Durability Of GFRP-concrete Bond Property Exposed To Sulfate Environment

GFRP-concrete structures are widely used in civil engineering,and the durability under stress and corrosion is a key issue in the long-term service safety of the structure.In this paper,the effects of immersion period and damage degree on the macroscopic mechanical properties and mesostructure of GFRP-concrete are studied from the macroscopic and mesoscale by the coupling effect of load damage and sulfate corrosion solution.The durability of GFRP-concrete bond properties under load damage and sulfate coupling was obtained.Conclusions were as following:(1)With the increase of immersion time in sulfate solution,the ultimate tensile strength of GFRP tends to decrease.The ultimate tensile strength of the bars decreased by 13.45% at 150 d,In the process of 0~30d,the tensile strength of GFRP tends to decrease fastest.After 90 days of corrosion,the rate of degradation of tensile strength gradually becomes slower;the elastic modulus and Poisson’s ratio both increase first and then decrease.(2)The change trend of bond strength can be divided into two stages: 0-90 d increases rapidly,and decreases slowly from 90 d to 150 d,The amount of slip increases with increasing corrosion time.The initial damage has little effect on the bond strength of GFRP-concrete,but it will lead to an increase in the amount of slip.The greater the damage,the more the slip increases.(3)Testing the mesostructure of the GFRP-concrete test piece interface,with the increase of soaking time,the proportion of Ca and Na in GFRP tends to increase,the proportion of Ca in concrete continues to decrease,the proportion of Na in mass continues to increase,and the rate of change of mass ratio of each element decreases with the increase of corrosion time.