Migrating corrosion inhibitor blend for reinforced concrete: Part 1 - Prevention of corrosion

The efficiency of a migrating corrosion inhibitor in preventing corrosion o f mild steel was investigated in saturated calcium hydroxide (Ca[OH](2)) so lutions and in mortar. The protective effect of the inhibitor against pitti ng corrosion caused by chloride attack and against uniform corrosion as a r esult of carbonation was determined. Results showed that high concentration s approximate to 10%) allowed the inhibition of pitting corrosion initiatio n In solution containing I M/L sodium chloride (NaCl). However, inhibiting properties can be lost by evaporation of the volatile constituent of the in hibitor or by the precipitation of the nonvolatile fraction of the inhibito r in presence of calcium ions. Addition of the inhibitor blend to mortar yi elded a retardation of the corrosion initiation in the case of chloride-ind uced corrosion, but no significant reduction in corrosion rate. No effect w as found in carbonated samples, and no influence on the corrosion rate was detected. Additionally, the estimation of the extent of the retarding effec t on corrosion initiation. on real structures was difficult, as the inhibit or was found to evaporate from the mortar. This evaporation resulted in a l oss of inhibiting properties. Hence, the long-term efficiency of the inhibi tor could not be guaranteed.