Evaluation of high temperature effects on concrete-reinforcement bar bond using automated digital image processing

Behavior of reinforced concrete is strongly affected by bonding between concrete and reinforcing bar. It is well known that adherence among concrete and reinforcing bar is remarkably influenced by several properties of reinforced concrete including compressive strength, tensile strength and cover depth. On the other hand, adherence of reinforcing bar is influenced from cross-sectional dimension, embedment length, corrosion and curing conditions. Another significant parameter which adversely affects bonding between concrete and reinforcing bar is high temperature. Thereby, in this investigation, an experimental study is performed to assess the effect of high temperatures on several properties of reinforced concrete. Consequently, an attempt is made to establish correlations among the determined parameters designating the bonding between concrete and reinforcement bar. Additionally, image processing techniques are utilized to quantify the morphological properties of cracks occurred. It is found that, when temperature rises beyond 500°C, behavior of reinforced concrete is dominated by bonding between concrete and reinforcing bar, rather than individual mechanical properties of concrete and reinforcing bar. © 2015, Indian Journal of Engineering and Materials Sciences. All rights reserved.