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42 Table 19. Success rates for identifying the physical differences of the HMA mixtures within a project. NDT Device PSPA PQI GPR FWD Success Rate, % 93 71 54 56 areas where the hypothesis was incorrectly rejected. Another modulus is used for all HMA layers. None of the NDT devices difference that was found but not planned (so it was excluded accurately predicted the modulus values that were measured in from Table 18) was the difference between the initial and the laboratory for the unbound materials and HMA mixtures supplemental sections of the US-280 project (see Chapter 5 (see Figures 17-1 and 17-2). All of the modulus estimating of NCHRP Web-Only Document 133). All NDT devices found NDT devices, however, did show a trend of increasing mod- a significant difference between these two areas--the supple- uli with increasing laboratory measured moduli. The follow- mental section had the higher dynamic modulus, which was ing subsections describe the use of adjustment factors for confirmed with laboratory dynamic modulus tests. Both the confirming the assumptions used for structural design. PSPA and FWD resulted in higher modulus values and the GPR estimated lower air voids, but the PQI resulted in much 2.2.1 Unbound Layers lower densities. The PSPA did identify all but one of the areas with anom- It has been previously reported that layer moduli calculated alies or differences. The non-nuclear density gauge did a rea- from deflection basins must be adjusted (multiplied) by a sonable job, while the GPR and FWD only identified slightly factor for pavement structural design procedures that are more than 50 percent of the areas with differences. The GPR, based on laboratory derived values at the same stress state however, did measure the HMA lift thickness placed, which (AASHTO 1993; Von Quintus and Killingsworth 1998). In was confirmed through field cores. Table 19 contains the suc- the 1993 AASHTO Pavement Design Manual, the adjustment cess rates for identifying the physical differences of the HMA factor is referred to as the "C-factor," and the value recom- mixtures within a project. mended for use is 0.33. Thus, there are differences between The PSPA had an excellent success rate, while the PQI had the field and laboratory conditions that can cause significant an acceptable rate. The GPR and FWD had lower rates that are bias when using NDT modulus values. considered unacceptable. Some of the important differences Von Quintus and Killingsworth found that this adjustment observed between the technologies and devices and the reasons factor was structure or layer dependent but not material type for the lower success rates of the GPR and FWD are listed dependent. Adjustment factors were determined for different as follows: types of structures. The C-factor found for embankment or subgrade soils ranged from 0.35 to 0.75 and averaged 0.62 for The FWD is believed to have been influenced by the sup- aggregate base materials. However, none of the deflection porting layers creating noise and additional variability basins measured in this study was measured on the surface making it more difficult to identify the localized areas. In of the unbound layers themselves. Conversely, all testing addition, its loading plate probably bridged some of the under this study was directly on the surface of the layer being localized anomalies making it difficult to detect differences evaluated. near the surface of the layer evaluated (e.g., segregation). To compensate for differences between the laboratory and The dielectric values measured by the GPR are minimally field conditions, an adjustment procedure was used to estimate affected by some of the properties that can change within the laboratory resilient modulus from the different NDT a project, and its success is heavily dependent on the num- technologies for making relative comparisons. The adjustment ber of cores taken for calibration purposes--similar to that procedure assumes that the NDT response and modulus of for unbound materials. laboratory prepared test specimens are directly related and In summary, the PSPA and non-nuclear density gauges proportional to changes in density and water content of the (PQI) are considered acceptable in identifying localized dif- material. Figures 18, 19, and 20 compare the seismic (PSPA) ferences in the physical condition of HMA mixtures. modulus measured on the samples used in preparing an M-D relationship. The PSPA modulus-water content relationship follows the M-D relationship. Thus, the assumption is believed 2.2 Estimating Target to be valid. Modulus Values For simplicity, the adjustment factors were derived using Laboratory measured modulus of a material is an input the same methodology within the FHWA-LTPP study, with parameter for all layers in the MEPDG. Resilient modulus is the exception that a constant, low stress state was used to the input for unbound layers and soils, while the dynamic determine the adjustment factor. In other words, the average

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43 DSPA, Fine-Grained DSPA, Coarse-Grained Line of Equality Geo., Fine-Grained Geo., Coarse-Grained 200 Elastic Modulus from NDT 150 Devices, ksi 100 50 0 0 10 20 30 40 50 60 Laboratory Resilient Modulus, ksi (a) DSPA and the GeoGauge. LWD, Fine-Grained LWD, Coarse-Grained DCP, Fine-Grained DCP, Coarse-Grained Line of Equality 60 Elastic Modulus from NDT 50 Devices, ksi 40 30 20 10 0 0 10 20 30 40 50 60 Laboratory Resilient Modulus, ksi (b) Deflection-Based and DCP methods. Figure 17-1. Comparison of laboratory resilient modulus and the elastic modulus values estimated with different NDT technologies and devices. Line of Equality FWD Modulus Line of Equality FWD Modulus PSPA Modulus - Part A PSPA Modulus - Part B PSPA Modulus - Part A PSPA Modulus - Part B NDT Estimated Modulus, NDT Estimated Modulus, 2000 900 800 1500 700 600 ksi ksi 1000 500 400 500 300 200 0 100 0 500 1000 1500 2000 100 200 300 400 500 600 700 800 900 Laboratory Measured Dynamic Modulus (In-Place Laboratory Measured Dynamic Modulus (In-Place Temperature and 5 Hz.), ksi Temperature and 5 Hz.), ksi (a) Entire data set. (b) Excludes data point for very stiff HMA mixture placed along SH-130. Figure 17-2. Comparison of laboratory dynamic modulus and the elastic modulus values estimated with differ- ent NDT technologies and devices.

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44 Seismic Modulus, ksi Dry Density, pcfi Poly. (Seismic Modulus, ksi) Poly. (Dry Density, pcfi) 116 90 114 80 Seismic Modulus, ksi 70 Dry Density, pcf 112 60 110 50 108 40 106 30 104 20 102 10 100 0 8.5 10 12 14.5 16 18 20 Moisture Content, I-85 Embankment, percent Figure 18. Comparison of the PSPA modulus to the M-D relationship for the I-85 low plasticity soil embankment. Dry Density Seismic Modulus Poly. (Seismic Modulus) Poly. (Dry Density) 128 100 90 Seismic Modulus, kis 126 80 Dry Density, pcf 124 70 122 60 50 120 40 118 30 20 116 10 114 0 7.5 8.5 9.6 10.5 12 13 14 15 16 Moisture Content, SH-130 Embankment, percent Figure 19. Comparison of the PSPA modulus to the M-D relationship for the SH-130 improved granular embankment. Dry Density Seismic Modulus Poly. (Seismic Modulus) Poly. (Dry Density) 131 140 130.5 Seismic Modulus, ksi 120 Dry Density, pcf 130 100 129.5 80 129 60 128.5 128 40 127.5 20 127 0 3.8 4.8 5.8 7 8 9 10 Moisture Content, US-280 Crushed Stone, percent Figure 20. Comparison of the PSPA modulus to the M-D relationship for the US-280 crushed stone base.

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45 Table 20. Adjustment factors or ratios applied to the NDT modulus values to represent laboratory conditions or values at low stress states; Part A projects. Percent of Ratio or Adjustment Factor Percent Project Material Optimum Compaction Geo. DSPA DCP LWD Moisture I-85 Low Plasticity Clay 91 165 0.19 0.087 0.53 0.39 Embankment TH-23 Silt-Sand-Gravel 100 132 0.90 0.41 0.95 3.13 Embankment Mix SH-21 High Plasticity Clay 99 84 1.16 0.99 2.94 2.78 Subgrade TH-23 Base Crushed Aggregate 104 55 0.71 0.30 0.68 1.69 SH-130 Improved Granular 105 101 1.39 1.04 1.67 1.43 Embankment Mix US-280 Base Crushed Stone 101 52 1.01 0.24 0.96 1.04 The adjustment ratio or factor was determined by dividing the average resilient modulus measured in the laboratory by the average modulus from the NDT device (for a specific stress state, see Table 21). laboratory measured modulus (triplicate repeated load resilient oratory (see Tables 21 and 22) for the Part A field evaluation modulus tests were performed) was divided by the average projects. moduli estimated with each NDT device. The adjustment factors do not appear to be related to the Table 20 contains the adjustment factors equating the percent compaction, percent of optimum water content, or NDT moduli to the resilient modulus measured in the lab- material type. The adjustment factors for the deflection-based Table 21. Average repeated load resilient modulus values measured in the laboratory at a specific stress state. Percent Laboratory Project & Dry Moisture Area Maximum Resilient Materials Density, pcf Content, % Density, % Modulus, ksi Before IC Section 1, I-85 Low 103.0 21.6 0.91 2.5 Rolling Lanes B,C,D Plasticity Clay After IC Section 1, Embankment 108.0 16.9 0.96 4.0 Rolling Lanes B,C,D NCAT; Oklahoma High Plasticity Clay 96.7 21.3 0.97 6.9 NCAT; South Carolina Crushed Granite Base 130.0 4.7 0.94 14.3 TH-23 South Lanes A,B 121.0 8.2 0.98 16.0 Embankment, Section Silt-Sand- North Lane B,C 122.4 9.1 1.00 16.4 Gravel Mix Section US-2 Embankment; Soil-Aggregate Mix 123.1 12.1 0.96 19.0 NCAT; Missouri Crushed Limestone Base 124.4 9.0 0.96 19.2 SH-21 High Area 1, with Lanes A,B 107.3 18.4 0.99 26.8 Plasticity Clay IC rolling TH-23 Crushed Middle Area Lane B 139.4 4.3 1.04 24.0 Aggregate Base South Area All Lanes 141.1 4.2 1.03 24.6 US-53 Crushed Aggregate Base, Type 304 136.0 9.1 1.01 27.5 NCAT; Florida Limerock Base 110.5 13.4 0.95 28.6 US-2 Class 5 Crushed Aggregate Base 134.4 5.9 0.95 32.4 SH-130 Improved Sections 2, 3 Lanes A,B 128.7 9.1 1.05 35.3 Granular US-280 Areas 1,2,3 150.6 3.2 1.01 48.4 Crushed Stone NOTES: Resilient modulus values for the fine-grained soils and embankments are for a low confining pressure (2 psi) and repeated stress of 4 psi, while a confining pressure of 6 psi and repeated stress of 6 psi was used for the granular base materials. These low stress conditions are not based on any theoretical analysis. One stress state for the embankment soils and one for aggregate base layers were selected for consistency in comparing the field estimated elastic modulus values from each NDT device to values measured in the laboratory, which were considered the target values. Percent maximum density is based on the maximum dry unit weight or density from the moisture-density relationship (the maximum dry densities are included in Table 23 for each material tested).

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46 Table 22. Elastic modulus values estimated from the NDT technologies and devices, without adjustments, in comparison to resilient modulus values measured in the laboratory. Project Material Area Modulus, ksi Lab.* GeoGauge DSPA DCP LWD I-85 Low Section 2, Lane A 2.2 10.6 24.1 5.0 --- Embankment Plasticity Section 1, All Lanes 2.5 15.4 30.0 5.9 --- Before IC Clay Section 2, Lanes B, Rolling 2.5 17.0 36.6 5.2 --- C, D I-85 Low Section 1 4.0 16.8 30.4 6.9 9.99 Embankment Plasticity After IC Clay Section 2 4.5 19.0 40.4 6.2 11.78 Rolling So. Section, Lane C 15.0 13.2 31.1 11.5 5.6 TH-23 Silt-Sand- So. Sect., Lanes A,B 16.0 18.3 43.6 15.2 5.7 Embankment Gravel Mix No. Sect., Lanes B,C 16.4 17.8 35.7 19.0 4.7 No. Sect., Lane A 17.0 22.0 51.7 18.5 4.7 SH-21 High Plasticity No IC Rolling 22.0 19.6 23.6 11.9 --- Subgrade Clay After IC Rolling 26.8 22.9 27.1 8.8 9.6 Middle Sect., Lane C 19.5 21.6 28.0 18.6 8.0 Crushed North Section, All TH-23 Base Aggregate Lanes; Middle 24.6 28.2 79.3 33.1 12.3 Base Section Lanes A, B South Section, Lanes 26.0 33.0 110.7 46.4 19.4 A, B SH-130 Section 3 34.5 19.4 33.3 20.7 24.1 Improved Granular Sections 1, 2 35.3 26.4 34.3 21.3 24.6 Embankment US-280 Base Crushed Area 4 40.0 35.1 117.4 34.3 18.5 Stone Areas 1, 2, 3 48.4 47.9 198.6 50.3 46.5 NOTES: * The repeated load resilient modulus values measured in the laboratory, but corrected to the actual dry density and moisture content measured for the specific section, in accordance with the LTPP procedure and regression equations. devices are approximately the inverse of the values reported ues, with the exception of the fine-grained, clay soils. The from the FHWA-LTPP study. Thus, the adjustment factors GeoGauge deviated significantly from the laboratory values derived from testing on bound pavement surfaces should for the fine-grained soils. The results also show that both the not be used when testing directly on the unbound layer being GeoGauge and DCP over- or under-predicted the laboratory evaluated. measured values for the same material, with a few exceptions. Another important observation from the Part A projects is These ratios were compared to the percent compaction, per- that the adjustment factors for all NDT devices for the I-85 low cent of optimum water content, and material type, but no rela- plasticity clay embankment prior to IC rolling are significantly tionship could be found. The GeoGauge and DSPA adjustment lower than for any of the other materials. This observation sug- ratios appear to be related to the amount of fines in the mate- gests that the resilient moduli measured in the laboratory are rial (percent passing number 200 sieve), as shown in Figure 21. much lower than for any of the other soils and materials. The In summary, the GeoGauge can be used to estimate the reason for the low values is unknown. This embankment soil resilient modulus measured in the laboratory for aggregate had the lowest dry density and highest water content relative to base materials and coarse-graded soil-aggregate embankments, its maximum dry density and optimum water content also see while the DCP provided a closer estimate for the fine-grained Table 23). However, these data were excluded from developing soils. However, the ratios for both of these devices were the adjustment factors and selection of an NDT device that can variable--even within the same soil or material group. The be used to confirm the structural design parameters because DSPA resulted in a positive bias (over-predicted the laboratory they were consistent across all NDT devices. resilient modulus) with variable ratios. It is suggested that Table 24 contains the adjustment factors for all projects repeated load resilient modulus tests be performed to deter- included in the field evaluation (Parts A and B). The LWD is mine the target or design value and that those results be used not included in Table 24 because it was excluded from the to calibrate the NDT devices for a specific soil or aggregate Part B projects. On average, the GeoGauge and DCP pro- base, because of the variability of these ratios. The resilient vided a reasonable estimate to the laboratory measured val- modulus test should be performed on bulk material sampled

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47 Table 23. Maximum dry density and optimum water content for the unbound materials and soils, as compared to the average test results from the EDG. Maximum Optimum Average Average Dry Project Material Dry Unit Water Water Density, pcf Weight, pcf Content, % Content, % NCAT, High Plasticity Clay 99.9 21.8 96.7 21.3 Oklahoma SH-21, High Plasticity Clay 108.0 21.9 107.3 18.4 TX Low Plasticity Soil; Pre-IC 107.98 16.9 I-85, AL 112.7 13.1 Low Plasticity Soil; Post-IC 107.98 16.9 SH-130, Improved Granular 122.0 9 123.3 8.32 TX Embankment Silt-Sand-Gravel Mix 122.77 8.69 TH-23, South Area 122.6 12 MN Silt-Sand-Gravel Mix 123.80 7.87 North Area Soil-Aggregate, US-2, ND 128.0 9.0 123.1 12.1 Embankment NCAT, Limerock Base 116.1 12.5 110.5 13.4 FL CR-103 Caliche Base 127.5 10.0 125.0 9.5 NCAT, Crushed Limestone 130.0 10.0 124.4 9.0 MO TH-23, Crushed Aggregate Base 135.3 7.8 129.82 4.3 MN US-53, Crushed Aggregate Base 134.1 8.5 136.0 9.1 OH NCAT, Crushed Granite Base 138.1 5.0 130.0 4.7 SC US-2, ND Crushed Gravel Base 141.1 6.0 134.4 5.9 US-280, Crushed Stone Base 148.5 6.2 147.58 3.9 AL NOTE: The maximum dry density and optimum water content for most of the materials and layers were determined using AASHTO T 180. The exception is the high plasticity clay from the Texas project and the North Dakota embankment material. from the stockpiles or the roadway during construction 1,2,3 = Principal stress, psi. (control strips). k1,2,3 = Regression constants from laboratory resilient mod- Most state agencies do not have a resilient modulus test- ulus test results. ing capability, so other procedures will need to be used to establish the design or target value during construction The k regression constants are material specific. The fol- (Darter et al. 1997). The resilient modulus was calculated at lowing defines the regression constants for the different the same stress state shown in Table 21 using the regression materials that were tested within the field evaluation proj- equations that were developed from an FHWA-LTPP study ects. These relationships for these regression constants were (Yau and Von Quintus). The following regression equations developed from the FHWA-LTPP study (Von Quintus and were used: Killingsworth). k k3 oct 2 Crushed Stone Base Materials M R = k1 ( pa ) + 1 (1) pa pa k1 = 0.7632 + 0.008 ( P3 8 ) + 0.0088(LL) - 0.037 ( w s ) Where: - 0.0001( dry ) (4) = Bulk Stress, psi = 1 + 2 + 3 (2) k2 = 2.2159 - 0.0016 ( P3 8 ) + 0.0008(LL) - 0.038 ( w s ) = Octahedral shear stress, psi dry 2 - 0.0006 ( dry ) + 0.00000024 (5) = ( ( 1 - 2 )2 + ( 2 - 3 )2 + ( 3 - 1 ) ) 2 0.5 (3) P#40 3 pa = Atmospheric pressure, 14.7 psi k3 = -1.1720 - 0.0082(LL) - 0.0014 ( w s ) + 0.0005 dry (6)

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48 Table 24. Adjustment factors applied to the NDT modulus values to represent laboratory conditions or values at low stress states, all projects. Adjustment Factors Relating Resilient Modulus, ksi Laboratory Values to NDT Values Project Identification Laboratory Predicted Measured with LTPP Geo Gauge DSPA DCP Value Equations Fine-Grained Clay Soils I-85 Low- Before IC Rolling 2.5 10.5 0.154 .0751 0.446 Plastic Soil After IC Rolling 4.0 13.1 0.223 0.113 0.606 NCAT; OK High Plastic Clay 6.9 19.7 0.266 0.166 0.802 SH-21, TX High Plastic Clay 26.8 19.6 1.170 0.989 3.045 Average Ratios for Fine-Grained Soil 0.454 0.336 1.225 Embankment Materials; Soil-Aggregate Mixture South Embankment 16.0 15.7 0.696 0.367 1.053 TH-23, MN North Embankment 16.4 16.3 0.735 0.459 0.863 US-2, ND Embankment 19.0 19.5 1.450 0.574 0.856 SH-130, TX Improved Soil 35.3 21.9 1.337 1.029 1.657 Average Ratios for Soil-Aggregate Mixtures; Embankments 1.055 0.607 1.107 Aggregate Base Materials Co. 103, TX Caliche Base --- 32.3 1.214 --- 1.436 NCAT, SC Crushed Granite 14.3 36.1 0.947 0.156 --- NCAT, MO Crushed Limestone 19.2 40.9 0.747 0.198 --- Crushed Stone, Middle 24.0 29.9 0.851 0.303 0.725 TH-23, MN Crushed Stone, South 26.0 35.6 0.788 0.235 0.560 US-53, OH Crushed Stone 27.5 38.3 1.170 0.449 0.862 NCAT, FL Limerock 28.6 28.1 0.574 0.324 0.619 US-2, ND Crushed Aggregate 32.4 39.8 1.884 0.623 1.129 US-280, AL Crushed Stone 48.4 49.3 1.010 0.244 0.962 Average Ratios for Aggregate Base Materials 1.021 0.316 0.899 Overall Average Values 0.942 0.422 1.084 NOTES: 1. The adjustment ratio is determined by dividing the resilient modulus measured in the laboratory at a specific stress state by the NDT estimated modulus. 2. The average ratios listed exclude the data from the I-85 low plasticity clay prior to IC rolling. The resilient modulus regression equations are provided in Equations 1 through 15. Embankments, Soil-Aggregate Mixture, Coarse- -Grained dry k3 = 0.9303 + 0.0293( P3 8 ) + 0.0036(LL) - 3.8903 (12) k1 = 0.5856 + 0.0130 ( P3 8 ) - 0.0174 ( P#4 ) + 0.0027 ( P#200 ) Max + 0.0149(PI ) + 0.0000016 ( max ) - 0.0426 ( w s ) Fine-Grained Clay Soil dry w 2Max k1 = 1.3577 + 0.0106 (Clay ) - 0.0437 ( w s ) (13) + 1.6456 + 0.3932 s - 0.00000082 (7) Max w Max x P#40 k2 = 0.5193 - 0.0073( P#4 ) + 0.0095 ( P#40 ) - 0.0027 ( P#2 200 ) k2 = 0.7833 - 0.0060 ( P#200 ) - 0.0081(PI ) + 0.0001( Max ) - 0.0030(LL) - 0.0049 ( w s ) (14) ws dry 2 k3 = 1.4258 - 0.0288 ( P#4 ) + 0.0303( P#40 ) - 0.0521( P#2 200 ) - 0.1483 + 0.00000027 (8) w opt P#40 + 0.025(Silt ) + 0.0535(LL) - 0.0672 ( w opt ) opt 2 ws k3 = -0.1906 - 0.0026 ( P#200 ) + 0.00000081 (9) - 0.0026 ( max ) + 0.0025 ( dry ) - 0.6055 P#40 w opt (15) Embankments, Soil-Aggregate Mixture,Fine-Gr rained Figure 22 compares the laboratory measured resilient k1 = 0.7668 + 0.0051( P#40 ) + 0.0128 ( P#200 ) + 0.0030(LL) modulus values and those calculated from the regression equations (see Table 24). Use of the regression equations, on dry average, resulted in a reasonable prediction of the labora- - 0.051( w opt ) + 1.179 (10) Max tory measured values. Yau and Von Quintus, however, reported that the regression equations can result in significant dry k2 = 0.4951 - 0.0141( P#4 ) - 0.0061( P#200 ) + 1.3941 (11) error and recommended that repeated load resilient modulus Max tests be performed.

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49 Fine-Grained Soil Aggregate-Soil Mixture Crushed Aggregate Base 2 Adjustment Ratio for 1.5 GeoGauge 1 0.5 0 0 20 40 60 80 100 Percent Passing Number 200 Sieve, % (a) GeoGauge. Fine-Grained Soil Soil-Aggregate Mixture Crushed Aggregate Base 1.2 Adjustment Ratio for 1 0.8 DSPA 0.6 0.4 0.2 0 0 20 40 60 80 100 Percent Passing Number 200 Sieve, % (b) DSPA. Figure 21. Effect of the amount of fines on the adjustment ratio for the GeoGauge and DSPA devices. 2.2.2 HMA Layers used to estimate the modulus values from the PSPA and FWD for making relative comparisons. This field adjustment pro- Table 25 lists the laboratory dynamic moduli measured at cedure is the same as that used for the unbound materials. a loading frequency of 5.0 Hz for the in-place average mixture The adjustment ratios were determined for the areas without temperature measured during NDT. As for the unbound any anomalies or physical differences from the target proper- materials, it is expected that the modulus values determined ties and are given in Table 26. from the deflection-based methods are affected by the sup- The PSPA adjustment ratios were found to be relatively close porting materials. To compensate for differences between the to unity, with the exception of the I-35/SH-130 HMA base laboratory and field conditions, an adjustment procedure was mixture. This HMA base mixture is a very stiff mixture in the Resilient Modulus Calculated 50 from LTPP Equations, ksi Line of Equality 40 Fine-Grained Soils 30 20 Embankment Soils; Coarse-Grained 10 Granular Base 0 0 10 20 30 40 50 Resilient Modulus Measured in Laboratory, ksi Figure 22. Comparison of the resilient modulus values measured in the laboratory to the resilient modulus values predicted with the LTPP regression equations.

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50 Table 25. Elastic modulus values estimated from NDT devices, without any adjustments, in comparison to dynamic modulus values measured in the laboratory. Laboratory Values, ksi NDT Values, ksi Project In Place Part Layer/Mixture 130 F & 5 Identification Temp. & 5 PSPA FWD Hz Hz B I-75, Michigan Dense-Graded; Type 3-C 190 400 435.2 --- B NCAT, Florida Base, Mix; PG67 203 390 447.1 --- NCAT, S. B Base Mix; PG67 214 410 495.2 --- Carolina Fine-Graded Surface; Type B I-75, Michigan 255 590 676.3 --- E10 A I-85, Alabama SMA Mixture 230 250 237 450 45% RAP; Sect. E-5, B NCAT, Alabama 250 450 510.7 --- PG67 B US-47, Missouri Fine-Graded Surface 276 530 457.6 --- TH-23, A HMA Base Mixture 319 810 480 --- Minnesota US-280, A HMA Base; Initial Area 330 650 462 165 Alabama B US-47, Missouri Coarse-Graded Base 344 420 605.3 --- Coarse-Graded Base; B US-2, N. Dakota 356 510 344.3 --- PG58-28 B NCAT, Florida Base Mix, SBS, PG76 366 590 475.8 --- 45% RAP, Sect. E-7; B NCAT, Alabama 421 610 444.3 --- PG76 (Sasobit) 45% RAP, Sect. E-6; B NCAT, Alabama 427 640 473.4 --- PG76 (SBS) B US-53, Ohio Coarse-graded Binder Mix 479 850 666.7 --- B I-20, Texas HMA Base, CMHB 520 340 435.5 --- US-280, HMA Base; Supplemental A 613 780 558 310 Alabama Area A SH-130, Texas HMA Base 965 1,750 342 725 Table 26. Dynamic modulus values measured in the laboratory and adjustment factors for the modulus estimating NDT devices. Dynamic Ratio or Adjustment Factor Project/Mixture Modulus, ksi PSPA FWD I-85 AL, SMA Overlay 250 1.055 0.556 TH-23 MN, HMA Base 810 1.688 NA US-280 AL, HMA Base; Initial Area 650 1.407 3.939 US-280 AL, HMA Base; Supplemental Area 780 1.398 2.516 I-35/SH-130 TX, HMA Base 1,750 5.117 3.253 I-75 MI, Dense-Graded Type 3-C 400 0.919 NA I-75 MI, Dense-Graded Type E-10 590 0.756 NA US-47 MO, Fine-Graded Surface 530 1.158 NA US-47 MO, Coarse-Graded Base Mix 420 0.694 NA I-20 TX, HMA Base, CMHB 340 0.799 NA US-53 OH, Coarse-Graded Base 850 1.275 NA US-2 ND, Coarse-Graded Base, PG58-28 510 1.482 NA NCAT SC, PG67 Base Mix 410 0.828 NA NCAT FL, PG67 Base Mix 390 0.872 NA NCAT FL, PG76 Base Mix 590 1.240 NA NCAT AL, PG76 with RAP and Sasobit 610 1.3760 NA NCAT AL, PG76 with RAP and SBS 640 1.352 NA NCAT AL, PG67 with RAP 450 0.881 NA Overall Average Ratio or Adjustment Factor 1.128 2.566 NOTES: 1. The adjustment factor or ratio was determined by dividing the dynamic modulus measured in the laboratory for the in-place temperature at a loading frequency of 5 Hz by the modulus estimated with the NDT device. 2. The laboratory dynamic modulus values listed are for a test temperature of a loading frequency of 5 Hz at the temperature of the mixture when the NDT was performed (see Table 25). 3. The overall average adjustment factor excludes the SH-130 mixture (shaded in the table) because it was found to be significantly different than any other mixture tested.