Experimental Study On Bond Behavior Between Reinforcement And Recycled Concrete With Carbonized Aggregate

Annually,a great of waste concrete has spent much resources and brought huge pressure on environment,so the research on recycling of that would take considerable economic and environmental benefits.However,the internal defects,weak interface and other bad factors of recycled coarse aggregate(RCA)takes disadvantage of the bond performance between recycled aggregate concrete(RAC)and bar.Thus,the experimental study for pretreatment of RCA and bond behavior.between RAC and reforcement is of significant for engineering.This paper mixed concrete with RCA by carbonizing in CO2,then researched whose basic mechanical and bond behavior with bars.The main work and achievements were as follows:1.Three kinds of CO2 pressure(0.1 Mpa,0.4Mpa,0.8Mpa)had been choosed to curing the RCA by 24 hours in the reactor,then choosed the most suitable CO2 pressure based on the basic properties of carbonized RCA.Otherwise,this paper also researched carbonized time whose effects for RCA.The results showed that only under suitable gas pressure could the basic properties of RCA be improved by carbonization.Besides,it got apparently enhance early and not significantly lately.2.Taking normal coarse aggregate(NCA),uncarbonized and carbonized RCA to making up RAC respectively and built 21 groups(6 specimens per group)standard cubes,21 groups(6 specimens per group)reinforcement short-anchorage specimens,5 groups(1 specimens per group)reinforcement short-anchorage specimens with strain gauge inside.According to testing cubic compressive strength and splitting tensile strength of RAC,the paper researched the effect of carbonized time and replacement rate of RCA on the mechanical properties of RAC.It showed these both increased with the extension of carbonized time and decreased as the increase of replacement ratio of RAC.3.The effects of replacement rate and carbonized time of RCA on the bonding between steel bar and RAC by pull-out test(126 specimens)with hanging basket was studied.Then,the relation of bond-slip about reforcement and RAC was proposed.It suggested that the bond behavior was better and the plan was more economical when the carbonation time was 24h.Furthermore,when the carbonized RCA took 30 percents proportion of RAC,each characteristic intensity got highest.4.The effects of replacement rate of RCA on the impact bond behavior between steel bar and recycled concrete by pull-out test(5 specimens)was studied when it was carbonized 24h.The study showed that the bond stress of the steel bar was most uniform along the direction of the anchorage length and the bond performance was the best when the replacement ratio of the RCA is 50%.