comparison of alternative asphalt concrete rut characterization

BERTHELOT, CROCKFORD & LYTTON 29coefficient of variation with the exception of the SHRP shear phase angle measurements. The highcoefficient of variation could only be attributed to experimental error. It is believed that the relativelyshort 50 mm sample height may have had a significant influence in the high variability of the SHRP sheartester measurements as witnessed in the high number of samples that failed during SHRP shear testing.This study determined that traditional phenomenological asphalt concrete characterization methodsdistinguished some significant differences between the Radisson SPS-9A asphalt concrete mixes.However, they did not provide material constitutive relations necessary for mechanistic road responsemodeling. The SHRP shear tester also distinguished some significant differences between the asphaltconcrete mixes and can provide material constitutive relations necessary for mechanistic road responsemodeling. However, the SHRP shear tester is expensive to own and operate, produces relatively highvariability, and was found to be impractical for use by most public road authorities, road consultants, androad contractors. The rapid triaxial tester determined the most significant difference between the asphaltconcrete mixes and was found to be an efficient mechanistic testing apparatus to complement the SHRPgyratory compactor. The measured materials properties obtained from the rapid triaxial tester were alsofound to best correlate predict correlate with the relative rutting behavior of the SPS-9A test sections afterthree years of service. The complex properties measured by the rapid triaxial tester could bemathematically transformed into linear viscoelastic constitutive relations which could be used forviscoelastic mechanistic road modeling. This ability to accurately measure viscoelastic constitutiveproperties under stress states, temperatures and load frequencies representative of those in the field maypose significant promise for reliably predicting rutting behavior of asphalt concrete pavements.DISCLAIMERThe viewpoints expressed herein are those of the authors, and are not necessarily endorsed by theagencies involved with this research.7.0 REFERENCES1. University of Illinois at Urbana-Champaign Construction Technology Laboratories. "CalibratedMechanistic Structural Analysis Procedures for Pavements" NCHRP 1-26 Final Report, Champaign,Illinois, (1990).2. Von Quintas H. "Development of Asphalt-Aggregate Mixture Analysis System: AAMAS" FinalReport, NCHRP 9-6(1), Washington, DC, (1989).3. Fernando E,, Lytton R. "Demonstration of Potential Benefits of Performance-Oriented Specifications"Transportation Research Record 1353, TRB, National Research Council, Washington, DC, 73-81(1992).4. Anderson D. "Performance Related Specification for Hot Mix Asphalt Concrete" Final Report,NCHRP 10-26A. Pennsylvania Transportation Institute, Pennsylvania State University, UniversityPark (1990).5. Uzan J, Zollinger D, Lytton R. "Mechanistic/Empirical Model for the Structural Design of FlexiblePavements" Report No. 455-1. FHWA. Texas Transportation Institute, The Texas A&M UniversitySystem, College Station (1991).6. Little D, Youssef H. "Improved ACP Mixture Design: Development and Verification" Report 1170–1F. Texas Transportation Institute, The Texas A&M University System, College Station, (1992).