Highly Reactive β-Dicalcium Silicate: V, Influence of Specific Surface Area on Hydration

The hydration of β-C₂S prepared from hillebrandite Ca₂(SiO₃)(OH)₂] and having specific surface areas of 6.8, 5.5, and 3.1 m²/g was investigated. Different specific areas were obtained by varying the dissociation temperature of hillebrandite. In addition, the hydration of β-C₂S synthesized from high-temperature solid-state reaction was also studied as a comparison. The specific surface area exerts a strong influence on the hydration rate, which increases as the surface area increases. The degree of influence changes with the reaction, becoming greater as hydration progresses. There is initially a linear relationship between specific area and the time required to complete a specific reaction. The specific surface area also affects the reaction mechanism. In the case of specific areas of 5.5 m²/g or less, the reaction changes from a chemical reaction to a diffusion-controlled one, and the degree of reaction comes almost to a halt at 80% to 85%. The Ca/Si ratios of hydrate and the silicate anion structures were also investigated in this study.