Experimental Study On The Basic Properties Of Hybrid Fiber Cement Concrete For Pavement Rapid Repair

In the Pavement of Road Surface project,cement concrete is the most widely used building materials.But its shortcomings such as low tensile strength,brittleness and poor durability,easily lead to road damage.Ordinary cement concrete repair materials needs long construction period,affecting healthy traffic.Therefore,fast repair materials are needed in order to realize the road open to traffic in a short time.The addition of fiber in pavement cement concrete can significantly improve the tensile strength and durability of concrete,enhancing the toughness.Compared with the relatively mature single fiber concrete,this paper studied the basic mechanical properties and durability of pavement cement concrete by using kinds of different materials.In this paper,the empirical formula is used to obtain the initial mixing ratio of pavement cement concrete,and then the orthogonal test design method is used to optimize the mixing ratio.The influence of various factors on the flexural strength of pavement cement concrete is analyzed by means of the range analysis,so that the optimal mix ratio of cement concrete is obtained.The effects of single fiber and mixed fiber on the basic mechanical properties and early crack resistance of pavement cement concrete were studied by adding steel fiber and polyacrylonitrile fiber on the basis of optimal mix ratio,and the optimal formula of mixed fiber is defined.The optimum dosage of mixed fiber is analyzed by this formula.By using recycled coarse aggregate instead of natural coarse aggregate,the effect of recycled coarse aggregate on the basic mechanical properties and frost resistance of regenerated cement concrete was studied on the basis of the best mixed fiber content.Because the flexural strength is used as strength design basis in the design of the pavement engineering,this paper studies the recycled coarse aggregate on flexural strength loss of pavement concrete after freeze-thaw cycle,more than specified compressive strength of the freeze-thaw cycle test.The results showed that:(1)When single steel fiber was mixed,compressive strength,flexural strength,splitting tensile strength and compressive elastic modulus are significantly improved.When of polyacrylonitrile fiber was mixed,bending strength,splitting tensile strength and compressive elastic modulus have a certain increase.Cube compressive strength slightly improved.When mixed with two mixed fibers,the compressive strength is more strong than that without the fiber.Flexural strength,compressive elastic modulus and splitting tensile strength were significantly improved.the degree of improvement depends on the fiber content and the proportion of the mixed effect.(2)The compressive strength of cement concrete with mixed fiber is reduced to a certain extent.Flexural strength and splitting tensile strength showed a significant decrease.The degree of reduction of the basic mechanical properties depends on the amount of recycled coarse aggregate.The freeze-drying test was carried out on mixed fiber reinforced concrete with mixed coarse aggregate and recycled coarse aggregate.It was found that the frost resistance of mixed fiber recycled concrete was lower than that of mixed fiber concrete,but the effect was not significant.The frost resistance of mixed fiber recycled concrete depends on the amount of recycled coarse aggregate.(3)The compressive strength,flexural strength and splitting tensile strength of the Pavement mixed fiber cement concrete and the Pavement mixed fiber recycled cement concrete meet the requirements of opened to traffic in 3 days,and reach the strength requirement of 28 days' secondary road pavement concrete.