Experimental Study On Pavement Performance Of Fiber Asphalt Mixture

The typical pavement structure of China's expressway is semi-rigid base asphalt pavement.The proportion of bituminous pavement has reached more than 85%.With the increase of highway service life or because of the large proportion of heavy-duty vehicles,there will occur cracks and ruts in the use of bituminous pavement.The use of road fibers can greatly improve the quality of bituminous pavement and extend its service life.Based on the experimental study on the performance of different fiber asphalt mortar as the core,to explore the mechanism of action and the effect of fiber in asphalt mixture.The research contents of this paper include:(1)Selection and test of raw materials.(2)Performance test and analysis of fiber bituminous pavement.The shear resistance of fiber asphalt mortar was studied by direct shear test.The mechanism of the effect of fibers on asphalt mortar was analyzed,based on the micro-test of asphalt mortar,(3)Proportion design of fiber asphalt mixture.(4)Pavement performance test of fiber asphalt mixture,study the high temperature stability,low temperature performance and water stability of asphalt mixtures with different fibers.The main conclusions of this paper are as follows:(1)SEM image analysis of asphalt mortar and asphalt mixture shows that fibers have adsorption,stabilization and reinforcing effects in asphalt and retard the propagation of internal micro-cracks.(2)The shear strength of asphalt mortar is significantly improved by adding fibers.The internal friction angle and cohesion of fiber asphalt mortar are greater than those of asphalt mortar without fiber.The internal friction angle increases by 0.4-0.5 times and the cohesion increases by 0.8-2.4 times.The degree of increase of internal friction angle of the three kinds of fibre mortars is not very different.The cohesion of carbon fiber and polyester fiber asphalt mortar increased significantly,which was larger than that of basalt fiber.(3)When the amount of fibers is the same,the internal friction angle and cohesion of asphalt mortar blended with polyester fibers and basalt fibers are the largest and the shear strength is the highest in all the ways of mixing(including single mixing and mixing).(4)The dynamic stability of fiber asphalt mixture is obviously higher than that of asphalt mixture without fiber.The dynamic stability of polyester fiber and basalt fiber asphalt mixture increased by 1.03 times.(5)The residual stability and splitting strength ratio of fiber asphalt mixture increase,and the water stability is improved.(6)The critical strain energy index shows that the lowtemperature crack resistance of fiber asphalt mixture is better than that of asphalt mixture without fiber.