A feasibility study of anticorrosion applications of modified hydrotalcites in reinforced concrete

A carbonate form of Mg-Al-hydrotalcite with Mg/Al =2 and its p-aminobenzoate (pAB) modified derivative were synthesized and characterized by means of XRD, IR and TG/DSC. Mg(2)Al-CO3 was prepared by a coprecipitation method and was subsequently modified by pAB through the calcination-rehydration technique. The results from the relevant characterizations combined with total organic carbon (TOC) analysis further confirmed that pAB anions were successfully intercalated into the interlayer space of the hydrotalcite. The anticorrosion behavior of Mg(2)Al-pAB was evaluated on the basis of open circuit potential (OCP) monitoring of carbon steel in simulated concrete pore solution at pH 13 contaminated with chloride. The preliminary results from this study demonstrated that ion-exchange indeed occurred between free chloride ions in simulated concrete pore solution and the intercalated pAB anions in Mg(2)Al-pAB structure. The simultaneously released pAB anions were found to exhibit the envisaged inhibiting effect and cause a shift of corrosion initiation of the steel to higher chloride concentrations than without the modified hydrotalcite.
Structural Engineering
Civil Engineering and Geosciences