Evaluating Low-Temperature Cracking and Stress Relaxation in Polyethylene-Modified Asphalt Mixtures: A Thermal and Mechanical Assessment

The main goal of the study is to evaluate the potential of polyethylene (PE) modification in improving cracking and stress relaxation properties of asphalt mixtures at low temperatures. In this process, PE and asphalt binder were subjected to differential scanning calorimeter (DSC) to evaluate the heat flow, glass transition ( T g ), and thermal responses at low temperatures (<0°C). Further, to determine the relaxation and modulus properties, dynamic mechanical analyzer (DMA) and bending beam rheometer (BBR) were used for PE and asphalt materials respectively. The thermal and modulus data of asphalt-PE materials obtained from DSC, dynamic complex modulus (DMA), and BBR were then used to correlate the performance of PE-modified asphalt mixtures. Disk-shaped compact tension test (DCT), three-point bending beam fracture test (3PBFE), low-temperature indirect tensile strength (IDT), and DCM tests were performed on PE-modified asphalt mixtures as a part of low-temperature cracking assessment. The study identified that PE and asphalt binder attain similar modulus values at low temperatures (<0°C) and merge approximately at T g of asphalt (−28°C). This unique phenomenon leads to a reduced influence of PE on asphalt mixtures at low temperatures, specifically below T g of asphalt. As a result, although PE was influential in improving the true tensile strength of asphalt mixtures above T g of asphalt (−28°C), its impact diminished below T g of asphalt (<−28°C). From master curves and phase angle analysis, PE imparted elastic behavior to asphalt mixtures and exhibited potential crack resistant tendency temperatures greater than T g of asphalt. Overall, the influence of PE modification on hot mix asphalt (HMA) mixtures at low temperatures is heavily relied on T g of asphalt binder.