Determination of Creep Compliance and Tensile Strength of Hot-Mix ...

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In general, the Poisson’s ratio values in Table 10 increase with increasingtemperature. However, there are four instances that do not follow this trend. Also,Poisson’s ratio decreases with increasing % air voids at -20°C, but it does notalways follow this trend at the higher temperatures.Tensile StrengthAll of the IDT strength testing as outlined in a previous section of this report wascompleted successfully. Summaries of the tensile strength results for the noninstrumentedtesting at -10°C, the instrumented testing at 21.1°C, the instrumentedtesting at 4.4°C, the instrumented testing at -10°C, and all testing at -10°C are givenin Tables 11 – 15, respectively. More detailed tables are given in Appendix B.Table 11: Non-instrumented Tensile Strength: -10°CMix ID Number ofReplicatesAverage AirVoids (%)S t(psi)SD*(psi)CV**(%)Equation 1Correction (psi)07-123 6 6.5 612 87.2 14.2 51506-105 3 6.5 616 18.2 3.0 51906-84 3 4.0 738 22.9 3.1 61406-84 3 6.5 620 24.4 3.9 52206-84 3 9.0 525 22.7 4.3 44706-101 3 4.0 841 42.8 5.1 69406-101 3 6.5 663 16.1 2.4 55506-101 3 9.0 601 12.8 2.1 50706-125 3 4.0 696 31.1 4.5 58106-125 3 6.5 623 10.0 1.6 52406-125 3 9.0 532 11.2 2.1 45306-150 3 4.0 786 48.8 6.2 65106-150 3 6.5 674 30.3 4.5 56406-150 3 9.0 599 21.1 3.5 505*Sample standard deviation**Sample coefficient of variationTable 11 shows the expected trend of tensile strength as a function of % air voids:the strength decreases with increasing voids. The strength values for mixescompacted to 6.5% voids are fairly consistent ranging from 612 to 674 psi. Mix 07-123 (BP1) shows a highly variable tensile strength which is not too surprising as it isthe lowest quality mix with the highest percentage of RAP (20%). Also, rememberthat there were two rounds of creep testing on 07-123 which is why 6 specimenswere tested for non-instrumented IDT strength. Also included in Table 11 are valuescalculated using Equation 1, the equation presented in the NCHRP 530 Report thatpurportedly corrects IDT strength test results to true tensile strength.29
Table 12: Instrumented Tensile Strength: 21.1°CMix ID No. Replicates Average Air Voids (%) S t (psi) SD (psi) CV (%)06-84 3 4.0 195 9.1 4.706-84 3 6.5 166 11.9 7.206-84 3 9.1 140 7.4 5.306-101 3 4.0 225 13.3 5.906-101 3 6.5 226 10.6 4.706-101 3 9.0 171 11.3 6.606-125 3 4.1 158 8.0 5.106-125 3 6.5 135 9.0 6.706-125 3 9.0 130 6.1 4.706-150 3 4.1 184 5.0 2.706-150 3 6.8 153 1.9 1.206-150 3 9.0 132 5.7 4.3Table 12 shows one anomaly in that the 06-101 mix IDT strength did not varybetween 4.0 and 6.5% air voids. This could be due to the fact that 06-101 uses ahighly modified binder, PG76-22. However, this anomaly could also be due tovariability among the replicates, as indicated by the statistics which show high CVvalues across all three levels of air voids.Table 13: Instrumented Tensile Strength: 4.4°CMix ID No. Replicates Average Air Voids (%) S t (psi) SD (psi) CV (%)06-84 3 4.0 460 18.8 4.106-84 3 6.5 419 23.2 5.506-84 3 9.0 341 3.0 0.906-101 3 4.0 543 27.0 5.006-101 3 6.4 492 22.6 4.606-101 3 9.0 401 28.5 7.106-125 3 4.1 465 5.8 1.206-125 3 6.4 380 18.0 4.706-125 3 9.0 335 3.9 1.206-150 3 4.1 520 21.9 4.206-150 3 6.8 438 16.5 3.806-150 3 9.0 388 17.0 4.4Table 13 shows the expected trend of decreasing IDT strength with increasing voids.The 06-101 mix again shows consistently higher variability among the replicates ofall mixes in Table 13 at all levels of air voids.30
Page 1 and 2: • • • • • • • • •
Page 3 and 4: TECHNICAL REPORT DOCUMENTATION PAGE
Page 5 and 6: TABLE OF CONTENTSACKNOWLEDGEMENTS .
Page 7 and 8: LIST OF FIGURESFigure 1: Test Equip
Page 9 and 10: LIST OF TABLESTable 1: HMA Mixes an
Page 11 and 12: OBJECTIVESThe objective of this pro
Page 13 and 14: voids generally describes the avera
Page 15 and 16: Figure 1: Test Equipment SetupCreep
Page 17 and 18: and level of % air voids. Although
Page 19 and 20: specimen is actually at the test te
Page 21 and 22: same four mixes but at 4.4°C (40°
Page 23 and 24: n Dn PNormalization Constant = ×
Page 25 and 26: where:0.05 ≤ ν ≤ 0.50Tensile S
Page 27 and 28: Table 4: Creep Compliance: 06-101 (
Page 29 and 30: 0.10Creep Compliance (1/GPa)07-123
Page 31 and 32: as it pertains to creep compliance,
Page 33 and 34: However, published documentation of
Page 35 and 36: Getting back to the issue of the er
Page 37: 0.090Creep Compliance @ 100 sec. @
Page 41 and 42: Table 15: All Tensile Strength: -10
Page 43 and 44: 100090080006-101Virgin binder = PG7
Page 45 and 46: Tensile Failure StrainThe tensile f
Page 47 and 48: Table 18: Tensile Failure Strain: -
Page 49 and 50: CONCLUSIONSExpected trends such as
Page 51 and 52: REFERENCES1. Guide for Mechanistic-
Page 53 and 54: APPENDIX A: CREEP COMPLIANCE
Page 55 and 56: 0.080.070.06Creep Compliance (1/GPa
Page 57 and 58: 0.200.180.160.14Creep Compliance (1
Page 63 and 64: 0.300.25Creep Compliance (1/GPa)0.2
Page 65 and 66: 0.140.12Creep Compliance (1/GPa)0.1
Page 67 and 68: Table B-19: Non-instrumented Data @
Page 69 and 70: Table B-21: Instrumented Data @ 21.
Page 71 and 72: Table B-23: Instrumented Data @ 4.4
Page 73 and 74: Table B-25: Instrumented Data @ -10

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