Study On Mechanical Properties Of Silica Fume/Steel-Basalt Hybrid Fiber Highstrength Concrete

With the rapid development of science and technology in the 21 st century,the level of civil engineering construction in my country has risen to a whole new level.Skyscrapers are changing with each passing day,high-speed railways are crisscrossed,and sea-crossing bridges are built longer and longer.The world regards China as an "infrastructure madman",And behind this hard power is the development and application of high-strength concrete.The performance of high-strength concrete far exceeds that of traditional concrete,but it still has the defects of easy cracking and low toughness.Fiber concrete has strong tensile strength and toughness.The representative steel fiber concrete is relatively widely used,but the components are self-heavy and the cost is slightly higher.Basalt fiber is a new type of material with excellent performance and low price.It has a better bond with the concrete matrix.Therefore,the concrete mixed with two kinds of fibers can take advantage of the advantages of different fibers in size and performance,and it is a new exploration combine with high-strength concrete.This paper designs the basic mechanical test of concrete test block and the bending test of beam structure.Firstly,the mechanical properties of concrete mixed with silica fume,basalt fiber and steel fiber were studied.Then,based on the optimum silica fume content,the mechanical properties of steel-basalt hybrid fiber high-strength concrete with different dosage combinations were studied.Finally,with the plain concrete beams with the same mix ratio and reinforcement ratio as a control,the bending test of the rectangular beams with the best combination of the three materials was carried out.In the mechanical test,the content of single-doped silica fume is 4%,6%,8%,10%,12%,the content of basalt fiber is 0.05%,0.10%,0.15%,0.20%,0.25%,the steel fiber content is 0.3%,0.6%,0.9%,1.2%,1.5%.Among them,the compressive strength,tensile strength and flexural strength of 8% silica fume concrete are all the best;basalt fiber hardly contributes to the compressive performance of concrete,but due to the fiber’s crack resistance,the tensile strength The strength is enhanced to a certain extent.When the basalt fiber content is 0.10%,the toughness is significantly improved;the steel fiber increases the mechanical properties of the concrete.When the steel fiber content is 1.20%,the tensile strength is increased by nearly 40%.The improvement effect of concrete toughness is better than that of basalt fiber.In the beam bending test,the concrete beam with C60 mix ratio was used as the control group,and 8% silica fume,0.10% basalt fiber and 1.20% steel fiber beam were added as the test group on the basis of it.Compared with ordinary concrete beams,hybrid fiber high-strength concrete beams increase the cracking load,yield load and ultimate load to a certain extent.In the plastic deformation stage,the ability of the hybrid fiber beam to resist deformation is enhanced,so its flexural rigidity is higher;when the tensile steel bar yields to the beam failure stage,the hybrid fiber beam has many but small cracks,large mid-span deformation,and better ductility than ordinary concrete Beam.