Assessment of crack propagation resistance in SMA mixtures with reclaimed asphalt pavement

Abstract

The need for periodic replacement of wearing courses, including those made from SMA mixtures, involves the possibility of acquiring and reusing high-quality reclaimed asphalt pavement (RAP). To date, the issue of the use of RAP and asphalt granulate for SMA mixtures has not been extensively analysed and studied. The implementation of the principles of a circular economy will soon force the widespread use of asphalt granulate also for SMA mixtures. In the process of replacing the wearing course, the new asphalt mixture is laid on top of the existing binder course, in which, as a result of previous use, micro-cracks can occur, among others, which will also propagate into the newly built wearing course during the further use of the pavement. The SMA mixture should therefore be characterised by resistance to crack propagation from lower asphalt layers. The use of recycled material containing aged asphalt binder in the SMA mixture may contribute to a reduction in crack resistance. It was assumed that the properties of a mineral-asphalt mixture could be shaped, among others, by modifying the parameters of the mixture production process. The effect of selected technological conditions for the production of SMA mixtures with asphalt granulate on their resistance to crack propagation assessed by the SCB method was analysed. Two SMA 11 asphalt mixtures with a mineral-asphalt granulate content of 20% and 40% m/m produced using hot-mix asphalt granulate batching technology were tested. On the basis of the analysis of the results obtained, it was shown that both the batching scheme adopted for the mixture components and the content of asphalt granulate have a significant influence on the values obtained for the parameters characterising the resistance to cracking of the mineralasphalt mixture.