Effect of application of corrosion inhibitors on the properties of concrete

Abstract

Reinforced concrete is the most widely used construction material but its durability issues still exist. Apart from structural design failures, the most significant cause of deterioration and premature failure of RC structures is the corrosion of the steel reinforcement. In last quarter century, many methods have been developed to reduce or prevent corrosion of steel in concrete. From all the methods available for corrosion protection, corrosion inhibitors sound very promising. In last two decades, corrosion inhibitors have been extensively used to protect steel reinforcement in RC structures. Most of the commercially available corrosion inhibitors are used for chloride (Cl-) induced corrosion and are not effective for carbonation induced corrosion. In this study, effectiveness of three corrosion inhibitors on the properties of concrete is evaluated. The three corrosion inhibitors used in this study are Aminoethanol, para-Aminobenzoic Acid and Sika ® FerroGard ®-903+. Sika ® FerroGard ®-903+ is a commercially available corrosion inhibitor, whereas, Aminoethanol and para-Aminobenzoic Acid are organic chemicals. Corrosion inhibition property on Ordinary Portland Cement - 43 Grade and Pozzolanic Portland Cement was studied. For this study, carbonation depth tests and compressive strength tests were conducted on concrete specimens. For carbonation depth test 100mm cubes were used. Whereas, for compressive strength test 150mm cubes were used. Compressive strength tests were conducted for 28 day and 56 day, from the day of casting. Carbonation depth was measured on specimens for 7 day, 14 day, 21 day, 28 day, 35 day, 42 day carbonation from the day, they were cured in carbonation chamber. It was observed that all the corrosion inhibitors presented positive results for carbonation depth tests. It was noted that Aminoethanol and para-Aminobenzoic Acid gave best results but corrosion inhibition was also shown by Sika ® FerroGard ®-903+. For compressive strength test, no adverse effect on the strength of concrete was noted on applying corrosion inhibitors.