Corrosion inhibitors and other protective systems in concrete repair: concepts or misconcepts

In recent times in many parts of the world, reinforcement corrosion has become the main factor in early, premature deterioration, and sometimes failure, of concrete structures. One of the major factors contributing to this deterioration process is the environmental and climatic conditions to which a concrete structure is exposed. When the severity of environment is compounded with poor quality concrete and/or defective design and construction practices, the process of deterioration becomes interactive, cumulative and very rapid, and a cancerous growth that cannot be easily stopped.The poor durability performance of many concrete structures is causing disruption and expenditure on remedial works which owners and society cannot afford and do not wish to see repeated.A glimpse of reinforcement corrosion and some of the protection options is presented in this paper. The effect of corrosion inhibiting admixtures in concrete and concrete repair is discussed in detail. The complex issue related to the effectiveness of inhibitors in repairs is addressed, based on analysis of the differences between electrochemical activities in new and repaired structures. The paper concludes that as long as one continues to blindly use protection methods applicable for newly constructed structures for concrete repairs, the business of “repairing the repairs” will be on the rise. A broader understanding of the electrochemical differences between new and repaired concrete is necessary for effective protection of reinforcement in repaired structures.