Comprehensive evaluation of cracking performance in modified HMA and WMA asphalt mixtures using the SCB test

Improving the cracking resistance of asphalt pavements remains a critical challenge for researchers and engineers for decades. While various strategies have been explored to enhance the cracking resistance of asphalt, some have demonstrated success, while others have been less effective. This study investigates the potential of incorporating recycled polyethylene terephthalate (PET) in combination with warm mix asphalt (WMA) technology to improve the cracking resistance of asphalt mixtures. Recycled PET was blended with asphalt binder at concentrations of 1 % and 2 % by weight, alongside the use of Sasobit, to produce modified hot mix asphalt (HMA) and WMA mixtures. The cracking resistance of these mixtures was evaluated using the semi-circular bend (SCB) test method, assessing several cracking indices, including fracture toughness ( K If , K IIf ), fracture energy ( G If , G IIf ), balanced cracking index ( BCI ), tensile strength ( TS ), and tensile stiffness index ( TSI ). Testing was conducted under various temperatures (-20°C, 0°C, and +20°C) and two loading modes (pure Mode I and Mode II). The results indicate that the addition of recycled PET and Sasobit significantly improves the cracking resistance of both HMA and WMA mixtures, both individually and in combination. The best performance was achieved with the mixture containing 2 % PET and 3 % Sasobit. This combination resulted in significant improvements in fracture toughness, with increases of up to 83 % and 57.5 %, as well as in fracture energy, which increased by up to 93 % and 47 %, compared to the HMA and WMA control mixtures, respectively. These improvements were observed across various temperatures and loading modes, underscoring the potential of this approach to enhance the durability of asphalt pavement against cracking.