Abstract
The magnesium silicate hydrate (MgO-SiO2-H2O) system is an innovative eco-friendly cementitious material. However, its poor volume stability and significant shrinkage have curtailed its widespread development and utilization. The primary component for preparing the MgO-SiO2-H2O system, MgO, has a substantial impact on the properties, particularly in relation to volume stability. This research examined the effects of MgO chemical activity on the volume stability of the system. The results suggested that reducing MgO chemical activity and increasing the Mg/Si ratio result in varying reductions in the water loss ratio and drying shrinkage, with the lowest drying shrinkage ratio being 0.913 %, representing a 14.1 % reduction compared to the sample with the highest drying shrinkage ratio. MgO chemical activity affected the shrinkage deformation of the system by influencing the generation rate and content of Mg(OH)2-induced volume expansion. Additionally, the increase in the Mg/Si ratio influenced the content of Mg(OH)2, ultimately reducing drying shrinkage. At an Mg/Si ratio of 1.25, the resulting M-S-H gel resembled a T:O structure, and promoted a higher degree of polymerization of the gel. In contrast, when the Mg/Si ratio is 1.00, the M-S-H gel exhibited characteristics more akin to a T:O:T structure, leading to an even higher degree of polymerization.
Published Version
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