Synthesis of modified hydrotalcites and preliminary evaluation of their corrosion

Two modified hydrotalcites (MHTs) intercalated with nitrate and aminoben-zonate anions, (i.e., CaAl-MHT-NO3 and CaAl-MHT-pAB) have been synthesized. The intercalation of CaAl-MHT-pAB was achieved by anion exchange of nitrate in the host material, CaAl-MHT-NO3, which was prepared by a coprecipitation method. Materials characterization was conducted by means of X-ray diffraction (XRD), IR-spectroscopy and thermal analysis. The results of thermal analysis combined with total organic carbon (TOC) analysis further confirmed paminobenzonate anion was successfully intercalated into the interlayer space of MHTs with a 33.1% intercalating rate. Volhard’s titrimetric analysis demonstrated that ion exchange occurred between free chloride ions in the simulated concrete pore solution and ions intercalated in MHTs. The preliminary results reported in this paper shed light on the promising use of MHTs as a new type of additive for improved corrosion protection of reinforced concrete