Evaluation of test methods for estimating resilient modulus of modules of pavement geomaterials

Abstract

Paper presented at the 28th Annual Southern African Transport Conference 6 - 9 July 2009 "Sustainable Transport", CSIR International Convention Centre, Pretoria, South Africa.

Resilient modulus is a key parameter required for the mechanistic empirical pavement design procedures currently being adopted around the world including the recently developed NCHRP 1- 37A design guide in the United States and the current South African Pavement Design Method(SAPDM). The determination of the resilient modulus requires sophisticated equipment and skilled personnel for laboratory and field testing. These requirements have contributed immensely to the proliferation of different resilient modulus test procedures. Commonly used resilient modulus laboratory test methods for pavement geomaterials such as subgrade soils and unbound granular materials have evolved from the American Association of State Highway and Transportation Officials (AASHTO) and the Strategic Highway Research Program (SHRP) test protocols. This paper presents an overview on the state-of-the-art test procedures for determining resilient modulus of pavement geomaterials. Differences between current test procedures, and some potential challenges with the adoption of a universal test procedure are discussed. Common resilient modulus models used for characterising pavement geomaterials in flexible pavement design are also presented.