Investigation of the Protection Efficiency of Repair Mortar Against Chloride Corrosion in Repaired Zones of Reinforced Concrete

In this study, specimens with concrete interfaces and repair mortar were designed to simulate a concrete repair system to investigate the efficiency of seven polymer-based cement repair mortars when they were applied to concrete supports. The steel protection capacity of the mortars against chloride attack and chloride diffusion along the interface between the concrete support and the repair mortar was analysed. The mortar/concrete support system was studied using accelerated chloride corrosion tests and open-circuit potential measurements to monitor the behaviour of the steel rebar embedded in the system. The results highlight that the performance of mortar against chloride corrosion depends on its durability and mechanical properties, such as porosity, pore-size distribution, chloride diffusion coefficient, compressive strength, and bond strength. A high-polymer proportion in the mortar (polymer/cement ratio = 0.21) helps reduce chloride penetration but reduces the critical chloride concentration responsible for the initiation of corrosion. In addition, the mortar’s bond strength of 0.8 MPa leads to crack development in the mortar/C30 concrete support system. A crack width of 5 m at the interface increases the chloride diffusivity along this interface, and consequently, the risk of corrosion initiation.