Performance and microstructural development of MgO-SiO2 binders under different curing conditions

- Performance of MgO-SiO2 binders under different curing conditions are evaluated.
- M-S-H formation and stability varied under ambient and elevated temperatures.
- Elevated temperatures at 60 °C increased initial hydration rate and early strength.
- Sealed conditions at 30 °C yielded highest strengths at longer (≥14 days) durations.
- Lower M-S-H content and polymerization observed under 60 °C without enough humidity.

This study investigated the strength and microstructural development of reactive MgO-SiO2 binder systems under different curing conditions. Rapid strength development associated with accelerated dissolution and hydration involving magnesium silicate hydrate (M-S-H) formation was observed at early ages under elevated temperatures (60 °C). Although samples cured under ambient temperatures demonstrated a slow rate of M-S-H formation at early ages, their hydration proceeded over time. Samples cured under sealed conditions achieved 28-day strengths >50 MPa because of higher M-S-H contents, higher polymerization and denser microstructures. The content, structure and stability of M-S-H under different conditions determined the overall strength development of MgO-SiO2 binders.