Characterization of Fracture in Asphaltic Mixes Based on a Molecular Approach

Abstract

In contradiction to the fracture mechanics approach, the fundamental absolute rate theory (ART) model describes the macroscopic behavior of processes on the molecular level. Attention is given to the theoretical background of the ART and its application to describing the crack growth process in asphalt concrete mixes. From the analyses, it is concluded that in the crack propagation phase, three parallel processes are distinguished: cohesive crack growth, adhesive crack growth, and a crack-retardant process. In the crack initiation phase, only cohesive crack growth is present. The difference between the mixes is specified by the free activation energy Qa: increase in crack growth resistance increases the Qa-value. This Qa-value, determined from mechanical tests, is close to the energy that bonds the bitumen to the aggregate, determined from chemical tests.