Study On Low-temperature Performance Of Coal Gangue Powder And Polyester Fiber Asphalt Mixture

With the development of expressways,asphalt concrete pavement has become the mainstream pavement.Under the service life of asphalt pavement,pavement cracking becomes more and more prominenL Reflective crack is one of the main damage forms of asphalt pavement,and it is a crack that extends upward from the bottom surface of the asphalt surface layer under the condition of low temperature and load.Once it is generated,it would expand quickly and have a harmful influence.In this regard,the low temperature crack resistance of asphalt mixture is studied from the perspective of material and environment.Coal gangue powder is used as the filler of asphalt mixture,the mass percentage that insteads mineral powder is 0%,25%,50%,75%,100%respectively.Polyester fiber is selected as the toughening material of asphalt mixture,the blending amount is 0%,0.3%,0.35%,0.4%,0.45%,0.5%of the total mass of the mixture,respectively.The coal gangue powder and polyester fiber asphalt mixture specimens have a diameter of 101.6 mm and a thickness of 31.75 mm,which are subjected to a semi-circular bending test(SCB test).In order to simulate the change of winter temperature,the test temperature is 0?,-10?,-20?.In order to study the effect of the reflective crack positions on the crack resistance of the asphalt mixture specimens,the pre-cuts with a depth of 10 mm and a width of 1.5 mm are producted at the bottom center,offset center 10 mm and 20 mm,respectively.SCB test results show that the optimum coal gangue powder replacement rate is 50%,and the optimum polyester fiber content is 0.4%.With the decrease of test temperature,coal gangue powder and polyester fiber asphalt mixture specimen becomes brittle,and its crack resistance firstly increases and then weakens.Under the test temperature of-10?,the crack resistance performance achieves the optimum.As the distance of the pre-cut that offsets the center position increases,the critical load of the specimen gradually decreases,and the crack resistance of the asphalt mixture gradually decreases.Scanning electron microscopy(SEM)results show that the specific surface area of coal gangue powder is much larger than mineral powder.The internal structure of asphalt mixture with 50%coal gangue powder is dense and has less voids,which indicates the better performance of crack resistance.0.4%polyester fiber has the best dispersibility in asphalt mixture,and the formed network structure can firmly lock the asphalt and the filler,which constitutes a stable entirety and optimum crack resistance.ANSYS results show that during the three-point bending process of the semi-circular specimen of asphalt mixture,most of the area is in the tension state,and the restraint position shows the compressive stress concentration.As the distance from the center of the pre-notch offset increases,the depth of influence of the compressive stress concentration gradually decreases.Figure[36]table[32]reference[68]...