An Experimental Research On Bond Behavior Between Recycled Concrete And Rebars

With the rapid development of the construction industry, the demand for concreterapidly increase, which make the coarse aggregate as important raw materials forconcrete appear obviously insufficient. At the same time, wasted concrete becomesmore and more. This makes the environmental problems increasingly significant. So,effective and reasonable recycling for large number of wasted concrete and achievingthe recyclability of resources is an urgent need for environmental protection andsustainable development strategy. In current, the application of recycled concrete mixedby recycled aggregate that produce by abandoned broken concrete has become a hotspot.With the research gradually thorough on design, construction and etc, it is needed toknow the bonding properties between recycled concrete and reinforcement.This topic studies the bonding properties between recycled concrete andreinforcing bar through the test. Firstly, the basic physical and mechanical properties aremeasured according to the specification of “pebble and stone for building”(GB/T14685-2001); Then, tests consisting of9specimens were conducted. The experimentalparameters are the recycled coarse aggregate replacement ratio and the bondinganchorage length. This experiment takes the method that partly slotted on reinforcementand cohere the inner strain gauges to do pull out test. And the reinforcing bar stress,strain curves and load-slip curve which change with the different locations wereobtained. Base on this, the influence regularity of the anchorage length and recycledcoarse aggregate replacement ratio for recycled concrete bond-slip performance wasanalyzed. The expressions of the bond-slip relationship between recycled concrete andreinforcement during rising phase have been derived. The experimental results showthat the compressive strength of recycled concrete decreases with the recycled concretecoarse aggregate replacement ratio increasing, and the bonding strength betweenrecycled concrete and reinforcement decreases as well. Slip value between the recycledconcrete and the reinforcement decreases with the anchorage length increases. When theanchorage length is greater than or equal to the bar diameter of20times, anchoragelength meet the anchoring requirements of the reinforcement. Then, the paper discussesthe characteristics of recycled concrete reinforcement anchorage length, and putsforward a suggestion for the bonding properties between recycled concrete andreinforcement. Under the premise of selecting the appropriate recycled coarse aggregate replacement ratio and mixture ratio, anchorage length of deformed bars in the recycledconcrete of100%recycled coarse aggregate replacement ratio can use thecorresponding standard of ordinary concrete. Finally, this article using the finite elementmethod analyzes and studies the influence of the recycled coarse aggregate replacementrate, the anchorage length, the protective layer thickness and diameter for the bondingproperties between recycled concrete and reinforcement, and compares with theexperimental results. Results of the comparison show that simulation results agree wellwith test results. This model can be used to calculate and analyze the bonding propertiesof recycled concrete and reinforcement.