Impact of different cold joints on corrosion vulnerability and structural behavior of reinforced concrete beams with microscale insights

Delays during concrete casting may form cold joints resulting in weak interfaces, increasing permeability and compromising the structural performance of reinforced concrete members. This study examines how different cold joint configurations affect the corrosion vulnerability and structural response of reinforced concrete beams. Beams with cold joints, both with and without adherence enhancers at the joint interfaces, were fabricated to evaluate the impact on corrosion extent. Microscale deterioration at the steel and concrete interface was investigated by SEM/EDS analyses. Among the specimens tested, the RBS-C beam, which contained a diagonal cold joint in the shear span, showed the largest reductions in load-carrying capacity and ductility and exhibited a brittle shear failure under the adopted corrosion and loading conditions. Although the horizontal joint at mid-span performed better than the diagonal shear region joint, it still showed considerable degradation. Microscale observations confirmed more severe chloride-induced corrosion and localized pitting in the diagonally jointed specimens. The outcomes of the study demonstrate how different cold joint configurations interact with corrosion processes and influence the durability and structural performance of reinforced concrete beams. Within the tested conditions, the results show how joint location and corrosion influenced the failure behavior and suggest that unplanned cold joints in regions of high shear demand warrant particular attention in chloride-exposed reinforced concrete members.