Experimental Study On Bond Behavior Between Recycled Concrete And Steel Bar

Recycled concrete is a new type of concrete,which is different from ordinary concrete by replacing natural aggregate with recycled aggregate.The main source of recycled aggregate is construction waste,concrete waste and so on.Coarse aggregate and fine aggregate is made by construction waste and concrete waste after mechanical crushing and sieving.The test produced a total of 72 recycled concrete pull-out specimens,by the pullout test to study the effects of recycled concrete strength(C30～C50),bond length(5d、8d、10d、12d),lateral hoops of recycled concrete bond behavior between steel bar and influence.The main results are as follows:(1)The influence of the strength of recycled concrete on the bond performance is not significantly different from the research results of ordinary concrete.Bond strength increases with the increase of concrete strength,but it is not proportional to the relationship between the bond strength and the concrete strength;Bonding strength is proportional to the splitting tensile strength of recycled concrete,but the ratio is higher than that of ordinary concrete.(2)The effect of bond length on the bond behavior of recycled concrete is consistent with common concrete.The bond strength decreased with the increase of bond length,but the decrease gradually decreases.The relative bond strength(τu/fcu)is linear with the relative bond length(la/d),(3)Stirrup lateral confinement effect can make concrete specimens have good bond ductility and bonding-slip curves of the declining segment,the bonding strength increased,but the amplitude is very small.(4)As with ordinary concrete,the bond slip curve of recycled concrete is divided into four parts,the micro slip stage,the strength rise stage,the strength peak stage and the strength decline stage.This distinction and characteristics of bond strength characteristics of slip feature points corresponding to the four stage,there are differences and common concrete,finally through the statistical analysis of bond constitutive relation given.