Calorimetry in the studies of by-pass cement kiln dust as an additive to the calcium aluminate cement

摘要

The studies focused on the kinetics of early hydration in the high-calcium aluminate cement (CAC 70)-by-pass cement kiln dusts (BPCKD)-mixtures. For this purpose, the mixtures of cement with this additive or with some potential constituents of dusts were produced. The microcalorimeter was applied to follow the kinetics of hydration. The investigations with the aim of finding the relationship between the components of initial mixtures and the modification of hydration process were carried out. The rheological properties were characterized, and the chemical shrinkage characteristics were produced. The phase assemblage characterization and microscopic observations were done as well. In case of the high-calcium aluminate-based binders, the modification of setting process was observed; the rheological properties and chemical shrinkage were affected too. The acceleration of heat evolution-the shortening of so-called induction period in the presence of BPCKD additive-was observed. The results were compared to those obtained for the CAC with ordinary Portland cement additive. The results of calorimetric measurements are discussed in terms of the chemical and phase assemblage of this additive as compared to the Portland cement clinker precursors and potassium chloride-the solid and liquid components of the dust.