Acceleration of M-S-H gel formation through the addition of alkali carbonates

The varied properties of different cements enable the cement industry to shift towards the manufacture of application-specific cements rather than a general-purpose binder. M-S-H cements could offer a good alternative for specialist application, and could potentially have a lower carbon footprint as they require much lower temperatures for their production compared with Portland cement (PC). M-S-H cements harden with M-S-H gel as a binding phase, which is the equivalent of calcium silicate hydrate (C-S-H) gel in PC. However, the development of M-S-H is much slower than that of C-S-H, resulting in insufficient strength development of the product; thus, limiting the applications of M-S-H cement. The present study investigates the effects of an additive to enhance the development of M-S-H gel. Sodium bicarbonate was tested, and its impacts on the evolution of M-S-H gel were studied. The obtained results indicate that sodium bicarbonate has the ability to aid the development of M-S-H by promoting the reaction of Mg(OH)2 and SiO2, which resulted in the accelerated development of M-S-H gel.