Low Temperature Characteristics Of BRA Composite Modified Asphalt And Its Pavement Performance

Low temperature cracking of asphalt pavement has always been a common problem to be considered in the design,construction and maintenance of road engineering,and the characteristics of asphalt binder are the main factors determining the low temperature cracking of pavement.Buton Rock Asphalt(BRA)has attracted the attention of road researchers in recent years because of its good high temperature performance and aging resistance,but its low temperature performance has not been effectively improved and improved.Based on the study of low temperature performance of BRA modified asphalt binder,two kinds of styrene-butadiene rubber(SBR)were added to improve the low temperature performance of BRA modified asphalt binder:one is powder,the other is latex,and then the basic performance of modified asphalt and pavement performance of mixture were evaluated comprehensively.The low temperature properties of BRA modified asphalt and BRA ash mortar were studied by penetration test,force ductility test and low temperature bending beam rheological test.The results show that the addition of BRA and its ash can decrease penetration and ductility of base asphalt,increase equivalent brittleness point,increase creep stiffness modulus and decrease creep rate,and the effect of BRA is more remarkable,combined with BRA modified leaching.The results of the four-component test show that the asphaltene content increases and the resin content decreases after adding BRA into the base asphalt,which results in the poor low temperature performance of the modified asphalt under the combined action of the ash content and asphalt component of BRA.In order to solve the problem of poor low temperature performance of BRA modified asphalt,SBR powder and SBR latex were used to optimize the low temperature performance of BRA modified asphalt.Two kinds of BRA-SBR composite modified asphalt were studied.The results show that SBR powder can improve the high temperature performance of BRA-SBR composite modified asphalt and slightly improve the low temperature performance of BRA modified asphalt.The addition of SBR latex can reduce the high temperature performance of BRA modified asphalt,but it can significantly improve the low temperature performance of BRA modified asphalt.When the content of SBR latex exceeds 5%,the low temperature grade of BRA-SBR composite modified asphalt can be upgraded by one grade.For two kinds of BRA-SBR composite modified asphalt mixtures,rutting test,immersion Marshall test,freeze-thaw splitting test and bending test were carried out in this paper.The results show that the two BRA-SBR composite modified asphalt mixtures have good high temperature stability and water damage resistance,and their low temperature crack resistance is also significantly improved.