Properties of cement pastes with zeolite during early stage of hydration

Abstract

Properties of cement pastes with various replacement levels of natural zeolite were tested by isothermal calorimetry and rotational rheology. Zeolite from the Eastern Slovakia region was used for tests. Kinetics of exothermic reaction during early stage of hydration were monitored by calorimetry. The role of different replacement level of zeolite on main rheological parameters is discussed in the paper. The onset point of formation of C-S-H products and the main calorimetric peak move to earlier times with increased zeolite content. Zeolite causes acceleration of hydration before the heat flow peak time and the following deceleration proportionally to its content. Zeolite in cement promotes the AFt formation, which increases the elastic response of fresh paste at the beginning of hydration. Trends of G’ and phase angle show that zeolite accelerates the hydration of C3S and early C-S-H formation.