Study On Mechanical Properties And Damage Modes Of Steel Polyvinyl Alcohol Hybrid Fiber Reinforced Concrete

Steel-polyvinyl alcohol hybrid fiber concrete is a new type of hybrid composite material prepared by mixing steel fiber and polyvinyl alcohol fiber into concrete.The composite material utilizes the positive hybrid effect produced by the synergistic superposition of steel fiber and polyvinyl alcohol fiber in the concrete matrix to enhance and improve various properties of the concrete matrix.It not only has the characteristics of high compressive strength of concrete,but also because the hybrid fiber inhibits the development of cracks,when it is destroyed,its brittleness is weakened,and the ductility of plasticity and toughness are strengthened.However,at present,there are few experimental studies on the steelpolyvinyl alcohol hybrid fiber concrete,and the research on its comprehensive mechanical properties and damage mechanism is not thorough enough.This paper intends to combine the basic mechanical experimental research and the theoretical analysis of fiber crack resistance to analyze the effect of different blending methods,different fiber content,and different blending ratios on the mechanical properties and damage of steel-polyvinyl alcohol hybrid fiber concrete,so as to provide a theoretical basis for its the application in engineering construction.The main research contents and conclusions of this paper are as follows:(1)In this paper,C30 concrete is selected as the base material of the test.By selecting the total content of three different fibers(0.4%,0.8%,1.2%)and controlling the ratio of steel fiber to polyvinyl alcohol fiber(1:3,1:6,1:9),16 groups of different concrete specimens with different mix proportions were prepared.Among them,there were one group of ordinary concrete,three groups of single steel fiber concrete,three groups of single polyvinyl alcohol fiber concrete,and nine groups of steel-polyvinyl alcohol hybrid fiber concrete prepared by mixing the above-mentioned fiber content and ratio.(2)The cube compression test,splitting tensile test,flexural test and prism axial compression test were carried out on 16 groups of specimens to analyze the effects of different fiber mixing methods,different fiber content and different mixing proportion on the mechanical properties and damage failure modes of concrete matrix.The expermental analysis shows that the addition of fiber weakens the brittleness of concrete failure mode and enhances the ductility;The steel-polyvinyl alcohol hybrid fiber can hinder the crack development of concrete matrix from different levels and levels;Theaddition of fiber also comprehensively improves many mechanical properties of concrete matrix.The compressive strength,splitting tensile strength and prismatic axial compressive strength of concrete matrix are most significantly improved by the single steel fiber with the total content of 0.8%,while the flexural strength of concrete matrix is most significantly enhanced by the hybrid fiber with the ratio of 1:6 under the total content of 0.8%.At 1.2% of the total content,hybrid fibers with different proportions are more effective than single fiber in improving the mechanical properties of concrete matrix.(3)Based on the energy equivalent principle and Weibull theory,the damage constitutive model of steel-polyvinyl alcohol hybrid fiber concrete under axial compression was deduced.The influence factor of fiber content was introduced to describe the influence of hybrid fiber on the damage constitutive model,and the parameters in the model were modified according to the axial compression test.Then the damage constitutive equation and damage evolution law of steel-polyvinyl alcohol hybrid fiber concrete under uniaxial load are obtained.The equation curve is compared with the test curve,and the two curves are in good agreement.