Low Temperature Performance And Water Stability Of Steel Slag Permeable Asphalt Mixture

In recent years,with the rapid development of China’s economy and transportation industry,and the increase of new highway mileage every year,the scarcity of high-quality aggregate is becoming increasingly serious.A new substitute with similar performance to traditional aggregate that can be applied to asphalt pavement needs to be developed urgently.In this case,the application of steel slag to pavement building materials not only solves the problems of scarcity of high-quality aggregate and pollution caused by steel slag accumulation,but also conforms to the sustainable development strategy of economy,environmental protection and resource recycling upheld by the international community.In the test,five kinds of steel slag replacement rates(0%、25%、50%、75%、100%)were used to replace limestone coarse aggregate of more than 2.36mm,and five kinds of polyester fibers(0%、0.30%、0.35%、0.40%、0.45%、0.50%)were selected to prepare permeable asphalt mixture.SCB tests at three temperatures(0℃、-10℃ and-20℃)were carried out to obtain the best content through specimen fracture behavior,The volume expansion and water stability of the mixture were tested by immersion Marshall test,Marshall residual stability test and freeze-thaw splitting test.The interfacial bonding mechanism of steel slag/polyester fiber permeable asphalt mixture was explored by SEM and XRD,which provided theoretical basis for the application and development of steel slag permeable asphalt pavement.The research results are as follows:(1)The volume method was used to replace limestone aggregate over 2.36mm,and the influence of fiber and steel slag on the optimum asphalt content of asphalt mixture was studied.(2)The low-temperature performance of steel slag/polyester fiber asphalt mixture is greatly affected by temperature,and the optimum content and improvement range are different at different temperatures.At 0℃,the best substitution rate of steel slag is 75%,and the best content of polyester fiber is 0.4%.At-10℃ and-20℃,the best substitution rate of steel slag is 25%,and the best content of polyester fiber is 0.45%.(3)The ultimate tensile stress,ultimate tensile strain and fracture energy index of SCB test show that when the test temperature is 0℃ the optimal content of steel slag/polyester fiber permeable asphalt mixture is G25X0.35,and when the test temperature is-10℃ and-20℃,the optimal content is G50X0.45.Immersion Marshall test(volume expansion test)and freeze-thaw splitting test show that G50X0.45 asphalt mixture has better volume stability and water loss resistance.(4)SEM scanning results show that the best locking structure of limestone and steel slag 1:1 and the spatial network structure formed by 0.45%polyester fiber in permeable asphalt mixture are the main factors to improve the low temperature performance of asphalt mixture.In addition,the interfacial phase strength plays a key role in improving the overall performance of permeable asphalt mixture.(5)XRD results show that the hydration products of steel slag asphalt mixture are mainly Ca(OH)2,Mg(OH)2 and C-S-H gel,which will affect the volume stability of the mixture.However,a proper amount of hydrolysate can fill and repair the defects in the interface transition zone,and has a certain waterproof effect,which hinders the deep hydration of steel slag,improves the water damage resistance of the mixture and prolongs the service life.Figure[25]Table[14]Reference[78]...