National Academies Press: OpenBook

Practices for Unbound Aggregate Pavement Layers (2013)

Chapter: Appendix F - Follow-up Survey on Resilient Modulus Testing

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Suggested Citation:"Appendix F - Follow-up Survey on Resilient Modulus Testing ." National Academies of Sciences, Engineering, and Medicine. 2013. Practices for Unbound Aggregate Pavement Layers. Washington, DC: The National Academies Press. doi: 10.17226/22469.
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Suggested Citation:"Appendix F - Follow-up Survey on Resilient Modulus Testing ." National Academies of Sciences, Engineering, and Medicine. 2013. Practices for Unbound Aggregate Pavement Layers. Washington, DC: The National Academies Press. doi: 10.17226/22469.
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Suggested Citation:"Appendix F - Follow-up Survey on Resilient Modulus Testing ." National Academies of Sciences, Engineering, and Medicine. 2013. Practices for Unbound Aggregate Pavement Layers. Washington, DC: The National Academies Press. doi: 10.17226/22469.
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Page 181

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179 APPENDIX F Follow-up Survey on Resilient Modulus Testing SuRvEy RESulT BRIEF: 46 ToTAl RESPoNDENTS – 14 indicated doing Mr TESTINg Idaho Transportation Department: Idaho uses a state- specific mechanistic design procedure (Winflex), which uses the Idaho R-Value as the main input parameter for base layers. They are considering a switch to MEPDG and are currently running companion tests (Idaho R-value and Mr) on sub- grade soils and some selected base materials for the purpose of improving on Level 3 inputs/defaults. The Materials Group has a GeoComp Test System, which is used experimentally to conduct resilient modulus tests using the AASHTO T307 method. This system uses one of two triaxial chambers (for either a 4-in. diameter × 8-in. height or 6-in. diameter × 12-in. height cylindrical test specimen) manufactured by GeoComp with externally mounted transducers (location of load cell and LVDTs). Idaho uses the bulk stress model (Mr = K1 (q)K2) to characterize stiffness as interpreted from the T307 data. Maryland State Highway: Maryland currently uses the 1993 AASHTO Guide design procedure and selects from a range of structural layer coefficients (0.08–0.14 with 0.11 typi- cal) as the main input parameter for base layers. The Materials Group has a GeoComp Test System that is used experimentally to conduct resilient modulus tests using the AASHTO T307 method. This system uses a triaxial chamber for 6-in. diam- eter × 12-in. height cylindrical test specimen, manufactured by GeoComp, with externally mounted transducers (location of load cell and LVDTs). Maryland uses the universal model (Mr = K1pa (q/pa)K2 ((toct/pa) + 1)K3) to characterize stiffness as interpreted from the T307 data. They have modeled materi- als from 30 quarries thus far, and are considering a switch to MEPDG. They consider the characterization of base materials critical with respect to the MEPDG, and are also using the lab data to confirm selection of structural layers coefficients used in their current designs. Additionally, they perceive the test will be a valuable discriminator when considering alternative materials such as RAP, RCP, and other sources. Arkansas State Highway and Transportation Depart- ment: Arkansas currently uses the 1993 AASHTO Guide design procedure and selects a structural layer coefficient as the main input parameter for base layers. Although the Materials Group has an Instron Test System capable of conducting the resilient modulus test on base materials, they currently only perform such tests (AASHTO T307 method) on subgrade soils. A research project was per- formed by a local university to characterize base materials using resilient modulus, but this test is not a current prac- tice in Arkansas. Oklahoma Department of Transportation: Although the Materials Group has an MTS Test System capable of con- ducting the resilient modulus test on base materials, they cur- rently only perform such tests (AASHTO T307 method) on subgrade soils. In years past, they used a Trautwein triaxial chamber for testing 6-in. diameter × 12-in. height cylindrical test specimen with externally mounted transducers (location of load cell and LVDTs), but found the process of remolding quality test specimens to be burdensome. Oklahoma currently uses the 1993 AASHTO Guide design procedure and uses a range of structural layer coefficients (0.10–0.14 based upon gradation) as the main input parameter for base layers. They are transitioning to MEPDG, and currently use 35,000 psi as an input for base layer modulus. Virginia Department of Transportation: Virginia cur- rently uses the 1993 AASHTO Guide design procedure and selects a structural layer coefficient as the main input parameter for base layers. Although the Materials Group has an Instron Test System capable of conducting the resilient modulus test on base materials, they currently only perform such tests (AASHTO T307 method) on subgrade soils. A research project was performed by a consultant (Instron Test System) to char- acterize base materials using resilient modulus (6 sources), but this test is not a current practice in Virginia. Mississippi Department of Transportation: Mississippi currently uses the 1993 AASHTO Guide design procedure and selects a structural layer coefficient as the main input parameter for base layers. A research project was performed by a consultant (Interlaken Test System) to characterize base materials using resilient modulus, but this test is not a current practice in Mississippi. They are transitioning to MEPDG, but most likely will rely on backcalculated base layer values as input for new designs. Utah Department of Transportation: Utah currently uses the 1993 AASHTO Guide design procedure and selects a structural layer coefficient as the main input parameter for base layers. A research project was performed by a local university (IPC Test System) to characterize base materials using resilient modulus, but this test is not a current practice in Utah. North Carolina Department of Transportation: North Carolina currently uses the 1972 AASHTO Interim Guide design procedure and a structural layer coefficient (0.14) as the main input parameter for base layers. The Materials Group has an Instron Test System which is used experimentally to conduct resilient modulus tests using the AASHTO T307 method. This system uses a triaxial chamber for 6-in. diam- eter × 12-in. height cylindrical test specimen, manufactured

180 by Karol-Warner, with externally mounted transducers (location of load cell and LVDTs). North Carolina uses the SHRP Model (Mr = K1(SC)K2(S3)K5) to characterize stiffness as interpreted from the T307 data. They are considering a switch to MEPDG, and intend to use the experimental data from their lab program to determine a single value to use as input. Presently, they are using 40,000 psi, but are fine-tuning and calibrating this value. Missouri Department of Transportation: Missouri shifted to the MEPDG design procedure in 2004 and currently uses resilient modulus as the main input parameter for base layers. A research project was performed by a local university (MTS Test System – GCTS 6-inch triaxial cell) to characterize base materials using resilient modulus. Missouri uses the universal model (Mr = K1pa (q/pa)K2 ((toct/pa)+1)K3) to model stiffness as interpreted from the T307 research data, and have used this study to calibrate models and supplement and/or replace Level 3 lookup values since the 2004 implementation. The resilient modulus test is not considered a routine practice in Missouri. South Dakota Department of Transportation: South Dakota currently uses the 1993 AASHTO Guide design pro- cedure and is considering using the MEPDG. They currently do not have the capability to perform resilient modulus tests to characterize base materials. If the need arises, they would contract the work to a university or consultant. Wisconsin Department of Transportation: Wisconsin currently uses the 1972 AASHTO Guide design procedure and is considering using the MEPDG. They currently do not have the capability to perform resilient modulus tests to characterize base materials. In preparation for the MEPDG, Wisconsin has initiated some research work in this speci- fic area to local universities, who conduct AASHTO T307 testing. Indiana Department of Transportation: Although the Materials Group has a GeoComp Test System capable of con- ducting the resilient modulus test on base materials, they cur- rently only perform such tests (AASHTO T307 method) on subgrade soils. This is due to the fact that they do not possess a large triaxial chamber for conducting tests on large-diameter specimens. Indiana has implemented the MEPDG procedure and currently uses 30,000 psi as the main input parameter for their base layer, based primarily on backcalculated values of existing pavement structures. They recognize this general use default value is restrictive and are exploring options to add robustness through research (develop a catalog of values) or active testing. Kansas Department of Transportation: Kansas cur- rently uses the 1993 AASHTO Guide design procedure and selects a structural layer coefficient as the main input param- eter for base layers. Although the Materials Group has an Interlaken Test System capable of conducting the resilient modulus test on base materials, they have not conducted tests for nearly 10 years. Minnesota Department of Transportation: Minnesota DOT currently uses FlexPave (R-value inputs) and Rigid- Pave for flexible and rigid pavement designs, respectively. The Materials Group (The Research Group) has an Inter- laken Test System, which is used currently (experimen- tally) to conduct resilient modulus tests using the NCHRP 1-28a method for research projects (although 3 internally- mounted LVDTs are used rather than the recommended 2 LVDTs, and a rigorous QA/QC protocol has been established to readily scan data for acceptance). This system uses a tri- axial chamber for 6-in. diameter × 12-in. height cylindrical test specimen, manufactured by Interlaken, with internally mounted transducers (location of load cell and LVDTs). Minnesota uses the Universal Model (Mr = K1pa (q/pa)K2 ((toct/pa) + 1)K3) to characterize stiffness as interpreted from the NCHRP 1-28a data. MnDOT currently uses MnPAVE and RigidPave for flexible and rigid pavement designs, respectively. They are developing a pavement design cata- log for rigid pavements using MEPDG (through research).

Abbreviations used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation

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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 445: Practices for Unbound Aggregate Pavement Layers consolidates information on the state-of-the-art and state-of-the-practice of designing and constructing unbound aggregate pavement layers. The report summarizes effective practices related to material selection, design, and construction of unbound aggregate layers to potentially improve pavement performance and longevity.

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