Effect of curing regimes on strength of magnesium silicate hydrate cement

Abstract

This study aimed to investigate the impact of different curing regimes on the strength of magnesium silicate hydrate cement (MSHC). The study employed various microscopic tests, including XRD, TG, SEM, and MIP, to analyze the underlying mechanisms. The research findings demonstrated that the use of short-term high-temperature curing under the two-stage variable temperature curing regime (TTC) significantly enhanced the early strength of MSHC, with a 3d strength exceeding 30 MPa. In contrast, under standard curing (SC), the strength was only around 2 MPa. The samples subjected to TTC did not exhibit the strength retrogression phenomenon observed under high-temperature curing in previous research, and a high-temperature curing duration of 48 h was found to be more beneficial for the strength development of MSHC. However, from a long-term perspective, the late-stage strength of the TTC samples was lower than that of the SC samples. Microscopic tests revealed that increasing the curing temperature substantially improved the early hydration degree of MSHC, reduced its porosity, and resulted in a more compact cement matrix, thereby enhancing the early strength. Under TTC, hydration continued in the later stage, leading to a decrease in porosity and promoting further strength growth. However, in the long-term, the microstructure of the TTC samples became loose, and the interface connection between silica particles and gel weakened. Compared to the SC samples, the TTC samples exhibited higher porosity, resulting in lower long-term strength.

Keywords

• Magnesium silicate hydrate cement
• Curing regime
• Strength
• Hydration degree
• Pore structure