Study On Bond Performance Of Reinforced Bar And Recycled Concrete

The research on new materials and environmental protection materials has become a trend at the present stage,and the comprehensive utilization of recycled aggregate concrete(RAC)can bring great economic and environmental benefits to the reduction of environmental pollution and the reuse of waste materials.Fiber reinforced composites,as new materials in recent years,have been widely used in engineering fields for their excellent properties.The combination of these two new materials has brought a variety of new research topics to many scholars.In this paper,the bond properties between reinforcement bars and RAC are studied by synthesizing these two materials,and three factors which influence the ratio of coarse aggregate substitution,aggregate particle size and bond anchoring length of reinforcement bar are selected to study and analyze.To study the bond behavior between reinforcement bars and RAC.This paper adopts the research method of combining experimental research with theoretical analysis.The experimental research includes the test of the mechanical properties of recycled concrete and the central pull-out test,and the experimental study of different aggregate substitution rate,different aggregate size and anchorage length of reinforcement bar.Study the contact of different factors and the effect to mechanical property and bond behavior.The major contributions as follows:(1)Through the concrete mechanics performance test(cube compressive strength test,splitting tensile test,axial compression test and modulus of elasticity test),study the bond behavior between reinforcement bars and RAC.It can summarize the mechanics performance of concrete under different aggregate substitution rate and different aggregate size through observe test phenomenon and test date.The research shows that with the increase of recycled aggregates,the strength of concrete is gradually reduced;with the increase of maximum aggregate size,the strength of concrete is gradually increased.(2)The emphases on this paper is through pull-out test to study the bond-slip stress and bond behavior of reinforcement bars and RAC.On basis of the test,we research the influence that different replacement ratio of recycled aggregate,the different aggregate size and anchorage length and stress distribution of reinforcement bars to the bonding property between reinforcement bars and RAC,and suggest the anchorage length of reinforcement bar.The results show that the peak of bond stress first increase and then decrease with the increase of anchorage length,it indicate that the 5D of the anchorage length can best reflect the bond behavior.The 100% replacement ratio of recycled aggregate is lower than the 0% replacement ratio on the maximum slippage.With the increase of aggregate size,the bond behavior is increased,and the range of increase is also increasing.(3)Based on the result of test and theoretical analysis to build the bond-slip constitutive relation.On basis of non-linear regression to study the effect that different replacement ratio of recycled aggregate,different aggregate size and anchorage length to bond-stress slip.Compared with the measured values of test,showed that the fitting and experimental values are excellent in matching.