Influence of corrosion on bond strength in reinforced recycled aggregate concrete with fly ash

Corrosion in RC structures significantly affects the bond between concrete and steel, leading to unpredictable failures of RC structures. Hence, this study aimed to assess the influence of corrosion on the bond strength (pull-out) of concrete and embedded steel reinforcement in concrete. Also, this research aimed to evaluate the impact of recycled concrete aggregates (RCA) and fly ash (FA) on the bond performance of RC elements. Concrete specimens of 150 mm size cubes with embedded reinforcement were cast with and without 20% FA and with and without 100% RCA. After curing for 28 days, these specimens were subjected to controlled corrosion conditions, targeting corrosion levels of 0%, 5%, 10%, and 15%. The experimental results showed that using RCA decreased ultimate bond strength by 40.86% compared to traditional concrete with 20% FA. Also, the study observed that a small amount of corrosion (up to 5%) could positively impact ultimate bond strength. However, as the corrosion level increased to 5%, 10%, and 15%, ultimate bond strength in specimens made with RCA and 20% FA decreased by 7.14%, 41%, and 60%, respectively. Similarly, ultimate bond strength in specimens made with NCA and 20% FA decreased by 34.84% and 43.61%, respectively at 10% and 15% corrosion levels. Analytical models from past literature validated the bond strength values obtained through pull-out tests.