Research On Mechanics Performance And Durability Of Steel Fiber Reinforced Ceramisite Concrete

Steel fiber lightweight aggregate concrete(SFRLC)is an energy conservation and environmental protection type concrete material,which has the advantages of light weight of lightweight aggregate concrete and high toughness of steel fiber reinforced concrete,and meets the requirements of construction industry development and the strategic target of energy conservation and green building.In view of the multiple factors of the actual environment of concrete,the influences of steel fiber and strength grade on the mechanical properties and durability under multiple factors of SFRLC were systematically investigated.The main research results are as follows:(1)Preparation technology of SFRLC was put forward.Refer to the mix proportion design method of relevant technical regulations,several different strength grades of SFRLC were prepared by using the overall calculation method.The influences of steel fiber and strength grade on the mechanical properties of SFRLC were investigated.The results show that the increase of steel fiber volume fraction can improve flexible strength and splitting tensile strength of SFRLC and the effect is not significant on compressive strength.Otherwise,the increase of matrix strength can increase mechanical properties of SFRLC which involves in this paper.Combined with the results of experiment and analysis,the corresponding mathematical models were established.(2)Sulfate attack resistance of SFRLC was studied.The influences of steel fiber volume fraction and strength grade on anticorrosion coefficient of compressive strength,mass loss rate and relative dynamic modulus of SFRLC were investigated when specimens were subjected to single sulfate attack,the coupling effects of sulfate attack & dry–wet cycles or sulfate attack & axial compression,and the coupling effects of these triple factors,respectively.Meanwhile,performance attenuation model and service life prediction model were established.The results show that the increase of steel fiber volume fraction can effectively restrain the decreases of relative dynamic modulus and compressive strength of SFRLC,but the effect is not obvious for mass loss.The increase of matrix strength grade can effectively restrain mass loss of SFRLC,especially for high strength grade SFRLC but the restrain effect is not obvious on the decreases of relative dynamic modulus and compressive strength.It also finds that,the increase of sulfate concentration can accelerate sulfate attack process.The influence on sulfate attack process is not obvious under the coupling effects of sulfate attack & dry–wet cycles.Otherwise,the sulfate attack process is accelerated under the coupling effects of sulfate attack & axial compression.Sulfate attack is most seriousness under the coupling effects of triple factors,but the restrain effect of steel fiber to sulfate attack is also most significant.According to damage analysis of SFRLC under the coupling effects of multiple factors,damage model for sulfate attack of SFRLC based on double indexes was proposed,According to damage result and performance attenuation law of SFRLC in sulfate attack environment,performance attenuation model and service life prediction model was proposed for SFRLC.(3)Chloride attack resistance of SFRLC was studied.The influences of steel fiber volume fraction and strength grade on mass loss rate,relative dynamic modulus and chlorine ion content of SFRLC were investigated when specimens were subjected to single chloride attack,or the coupling effects of chloride attack & dry–wet cycles.Meanwhile,performance attenuation model and service life prediction model were established.The results show that the increase of steel fiber volume fraction can effectively restrain mass loss and chloride penetration velocity,but the effect is not obvious for relative dynamic modulus.The increase of matrix strength grade can effectively restrain mass loss of SFRLC and but the restrain effect is not obvious on chloride penetration velocity and the decrease of relative dynamic modulus.It also finds that,the increase of chlorine ion content can obviously accelerate mass loss and chloride penetration velocity of SFRLC,but the effect is not obvious for relative dynamic modulus.Dry–wet cycles can accelerate the chloride penetration velocity,but the influences on mass loss and relative dynamic modulus of SFRLC are not obvious.According to erosion laws of chloride,damage model for chloride attack of SFRLC based on double indexes with relative dynamic modulus loss and mass loss was proposed.According to damage result and performance attenuation law of SFRLC in chloride attack environment,service life prediction model was proposed for SFRLC.