Study of Various Corrosion Mitigation Methods for Reinforced Concrete

Abstract

Reinforced concrete is the most widely used building material in the modern world, owing to its ability to sustain loading over a very large span of time. But the functioning of reinforced concrete may be affected due to initiation of corrosion, which is one of the major mechanisms of deterioration in reinforced concrete. Harmful effects of corrosion become increasingly prominent as the environment that the concrete is subjected to becomes more severe. It is difficult to remedy a structure affected by corrosion, as the effects of corrosion manifest visually after a certain degree of deterioration has already occurred, and so addressing the root cause becomes necessary. For this, newer buildings are being provided with mitigation techniques during construction to prolong their life, especially in the presence of severe environments.

This study aims to compare different mitigation techniques in similar environments to study their effectiveness in detail. For this, Concrete beam specimens of size 200mm x 200mm x 400mm with embedded reinforcement of 12mm diameter, and concrete cylinder specimens of 150mm diameter and 300mm height with 12mm diameter centrally embedded reinforcement were cast with corrosion mitigation techniques such as Corrosion Inhibiting Admixture, Concrete and Reinforcement Coatings, and Cathodic Protection. These specimens were then submerged in 5% NaCl solution. Electrochemical measurements for corrosion potential and corrosion rate were done using Half-Cell potential and Linear Polarization Resistance methods of corrosion evaluation.

The study concluded that Cathodic protection provided the best performance in extreme environments, and can be recommended over all other methods. Reinforcement surface coating also performs excellently in short term, but long-term application may not be recommended for extreme environments due to higher activity. Concrete Surface coating performs good in extreme conditions, but damage to the surface coating layer may lead to localized corrosion, thus making its application viable in cases where the wear and tear is minimum. Corrosion inhibitor performs poorly in extreme conditions, but application may still be viable in mild and moderate conditions.