Evaluation of simple performance tests on hot-mix asphalt mixtures from south central United States

Abstract

Since development of the Superpave® mix design procedure under the Strategic Highway Research Program about a decade ago, there has been a need to develop some type of a simple physical test to complement the Level 1 volumetric mixture design procedure. NCHRP Project 9-19 recognized the dynamic modulus test along with the flow time and flow number tests as the top three candidates for a simple performance test that could identify mixtures susceptible to permanent deformation. A critical evaluation of these three tests is presented along with the Superpave shear test-frequency sweep at constant height with the asphalt pavement analyzer (APA) as the torture test to identify mixes susceptible to permanent deformation. The Hamburg wheel-tracking device (HWTD) also was used on selected mixtures. Special laboratory hot-mix asphalt mixes designed to exhibit low dynamic modulus but high recovery of strains were included in this evaluation. Results indicated that flow number value and flow time slope correlated better with laboratory rutting (APA and HWTD) than dynamic modulus. Flow number value, flow time slope, E*/sin at 1 Hz, flow number slope, and flow time value were among the best five correlations with both the APA and the HWTD rut depths.