Optimization of deep cryogenic treatment for enhancing corrosion resistance of rebar and structural steel

Abstract

Steel is used as reinforcement member in Reinforced cement concrete. Steel is embedded in such a manner that the steel and concrete act together in resisting forces, where tensile and shear stresses are absorbed by the steel and compressive stress by the concrete. Since steel acts as a skeleton in reinforced concrete, the performance of steel is vital. Corrosion leads to volumetric expansion of the steel bars. The corrosion products exert compressive pressure on the surrounding concrete which leads to development of tensile stress field near the interface. Concrete being vulnerable to tensile force results in the formation of cracks from the proximity of the bar to the surface or between the bars. The crack resulted will allow direct exposure of steel to oxygen and moisture from the ambient ir which will accelerate the corrosion process and cause spalling of concrete from the surface of the structure. In this context the corrosion resistance of steel is of high premium. Deep cryogenic treatment is claimed to be a process hat enhances the corrosion resistance of steel. eep cryogenic treatment is a process attempted by researchers to upplement the conventional heat treatment to improve the mechanical properties of materials. Cryogenic treatment, unlike coatings, is an nexpensive one-time permanent treatment affecting the entire section of the omponent. The treatment is an add-on process over the conventional heat reatment in which the samples are cooled down to the prescribed cryogenic temperature level at a slow rate (cooling rate), maintained at this temperature (soaking temperature) for a long time (soaking period) and then heated back to room temperature (heating rate) newline