency from IE (a) Slab 5 0 0.5 1 1.5 2 2.5 3 x 10 -3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Ac ce le ra tio n (m /s 2) Time (s) 1st Receiver 2nd Receiver Longitudinal Distance from Center (in.) Tr an sv er se D is ta nc e fro m C en te r ( in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) Longitudinal Distance from Center (in.) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (f) IE Spectral B-scan along centerline(e) USW B-scan along centerline Longitudinal Distance from Center (in.) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) Longitudinal Distance from Center (in.) Fr eq ue nc y (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude Figure U.13. Contour maps of acquired results from traditional PSPA for concrete Slab 5 (24-in.-thick intact slab).
328 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta n ce fr o m Ce n te r (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.14. Contour maps of acquired results from new PSPA for concrete Slab 4 (24-in.-thick intact slab). Figure U.15. Contour maps of acquired results from traditional PSPA for concrete Slab 6 (15-in.-thick intact slab). (Continued on next page.) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.1 -0.05 0 0.05 0.1 0.15 Ac ce le ra tio n (m /s 2) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 6
329 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.16. Contour maps of acquired results from new PSPA for concrete Slab 6 (15-in.-thick intact slab). Figure U.15. (Continued.) Longitudinal Distance from Center (in) D ep th (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (e) USW B-scan along centerline Longitudinal Distance from Center (in) Fr e qu en cy (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude (f) IE Spectral B-scan along centerline
330 (a) Slab 7 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (f) IE Spectral B-Scan along center line Longitudinal Distance from Center (in) Fr eq ue nc y (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 (e) USW B-Scan along center line Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) Figure U.17. Contour maps of acquired results from traditional PSPA for concrete Slab 7 (15 in. thick, delaminated at 2 in.).
331 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 Figure U.18. Contour maps of acquired results from new PSPA for concrete Slab 7 (15 in. thick, delaminated at 2 in.). (a) Slab 8 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 Ac ce le ra tio n (m /s 2) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE Figure U.19. Contour maps of acquired results from traditional PSPA for concrete Slab 8 (15 in. thick, delaminated at 3 in.). (Continued on next page.)
332 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.20. Contour maps of acquired results from new PSPA for concrete Slab 8 (15 in. thick, delaminated at 3 in.). Figure U.19. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu e n c y (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude
333 (a) Slab 9 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -3 -2 -1 0 1 2 3 Ac ce le ra tio n (m /s 2) Time (s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 240 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude Figure U.21. Contour maps of acquired results from traditional PSPA for concrete Slab 9 (15 in. thick, delaminated at 1 in.).
334 (a) Slab view in 2011 (b) Slab view in 2013 Figure U.22. Crack progression on Slab 10 in a 2-year period of testing. (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 10 Figure U.23. Contour maps of acquired results from traditional PSPA for concrete Slab 10 (15 in. thick with air void at 8 in. deep). (Continued on next page.)
335 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.24. Contour maps of acquired results from new PSPA for concrete Slab 10 (15 in. thick with air void at 8 in. deep). Figure U.23. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu e n c y (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude
336 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.25 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 Ac ce le ra tio n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (a) Slab 11 Figure U.25. Contour maps of acquired results from traditional PSPA for concrete Slab 11 (15 in. thick with water void at 8 in. deep).
337 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24-18-12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 3000 3500 4000 4500 5000 5500 6000 6500 Figure U.26. Contour maps of acquired results from new PSPA for concrete Slab 11 (15 in. thick with water void at 8 in. deep). Figure U.24a. The manifestation of the deep void was not readily detectable from the USW results with the traditional or new PSPA (Figures U.23c and U.24a). According to the princi- ples of wave propagation, the detection of voids with USW becomes less effective as the depth of the defect increases. In this case, surface waves propagated along a cylindrical front, and as such, they became less sensitive to horizontal discontinuities with depth. However, the air void was clearly mapped in contour maps of dominant frequency from the IE method with both the tra- ditional and new PSPAs (Figures U.23d and U.24b). The void seems to have propagated beyond the boundaries intended. Similar results can be observed for Slab 11 with the water-filled void in Figures U.25 and U.26 from the traditional and new PSPAs, respectively. Intact Shotcrete Slabs By nature, shotcrete is quite variable in its properties. The tra- ditional and new PSPA results from four intact shot crete slabs with thicknesses of 4 in., 6 in., 8 in., and 12 in. are shown in Figures U.27 through U.33. The thicknesses of the 4-in. and 6-in. slabs could not be ascertained with the IE results from the traditional and new PSPAs because of the sourceâreceiver con- figurations in both PSPAs. The thickness of Slab 3 and Slab 13 (thicknesses of 8 in. and 12 in.) was estimated as 9.8 in. and 13.1 in., respectively, with the traditional PSPA using the prop- erties of concrete and dominant frequency. The new PSPA seems to be more promising in detecting the bottom of Slab 13; the IE method gives an average thickness of 11.5 in. for Slab 13 with the thickness of 12 in. However, the new PSPA could not estimate the thickness of 8 in. for Slab 3 accurately. Unlike the concrete slabs, the reported thicknesses from the traditional and new PSPAs resulted in high standard deviations, making the IE method suitable for only a rough estimation of the thickness of shotcrete. The reason is the rough surface of shotcrete slab that makes a poor contact between the sensors and the surface. The average and standard deviation of the modulus from the traditional and new PSPAs of each intact shotcrete slab are shown in Table U.2. The average moduli varied signifi- cantly among the slabs, and the standard deviation increased (uniformity of construction decreased) as the shotcrete slab became thicker. Generally, the mean average modulus for each slab decreased from 2011 to 2013. Delaminated Shotcrete Slabs Five 12-in.-thick slabs (Slabs 8 through 12) were similar to Slab 13, except that they contained 1-ft-square delaminated zones at depths varying from 8 in. to 1 in. from the top sur- face. Some of the delaminated slabs were selected for investi- gation with the new PSPA. The results from the tested slabs are shown in Figures U.34 through U.41. These slabs exhib- ited nonuniform finishes and contained microcracks (often) and macrocracks in a few cases. By simply comparing the waveforms in Figures U.34b, U.36, U.38, U.39, and U.41 with the time record in Figure U.32b (intact Slab 13), one can conclude that Slabs 8 through 12 were delaminated. The higher amplitude in time records in Figures U.39b and U.41b indicate very shallow delamination. Therefore, the operator could roughly interpret time signals at the time of testing. As reflected in Figures U.34c, U.35a, U.36c, and U.37a, USW results from the traditional and new PSPAs were not as promis- ing in estimating deep delamination as they were in locating shallower ones (Figures U.38 through U.41). However, the 8-in.- deep and 4-in.-deep delaminated zones were clearly detectable
338 (a) Slab 1 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 1500 2000 2500 3000 3500 4000 Apparent M oduli (ksi) (c) Average modulus from USW Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 1500 2000 2500 3000 3500 4000 Apparent M oduli (ksi) (e) USW B-scan along centerline 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.15 -0.1 -0.05 0 0.05 0.1 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 0.5 1 1.5 2 2.5 3x 10 4 Dom inant Frequency (Hz) (d) Dominant frequency from IE Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (f) IE Spectral B-scan along centerline Figure U.27. Contour maps of acquired results from traditional PSPA for shotcrete Slab 1 (4-in.-thick intact slab).
339 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 1500 2000 2500 3000 3500 4000 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.15 -0.1 -0.05 0 0.05 0.1 Ac ce ler at io n (m /s 2) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 4000 6000 8000 10000 12000 14000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 1500 2000 2500 3000 3500 4000 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (a) Slab 2 Figure U.28. Contour maps of acquired results from traditional PSPA for shotcrete Slab 2 (6-in.-thick intact slab).
340 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta n ce fr o m Ce n te r (in ) -16 -12 -8 -4 0 4 8 12 16 -16 -12 -8 -4 0 4 8 12 16 1500 2000 2500 3000 3500 4000 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta n ce fr o m Ce n te r (in ) -16 -12 -8 -4 0 4 8 12 16 -16 -12 -8 -4 0 4 8 12 16 4000 6000 8000 10000 12000 14000 Figure U.29. Contour maps of acquired results from new PSPA for shotcrete Slab 2 (6-in.-thick intact slab). (a) Slab 3 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er s e D is ta n c e fr o m Ce nt e r (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 1500 2000 2500 3000 3500 4000 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 A c c e le ra tio n (m /s 2) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr a n s v e rs e D is ta n c e fr o m Ce n te r (in ) -20 -16 -12 -8 -4 0 4 8 12 16 20 -20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 10000 D om inant Frequency (Hz) (d) Dominant frequency from IE Figure U.30. Contour maps of acquired results from traditional PSPA for shotcrete Slab 3 (8-in.-thick intact slab). (Continued on next page.)
341 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -16 -12 -8 -4 0 4 8 12 16 -16 -12 -8 -4 0 4 8 12 16 1500 2000 2500 3000 3500 4000 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce nt er (in ) -16 -12 -8 -4 0 4 8 12 16 -16 -12 -8 -4 0 4 8 12 16 2000 3000 4000 5000 6000 7000 8000 9000 10000 Figure U.31. Contour maps of acquired results from new PSPA for shotcrete Slab 3 (8-in.-thick intact slab). Figure U.30. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 1500 2000 2500 3000 3500 4000 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu en cy (H z) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude
342 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.025 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -20 -16 -12 -8 -4 0 4 8 12 16 20-20 -16 -12 -8 -4 0 4 8 12 16 20 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -20 -16 -12 -8 -4 0 4 8 12 16 20 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -20 -16 -12 -8 -4 0 4 8 12 16 20 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (a) Slab 13 Figure U.32. Contour maps of acquired results from traditional PSPA for shotcrete Slab 13 (12-in.-thick intact slab).
343 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Figure U-33. Contour maps of acquired results from new PSPA for shotcrete Slab 13 (12-in.-thick intact slab). in the contour maps of the dominant return frequency from the IE method with both the traditional and new PSPAs (Fig- ures U.34d, U.35b, U.36d, and U.37b). The IE results from the new PSPA indicate a more confined area for the 2-in.-deep delamination in Slab 11. The size of detected delamination in Slab 11 with the traditional PSPA was bigger than it was expected to be. Shotcrete Slabs with Voids Slabs 4 through 7 contained different sizes of bags that simu- lated air-filled voids and water-filled voids at different depths. In Slabs 4 and 5, the voids were embedded at a depth of 7.5 in. from the surface and in Slabs 6 and 7 at a depth of 3 in. Slab 6 was tested with the new PSPA. Again, the time signals in Fig- ures U.42b through U.44b are significantly different from the time records of a similar intact slab (Slab 13) in Figure U.33b. As in the case of concrete slabs, the USW method lost its resolving power as the defects were placed deeper. As shown Table U.2. Average and Standard Deviation of Moduli of Intact Shotcrete Slabs Slab USW Modulus (ksi) Traditional PSPA New PSPA Average SD Average SD 1 3,460 386 Not tested Not tested 2 4,178 549 3,440 506 3 3,607 506 3,610 464 13 4,401 684 3,990 777 in Figures U.42c and U.43c, the deep voids were not as readily detectable from the USW results as were the shallower ones with the traditional and new PSPAs, shown in Figures U.44c, U.45b, and U.46c. The deep and shallow voids were mapped in contour maps of the dominant frequency from the IE method with the traditional and new PSPAs (Figures U.42d, U.43d, U.44d, U.45b, and U.46d). The voids in Slabs 6 and 7 were apparently bigger than intended, and they shifted when the slabs were constructed. estimation of Depth of Defects One of the goals of this study was to estimate the depth of defects, especially the shallow ones (less than 4 in.). For severe defects like the ones installed in the TTI slabs, the flexural mode of vibration controls the responses obtained from the IE method. However, as demonstrated in two concurrent SHRP 2 Renewal projects (R06A for concrete and R06C for hot-mix asphalt) the depth-to-defect can be estimated from the USW B-scans. To demonstrate this concept, the USW B-scans from the traditional PSPA for the defective concrete and shotcrete slabs were recontoured, as seen in Figures U.47 through U.48. The recontouring process was needed because, as reflected in Azari et al. (2012), the previous contour maps were optimized to accentuate the existence of the defects. The reported depths of defects are shown with a black solid line in Figures U.47 and U.48. Given the limitation of the minimum depth of investiga- tion of the PSPA (2 in.), the depths of delamination were fairly accurate for Slabs 7, 8, and 9. Figures U.47b and U.47c indicate that the delaminated zone extended beyond the intended areas. As was previously discussed, the predictive power of the USW method diminished with depth. As reflected in Fig- ure U.47d, the quality of the concrete above the 8-in.-deep air
344 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (a) Slab 8 Figure U.34. Contour maps of acquired results from traditional PSPA for shotcrete Slab 8 (12 in. thick, delaminated at 8-in. depth).
345 (a) Average modulus from USW (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta n ce fr o m Ce nt er (in ) -24-18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.35. Contour maps of acquired results from new PSPA for shotcrete Slab 8 (12 in. thick, delaminated at 8-in. depth). (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 9 Figure U.36. Contour maps of acquired results from traditional PSPA for shotcrete Slab 9 (12 in. thick, delaminated at 4-in. depth). (Continued on next page.)
346 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.37. Contour maps of acquired results from new PSPA for shotcrete Slab 9 (12 in. thick, delaminated at 4-in. depth). Figure U.36. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu en cy (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude
347 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.15 -0.1 -0.05 0 0.05 0.1 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (a) Slab 10 Figure U.38. Contour maps of acquired results from traditional PSPA for shotcrete Slab 10 (12 in. thick, delaminated at 3-in. depth).
348 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 Ac ce le ra tio n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-Scan along center line Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-Scan along center line Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude (a) Slab 11 Figure U.39. Contour maps of acquired results from traditional PSPA for shotcrete Slab 11 (12 in. thick, delaminated at 2-in. depth).
349 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta n ce fr o m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m Ce n te r (in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Figure U.40. Contour maps of acquired results from new PSPA for shotcrete Slab 11 (12 in. thick, delaminated at 2-in. depth). (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -3 -2 -1 0 1 2 3 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 12 Figure U.41. Contour maps of acquired results from traditional PSPA for shotcrete Slab 12 (12 in. thick, delaminated at 1-in. depth). (Continued on next page.)
350 Figure U.41. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu en cy (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 4 Figure U.42. Contour maps of acquired results from traditional PSPA for shotcrete Slab 4 (12 in. thick, with air void at 7.5-in. depth). (Continued on next page.)
351 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 5 Figure U.43. Contour maps of acquired results from traditional PSPA for shotcrete Slab 5 (12 in. thick, with water void at 7.5-in. depth). (Continued on next page.) Figure U.42. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue n c y (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude
352 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent M oduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (a) Slab 6 Figure U.44. Contour maps of acquired results from traditional PSPA for shotcrete Slab 6 (12 in. thick, with air void at 3-in. depth). (Continued on next page.) Figure U.43. (Continued.) (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu en cy (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized Am plitude
353 Figure U.44. (Continued.) (b) Dominant frequency from IE Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 (a) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D is ta nc e fro m C en te r ( in) -24-18 -12 -9 -6 -3 0 3 6 9 12 18 24 -18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Figure U.45. Contour maps of acquired results from new PSPA for shotcrete Slab 6 (12 in. thick, with air void at 3-in. depth). (e) USW B-scan along centerline Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr e qu en cy (H z) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized A m plitude
354 (a) Slab 7 (c) Average modulus from USW Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2500 3000 3500 4000 4500 Apparent Moduli (ksi) 0 0.5 1 1.5 2 2.5 3 x 10-3 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 Ac ce ler at io n (m /s2 ) Time(s) 1st Receiver 2nd Receiver (b) Waveform obtained from PSPA at center point Longitudinal Distance from Center (in) Tr an sv er se D ist an ce fr om C en te r ( in ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24-18 -12 -9 -6 -3 0 3 6 9 12 18 2000 3000 4000 5000 6000 7000 8000 9000 Dom inant Frequency (Hz) (d) Dominant frequency from IE (e) USW B-scan along centerline Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (f) IE Spectral B-scan along centerline Longitudinal Distance from Center (in) Fr eq ue nc y ( Hz ) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Norm alized Am plitude Figure U.46. Contour maps of acquired results from traditional PSPA for shotcrete Slab 7 (12 in. thick, with water void at 3-in. depth).
355 De pt h (in .) (a) Slab 7 (delamination at 2-inch depth) Longitudinal Distance from Center (in) -20 -16 -12 -8 -4 0 4 8 12 16 20 2 3 4 5 6 7 8 9 10 11 12 (c) Slab 9 (delamination at 1-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 3 4 5 6 7 8 9 10 11 12 2 (b) Slab 8 (delamination at 3-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (d) Slab 10 (air void at 8-inch depth with surficial cracks) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) (e) Slab 11 (water void at 8-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi) Figure U.47. USW B-scan along centerline for concrete slabs.
356 (a) Slab 4 (air void at 7.5-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 (c) Slab 6 (air void at 3-inch depth with surficial cracks) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 (b) Slab 5 (water void at 7.5-inch depth with surficial cracks) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 1500 2000 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (d) Slab 7 (water void at 3-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 1500 2000 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (e) Slab 8 (delamination at 8-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 (f) Slab 9 (delamination at 4-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 1500 2000 2500 3000 3500 4000 4500 Apparent M oduli (ksi) Figure U.48. USW B-scan along centerline for shotcrete slabs. (Continued on next page.)
357 (g) Slab 10 (delamination at 3-inch depth) Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 (h) Slab 11 (delamination at 2-inch depth) Longitudinal Distance from Center (in) D ep th (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 1500 2000 2500 3000 3500 4000 4500 Apparent M oduli (ksi) (i) Slab 12 (delamination at 3-inch depth) Longitudinal Distance from Center (in) De pt h (in .) -24 -18 -12 -9 -6 -3 0 3 6 9 12 18 24 2 3 4 5 6 7 8 9 10 11 12 1500 2000 2500 3000 3500 4000 4500 Apparent M oduli (ksi) Figure U.48. (Continued.) void was quite low, manifesting as severe cracking on the slab surface (see Figure U.23). The manifestation of the water- filled void at the same depth in Slab 11 could be detected; however, once again the quality of the concrete above that void was lower than the intact areas. Similar results were obtained in the defective shotcrete slabs in Figure U.48. The depths of the defects could be quantitatively estimated from the new B-scans only in an approximate fashion. However, the USW B-scans provided information about the change in quality of concrete placed after the installation of the defects. That is why the indication of defect (lower modulus) in some of the slabs started a few inches above the top of the defects. references Azari, H., D. Yuan, S. Nazarian, and N. Gucunski. 2012. Impact of Test- ing Configuration and Data Analysis Approach on Detection of Delamination in Concrete Bridge Deck with Sonic Methods. In Transportation Research Record: Journal of Transportation Research Board, No. 22292, Transportation Research Board of the National Academies, Washington, D.C., pp. 113â124. Carino, N. J., M. Sansalone, and N. N. Hsu. 1986. A Point SourceâPoint Receiver, Pulse-Echo Technique for Flaw Detection in Concrete. ACI Material Journal, Vol. 83, No. 2, pp. 199â208. Gucunski, N., and A. Maher. 1998. Bridge Deck Condition Monitoring by Impact Echo Method. Proc., International Conference MATEST â98âLife Extension, Brijuni, Croatia, pp. 39â45.
