Effects of Interface Bonding Agent and Surface Roughness on the Direct-Shear Bond between Existing Concrete and New Concrete

Abstract

Bonding new concrete on existing concrete for structural repair or strengthening must consider the various transferring forces occurred at the connection such as tensile, compression, and moment. One of the important transferring force is the shear force which depends on various factors. This research is the study of the parameters affecting on the direct-shear bond between existing concrete and new concrete. The sample used in the direct-shear bond test was a cylinder, diameter 150 mm, length 300 mm, connected in the middle between the existing concrete and the new concrete. The parameters of this study were: (1) two different types of the surfaces of existing concrete defined as smooth surfaces and rough surfaces; and (2) various types of bonding agent (Epoxy resins, Latex, Cement glue and Crystallization). The results of this study were found that the interface with rough surfaces would provide a better direct-shear bond than smooth surfaces. The use of the bonding agent as the interface layer, especially epoxy resin, would enhance significantly the direct-shear bond.