Investigation of low temperature cracking in asphalt mixtures using TSRST

In this paper the factors affecting asphalt pavements low temperature cracking are investigated by means of the Thermal Stress Restrained Specimen Test (TSRST). Asphalt mixtures slabs cut from field pavement sections as well as slabs produced in the laboratory, were used to study the influence of binder type, aggregate type, air void content, cooling rate and specimen geometry on the fracture strength and fracture temperature. For the laboratory mixtures, two levels of air void content: 4% and 7%, two levels of binder content: the design value and the design value plus 0.5% and two types of aggregates: limestone and granite were used to prepare the laboratory mixtures. It was found that mixtures with 4% of air void content are less prone to low temperature cracking than mixtures with 7% air void, and that, on average the granite mixtures performed slightly better than the limestone mixtures. A preliminary investigation of the feasibility of using acoustic emission monitoring during TSRST testing was performed including microcracks localization and acoustic events counting.