Experimental Study On Aging Performance Of Asphalt Mixture With Different Admixtures

With the increasing traffic load and the influence of oxygen,heat and other environmental factors in the service process of asphalt pavement,asphalt pavement diseases occur from time to time,among which rutting and cracking are the most common.The use of high modulus agent,anti rutting agent,high viscosity agent,fiber and other external modifiers is an important technical means to improve the performance of asphalt pavement.At present,the research of external admixtures of asphalt mixture mainly focuses on the high temperature,low temperature,water stability and other aspects of road performance of fresh asphalt mixture,but the long-term use effect is unknown,which lays a hidden danger for road construction.Therefore,this paper studies the long-term performance of asphalt mixture with different admixtures based on the high temperature performance and crack resistance performance,clarifies the long-term performance evolution law and use effect of asphalt mixture with different admixtures,and provides the basis for the selection of asphalt mixture with different admixtures.Firstly,this paper selects AC-13 and SMA-13 asphalt mixture as the research object,adding basalt fiber,high modulus agent,anti rutting agent and high viscosity modifier respectively.Marshall design method is used to design the mix proportion of asphalt mixture with different admixtures to determine the mineral composition and the best asphalt aggregate ratio.Through rutting test,low temperature trabecular bending test,immersion Marshall test,sherenberg leakage test and Kentucky dispersion test,the road performance of several asphalt mixtures is studied.The results show that the road performance of several asphalt mixtures designed in this paper meets the requirements of the specification.Secondly,by extending the indoor long-term aging standard test time of asphalt mixture,the asphalt mixture with different service life is simulated by heating continuously for 5 days to 10 days and 15 days.The long-term high temperature performance of asphalt mixture with different admixtures was studied by uniaxial penetration test.The results show that for the fresh,short-term aging,long-term aging 5 days,10 days,15 days of asphalt mixture,with the extension of aging time,the penetration strength of various types of asphalt mixture presents the change trend of"first decline,then rise",and all show the minimum penetration strength when the aging time is 5 days.However,the rising and falling ranges of asphalt mixture with different admixtures are not consistent.The decreasing range of basalt fiber asphalt mixture is relatively slow and the rising range is relatively large,which indicates that basalt fiber and asphalt binder show different synergistic effects due to different stiffness of asphalt binder,and have more stable and better high temperature performance during the whole service period of asphalt pavement.Finally,the long-term crack resistance of asphalt mixture with different admixtures is studied through ideal-ct test.The results show that the ctindex of various types of asphalt mixture shows a continuous downward trend.In the whole aging process,the decay rate of ctindex of basalt fiber asphalt mixture is less than that of other asphalt mixtures,and the value of ctindex is higher than that of other asphalt mixtures,It shows that basalt fiber can improve the anti cracking strength of asphalt mixture to a certain extent,and delay the attenuation of long-term anti cracking performance of asphalt mixture.Comprehensive research results show that the performance of several asphalt mixtures commonly used in engineering,such as high modulus,anti rutting,high viscosity,basalt fiber,can meet the requirements of the specification;With the prolongation of the service time,the performance change laws of several mixtures are basically the same;However,the long-term performance of basalt fiber asphalt mixture and anti rutting agent asphalt mixture is obviously better than that of high modulus and high viscosity asphalt mixture,and the performance of basalt fiber asphalt mixture is stable.Basalt fiber can make up for the adverse effect caused by the long-term aging of asphalt.