Magnesium silicate hydrate (M-S-H) is the principal binding phase in MgO-SiO2 cement systems. It forms through the hydration of MgO into brucite, which subsequently reacts with amorphous silica. The formation process is relatively slow in suspensions or pastes, but can be accelerated by additives such as phosphate salts and sodium carbonate, which also influence the final structure.

One of the main processing challenges of MgO-SiO2 cement systems is the high water demand of both MgO and silica, particularly those with high specific surface area (SSA). Standard dispersants designed for Portland cement are often ineffective in these systems, whereas phosphate-based dispersants such as sodium hexametaphosphate (NaHMP) have shown improved performance. While several studies have investigated the mechanical strength of MgO–SiO₂ systems, the use of additives and fillers, such as sand, often complicates direct interpretation of the results.

To better understand and improve these materials, advanced techniques like nanoindentation and 1H NMR are being used to explore how additives affect the microstructure and mechanical behavior of M-S-H.

Contact: Charlotte Dewitte, Ellina Bernard, Mateusz Wyrzykowski

Publications:

C. Dewitte, M. Neji, M. Wyrzykowski, E. Bernard, Influence of carbonates on chemo-mechanical properties of magnesium silicate hydrates, Proceedings of the RILEM Spring Convention and Conference 2025.

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