Bond Property Between TRC-Confined Concrete And Steel Bar Under Chloride Salt Dry-wet Cycle

Most of the strengthed concrete structures in marine environment are destroyed before they reach the design life,and the bond property between concrete and steel bar is the key to the cooperation of the two.Textile strengthed concrete(TRC)is a kind of cement-based composite material composed of textile and fine-grain concrete,has good bearing capacity,crack Ultimateing,impermeability,and corrosion resistance.At present,the research on the bond property between concrete and steel bar under conventional environment is more mature,but the study on the bond property between TRC-confined concrete and steel bar still needs to be further explored.In this paper,the bond property between TRC-confined concrete and steel bar under chloride salt dry-wet cycle are studied.The damage form and bond slip curve of specimen are analyzed,and the degradation of bond property between TRC-confined concrete and steel bar under different factors is obtained.Finally,the bond-slip model between TRC-confined concrete and steel bar under chloride salt dry-wet cycle was deduced based on the experimental results.The main work and conclusions are as follows:(1)Under conventional environment,compared with the unstrengthed specimen,specimen with light steel bar is still pull-out damage,the ultimate bond strength is not much different,but the residual strength is improved;the ultimate bond strength of deformed steel bar is improved by the TRC reinforcement,and the failure mode is changed from splitting damage to splitting-pulling damage.(2)The ultimate bond strength decreases with the increase of steel bar diameter,and increases with the thickness of concrete cover and the number of TRC strengthened layers.However,when the number of reinforcement layers is three or four,or the thickness of the concrete protection layer is 60 mm,the damage form is still splitting-failure.Compared with the unstrengthed specimen,the ultimate bond strength of the specimen strengthed by TRC increases,and the lower the strength of concrete is,the more obvious the reinforcement effect is,and the effect of reinforcement of specimen with different thickness of protective layer is basically the same.With the increase of dry-wet cycle times,the ultimate bond strength of deformed steel bar specimen decreases,the ultimate slip increases,and light steel bar specimen basically no change;although the bond property is greatly improved when TRC strengthed after dry-wet cycle specimen is compared with the unstrengthed specimen,the reinforcement effect is not as good as that of the TRC strengthed then dry-wet cycle specimens;finally,a bond-slip model of TRC-confined concrete and steel bar with different chlorine salt dry-wet cycle times is established.(3)With the increase of initial corrosion rate,the ultimate bond strength and ulitimate slip of group USC(unstrengthed corrosion)are significantly reduced;as for group SC(strengthed corrosion),the residual strength decreased,and the ultimate bond strength first increase slightly and then decreased.When the corrosion rate is 5%,as the dry-wet cycle times increases,the ultimate bond strength of group USC decreased significantly,while the group SC and group CS(corrosion unstrengthed)do not change obviously.Compared with three different sequences of specimens,the best TRC-confined effect is obtained by group SC.Finally,a bond-slip model for three different sequences of specimens with different chlorine salt dry-wet cycle times is established when the corrosion rate was 5%.