Investigation of treated CRCA in HMA mixtures through evaluating low temperature cracking

One of the most important concerns for asphalt pavement in the cold regions of the world is the prospect of thermal cracks or low-temperature cracks. This is mainly attributed to the development of stresses, which exceed the pavement strength, leading to pavement cracking at extremely low temperatures. To evaluate the performance at low temperatures, the thermal stress restrained specimen test (TSRST) is performed to assess the influence of (CRCA) addition into asphalt mixtures based on Ontario Superpave specifications. The effect of different CRCA types with various proportions on the fracture stress and fracture temperature of asphalt mixtures is also examined. To achieve the objective, two different types of CRCA with various percentages (0%, 15%, and 30%) were chosen. The impact of treated CRCA on the behaviour of asphalt mixtures at low temperatures is further evaluated by applying combinations of various treatment methods. Heat treatment at 300°C followed by a short mechanical treatment is applied to enhance the physical and mechanical properties of CRCA. The application of the combination technique of heat treatment at 300 °C and short mechanical treatment method is very successful in improving various RCA properties. The addition of both CRCA types into the asphalt mixtures at various proportions is successful in achieving all MTO requirements for volumetric properties. While the application of the combination of various treatments leads to a significant reduction in the average fracture temperature, there is no impact for this technique on the fracture stress of the asphalt mixtures.