Performance of corrosion inhibitors in cracked and uncracked silica fume cement concrete beams

Abstract

In the reported study, the performance of some generic and proprietary inhibitors in inhibiting corrosion of reinforcing steel in cracked and uncracked silica fume cement concrete beams was evaluated. Two types of concrete beams, uncracked and cracked, were prepared according to ASTM G109 and they were exposed to wetting and drying cycles of salty water. The performance of the selected inhibitors in decreasing reinforcement corrosion in the concrete beams was monitored by measuring the micro-cell current and corrosion potentials. Furthermore, the top bars in the beams were removed and visually inspected to note the type and extent of corrosion. All the selected corrosion inhibitors performed well in the uncracked concrete beams. The overall cost per year for uncracked beams incorporating the selected inhibitors decreased by 2.75 to 4.8 times compared to the control specimens, i.e. without an inhibitor. The calcium nitrite-based inhibitors exhibited the best performance in terms of corrosion protection in the cracked concrete beams. However, other inhibitors, such as generic inhibitor based on calcium nitrite, liquid concrete admixture based on amine carboxylate and liquid concrete admixture based on modified amino alcohol, provided none or at best limited protection to the reinforcing steel. The mechanism of corrosion inhibition of the selected inhibitors is also presented.

Keywords:

• Inhibitors
• cracked and uncracked silica fume cement concrete
• micro-cell current
• reinforcement corrosion

Acknowledgements

The support provided by King Fahd University of Petroleum and Minerals is acknowledged. The first author also acknowledges the scholarship provided by Thamar University, Yemen, for his higher studies.