Effect of organic corrosion inhibitors on the void content properties of repair mortars

The deterioration of reinforced concrete (RC) structures due to durability issues has become a global concern, with reinforcement corrosion being a leading cause of premature failure. In response, the use of repair mortars with additives such as corrosion inhibitors has emerged as an effective solution to retrofit structures and prevent further corrosion. However, assessing the properties of repair mortars combined with corrosion inhibitors before application is essential, as they may negatively impact performance. Void content, also known as porosity, is one of the most commonly determined physical properties of building materials, which directly impacts durability. High void content can reduce the effectiveness of repair materials by lowering strength and allowing harmful substances to penetrate, weakening the bond. Therefore, this study experimentally investigated the effect of organic corrosion inhibitors (OCIs) on void content in four types of repair mortars: commercial polymer mortar, general cementitious mortar, fine-grained mortar, and alkali-activated geopolymer mortar. Two OCIs, based on alkanol amine and sodium gluconate, were introduced at varying levels to the repair mortars to assess their impact on void content. The results indicated that both OCIs caused increments in void contents in the 2% to 82% range, highlighting the need for caution when balancing their benefits with potential risks. The results of this experimental investigation were used to propose a simple model for predicting the void content resulting from OCI addition in repair mortars, offering a valuable tool for optimising repair materials and enhancing long-term durability in restoration projects.