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

Abstract

The hydration of β‐C 2 S prepared from hillebrandite [Ca 2 (SiO 3 )(OH) 2 ] and having specific surface areas of 6.8, 5.5, and 3.1 m 2 /g was investigated. Different specific areas were obtained by varying the dissociation temperature of hillebrandite. In addition, the hydration of β‐C 2 S 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 m 2 /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.