Effect of Rust Protective Coating and Bar Size on Bond Strength of Rebar in Concrete

Abstract

This study presents an experimental investigation on bond performance of various rust protective coated steel with concrete. The aim of the research is to evaluate the effectiveness of different coatings in enhancing the bond strength between reinforcement bars and concrete. Different cases of coatings were considered such as case-I (untreated), case-II (acrylic polymer coated) and case-III (epoxy coated). The study used three distinct bar sizes, including 12 mm, 16 mm, and 20 mm, to assess the impact of bar sizes on bond performance. Pull-out tests were used in the experimental program to investigate how well the coated bars adhered to the concrete. The study's findings demonstrated that using coated bars increased the binding strength of steel bars in concrete. The epoxy-coated bars had the higher bond strength, followed by the acrylic polymer-coated bars, compared to the untreated bars. Due to the production of a thin layer of corrosion products on the steel surface, the corrosion of steel bars in concrete weakens the binding strength between the steel bars and concrete. This thin layer limits the surface area in which the steel bar contacts the concrete, which lowers the bond strength. Because of their greater chemical resistance, increased tensile strength, and less permeability, epoxy coatings often offer better corrosion protection and adhesion than acrylic polymer coatings. The 12 mm bars showed higher bond strength compared to the 16 mm and 20 mm bars. Overall, the study found that the performance of the connection between concrete and steel can be enhanced by the use of corrosion protective coatings on steel bars. The outcomes also made clear how crucial it is to choose the right coatings and bar sizes for reinforced concrete structures to get the best possible bond behavior.