A new test to simulate asphalt crack development at particle contacts

Abstract

Fatigue cracking in a bituminous layer is caused by tensile strains induced by repeated traffic loading. It is also widely accepted that, in a bituminous mixture, fatigue cracking predominantly propagates through the bituminous binder. In this study, a new apparatus, called the Asphalt Particle Contact Test (APCT), was successfully developed to investigate the mechanical behaviour of the binder at particle contact points in asphalt mixtures. This new equipment was then used to evaluate one pure bitumen and two polymer-modified binders using different simulated shaped ends, tested under various temperatures and load levels. The results indicate that the APCT successfully simulates conditions at idealised particle contact points in asphalt mixtures, and the initiation and propagation of microcracks at and around the contact can reasonably be inferred. Predictions, based on a microcrack simulation model, were conducted and compared to APCT data, and agreements and discrepancies discussed.