Comparative Study of Inhibitors on the Corrosion of Mild Steel Reinforcement in Concrete

The suitability of some inhibitors in reducing corrosion of mild steel reinforcement in concrete (immersed in seawater and dilute sulphuric acid) to simulate two factors was investigated, using the potential monitoring technique. Potential readings were taken in accordance with ASTMC 109-92 and compressive strengths determined as laid down by ASTMC 39-96. Initial Voltage readings were recorded for each block and subsequent readings taken at an interval of one month for a year. The experimental results show that in seawater, admixture of potassium dichromate and formaldehyde were identified as good inhibitor for concrete mix, but it caused a substantial loss of compressive strength. Calcium nitrite on the other hand, exhibited the best inhibiting qualities with negligible effect on the compressive strength of the concrete. It is also evidence from the results, that all the inhibitors tested showed good inhibiting properties when the blocks were immersed in dilute sulphuric acid solution. It is therefore recommended that calcium nitrite be adopted for concretes expose to marine conditions and acidic environment whereas the admixture of potassium dichromate and formaldehyde is highly recommended for concrete structure exposed to acidic environments.