Study On Mechanical Properties Of Steel/Polyacrylonitrile Hybrid Fiber Concrete

In this paper,the effects of copper-plated steel fibers,polyacrylonitrile fibers and the hybrid of the two fibers on the compressive properties,splitting tensile properties and axial compressive stress-strain curves of prisms have been systematically studied.The research and analysis show that in the matrix strength of C30 / C40 / C50 concrete,the overall value of the compressive strength of C30 / C40 / C50 concrete does not change obviously after adding fiber,but has a slight increase,increasing about 10%.When the fiber content is too much,the compressive strength of concrete will decrease to a certain extent compared with that of ordinary concrete,and even lower than that of ordinary concrete.However,the value of splitting tensile strength increases obviously.The higher the matrix strength is,the greater the force value increases.In the C30 matrix,when the volume fraction of steel fiber and polyacrylonitrile fiber is1.8% and 0.3%,respectively,the splitting tensile strength reaches the maximum in this fibre reinforced concrete.When the volume ratio of steel fiber and polyacrylonitrile fiber is 1.2 %and 0.1 %,respectively,the compressive strength of the test block reaches the maximum of the fibre reinforced concrete.In the C40 matrix,when the volume fraction of steel fiber and polyacrylonitrile fiber is1.8% and 0.3%,respectively,the splitting tensile strength reaches the maximum in this fibre reinforced concrete.When the volume ratio of steel fiber and polyacrylonitrile fiber is 1.2 %and 0.2 %,respectively,the compressive strength of the test block reaches the maximum of the fibre reinforced concrete.In the C50 matrix,when the volume fraction of steel fiber and polyacrylonitrile fiber is1.8% and 0.2%,respectively,the splitting tensile strength reaches the maximum in this fibre reinforced concrete.When the volume ratio of steel fiber and polyacrylonitrile fiber is 0.6 %and 0.2 %,respectively,the compressive strength of the test block reaches the maximum of the fibre reinforced concrete.Both fibers can improve the integrity of concrete after destroying.Polyacrylonitrile fiber mainly improves the integrity of concrete after destroying but has little effect on toughening.Steel fiber is more obvious than polyacrylonitrile fiber in improving the integrity and toughness of concrete.After the concrete is broken by splitting and pulling,the polyacrylonitrile fiber is mainly shown to be broken by pulling,while the steel fiber is mainly shown to be pulled out or to have relative slippage in the crack by observing the crack under a microscope.