Experimental Study On Rubber Powder Polypropylene Fiber Composite Modified Semi-rigid Base Material

Semi-rigid base asphalt pavement,as the main highway pavement in China,has the characteristics of high strength,good slab property,good water stability and easy construction.But there is a large contraction,easy to produce pavement cracking problem.To solve this problem,a new type of semi-rigid base material modified by rubber powder and polypropylene fiber was studied in this paper.The research contents and main research results of this paper are as follows:(1)Optimization of raw material selection and material mix ratio at the base level:first,conduct raw material performance index tests for all raw materials purchased based on the project;Then,the use of rubber powder and polypropylene fiber as the additive agent,without changing the original grading standard for mineral aggregate composition design,based on the orthogonal experiment design adding rubber powder and polypropylene fiber cement stable macadam mixture,7 d unconfined compressive strength and 7 d shrinkage anti-cracking coefficient as evaluation indicators,to obtain a set of optimal mixture ratio:the powder particle size was 60 mesh,powder content is 1%,fiber length is 9 mm,fiber content is 0.1 1%,the cement content of 4.5%.(2)the rubber powder and polypropylene fiber mixture on the base of the cement stabilized macadam road use performance test research:the rubber powder and polypropylene fiber mixture on the base of the cement stabilized macadam and common cement stabilized macadam base mixture for road use performance contrast test,the test results show that the composite modification of polypropylene and rubber powder can increase the semi-rigid base of unconfined compressive strength,splitting strength and compressive modulus of resilience of decrease;The crack resistance and frost resistance of semi-rigid base can be improved.(3)on the basis of engineering test road paving and inspection:on the basis of the above research,this paper carried out the test road paving work in combination with the construction of huaihua-zhijiang expressway project in luojiu town,zhijiang county,hunan province Pile number of test section:AK0+100～AK0+200.After the paving of the test road,field sampling of the test section was carried out The compressive strength of the test modified section in 7d and 28d was 6%and 9.2%higher than that of the normal section,Similarly,for the splitting strength of 28d and 90d,the experimental modified section was 32%and 27%higher than the ordinary section,No cracks were found in the paved test road.The experimental results show that adding polypropylene fiber and rubber powder can improve the pavement performance of the base.