Gradation Optimization Design And Engineering Application Of Rubber Asphalt Mixture

In order to improve the performance of rubber asphalt mixture on the surface layer,this paper analyzes the influence of long-distance transportation of high-performance finished rubber asphalt on its performance,and studies the optimization of ARAC-13G gradation range and construction performance,which further improves the comprehensive performance of rubber asphalt mixture and provides reference for the improvement of technical performance of rubber asphalt pavement.The main research results are as follows:Firstly,the significance of the change of rubber asphalt performance index after long-distance transportation is analyzed by mathematical statistics method,and the linear and nonlinear fitting of each performance change value is carried out.According to the fitting results and the stability control index,the performance change control range of finished rubber asphalt after long-distance transportation is proposed.The results show that after long-distance transportation,the softening point and elastic recovery of the finished rubber modified asphalt decrease,and the penetration and ductility increase.The change of ductility is the most obvious,followed by penetration and elastic recovery,and the change of softening point is the least significant.The results show that in order to ensure the stability of finished rubber asphalt after long-distance transportation,the penetration reduction value should be less than 1.0 mm,the elastic recovery reduction value should be less than 3.1%,and the ductility increase value should be less than 4.69 cm.Secondly,the gradation of rubber asphalt mixture is optimized.According to the Marshall test,the optimum asphalt-aggregate ratios of ARAC-13G-1,ARAC-13G-2,ARAC-13G-3,ARAC-13G-4 and ARAC-13G-5 were determined to be 6.0%,6.1%,5.8%,5.6%and 5.7%,respectively,and their road performance and mechanical properties were tested.Based on the fractal theory,the fitting method is used to analyze and explore the influence of aggregate specifications on the performance of the mixture from the perspective of high strength correlation,and the comprehensive performance of ARAC-13G is further controlled by reasonable fractal dimension value.The results show that the fractal dimension of coarse aggregate has a strong correlation with high temperature stability and skid resistance.When D_cis controlled at 1.89-1.92,the skeleton interlocking force of ARAC-13G is higher,the skid resistance is superior and the high temperature stability is the best.The fractal dimension of fine aggregate has a better correlation with water stability.When D_f is greater than 2.53,the cohesion of the mixture is improved and the water stability is stronger.When ARAC-13G is used for gradation design of rubber asphalt mixture,D_c should be controlled at 1.89-1.92,and D_f should be greater than 2.53.Thirdly,by changing the forming temperature,compaction or rolling times and oil-stone ratio of ARAC-13G,the construction site was simulated by rutting test and freeze-thaw splitting test.The results showed that with the increase of temperature or compaction times,the high temperature stability of ARAC-13G gradually increased,and the water stability increases first and then decreases slightly.With the increase of oil-stone ratio,the water stability of ARAC-13G gradually increased,while the high temperature stability increased first and then decreased significantly.Finally,based on the actual project,the rubber modified asphalt mixture ARAC-13G was verified.Compared with the paving of SBS asphalt test road and the test results of the road surface,the rubber asphalt pavement has better high temperature stability and skid resistance.