Influence of nesquehonite seeds on hydration and carbonation of reactive magnesia cement

Among all carbonation products of reactive magnesia cement (RMC), nesquehonite exhibited the highest CO2 amount of sequestration per molar. Inducing the nesquehonite formation may improve the CO2 sequestration capacity of RMC. In this paper, nesquehonite seeds were introduced to promote the formation of nesquehonite in RMC. The performances of RMCs with 0%, 0.5%, 1%, 1.5% and 2% nesquehonite seeds were studied and compared with that of RMC mixed with hydromagnesite seeds. It was found that the hydration of RMC could be facilitated by nesquehonite seeds, resulting in reduced setting times. The nucleation effect of nesquehonite seeds was demonstrated, resulting in increased nesquehonite formation and carbonation degree. Nesquehonite seeds combined with hydration agent can further promote the compressive strength of RMC through forming more amounts of nesqeuhonite crystals and amorphous hydrated magnesium carbonates. Compared with the hydro-magnesite seeds, the nesquehonite seeds showed a more significant increase in the CO2 sequestration capacity of RMC.