Study On The Preparation And Properties Of Steel Fiber Self-compacting Concrete

Self-compacting concrete has been widely concerned due to its excellent workability and can ensure the molding quality without the need of vibrating in the complicated structural reinforcement area.It is an important research direction for concrete materials.Due to the large amount of cementitious materials,it results in large shrinkage and easy cracking,which affects the durability of the concrete.Steel fiber has the function of strengthening,toughening,and cracking.Therefore,it is incorporated into self-compacting concrete to study its effect on the performance of self-compacting concrete.With steel fiber self-compacting concrete as the research object,this paper,based on laboratory tests,orthogonal test methods and ultra-volume methods,studies the steel fiber self-compacting concrete fiber content of the best fiber,work performance,mechanical properties and durability and so on.The main research results obtained are as follows:(1)The results of research on workability show that although the workability of self-compacting concrete with steel fiber added has decreased,it still meets the requirements for use and still retains the advantages of high workability.(2)The incorporation of steel fibers can improve the compressive strength,flexural strength,split tensile strength,and elastic modulus of self-compacting concrete.The compressive strength can be increased by 30%,and the ratio of axial compressive strength to cubic compressive strength is between 0.69 and 0.91,which is an increase compared to ordinary concrete.The incorporation of steel fibers can significantly increase the flexural strength and splitting tensile strength of self-compacting concrete.The flexural strength can reach 1/3 of the cubic compressive strength,and the splitting resistance can be reached when the volume ratio of steel fibers is 1.2%.Tensile strength increased by 89.7%.The small volume fraction of steel fiber has little effect on the elastic modulus,and the increase rate is only 7% at 14 days.For each mechanical property,the strength value increases with the age and the intensity increases rapidly 14 days before,and tends to be stable in the later period.Moreover,the steel fiber fully exerts its own enhancement,toughening,and crack-resistance in the interior of the concrete and improves the ductility and destruction of the concrete.(3)Through the mechanical properties test of steel fiber self-compacting concrete,the cubic compressive strength of steel fiber self-compacting concrete shows a logarithmic and linear relationship with the age and the axial compressive strength;the flexural strength and the cubic compressive strength The polymorphism and logarithmic relationship were observed between the age and the age,and the linear and logarithmic relationships between the elastic modulus and the compressive strength and age of the cube,respectively.The tensile strength of the cleavage was linearly related to the cubic compressive strength and age.Then the formula of different steel fiber volume rate was obtained,and the degree of conformity was better.(4)Through the durability test of steel fiber self-compacting concrete,it was found that the incorporation of steel fibers increased the impermeability rating and the maximum increase was 58.3%;the water seepage height was reduced and the maximum reduction was 50% and the carbonization depth was also reduced.The maximum reduction is 51%.However,the smaller and larger steel fiber volume fraction has little effect on its durability,and the best volume rate is 0.9% for anti-permeability and carbonization resistance.(5)Using ANSYS CFX software,the pouring process of self-compacting concrete beams with 0.9% steel fiber volume rate was simulated.Through the cloud image,it was found that the distribution of steel fibers in the first half of the beam was more uniform and that in the latter half was re-distribution.Using the pouring speed as a parameter,the results of 0.35 m/s,0.5 m/s,and 0.65 m/s pouring speed were quantified,and the number of steel fibers in each beam segment was approximately calculated.The results show that when the pouring speed is 0.35m/s,the distribution of steel fibers is more uniform than other casting speeds.