Anisotropic Aggregate Base Inputs for Mechanistic Pavement Analysis Considering Effects of Moving Wheel Loads

Abstract

A new methodology is presented in this paper for determining cross-anisotropic aggregate base properties, i.e., directional dependency of moduli and Poisson’s ratios, as inputs into mechanistic pavement analysis considering effects of actual traffic or moving wheel loading. The proposed materials characterization requires conducting constant stress path triaxial tests and incrementally varying loading stress path slopes at similar stress states that are representative of various moving wheel loading conditions in the laboratory. In accordance, cross-anisotropic aggregate properties are determined by varying slightly the stress path slopes during testing and then by employing an error minimization approach to interpret the test results. Crushed aggregate specimens were prepared and tested to obtain cross-anisotropic properties at five different stress path slopes representative of various moving wheel load induced compression and extension type pavement stress states. Vertical resilient moduli were commonly found to be larger than horizontal ones and critically low resilient moduli were also obtained for some extension states. The findings point to advances needed in granular materials characterization such as incorporating anisotropic and stress dependent behavior into mechanistic pavement analysis and properly considering the effects of moving wheel loading on pavement response.