Study On New Composite Rock-to-Asphalt Concrete Technology Based On Structural Performance

Qingchuan natural rock asphalt has good compatibility with base asphalt and seldom segregation occurs.It can significantly improve the softening point of asphalt,improve the high temperature rutting resistance of asphalt,and has the advantages of simple construction technology.It has been widely used in road construction.However,little research has been carried out on the structural properties of rock asphalt modified asphalt mixture and rock asphalt and SBS composite modified asphalt mixture.In this paper,the performance of rock asphalt modified asphalt,rock asphalt and SBS composite modified asphalt and their asphalt mixtures were studied through laboratory tests and accelerated loading tests of structural composite specimens combined with theoretical analysis.Rock asphalt modified asphalt with 3%,5%,7% and 9% content of Qingchuan rock asphalt and rock asphalt with 2.5%,5% and 7.5% content of Qingchuan rock asphalt and SBS composite modified asphalt were prepared by "wet method" process respectively.Through PG performance grading test and conventional asphalt performance test,based on asphalt performance index and rheological performance index,rock asphalt modified asphalt produced by 7% content of rock asphalt was determined.The rock asphalt and SBS composite modified asphalt with 2.5% rock asphalt have the best performance,good uniformity and stability.The rock asphalt modified asphalt with 7% rock asphalt content is used in the lower layer(AC-16)and the upper layer(AC-10),respectively.Compared with the base asphalt,the upper layer is base asphalt,7% rock asphalt modified asphalt,SBS modified asphalt and rock asphalt mixed with 2.5% rock asphalt and SBS modified asphalt;and the lower layer is 7% rock asphalt modified asphalt,the upper layer is base asphalt,respectively.Based on laboratory tests and 1/3 scale accelerated loading tests,the high temperature performance,water damage resistance and fatigue performance of the composite asphalt specimens were evaluated for 8 kinds of doublelayer asphalt mixtures,including Qinghai-7% rock asphalt modified asphalt,SBS modified asphalt and rock asphalt with 2.5% rock asphalt and SBS modified asphalt.Compared with the base asphalt mixture,the rutting depth at high temperature,the deformation amount of the same rolling times in Hamburg test,the micro-strain at the same temperature and the same loading times in multi-creep test are significantly reduced,and the Flow Number,dynamic modulus and stiffness modulus of the rock-modified asphalt mixture at the same temperature and the same loading times are significantly increased.Composite modified asphalt mixture and SBS modified asphalt mixture also show the same law,and the road performance index of rock modified asphalt mixture is similar to that of composite modified asphalt mixture,which shows that rock modified asphalt can improve the high temperature performance,water stability and fatigue resistance of asphalt mixture;1/3 scale accelerated loading full thickness rutting test vehicle The process curve of rutting with time is basically the same as that of conventional rutting test with equal thickness.Accelerated loading test can more accurately characterize the high temperature rutting resistance of asphalt mixture or pavement and its attenuation law.