Study On The Anti-shear Behavior Of Bond-Interface Between New And Old Concrete

The repair and strengthening of concrete structure has become an important content of project field. The problem of anti-shear behavior of Bond-Interface between New and Old concrete is often encourtered in the repair and strengthening of concrete structure and new concrete building. In order to the security of the repair of concrete structure, the study on the mechanics performance of adherence of young on old concrete has important significance.There are a large amount of factors on the effects of anti-shear of Bond-interface, the process of anti-shear is complicated. so I do some experiments and analysis about anti-shear behavior of Bond-Interface between New and Old concrete.The main content as follows.1)Shear test of Bond-Interface of 9 new and old concrete are presented. The influences of several important factors on bond mechanics property are discussed, such as artificial chiseling on bond-interface, artificial chiseling and planting steel bar on bond-interface, greasing, artificial chiseling and planting steel bar on bond-interface. the anti-shear principle is analyzed in these experiments. every steel bar is bonded four strain guage. The changes of strain guage are observed with the increase of shear. the effect of the steel bar is analyzed though the shear tests of bond-interface of new and old concrete.2)Shear test of Bond-Interface of 57 new and old concrete are presented. The influences of several important factors on bond mechanics property are discussed, such as strength of new and old concrete, the ratio of embedded bar and interface treatment. Base on the tests, some curves are getted, such as shear-shear displacement and shear-crack width.3)Base on the comparative tests on the different concrete strength, the research prove that, with the increase of concrete strength, the shear of initial cracking of Bond-interface increases and shear-displacement decreases. with the increase of concrete strength, the second max shear increase and shear-displacement decrease. The formula about the relationship of the concrete strength and the shear of initial cracking is summarized4)Base on the comparative tests on the different ratios of embedded bar, The research prove that with the increase of the ratio of planting bar on bond-interface, the second max shear increases, shear-displacement and the crack width decrease. But when the rate of planting bar on bond-interface get to the max-ratio of planting bar, the second max shear do not increase. The notions of the max-ratio and the min-ratio of planting bar on Bond-interface are defined. as well as summarizing the formula about the min-ratio of planting bar.5)Base on the comparative tests on the different interface treatments, proving that high pressure water jet chiseling is much better than artificial chiseling, because that it can increase the shear of initial cracking of bond-interface and shear stiffness.6)Base on the research about the curves of shear-shear displacement and shear-crack width, summarizing the simplified curves of shear-shear displacement and shear-crack width.7) Base on the research about the curves of shear-shear displacement, the formula of the ductility coefficient is defined in order to reflect deformation capacity about anti-shear of bond-interface between old and new concrete under planting bar.