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The effect of two types of modified Mg-Al hydrotalcites on reinforcement corrosion in cement mortar

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Author: Yang, Z. · Polder, R. · Mol, J.M.C. · Andrade, C.
Type:article
Date:2017
Source:Cement and Concrete Research, 100, 186-202
Identifier: 777402
doi: doi:10.1016/j.cemconres.2017.06.004
Keywords: Architecture and Building · Chloride (D) · Corrosion (C) · Durability (C) · Modified hydrotalcites · Mortar (E) · Buildings and Infrastructures · 2015 Urbanisation · 2015 Fluid & Solid Mechanics · SR - Structural Reliability · TS - Technical Sciences

Abstract

Two modified Mg-Al hydrotalcites (MHTs), (MHT-pAB and MHT-NO2) were incorporated into mortar (with different w/c ratios) in two different ways: (1) as one of the mixing components in bulk mortar; (2) as part of cement paste coating of the reinforcing steel. Accelerated chloride migration, cyclic wetting-drying and diffusion tests were performed to investigate their effect on reinforcement corrosion. The results indicated that MHTs could be promising alternatives for preventing chloride-induced corrosion when an appropriate dosage is adopted and applied in a proper way, particularly, replacing 5% mass of cement by MHT-pAB in bulk mortar or as a coating of reinforcing steel (MHT-pAB/MHT-NO2 to replace 20% mass of cement). The effect of MHT-pAB on time-to-corrosion initiation (TTC) of reinforcing steel was estimated using the DuraCrete model. It was found that the incorporation of 5% MHT-pAB in bulk mortar led to a more than double TTC relative to reference mortar without MHTs.