Experimental Study On The Effect Of Recycled Aggregate On Bond Behavior Between Steel Rebar And Concrete

Currently,China is faced with the situation of high yield and low recovery of recycled concrete,and the application of recycled concrete is an effective way to solve this problem.Scientific Outlook on Development requires the construction of a resource-saving and environment-friendly society,adhering to the path of sustainable development.In order to save natural resources and protect the living environment,it is necessary to deal with the construction waste.The production and utilization of recycled concrete is an effective way to solve the problem of construction waste.In order to study the influence of different parameters on the bond behavior between steel bars and recycled concrete,the amount of recycled fine aggregate,the diameter of steel bar and the length of anchor were considered.126 recycled concrete pull-out specimens was carried out by means of strain gauges in the steel reinforcement.Experimental study shows: 1)Under the same conditions,both the ultimate bearing capacity and the bond strength of the specimens were increased with the increase of the diameter of the steel bars;2)under the same conditions,no matter adding the recycled coarse aggregate or adding the recycled fine aggregate,the ultimate load of the specimen was increased with the increase of the anchorage length,but the average bond stress was decreased gradually.The smaller the diameter of steel bars is,the lower the average bond strength is.3)The shape of steel bars has a great influence on the bond strength.Under the same conditions,the bond strength of HRB400 steel bars is much higher than that of HPB300 bars,and the bond strength between recycled concrete and HRB400 steel bars is 4~5 times of that of HRB300 steel bars;4)Under the condition of the same mixture ratio,When the replacement ratio of recycled coarse aggregate is 100%,the bond strength between steel rebar and recycled concrete decrease,but the relative bond strength increased,therefore,considering the bond slip,using recycled concrete with 100% recycled coarse aggregate is feasible in engineering;5)It is suggested that the anchorage length of steel bar in recycled concrete is the same as that of common concrete.6)Compared to the reference specimen,adding 50% recycled coarse aggregate,30% recycled fine aggregate relative bond strength between concrete and steel is improved,therefore,considering the bond performance,using recycled concrete with 50% recycled coarse aggregate,30% recycled fine aggregate in practical engineering is feasible.7)Whether adding the recycled coarse aggregate or adding the recycled fine aggregate,it is suggested that the value of the parameter a of the HPB300 steel rebar is 0.15,and the value of the parameter a of the HRB400 steel rebar is 0.1.