Hydration and phase evolution of blended cement composites containing lithium and saturated metakaolin: Fid-Bau Portal

Hydration and phase evolution of blended cement composites containing lithium and saturated metakaolin

Luo, Dayou / Wei, Jianqiang

Abstract Although the high efficiency of coupled lithium and saturated metakaolin in alkali-silica reaction mitigation has been documented, its influence on cement hydration remains uninvestigated. In this study, saturated metakaolin with varying degrees of saturation and its combined influence with lithium on the hydration kinetics, phase evolution, and development of microstructure and molecular structures of hydration products in the blended cement composite was investigated. The experimental and thermodynamic modeling results indicate the synergistic effect between saturated metakaolin and lithium in enhancing the hydration of cement, interaction between metakaolin and cement, incorporation of Al in the silicate chains, and precipitations of Al-rich phases. In the blended cement matrix, the dissolution of metakaolin, formation of calcium silicate hydrates with incorporated aluminum (C-(A)-S-H), and precipitation of strätlingite are improved by 19.6%, 17.6%, and 20.0%, respectively, and the formation of cubic siliceous hydrogarnet was triggered.

Highlights • Hydration of blended cement containing saturated metakaolin and lithium is studied. • Remarkable enhanceemnts of cement hydration and metakaolin dissolution are obtained. • Chain length of aluminosilicate tetrahedra and polymerization degree are increased. • Precipitation of strätlingite and Al incorporation in silicate chain are improved. • Formation of cubic silicious-hydrogarnet and multilayered C-(A)-S-H are triggered.