Crack and crack growth behavior analysis of asphalt mixtures based on the digital speckle correlation method

- We report the results of analyzing asphalt crack initiation and propagation rules using semi-circular bending (SCB) tests and the DSCM on the microscopic level.
- The strain field (Exx) and the rate of change displacement field (dU/dt) are well suited to study the properties of crack and fracture characteristics of asphalt mixtures.
- Analysis of the differences in the deformation properties of asphalt binder, stone, interface, and crack-tip; comparative analysis of the cracking rules of CR-and SBS-modified asphalt mixtures.

Cracking is one of the main reasons for asphalt pavement damage. Because of the anisotropism of asphalt mixtures, traditional experimental methods cannot analyze displacement and strain fields accurately. A full-field, noncontact measurement technology-the digital speckle correlation method (DSCM)-is a good method to analyze the deformation characteristics of asphalt mixtures. By using DSCM and a semi-circular bending (SCB) test, the crack initiation and propagation rules can be tested experimentally; the full-field displacement and strain can be analyzed by vic-3D software. The results show that the strain field (Exx) and the rate of change displacement field (dU/dt) are well suited to study the properties of crack and fracture characteristics of asphalt mixtures. The interface between asphalt binder and stone is the weakest part of the entire structure, and comparing the crack growth rate and load displacement curve of a crumb-rubber (CR) modified asphalt mixtures and a styrene-butadienestyrene (SBS) modified asphalt mixtures, it is found that the carrying capacity of a CR modified asphalt mixtures is stronger than that of a SBS modified asphalt mixtures.