Study On Polymer Composite Modified Asphalt And Asphalt Mixture Performance

In order to adapt to the continuous growth of road traffic,prolong the service life of pavement and improve the comprehensive performance of modified asphalt,this paper mainly studies the modification process by selecting different kinds of modifiers to prepare modified asphalt and analyzing the performance of each.The influence of modified asphalt performance is provided for the preparation of composite modified asphalt.At the same time,the composite modified asphalt with better comprehensive performance is prepared according to the modification effect of CRP,SBS and SBR modifiers.Finally,the comparison test proves basic road performance of composite modified asphalt mixture.According to the test results,the following conclusions are drawn:(1)The modified asphalt was prepared by different kinds of modifiers and two kinds of matrix asphalts.The modified asphalt with SK-70# matrix asphalt as raw material had better performance through comparison of three indexes and isolation test.And through the experimental comparison,the optimal blending amount of SBS and SBR modifier is 5%,and the optimum blending amount of CRP modifier is 6%.(2)The shear time,shear rate and shear temperature of the modified asphalt were changed respectively.The shearing time of the CRP and SBR modifiers was determined by three major indexes and isolation tests.The SBS modifier was determined.The shearing time was 35min;the shear rates of CRP,SBS and SBR modifiers were all4500rpm;the shear temperatures of the three modifiers were all selected at 180°C.(3)Based on the analysis of CRP,SBS and SBR modified asphalt preparation process parameters and modifier dosage,the modifier addition sequence,blending ratio and preparation process of CRP/SBS and CRP/SBR composite modified asphalt were studied.When preparing CRP/SBS composite modified asphalt,the ratio of CRP+SBS blending is 4%+2%.The SBS modifier is firstly cut into the matrix asphalt for 35 min,and then mixed with CRP modifier for 25 min.The shear rate of SBS and CRP modifier was 4500 rpm,and the shear temperature was 180°C.When preparing CRP/SBR composite modified asphalt,the blending ratio of CRP+SBR composite modifier was3%+3%,while the CRP and SBR modifiers were blended into the asphalt for 35 min,the shear rate was selected to be 5500 rpm,and the shear temperature was selected to be180°C.Compared with CRP,SBS,SBR modified asphalt and CRP/SBS and CRP/SBR composite modified asphalt,it is found that CRP/SBR composite modified asphalt has the best comprehensive performance,and the softening point can reach 80°C.The 5°C ductility can reach 76 cm,meeting the expected requirements.(4)The basic road performance of CRP/SBR composite modified asphalt mixture was verified by rutting test,freeze-thaw split test and trabecular low temperature bending test.The rutting test results show that the high temperature performance of CRP/SBR composite modified asphalt mixture is less than that of SBS modified asphalt mixture,which is 22.5% higher than that of SBR modified asphalt mixture,indicating CRP/SBR composite modified asphalt mixture.The material has good high temperature stability performance;the freeze-thaw split test results show that the freeze-thaw splitting strength ratio of CRP/SBR composite modified asphalt mixture is only 1%smaller than that of CRP modified asphalt mixture,so the freeze-thaw of the three The splitting strength ratio is not much different,indicating that the water stability of the three is comparable,while the freeze-thaw splitting strength of the CRP/SBR composite modified asphalt mixture is 6.5% higher than that of the SBR modified asphalt,further illustrating the CRP/SBR composite modification.The asphalt mixture has good water damage resistance;the low beam bending test results show that the CRP/SBR composite modified asphalt mixture has lower bending strength index and maximum bending strain index than SBR modification under low temperature conditions.Asphalt mixture,but the difference is not big and obviously better than SBS and CRP modified asphalt mixture,indicating that CRP/SBR composite modified asphalt mixture has good low temperature crack resistance.By comparing the basic properties of CRP,SBS and SBR modified asphalt and CRP/SBS,CRP/SBR composite modified asphalt and its mixture,it is found that the comprehensive performance of CRP/SBR composite modified asphalt and its mixture is optimal and meets the expected requirements.