Asphalt Mixture Proportion Design And Performance Evaluation Of Ultra-Thin Wearing Course

The ultra-thin wearing course of asphalt pavement can significantly improve the pavement performance,but there are problems such as insufficient looseness resistance,insufficient interlayer bonding performance,and insufficient skid resistance.Therefore,it is urgent to explore the factors affecting the performance of ultra-thin wearing course.In this paper,compound high-viscosity modified asphalt was prepared by adding two modifiers,SBS and high-viscosity agent.Five grades of A-5-SMA,A-5-AC,B-8-AC,B-6.7-ECA,C-5-GX,studied the road performance,interlayer bonding performance and economy of asphalt mixtures with different grades.The main research contents and conclusions include:Compound high-viscosity modified asphalt was prepared by adding two modifiers,SBS and high-viscosity agent.Through three index tests and dynamic viscosity tests,it was determined that the optimal formula of composite high-viscosity modified asphalt was matrix asphalt:high viscosity.Adhesive:SBS=100:11:4.Summarize the grading requirements in the existing ultra-thin wearing course related specifications,select 5 kinds of grading named A-5SMA,A-5-AC,B-8-AC,B-6.7-ECA,C-5-GX,The optimum oil-to-stone ratios were determined by Marshall test to be 6.25%,5,79%,5.96%,6.20%and 5.79%.Based on road performance tests such as rutting test,water immersion Marshall test,structural depth test and pendulum value test,it is found that on the whole,the performance of the graded asphalt mixture in areas B and C is better than that in area A.C-5-GX grading has the best high and low temperature and water stability performance,B-8-AC grading has the best anti-slip performance;based on wheel wear test,B-8-AC grading has the best anti-slip decay performance and the worst of the A-5-AC gradation.It is found that MTD,MPD,Ra,Rq and other indicators decrease with the increase of wear times,and tend to be flat after reaching 5000 rpm,while the Rsk index increases with the increase of wear times.Select high-viscosity emulsified asphalt and SBS modified emulsified asphalt,and conduct oblique shear tests on three grades of B-8-AC,B-6.7-ECA,and C-5-GX at 40℃ and 60℃,respectively.It is found that the interlayer bonding of high-viscosity emulsified asphalt is better than that of SBS emulsified asphalt;with the increase of temperature,the shear strength and tensile strength of the two emulsified asphalts decrease significantly;The distribution amount is about 0.6kg/m2,and the temperature has no obvious effect on the optimal distribution amount;C-5-GX gradation is better than B-8-AC is better than B-6.7-ECA.4 kinds of maintenance schemes including 10mmC-5-GX ultra-thin wearing course,15mmB-8-AC ultra-thin wearing course,30mmSMA-10 and 40mmSMA-13 are selected for economic analysis.It is found that the use of ultra-thin wearing course can reduce the cost of raw materials and mechanical use by half,and can greatly extend the service life of the pavement.