Limestone particle sizes and sulfate impact on the early hydration of limestone calcined clay cement

Abstract

This study explores the underlying mechanisms behind the varying grain size distribution of limestone and sulfate requirement in Limestone Calcined Clay Cements (LC3) on the effects of early hydration and rheological properties. In this paper, the experimental study involving a 45 % replacement of cement demonstrates that the filler effect increases with the fineness of limestone. This is evidenced by the observed acceleration and enhancement of silicate reaction, as monitored through isothermal calorimetry (ICC). The precipitation rate of calcium-silicate-hydrate (C-S-H) increases, and the sulfate adsorption by C-S-H is also augmented correspondingly, leading to accelerated depletion of gypsum during the hydration process. The effect of limestone on the particle size of rheology was also shown that the finer the limestone, the greater the yield stress, while the sulfate has the opposite effect. The results of the Krstulovic-Dabic kinetic model indicated that the exponent and rate constant values decreased with the finer limestone and increased with the addition of gypsum. These results aid in understanding the role of limestone and sulfate requirements on LC3 systems.