Experimental Study On Influence Of Steel Fiber On The Durability Of High Performance Concrete

In recent years,high-performance concrete has been increasingly applied in practical engineering due to its excellent properties of carbonation resistance,frost resistance,impermeability,chloride ion resistance and corrosion resistance.Because of the high ductility,good mechanical properties and durability,steel fiber reinforced concrete(SFRC)is widely concerned.However,in the current research results,there are few research materials about the influence of steel fiber on the durability of HPC.In view of this,the mix proportion of HPC is designed in this paper,a series of durability tests for steel fiber HPC are carried out,and the theoretical analysis are made based on the test results.The research content and main work of this paper are as follows:(1)Through the determination of slump,slump flow and strength,the influence of steel fiber on the fluidity and mechanical properties of HPC was studied,the results showed that steel fiber reduced the fluidity of concrete;steel fiber can also improve the mechanical properties of HPC,and the growth rate of mechanical properties is related to the fiber content.(2)The effect of steel fiber content and carbonation age on carbonation was tested by rapid carbonization,steel fiber can improve the carbonation resistance of concrete and delay the process of carbonation;the measured carbonation depth of steel fiber highperformance concrete basically conformed to the empirical equation of(3 6)?.(3)The influence of steel fiber content on permeability of high performance concrete was studied by infiltrate method and rapid migration test,and microstructure were observed by electron microscope scanning of concrete,the results showed that the steel fiber can improve the resistance to water penetration and the chloride ion erosion resistance of high performance concrete,and the permeability of both all drop at first and rose later with the increase of steel fiber content;steel fiber can optimize the internal structure of concrete and improve its compactness.(4)The effect of steel fiber content and freeze-thaw cycle times on the frost resistance was studied by quick freezing method.The results showed that the frost resistance of concrete decreased with the increase of freeze-thaw cycle times;the steel fiber can limit the frost heaving of moisture in the concrete,reduce the internal damage of high-performance concrete,and slow down the loss of relative dynamic modulus and mass.