Research Of Steel Fiber Types And Curing Methods On Mechanical Properties Of RPC

Ultra-high performance concrete has the advantages of high strength,good durability and remarkable anti-seepage effect.More and more ocean engineering and island engineering also use ultra-high performance concrete to build structures or components.At the same time,a new kind of copper-plated bending microfilament steel fiber is being used widely.The copper-plated microfilament is curved,its bonding property is better than that of straight microfilament,and its surface is coated with copper film,so its corrosion resistance is remarkable.In this paper,from the copper-plated bending steel fiber and sea water curing as a starting point,the main work is to prepare fiber-free ultra-high performance concrete,and then on this basis to study different types of steel fiber(with emphasis on copper-plated steel fiber)and different curing conditions(with emphasis on sea water curing)for ultra-high performance concrete.The influence of mechanical properties.The research contents include the following three aspects:(1)the preparation of ultra high performance concrete.On the basis of the existing research on ultra-high performance concrete at home and abroad,according to the local actual situation,super-high performance concrete with compressive strength up to 120 MPa has been developed by using ordinary soil and wood materials and conventional technology.The results show that the optimum water binder ratio is 0.18~0.2,the content of water reducer is about 2%,and the kinds of water reducer have their own advantages and disadvantages.(2)the effect of different volume fraction and different kinds of steel fibers on the mechanical properties of ultra-high performance concrete is studied.It includes compressive strength,tensile strength and flexural strength.The research shows that the tensile strength and flexural strength of the concrete are significantly improved.Compared with plain concrete,the splitting tensile strength and flexural strength of copper-coated steel fiber reinforced ultra-high performance concrete increased by 211% and 92% when the volume ratio was 3%,and 53% and 44% respectively when the volume ratio was 3%.(3)to explore the effect of curing methods on the early mechanical properties of steel fiber ultra high performance concrete.The mechanical properties of steel fiber reinforced concrete(SFRC)cured by standard curing,fresh water curing and seawater curing were tested,and the scanning electron microscopy(SEM)was carried out.The results show that the early mechanical properties of plain concrete cured in seawater are similar to those cured in fresh water,and the harmful ions in seawater have little effect on the mechanical properties of plain concrete.In addition,the mechanical properties of ultrahigh performance concrete cured by copper-coated steel fiber under seawater and freshwater are similar,indicating that the harmful ions of seawater have little effect on the early mechanical properties of steel fiber reinforced ultra-high performance concrete,and the corrosion resistance of copper-coated steel fiber in a short period of time is not very good.