Verification of modulus and fatigue cracking models for hot-mix asphalt with asbuton in laboratory scale

Abstract

Design and analysis of flexible pavement structure using mechanistic approaches require, among other input data, the dynamic modulus of asphalt layer (E*) and it's resistance to fatigue cracking (N f ). These material characteristics can be obtained from both laboratory test results and calibrated against field conditions and from mathematical models, such as the Asphalt Institute's. The two values are to be compared for assessing the applicability of the models for mixes using petroleum bitumen (pen 60/70) and using modified asphalt (with 8% asbuton). The laboratory tests were conducted using Asphalt Mixture Performance Test (AMPT) and Four Point Loading equipment. It was found that the resulting curves are consistent with the Asphalt Institute's model for both types of mixes. Meanwhile, fatigue life model curves show a similar trend to the Asphalt Institute's model on the conservative side. This is explainable the laboratory model needs to be calibrated for variations of wheel track and loading time occuring on site.