Study on Low Temperature Crack Resistance of Coal Gangue Powder/Polyester Fiber Asphalt Mixture

In order to study the effect of coal gangue powder, polyester fiber and reflective crack on the low temperature crack resistance of asphalt mixture, the low temperature crack resistance of asphalt mixture was studied by three-point bending loading test. In the test, asphalt mixture specimens were processed into semi-circular disc with no pre-cut and pre-notch (simulated reflection cracks) offset center 0 mm, 10 mm, 20 mm on the bottom. Five replacement rates of coal gangue powder were selected as 0%, 25%, 50%, 75%, 100%, and six kinds of polyester fiber content were chosen as 0%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%. The improvement mechanism of coal gangue powder and polyester fiber on low tempe-rature crack resistance of asphalt mixture was analyzed by SEM. Through experiments, the optimum amount of polyester fiber is 0.4% for SCB specimens with no pre-cut, and the optimum replacement rate of coal gangue powder is 50%; for SCB specimens with pre-cut, the optimum do-sage of polyester fibers ranges from 0.38% to 0.42%. With the increase of the offset distance of the pre-cut, the ultimate load of the asphalt mixture gradually decreases, and the semi-circular disc is more likely to be destroyed. The microscopic mechanism analysis shows that the incorporation of coal gangue powder makes the filler grading further refined, which is more conducive to improving the crack resistance of the asphalt mixture. At the same time, the polyester fiber can fully form a grid that evenly overlaps each other in the asphalt mixture and asphalt mixture has the best low temperature crack resistance. Therefore, the addition of coal gangue powder and polyester fiber can reduce the damage of reflective cracks to the low temperature crack resistance of asphalt mixture. © 2021, Materials Review Magazine. All right reserved.