Influence of curing conditions on hydration of magnesium silicate hydrate cement

Magnesium-based cement is considered as one promising green cementitious material. However, the issues of delayed early compressive strength growth and considerable shrinkage limit the wide application of magnesium silicate cement. Applying a suitable curing system is a good way to solve the problems discussed above. In this study, superabsorbent polymer (SAP) was added into magnesium silicate hydrate cement (MSHC) to apply an internal curing condition. The samples with internal condition showed a dramatically enhanced early age compressive strength of 19.3 MPa at 7 d, while the sample with normal curing only showed 9.2 MPa. Samples under internal condition achieved 28-day compressive strength > 60 MPa because of the water regulation effect of SAP accelerated the hydration process. Although the addition of SAP will leave macropores inside the cement-based material, it reduces the cumulative pore volume of capillary pores (100-10000 nm), thus effectively alleviating the autogenous shrinkage effect of the MSHC.

Automated summary

Magnesium-based cement is a promising green cementitious material, but it faces issues with delayed early compressive strength growth and significant shrinkage. This study found that adding superabsorbent polymer (SAP) into magnesium silicate hydrate cement (MSHC) as an internal curing condition can dramatically enhance early age compressive strength and alleviate autogenous shrinkage.