Experimental Study On Bond-slip Between Steel Bar And Recycled Concrete

In recent years, as the continuous consumption of natural resources and the increase of construction waste, in addition, recycled concrete has superiority of environmental protection and economic efficiency. These all cause the research of recycled concrete becoming the hot spot. So that promotion the research of recycled concrete develops unceasingly. But it is just not systematic and comprehensive. The engineering design and the construction aspect urgent need to understand the bond properties between recycled concrete and steel bar. At present, although the domestic and foreign scholars have carried out some research work, but most of it is under static load, the research of bond-slip between recycled concrete and steel bar is relatively few.Firstly, this article according to the request of "Concrete Structure Design Code" (GB50010-2002), the experimental of recycled concrete has been carried on under static load. As many influence factors of bond and anchorage is analyzed, some main influence factors are made to carry out a trial protect design, which including recycled concrete strength, recycled coarse aggregate replacement percentage, cover thickness and anchorage length. So that, just about five different recycled aggregate replacement percentage(0%,30%,50%,75%,100%) concrete of total twenty-four specimens are designed to complete the experiment. In this process, the destruction phenomenon and the failure modes of specimens are observed. Based the analysis of the test data, the load-slip curve and the average bond stress-slip curve are draw.Secondly, according to the experimental results, the factors that affect on recycled concrete bond properties are analyzed one by one, so the influence on bond properties are also discussed. In addition, this article also analyzed the bond and anchorage mechanism between recycled concrete and steel bar. Through carries on the statistical regression to the test data, and combined with predecessor's research results, get the bond-slip constitutive model that can be suitable in recycled concrete.Thirdly, after understanding the bond behavior between recycled concrete and steel bar under static load, this article also study the bond behavior between recycled concrete and steel bar under low circle repeated load that to inspect the dynamic properties of recycled concrete. And also many influence factors of bond and anchorage is analyzed, these main influence factors are made to carry out a trial protect design, which including recycled concrete strength, recycled coarse aggregate replacement percentage(0%,30%,50%), stress ratio, stress level and amplitude. So, about fifty groups with total forty-five specimens are observed. In this process, the destruction phenomenon and the failure modes of specimens are observed. Based the analysis of the test data, the load-slip curve and the average bond stress-slip curve are draw.Finally, according to the test data, the factors impact on recycled concrete under dynamic load have been detailed analyzed, and contrastive analysis to that is under static load. So that we can get further research about the bond deterioration that caused by these factors. Base on this, we also analyzed the bond and anchorage mechanism between recycled concrete and steel bar that under low circle repeated load. Through carries on the statistical regression to the test data, and combined with predecessor's research results, get the bond-slip constitutive model that can be suitable in dynamic load.