Challenges in using the Disc-Shaped Compact Tension (DCT) test to determine role of asphalt mix design variables in cracking resistance at low temperatures

ABSTRACT There have been many fracture tests – the Thermal Stress Restrained Specimen Test, the Single-Edge Notched Beam test, the Semi-Circular bend test, the Indirect Tensile Test and the Disc-Shaped Compact Tension (DCT) test – developed to understand thermal cracking in asphalt pavement. Among these tests, the DCT test is the most recent test method developed that has gained significant interest. This paper includes a laboratory study to measure the effect of different mixture design parameters on the DCT test results. The parameters include per cent binder replacement from recycled asphalt pavement, binder modification, low-temperature binder grade, oxidative ageing and mix design traffic level. To investigate the significance on the factors controlled, ANOVA and multi-linear regression analyses are used to show that only a few factors can be considered significant in terms of their effects on DCT parameters, and the significance of those factors could not explain the range in DCT response variables. Some of the trends in change in the DCT test responses with mixture ageing and some other factors are also found to be illogical. This paper does not offer solutions, but highlights some of the challenges experienced when applying the DCT test to performance specifications.