Evaluation of migrating corrosion inhibitors for the protection of steel reinforcement in concrete exposed to coastal marine conditions in Khanh Hoa (Vietnam)

• N.L. Cao¹, D.S. Shevtsov², V.C. Nguyen¹, D.A. Nguyen¹, V.T. Tran¹, T.M.H. Le¹, V.K. Dong¹, K.N. Ho¹, Q.Q. Nong¹ and I.D. Zartsyn²

¹ Coastal Branch, the Joint Vietnam-Russia Tropical Science and Technology Research Center, 30 Nguyen Thien Thuat, Nha Trang, Vietnam
² Faculty of Chemistry, Voronezh State University, Universitetskaya pl. 1, Voronezh, 394018, Russia

Abstract: Two commercial migrating corrosion inhibitors (MCIs): MasterProtect 8000 CI, MasterProtect 8500 CI (MBCC Group), and one promising product, MCI-VN, were tested for the protection of steel reinforcement in concrete exposed to seawater along the Khanh Hoa coast (Vietnam) over 6 months. It was found that the alkoxysilane-based impregnations MasterProtect 8000 CI and MasterProtect 8500 CI reduced biofouling on the concrete surface by approximately twofold compared to the control samples without inhibitors. This effect is presumed to be associated with surface hydrophobization. The MCI-VN impregnation reduced biofouling by 30%, while other application methods of MCI showed no significant impact on biofouling. The corrosion state of the reinforcing steel was assessed using electrochemical methods and visual inspection of the steel surface following GOST 31383-2008. A passive state of the steel was observed when MCI-VN was applied as migrating impregnations to the surface of hardened concrete before seawater exposure. When MCI-VN was used as an admixture during concrete preparation, and in the case of MasterProtect 8000 CI and MasterProtect 8500 CI impregnations, electrochemical measurements indicated a passive state. However, visual inspection revealed surface corrosion spots on the reinforcement, classifying the condition as unstable passive. Possible directions for improving regulatory guidelines for assessing the corrosion state of steel reinforcement and corrosion rate have been proposed to distinguish the effectiveness of various corrosion protection measures, including MCIs.

Keywords: migrating corrosion inhibitor, pitting corrosion, reinforcing steel, concrete

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1190-1203
doi: 10.17675/2305-6894-2025-14-3-10

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