Research On The Influence Of Composite Fiber On The Road Performance Of SMA-13asphalt Mixture

China is in a period of high-speed economic development,which requires the development of the transportation industry to be more and more demanding.With the increase of heavy and over-loaded vehicles,the amount of traffic load on the road is increasing,and because of the influence of some extreme weather,therefore,how to improve and improve the performance of asphalt pavement and reduce the cost of investment and construction will be the research focus of the majority of road workers.The excellent working performance of SMA asphalt pavement has been widely used in road construction.After research,it is found that different types of fiber have different emphasis on improving the road performance of the mixture,and the price of fiber is quite different,this raises new questions for road builders.Therefore,this paper will be used in SMA asphalt pavement by the way of fiber composite admixture,using the two kinds of fiber respective performance characteristics,and taking into account the principle of economy,the fiber composite asphalt mixture is tested.(1)The properties of the selected basalt fiber,polyester fiber and Lignin fiber were tested and compared,and the micro-morphology of the three fibers was analyzed.Two different fibers were added into the asphalt with different blending ratios,through the tests of softening point,cone penetration,adhesion between fiber and asphalt,the distribution of fiber in asphalt was analyzed.The results show that basalt fiber has the best properties and Lignin fiber has the coarsest microcosmic interface,and adding fiber can improve the softening point and shear strength of asphalt,when the ratio of basalt fiber to polyester fiber is 2:1,the softening point and shear strength of asphalt are increased the most,and the adsorption capacity of Lignin fiber to asphalt is the best,it has a tackifying effect on asphalt.(2)SMA-13 gradation is selected to design the mixture ratio of basalt fiber asphalt mixture,which is based on basalt fiber and mixed with polyester fiber and Lignin fiber respectively,and the mixture ratio of 3:0,2:1,1:1,1:2,0:3 is used to determine the optimum asphalt-aggregate ratio,and the rationality of the asphalt-aggregate ratio is tested,then through rutting test,beam bending test,immersion Marshall Test and freeze-thaw crack test,the influence of two kinds of fiber and different fiber blending ratio on the performance of asphalt mixture is analyzed.The results show that the fly-off test of Kentaburst and the leak-off test of Shellenburg asphalt both meet the requirements of the code,the effect of improving the high-temperature performance of the mixture is obvious when the mixture of basalt fiber and polyester fiber is blended,and the best effect is obtained when the blending ratio of the two fibers is 2:1,when the ratio of basalt fiber to wood fiber is 1:1,the water stability of asphalt mixture is outstanding,and the low temperature performance of asphalt mixture with basalt fiber alone is the best,the mechanical properties of Basalt Fiber and polyester fiber are obviously higher than that of basalt fiber and Lignin fiber.(3)Through the analysis of the macro-micro morphology of the fracture surface of the beam,the number of holes,the size of holes,the fracture of aggregate,the trend of cracks and the distribution of fibers in the mixture were observed.The results show that the holes of basalt fiber asphalt mixture are small and uniform,and the dispersion of basalt fiber is the best,the results show that the mechanical properties of basalt fiber asphalt mixture are excellent,and the irregular fiber network formed by fiber and composite fiber in the asphalt mixture plays the role of reinforcement and crack resistance,effectively explaining the macro-performance of the mixture.(4)To evaluate the road performance of different fiber blending ratios by the efficiency coefficient method,and then to evaluate the economy of composite fiber-blending asphalt mixture by considering the price factor,the results show that the mixture of basalt fiber and polyester fiber not only enhances the road performance,but also has good economy,at the same time,it is concluded that the composite fiber has a better effect in improving the overall performance of the mixture than the single fiber,and the basalt fiber/polyester fiber ratio of 2:1 is suitable for high temperature and rainy area,the asphalt mixture with basalt fiber is suitable for cold area in north China.