Flexural performance of reinforced concrete beams repaired using conventional cementitious mortars

Initial defects in reinforced concrete (RC) structures frequently arise during and after construction due to deficiencies in materials, methods, workmanship, or environmental conditions. In developing countries, the repair of RC structures is often constrained by limited resource availability, necessitating the utilization of conventional cementitious repair materials. This research investigates the efficacy of various cementitious repair materials on the flexural behavior of nine RC beam specimens. The repair materials evaluated include ordinary Portland cement mortar (OPCM), OPCM incorporating polypropylene fiber (PF), and a polymer-modified cement mortar. Each repair material was used with and without epoxy resin (ER). Standardized surface preparation was implemented on all RC beam specimens before the application of repair materials. The flexural performance of damaged RC beams is evaluated by analyzing the load-bearing capacity, deformation behavior, crack resistance, and failure modes through a comparative assessment of different repair cementitious material combinations. The results demonstrate that incorporating ER and PF within the OPCM matrix effectively restores the load-bearing capacity of the repaired RC beam specimens to between 90% and 105% of the original capacity in control specimens. Additionally, the research emphasizes the significance of material compatibility in achieving adequate bond conditions and controlling crack development for successful RC beam repair. Finite-element analysis further validates the experimental findings, demonstrating good agreement. These results provide valuable insights into the repair strategies and the application of ordinary Portland cement-based materials for damaged RC structures, particularly in resource-limited contexts.