Effects of surface washing on the mitigation of concrete corrosion under sewer conditions

• Washing disturbed the concrete corrosion activity over a few months.
• Washing posed largest pH increase & SUR decrease on the most severely corroded coupon.
• The slowest recovery of SUR occurred on the most severely corroded coupon.
• Washing caused no significant difference of concrete loss over 4.5 years.
• Frequent washing at short intervals might be needed to control corrosion in long term.

This study systematically investigated the potential of mitigating sulfide induced sewer concrete corrosion by surface washing. Washing interrupted the corrosion activity of concrete coupons by increasing the surface pH and decreasing the H2S uptake rates (SUR). The SUR recovered to the level prior to washing within 60–140 days. The slowest recovery rate was from the most severely corroded coupon. However, no significant difference was observed for concrete mass loss of the washed and unwashed coupons after 54 months. The results suggest that frequent washing at short intervals of a few months might be needed to control corrosion over a long term.