Comparison between resilient modulus and dynamic modulus of Western Australian hot mix asphalt based on flexible pavement design perspectives

Abstract

The modulus of asphalt concrete material is one of the major input parameters in mechanical-empirical pavement design and analysis. In Australia, current pavement design approaches rely on the resilient modulus of the asphalt material, and visco-elastic behaviour cannot be incorporated into this pavement analysis and design. However, in the USA, the NCHRP 1-37A design guide for Mechanistic-Empirical pavement design (ME design) uses the dynamic modulus to express the intrinsic behaviour of this important input parameter, i.e., the visco-elasticity of an asphalt material, over a range of temperatures and loading frequencies. This study aims to examine whether the dynamic modulus which is converted from a resilient modulus test is different to the resilient modulus when considering as a modulus input for pavement design. Three different asphalt concrete mixes, with varying maximum aggregate sizes of 7, 10, and 14 mm were selected as mix representatives. All test specimens were controlled using a - gyratory compactor to produce a 5% air void. To determine the resilient modulus and the dynamic modulus respectively, a UTM-25P and an Asphalt Mixture Performance Tester (AMPT) were used. In addition, pavement design exercises were performed on pavement structures typical to Western Australia. The exercises evaluated the difference of tensile strains at the bottom of asphalt layer derived from the different input parameters of the resilient and dynamic moduli.