Experimental Study On The Bond-SLIP Properties Of Recycled Concrete Reinforced With Stirrups

With advantages such as saving resources and protecting the environment, recycled concrete is becoming a new type of green building materials. It’s an important aspect to study the properties of recycled concrete which can be caused by the problem of bond-slip with reinforced. Using the experimental studies and theoretical analysis methods, the bond-slip properties of recycled concrete reinforced with stirrup were studied. Completed works are as follows:Firstly, the mix ratio with same strength of 5 kinds of replacement rate (0, 30%,50%,70%,100%) of recycled concrete is selected from 15 kinds of mix ratios with reference to the mix design of common concrete mix ratio. Based on this mix ratio, the cube axis strength, splitting tensile strength and axis tensile strength of the 15 groups of specimens were tested. The basic mechanical parameters of recycled concrete materials are obtained.Secondly,60 ordinary simple drawing tests were completed which were used to study the reinforced recycled concrete bond slip performance, under different conditions. The test results show that, the peak bond stress, residual adhesive stress, peak slip value and total energy of specimens with stirrup were more than specimens without stirrups. Under the same reinforcement conditions, peak slip and brittleness coefficient of specimens increased when recycled aggregate replacement increased. As the bar diameter reduced, the peak bond stress, peak slip value, total energy and brittle coefficient of specimens increase.Then, in order to obtain the unified value of the control parameters and all average bond slip curves were calculated. In comparison with the specimens without stirrup, the value a is basically the same, and the value b is 1 which can be used as the boundary point to distinguish brittle failure to ductile failure.Finally, bond stress distribution curve of recycled concrete with stirrup were studied on the based of the inner-embedded strain-gauge method. On the anchorage position function of recycled concrete, stirrup is very important. Compared to recycled concrete without stirrup, the average bond stiffness of recycled concrete with stirrup between steel bar and recycled concrete increase, and bond stress distribution was more homogeneous. At last, the stirrup restraint reinforced recycled concrete bond-slip constitutive relation was established.