Layered double hydroxides modify the reaction of sodium silicate-activated slag cements

Xinyuan Ke, Susan A. Bernal, John L. Provis

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10 Citations (SciVal)

Abstract

The impact of adding two types of layered double hydroxides (LDHs), commercial hydrotalcite (HT) and its thermally treated form (CLDH), on the reaction kinetics and phase assemblage development of a sodium silicate-activated slag cement was investigated. The reaction kinetics of LDH-modified cements was assessed by isothermal calorimetry, and the results were correlated with in situ attenuated total reflection Fourier transform infrared spectroscopy results collected over the first days of reaction, to identify the structural evolution of the main binding phase forming in these cements: a sodium-containing calcium aluminosilicate hydrate (C-(N)-A-S-H)-type gel. The addition of either HT or CLDH into sodium silicate-activated slag paste accelerates the precipitation of reaction products and increases the formation of HT in these cements, without causing significant changes to the C-(N)-A-S-H binding phase. This is extremely relevant in terms of the durability of alkali-activated slag cements, as a higher content of the HT-like phase has the potential to reduce their chloride permeability and enhance carbonation resistance.
Original languageEnglish
Pages (from-to)52-60
Number of pages8
JournalGreen Materials
Volume7
Issue number2
Early online date14 Jun 2019
DOIs
Publication statusPublished - 30 Jun 2019

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