Experimental Study On Bond Behavior Of Corroded Steel Bars And Recycled Concrete

At present,most of the construction waste in our country cause the waste of resources and environmental pollution.Recycled concrete technology is one of the important measures for the development of green concrete,which can realize the sustainable development of architecture,resources and environment.The characteristics of recycled aggregate bond properties of recycled concrete and steel is different from ordinary concrete,steel corrosion has great influence on the safety and durability of reinforced concrete structure,the research problem of bonding between corroded steel bars and recycled concrete has important significance and engineering value.The main contents and results of this paper are as follows:1.Based on the replacement rate of recycled coarse aggregate which was 70%,the influence of recycled fine aggregate on the basic mechanical properties of recycled concrete was studied through carbonation strengthening treatment.The replacement rate of recycled fine aggregate was 0%,20%,30%,40%,and the condition of fine aggregate was compared with that non-carbonated recycled fine aggregate.The experimental results show that the compressive strength of recycled concrete decreases with the increase of the replacement rate of recycled fine aggregate,the carbonated recycled fine aggregate can increase the compressive strength of recycled concrete.2.This paper was to design 11 sets of mix ratios and fabricated 132 drawing specimens with the size of 160mm × 160mm × 160mm.The accelerated corrosion method was used to the steel bars in test pieces,study the steel corrosion rate(0%,1%,2%,4%),the replacement rate of recycled coarse aggregate(0%,30%,50%,70%,100%),carbonation recycled fine aggregate replacement rate(0%,20%,30%,40%)on influence of-specimen bond stiffness,peak slip and peak uplift resistance of recycled concrete,and compared with that non-carbonated condition.3.This paper carried out center pulling test under monotonic load,the influence of the peak tensile stress,the peak slip and the bond stiffness of the specimen on the corrosion rate of the reinforcement,the replacement rate of recycled coarse and fine aggregate,and the carbonation of recycled fine aggregate were obtained.4.According to the test data,the load slip curves between corroded steel bars and recycled concrete are established,and the shape of the curve is roughly similar to that of ordinary concrete.With the increase of the replacement ratio of recycled coarse and fine aggregate,the peak slip of the slip curve between the corroded steel bar and the recycled concrete which have through carbonation strengthening treatment decreases gradually,and the lower the slope is,the smaller the residual strength is;Compared with non-carbonated recycled fine aggregate,the load slip curves between recycled fine aggregate concrete and corroded steel bars were more smooth,and the residual strength was greater than that of the recycled fine aggregate;With the increase of corrosion rate of reinforcement,the bond strength between corroded reinforcement and recycled concrete increases first and then decreases,and the residual strength of the curve is smaller.The test data are fitted and the relationship between average bond stress slip of corroded reinforcement and recycled concrete under monotonic load is presented.