Characterisation of micro-structural damage in asphalt mixtures using image analysis

•X-ray CT Scanning and Digital Image Processing.•Validating the 2D analysis and image Slices Verification for Damage Comparison.•Extracting the damage area from X-ray CT images.•Microstructural Changes in Air Voids Properties and Analysis of the Damage for Specimen Subjected to Compression.•Quantification of crack formation and crack propagation and analysis of the Damage for Specimen Subjected to Fatigue. This paper is an attempt to provide information on the application of an image analysis technique to characterise the internal structural damage of asphalt mixtures captured on X-ray images. In this paper, two modes of failures under uniaxial monotonic compression and indirect tensile fatigue were employed for illustrating the procedures undertaken. Air voids and crack properties as a result of the applied stresses and strains were analysed using two-dimensional image analysis and introduced as damage indicators for characterising the micro-structural damage of asphalt mixtures. A set of procedures for extracting and verifying the damage area were also established by comparing the X-ray images before and after the loading application. The proposed damage parameters were showed to be useful for interpreting the damage behaviour particularly the changes in air void properties and the characteristics of crack formation and crack propagation. In addition, it was also found that the damage parameters adopted are subjected to failure type.