Study On Properties Of Calcium Sulfate Whisker-styrene Butadiene Rubber Compound Modified Asphalt And Mixture

Asphalt pavement,as a kind of continuous non-joint pavement,has been widely used in the construction of high-grade highways because of its good pavement bearing capacity,driving comfort,no vibration and low noise.In the expressway and the first level road surface that have been built in our country,the proportion of asphalt pavement accounts for about 80% of the total road surface.In hot summer and cold winter regions,traditional asphalt mixture is difficult to meet good pavement performance and durability in a large temperature range at the same time.However,traditional asphalt pavement is prone to rutting,bagging,cracking and other diseases under adverse environmental conditions and vehicle cyclic load,which seriously reduces the service life of asphalt pavement.Relevant studies have shown that CSW has a significant role in improving the high temperature performance of asphalt pavement,while SBR has been proved to have advantages in enhancing the low temperature performance of asphalt pavement.Moreover,polymer/filler composite modified asphalt can improve the comprehensive performance of asphalt pavement.Taking "environmental protection and quality improvement" as the goal,this paper takes stearic acid modified calcium sulfate whisker(YCSW)and SBR as modifiers,asphalt and asphalt mixture as the matrix material,and studies the performance of YCSW-SBR composite modified asphalt and its mixture through laboratory tests.Specific research contents are as follows:The surface modification of calcium sulfate whiskers was carried out,and the effectiveness of surface modification of stearic acid was studied by microcosmic test.The effect of surface modification on asphalt properties was also studied by laboratory routine test.The results show that the surface modification of the whisker is helpful to the improvement of the properties of the whisker modified asphalt.The high and low temperature properties,viscosity and temperature properties of matrix asphalt,SBR-modified asphalt and composite modified asphalt were compared and studied through laboratory routine tests.The microscopic action mechanism of SBR and CSW on asphalt was discussed by means of FT-IR,fluorescence microscopy,SEM and other microscopic tests.The results show that the addition of YCSW and SBR can improve the high and low temperature performance and reduce the temperature sensitivity of asphalt.Both SBR and YCSW can be uniformly distributed in asphalt.SBR particles are embedded in asphalt and can be cross-linked with asphalt.The addition of YCSW is helpful to the distribution of SBR in asphalt.The surface of YCSW can absorb asphalt film of a certain thickness,and form a spatial network in asphalt.There is no obvious chemical reaction between YCSW and asphalt,and its blending belongs to physical blending.Through the rutting test,the trabecular bending test,splitting freeze-thaw splitting test,freeze-thaw cycles and freeze-thaw cycle fatigue test to study the matrix asphalt,SBR modified asphalt,composite modified asphalt mixture of road performance and durable performance,discusses the incorporation of SBR and CSW high and low temperature performance of asphalt mixture,water stability and durability.The enhancement mechanism of CSW on asphalt mixture was investigated by SEM.The results show that the addition of SBR and YCSW can improve the rutting resistance at high temperature,cracking resistance at low temperature,water stability,and the voidag,splitting tensile strength and fatigue properties of asphalt mixture after freeze-thaw cycles.YCSW can be evenly distributed in asphalt mixture,and form a spatial network structure,and has a good bond with asphalt.It can play the role of reinforcing,dispersing and transferring stress in asphalt mixture,and can play the role of bridging cracks,slowing down crack expansion,dispersing and transferring stress.