Modified hydrotalcites for improved corrosion protection of reinforcing steel in concrete-preparation, characterization, and assessment in alkaline chloride solution

Journal article (2016)

Authors

Z. Yang Materials and Environment - CEG
H. Fischer External organisation
J.M.C. Mol (OLD) MSE-6
R.B. Polder Materials and Environment - CEG
Research Group
Materials and Environment (CEG) (TU Delft)
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Published Date

2016

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Materials- Mechanics- Management & Design

Research Group

Materials and Environment

Abstract

Six MgAl hydrotalcites (Mg/Al = 2 and 3) were synthesized through the modification of two carbonate hydrotalcites (i.e., Mg(2)AlCO3 and Mg(3)AlCO3) by two amino acids (11aminoundecanoic acid and paminobenzoic acid) and sodium nitrite. They were characterized by means of XRD, FTIR, TG/DSC, and elemental analysis. The ion exchange of the modified hydrotalcites (MHTs) were investigated in alkaline chloride solution and the results showed that ion exchange occurred between free chloride ions and the intercalated inhibitive anions in MHT. The corrosion inhibition of three MHTs (Mg/Al = 2) was evaluated based on the open circuit potential and linear polarization resistance evolution of steel coupons in 0.1 M NaOH solution stepwise enriched with chlorides and the results showed that MHT, in particular, Mg(2)AlpAB exhibited an improved corrosion inhibiting effect in terms of a higher chloride threshold compared to its constituent free inhibitor ions (i.e., pAB). This study confirms the dual protection that MHT, in particular, Mg(2)AlpAB, offers to the steel: capturing chlorides and simultaneously releasing the intercalated inhibitors to further protect the steel from corrosion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim