Low-temperature crack resistance of coal gangue powder and polyester fibre asphalt mixture

Abstract

To improve the low-temperature crack resistance of asphalt mixture, coal gangue powder (CGP) and polyester fibre (PF) are added for modifying the performance of asphalt mixture. Five replacement rates that CGP replaces mineral powder (0%, 25%, 50%, 75% and 100% by the weight of the mineral powder) and six PF contents (0%, 0.3%, 0.35%, 0.4%, 0.45% and 0.5% by the weight of the mixture) are used in asphalt mixture. Semi-circular bending (SCB) test is conducted at three test temperatures (0 °C, −10 °C and −20 °C). SCB test results show that the optimum PF content is 0.4%, and the optimum CGP replacement rate is 50%. As the test temperature decreases, the critical temperature in which asphalt mixture begins cracking delays from −6.585 °C to −7.628 °C after adding the optimum PF and CGP. Moreover, the low-temperature crack resistance of asphalt mixture improves by 36.64%, 37.27% and 45.94% at 0 °C, −10 °C and −20 °C, respectively. Scanning electron microscope results indicate that the interaction of asphalt, PF, CGP and mineral powder in asphalt mixture is harmonious. This interaction performs with excellent integrity and low-temperature crack resistance under the optimum PF and CGP.