Study On Static Force And Fatigue Properties Of PVA Fiber Reinforced Cement Matrix Composites After Seawater Corrosion

PVA fiber cement-based composite(PVA-FRCC)is an environmentally friendly high toughness material with low price,good toughness and certain corrosion resistance,which is widely used in engineering.In the application of coastal engineering will be affected by seawater erosion,some buildings will also be subjected to cyclic loading,causing great damage to the building.In this paper,the mechanical properties,durability and fatigue properties of PVA-FRCC after seawater corrosion were studied.The specific contents and conclusions are as follows :(1)The PVA-FRCC with different fiber content(0,0.5%,1%,1.5%,2%)was wet-dry cycle corroded by 10 % seawater solution.The compressive strength,flexural strength,mass loss,chloride ion content and dynamic elastic modulus of PVA-FRCC with different corrosion ages were tested,and the effects of fiber content and corrosion age on the performance of PVA-FRCC were analyzed.The results show that the compressive strength,flexural strength,mass,relative dynamic elastic modulus loss rate and chloride ion content of the material are significantly reduced after adding fiber,and the specimen with 1.5 % fiber content is the most obvious.(2)The flexural fatigue test of PVA-FRCC with 0 and 180 days corrosion age was carried out under stress levels of 0.9,0.8 and 0.7,and the fatigue life of each fiber content specimen was obtained.The relationship between fiber content and seawater corrosion and the flexural fatigue life of the specimen was analyzed,and the strain-fatigue life curve was drawn.It was found that the PVA-FRCC before and after corrosion conformed to the three-stage law.(3)The flexural fatigue life of PVA-FRCC is analyzed by Weibull distribution theory.The results show that the flexural fatigue life of PVA-FRCC conforms to the two-parameter Weibull distribution;the double logarithmic fatigue equation of PVA-FRCC was derived by linear fitting,and the fatigue limit strength was obtained by fatigue equation.(4)The compressive fatigue residual strength test of specimens with 0 and 1.5% fiber content before and after seawater corrosion was carried out.The results show that the compressive fatigue life of PVA-FRCC before and after corrosion conforms to the logarithmic normal distribution.The fatigue life of specimens under different failure probability can be calculated by the life function obtained by linear regression.Through the statistical analysis of the initial compressive strength and residual strength test data of PVA-FRCC,the probability distribution model of the initial compressive strength and residual strength of cement-based specimens with different fiber content based on normal distribution parameters is obtained.The results show that the initial compressive strength and residual compressive strength of PVA-FRCC are well fitted based on normal distribution.(5)Based on the initial compressive strength and residual compressive strength normal distribution model and residual compressive strength model,the P-R function expression can be obtained,and the residual strength of PVA-FRCC under the failure probability of 0.05,0.5and 0.95 can be obtained.The residual strength attenuation model and residual strength attenuation expression are obtained by curve fitting,so as to predict the compressive fatigue residual strength under different fatigue loading times before and after PVA-FRCC corrosion.