Earth stabilisation with MgO-based cement
Authors: Ellina Bernard, Daniel Rentsch, Raphael Kuhn, Guillaume Habert, Pietro Lura
This study compares, for the first time, MgO-based (MB) cement and Portland-based (PB) cement for stabilizing earth mortars. While MB and PB earth mortars reach similar strength, MB cement stabilization demonstrates superior early-age performance. Thermogravimetric analysis, X-ray diffraction, 29Si and 31P NMR spectroscopies show that the cement reacts in both systems and allow to establish the phase assemblages. The stabilized earth pastes contain less hydroxide phases, indicating a pozzolanic reaction in both cases.
MB-stabilized clay mortars retain about 1/3 of the compressive strength of pure MB mortar, while with PB this proportion is only 1/5. This difference demonstrates that MB is more compatible with clay minerals and more suitable for stabilizing earth mortars. If MB cement could be produced with renewable energy from CO2-free sources (instead of from magnesite), stabilization of earth mortars with MB would be substantially more CO2 efficient than with PB.
Keywords: MgO-based cement; Magnesium silicate hydrates (M-S-H); Raw clays.
