Experimental Research On Stressing Performances Of Self-compacting Recycled Concrete Beams

With the rapid development of urbanization,a large amount of construction waste and the inefficient construction of ordinary concrete cannot meet the basic state policy of energy saving and emission reduction,and obstructing the rapid rise of high and complex structures.Self-compacting recycled concrete formed by using 100% recycled coarse aggregate for self-compacting concrete has the advantages of resource conservation,simple construction and low cost and so on.In view of the fact that beam is an important load-bearing component in the building structure,reinforcement is densely distributed and concrete are not easy to pour at the ends and the bottom,and their mechanical properties are seriously affected by pouring quality.The paper will apply self-compacting recycled concrete to structural beams and systematically studies the flexural and shear behavior.In order to study the flexural behavior of self-compacting recycled concrete beams,five self-compacting recycled concrete beams and two ordinary concrete beams were produced.The influence of reinforcement ratios and types of concrete on the cracking moment,ultimate load,short-term stiffness,maximum crack width,curvature ductility and displacement ductility of self-compacting recycled concrete were tested.Test results show that the ultimate load of self-compacting recycled concrete beams is equivalent to that of ordinary concrete beams.The flexural moment and short-term stiffness of self-compacting recycled concrete beam are 18% and 13.7% lower than ordinary concrete beams.Curvature ductility and displacement ductility are 1.3 times and 1.69 times than that of ordinary concrete beams,respectively.In addition,formulas for cracking moment and short-term stiffness of self-compacting recycled concrete beam are proposed.Minimum reinforcement ratio,maximum reinforcement ratio and optimal reinforcement ratio of self-compacting recycled concrete beams were decided.In order to study the shear performance of self-compacting recycled concrete beams,a total of 10 self-compacting recycled concrete beams with stirrups and 4 self-compacting recycled concrete beams without stirrups and 2 ordinary reinforced concrete beams were tested.The effects of the type o f concrete,compressive strength of concrete,shear span-depth ratio,stirrup ratio on the failure mode,load-deflection curve,shear capacity and deformation performance of self-compacting recycled concrete beams are systematically analyzed.Test results show that the failure mode and load-deflection curves of self-compacting recycled concrete beams are similar to the ordinary concrete beams,the ultimate load is equivalent to ordinary concrete beams,deformation of self-compacting recycled concrete beams is superior to ordinary concrete beams,shear ductility is about 1.5 times than the ordinary concrete beams.In addition,the paper also recommends that the maximum stirrup ratio of self-compacting recycled concrete beams is 0.75%,the best stirrup ratio is 0.35%.Besides,a formula for calculating the shear capacity is proposed.