Study On Workability And Mechanical Performance Of Steel Fiber Reinforced Two-graded Aggregate Concrete

Two-graded aggregate concrete with coarse aggregate maximum size of 40 mm compares to that of 20 mm,when the intensity of phase at the same level,two-graded aggregate concrete of cement,concrete adiabatic temperature rise and drying shrinkage can obviously decrease,and has a tendency to use in hydraulic structures,but due to the concrete itself characteristic,in terms of crack cannot completely meet the requirement of the engineering practice.Adding steel fiber to two-graded aggregate concrete can be a good solution.As the size is larger and the steel fiber is long in steel fiber reinforced two-graded aggregate concrete,whether the study on mixture ratio design,workability and mechanical performance of steel fiber reinforced concrete with coarse aggregate maximum size of 20 mm can be fully used in that of 40 mm needs to be explored.In this paper,based on national natural science foundation of China: study on toughness and fracture performance of steel fiber reinforced two-graded concrete(51679221),workability,rheological property and mechanical performance of C30 steel fiber reinforced two-graded concrete mixture were studied.The main conclusions are as follows:(1)The effects of sand ratio,water consumption and steel fiber content on the slump of mixture were studied by steel fiber reinforced two-graded aggregate concrete mixture slump test of 100 groups.The results show that slump of mixture increases with the increase of sand ratio and water consumption while decreases with the increase of steel fiber content.Based on the test results,a model of the variation of slump of steel fiber reinforced two-graded aggregate concrete with sand rate and water consumption is given.(2)The influence factors of rheological property of steel fiber reinforced twograded aggregate concrete were studied by rheological test.The results show that the yield stress of mixing material decreases with the increase of sand ratio,with the increase of steel fiber content and water consumption yield stress remains basically the same.The plastic viscosity increases with the increase of sand ratio and decreases with the increase of water consumption.Within the testing range,the greater the plastic viscosity value of the mixing material,the better the cohesiveness of the mixing material.(3)The effects of steel fiber content and sand ratio on compressive strength of steel fiber reinforced two-graded aggregate concrete were studied by compression strength test.The results show that the compressive strength increases with the increase of steel fiber content and it can increase 28.5% with the steel fiber content of 1.25%.When the sand ratio is less than 36%,the compressive strength increases with the increase of the sand ratio.When the sand rate is between 36% and 42%,the compressive strength does not change significantly.On the basis of experiments,the stress-strain relationship model of steel fiber secondary concrete under uniaxial compression failure is established based on damage theory and numerical fitting,and the damage evolution model is established based on Weibull distribution and linear distribution.(4)The effects of steel fiber content and sand ratio on splitting tensile strength of steel fiber reinforced two-graded aggregate concrete were studied.The results show that the splitting tensile strength increases with the increase of the steel fiber content,and the increase is the largest when the steel fiber content was 1.25%,up to 80.9%;it does not change obviously with the increase of sand ratio.The influence coefficient of steel fiber reinforced concrete(SFRC)splitting strength is calculated according to the specification.The influence coefficient of steel fiber reinforced concrete splitting strength was calculated according to the specification,and the result shows that the influence coefficient of steel fiber reinforced two-graded aggregate concrete is less than that of plain concrete.(6)According to the workability and mechanical performance test results,a practical engineering advice of steel fiber reinforced two-graded aggregate concrete mixture were given: advice steel fiber secondary distribution of steel fiber concrete content was 0.5%,the smallest sand rate was 36%,the smallest unit water consumption is 200 kg,on this basis,the steel fiber content increase 0.1%,and the corresponding minimum sand ratio increased by 1%,the smallest unit water consumption increases 3kg to meet the workability and mechanical properties.