Study On Mechanical Properties And Relationship Of Steel Fiber Reinforced Concrete Cubic And Cylinderical Specimen

In this paper, steel fiber reinforced concrete(SFRC) compressive strength,splitting tensile strength and deformation tests were conducted on cubic and cylinderical specimens and mechanical performance was analyzed. The main research contents and results are as follows:1.Compression test was conducted on 168 150mm×150mm×150mm cubes and168 150 mm x 300 mm cylinders to study the effect of steel fiber volume fraction,shape and aspect ratio, concrete strength grade and specimen shape on the compressive strength of SFRC. Besides, the relationship between the compressive strength of SFRC cubes and cylinders was analyzed and a conversion factor was proposed. The test results showed that: the compressive strength increases slightly with the growth of volume fraction of steel fibers, but has a tendency to decline with the increase of aspect ratio of steel fibers; shear corrugated steel fibers have the best enhancement on the compressive strength, hooked-end better and wave shape worse;with the improvement of the strength grade of concrete, growth rate of compressive strength of SFRC rises; the conversion factor of compressive strength between SFRC cube and cylinder specimen is increasing with the improvement of concrete strength,and bigger than that of ordinary concrete.2.Splitting tensile test was conducted on 168 150mm×150mm×150mm cubes and 168 150 mm x 300 mm cylinders to study the effect of steel fiber parameters(volume fraction, shape, aspect ratio and tensile strength grade), concrete strength grade and specimen shape on the splitting tensile strength of SFRC. Besides,the relationship between the splitting tensile strength of SFRC cubes and cylinders was analyzed and a conversion factor was proposed. The test results showed that: the splitting tensile strength improves dramatically with the increase of the steel fiber volume fraction and aspect ratio; and the effect of hooked-end steel fibers and shear corrugated steel fibers on splitting tensile strength is better, and that of wave form steel fibers is poor; when the concrete strength grade is low, the tensile strength of steel fiber has no obvious influence on the splitting tensile strength of SFRC, whilethe strength grade is higher, the 600 MPa grade steel fiber reinforcement effect is lower than that of 1000 MPa and 1300 MPa grade steel fiber; with the increase of concrete strength, the splitting tensile strength growth rate increases; there is no obvious relevance between the splitting tensile strength of cube and cylinder specimen, and the obtained average conversion factor between them is 1.03.3.Based on the experimental results of the present study and the existing domestic and foreign research achievements on the tensile strength of the SFRC,regression analysis was conducted on hooked-end steel fiber reinforced coefficient of tensile strength of SFRC. Research results show that: the influence coefficient of hooked-end steel fiber on concrete splitting tensile strength of is 0.81, when concrete strength is in the range of CF20 to CF45 and 1.05 for CF50 to CF80, and the calculated value matches well with the test value, but is slightly larger than the value provided by current domestic specification.4.Splitting tensile deformation test was conducted on 168150mm×150mm×150mm cubes to study the characteristics of splitting load-deformation curves of SFRC when the steel fiber volume fraction, shape, aspect ratio and concrete strength grade changes. At the same time, the equivalent splitting tensile strength and toughness ratio were calculated to study the toughness of SFRC.The test results showed that: The bigger the steel fiber volume fraction and aspect ratio, the higher the load-deformation curve. Besides, the curve is full, and equivalent splitting tensile strength is larger; hooked-end steel fiber and shear corrugated steel fiber has relatively higher peak value of load- deformation curve, and the curve is fuller, equivalent splitting tensile strength is bigger, but wave form steel fiber is not as well as the former two; The higher the concrete strength grade, the greater the ultimate load, and when the concrete strength is high, the curve of load unload to a certain degree and then rise; Splitting tensile toughness ratio to a certain extent,reflects the toughness of concrete, the minimum value of splitting tensile toughness ratio in this test can provide reference for the design of the steel fiber reinforced concrete.