Experimental Study On Performance Of Basalt Fiber Dense Graded Asphalt Mixture With Different Traits

As a non-polluting and high-performance pavement material in the 21 st century,basalt fiber has been widely used in the engineering practice of asphalt pavement.Its length and content are important parameters related to the performance of asphalt mixture.More and more researche rs and practitioners pay attention to it and have proved the adaptability of fibers length,content and dense graded asphalt mixture.However,the research on the influence of fiber traits on the comprehensive performance of dense graded asphalt mixture is very limited.Therefore,this paper intends to study the performance test of dense graded asphalt mixture with different basalt fiber traits,especially the dynamic modulus test of the mixture.Firstly,two kinds of basalt fibers with different traits(chopped basalt fiber and flocculent basalt fiber)were used to study the rheological properties of fiber-asphalt binders and analyze its microscopic morphology.The results show that the rutting resistance of asphalt binder is enhanced by adding basalt fiber,and the high temperature stability of asphalt binder is better after adding flocculent basalt fiber.Secondly,the Marshall design method is used to design the mix ratio of three dense-graded asphalt mixtures.The results show that the optimum asphalt aggregate ratio of dense graded asphalt mixture increases slightly after adding basalt fiber with different traits.Among them,the optimum asphalt aggregate ratio of ordinary no fiber dense graded asphalt mixture is 4.9%,the optimum asphalt aggregate ratio of chopped basalt fiber dense gradation asphalt mixture is 5.1%and the optimum asphalt aggregate ratio of flocculent basalt fiber dense-graded asphalt mixture is 5.2%.Then,a series of indoor tests were carried out on different dense gradation asphalt mixtures.The test results show that compared with the ordinary no fiber dense graded asphalt mixture,in the high temperature stability test,the incorporation of chopped basalt fiber increases the dynamic stability and penetration strength of the ordinary no fiber dense graded asphalt mixture by about 27.8%and 23.2%,respectively,while the incorporation of flocculent basalt fiber increases the dynamic stability and penetration strength of the ordinary non-fiber dense-graded asphalt mixture by about 31.7%and 31.6%,respectively.In the cracking resistance test,the cracking index CTIndex of the mixture after adding chopped basalt fiber and flocculent basalt fiber increased by 81.7%and 109.1%respectively,and the flexibility index FI increased to varying degrees.Combined with digital image speckle technology,the crack development rate of the mixture after adding chopped basalt fiber and flocculent basalt fiber was delayed by 39.6%and 55.4%respectively.In the water stability performance test,the change of water stability performance of the mixture after adding chopped basalt fiber has no obvious effect,while the immersion residual stability and freeze thaw splitting strength ratio of the mixture after adding flocculent basalt fiber increase by 20.0%and 34.5%respectively.In the fatigue resistance test,under the strain of 450με,650με and 850με,the fatigue times of flocculent basalt fiber asphalt mixture are 22.6%,41.9%and 37.8%higher than that of chopped basalt fiber asphalt mixture,respectively.Finally,the dynamic modulus test of three dense graded asphalt mixtures was carried out.Under the same dosage,the dynamic modulus of flocculent basalt fiber asphalt mixture is higher than that of chopped basalt fiber in high frequency region,while the dynamic modulus of flocculent basalt fiber asphalt mixture is lower than that of chopped basalt fiber in low frequency region,indicating that the influence of flocculent basalt fiber on the high temperature and low temperature performance of asphalt mixture is more prominent than that of chopped basalt fiber.The correlation between dynamic modulus and performance is analyzed,and the results show that the dynamic modulus and performance show a good correlation.The research results have a certain guiding role in improving the performance of dense graded asphalt mixture,and provide some reference value for the design of fiber asphalt mixture.