| Concrete has been used widely in civil engineering and hydraulic engineering,and the durability of the material affects the use and safety of concrete structure directly,so the research of concrete du-rability is highly valued by domestic and foreign research field.However,the research on ratio of length-diameter of steel fiber is insufficient.In this paper,the effects of steel fiber and its ratio of length-diameter on freeze-thaw resistance and the early cracking resistance of C60 concrete were stud-ied.The main contents of this paper are as follows:(1)Through orthogonal test,the influence of factors such as water binder ratio,fly ash content and steel fiber volume ratio on the three mechanical properties(the tensile splitting strength,the ten-sion-compression ratio and the compressive strength)of C60 concrete in 28 days was comprehensively analyzed.The main conclusions were as follows:?The reinforcing effect of the tensile splitting strength and the tension-compression ratio of steel fiber reinforced concrete is very large,but it has little effect on the compressive strength.When the steel fiber content is too much,these three properties will be weakened.?The preparation of steel fiber concrete of the optimum mix C60 is:0.30 of the water to binder ratio,the content of fly ash is up to 20%,and the volume ratio of steel fiber is about 1.50%.(2)Based on the best mix proportion,the influence of steel fiber's ratio of length-diameter on the early cracking resistance,the mechanical properties before and after freeze-thaw and the frost re-sistance of C60 concrete was studied.The main conclusions are as follow:?the steel fiber can suppress the early crack of high strength concrete.When the area and quantity of the early cracks are reduced to a minimum,the ratio of length-diameter of the steel fiber is 50,and the crack resistance grade of the high strength concrete reaches the first grade.?The compressive strength,splitting tensile strength and flex-ural strength of C60 steel fiber reinforced concrete reach the maximum at the ratio of length-diameter of steel fiber is 75,50 and 50 separately.Considering the ratio of length-diameter of 50,the mechanical properties of steel fiber are the best.?The effect of ratio of length-diameter of steel fiber on the com-pressive strength of the matrix is less than that of freeze-thaw cycles.?When the ratio of length-diameter of steel fiber is 50,the flexural strength and splitting tensile strength loss are the small-est.When the ratio of length-diameter is 75,the loss is less than the ratio of length-diameter of 50.Without steel fiber and the ratio of length to diameter is 25,the loss was the largest.?The ratio of length-diameter of steel fiber 50 and 75 have obvious enhancement effect on the frost resistance of high strength concrete.In this paper,the influence of steel fiber's ratio of length-diameter on the mechanical properties and durability of C60 concrete.The results show that the C60 steel fiber reinforced concrete with the best anti cracking,frost resistance and mechanical properties is:the water to binder ratio is 0.30,the fly ash content is taken by 20%,the volume ratio of steel fiber is taken to be 1.50%,and the length to di-ameter ratio of steel fiber is taken up to 50.It provides a theoretical basis for the establishment of steel fiber concrete frost resistance index,it also provides reference and direction for the experimental study on the influence of steel fiber length diameter ratio on the durability of high strength concrete. |
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