Asphalt damage characterisation from cyclic test and X-ray computed tomography

Imaging techniques have been used to characterise laboratory fatigue testing on asphalt mixtures. Specimens were tested in tension-compression cyclic testing at different temperatures. Testing was stopped at predefined stages, and specimens were scanned in X-ray computed tomography. A three-dimensional image of the original specimens was developed for analysis. It was found from the image analysis that the damage (air voids) were found to be increasing with an increase in strain as damage accumulated in the specimens. An energy-based damage mechanics model was used to calculate the increase in damage. Dissipated pseudo-strain energy and adhesion between binder and aggregate were used in the model. Pseudo-strain energy was calculated from laboratory testing, and the adhesion parameter was determined from surface energies of aggregate and bitumen (binder). Values obtained from a numerical model were found to have a similar trend as that of the data from X-ray computed tomography and image analysis.