Study On Preparation And Bending Toughness Of Gradient Distributed Steel Fiber Concrete

High strength and high performance have become the development direction of modern concrete,and traditional mix design methods tend to be empirical.In order to make the concrete structure more dense,improve the utilization rate of concrete voidage,reduce the amount of cementing material,and improve the strength of concrete matrix,this thesis studies the aggregate gradation of high-strength concrete based on the particle interference theory.On this basis,it optimizes the mix ratio with the allocation coefficient and water-cement ratio.In order to improve the brittleness of High Strength Concrete(HSC),Steel Fiber Reinforced High Strength Concrete(SFRHSC)was prepared by adding steel fiber reinforced high strength concrete(SFRHSC).Steel fiber high strength concrete has been widely used in various projects because of its excellent performance.But in fact,the use of steel fiber cost is high,the material utilization rate is low,in the process of mixing forming easy clumping,is not conducive to the work of concrete,so that steel fiber high strength concrete in the forming or construction and face some technical difficulties.Layered Steel Fiber Reinforced Concrete(LSFRC)and Composite Steel Fiber Reinforced Concrete(Composite Steel Fiber Reinforced Concrete),The emergence of CSFRC provides a new way to solve the above problems.In this thesis,the bending toughness of steel fiber high-strength concrete with gradient distribution of steel fiber is analyzed from the Angle of layered gradient distribution,volume content and type of steel fiber concrete,and the comparison is made with the mixed fiber concrete steel fiber concrete and composite steel fiber concrete.The main contents are as follows:(1)Based on particle interference theory,flow and cube compressive strength tests were conducted on the proportions of discontinuous and continuous gradations with maximum particle sizes of 19,9.5 and 4.75 mm,respectively,to study the influence of aggregate gradation on the flow and compressive strength of high-strength concrete.The influence of water-binder ratio and stripping coefficient on concrete is also explored.(2)The effect of curing temperature on compressive strength of concrete was analyzed by setting temperature gradient of 20,40 and 60℃ and maintaining curing humidity above 95%.The drying shrinkage at 1,3,7 and 14 days after each curing temperature was tested,and the influence of each curing temperature on the volume deformation of graded high-strength concrete was explored.(3)The effect of the volume fraction of fine steel fibers on the fluidity,compressive strength and bending toughness of the mixed high-strength concrete was studied by adding the volume fraction of fine steel fibers at 0,0.5,1.0,1.5 and 2.0%.(4)The influence of laminate gradient and laminate gradient content on the bending toughness of LSFRC was analyzed by controlling the total volume and content of laminate steel fiber as 1% and 2%.The effects of layered gradient distribution on bending toughness of LSFRC were analyzed by microsteel fiber(WX12),shear steel fiber(JQ)and end-hook steel fiber(DG25,DG35 and DG60)with different length-diameter ratios.(5)By controlling the total volume rate of steel fiber composite way is 0.5%,the bending toughness of two kinds of composite steel fiber concrete and mixed steel fiber concrete is compared and analyzed,and the advantages and disadvantages of composite steel fiber concrete are analyzed.(6)The effect of layered gradient distribution on flexural toughness of high-strength concrete is analyzed by combining composite steel fiber concrete with steel fiber volume ratio of 1 and 2%.