Hydration of cement by-pass dust

Abstract Cement kiln dusts (CKD) generated during the production of Portland cement clinker differ markedly in composition and, hence, in properties. These dusts are commonly used as an addition to cement. In this article the way in which the selected dusts obtained from the cement kiln bypass system (CBPD) react with water and the phenomena accompanying this process at early stage are discussed. For this purpose, the kinetics of hydration was investigated using the calorimetric method and volume change observations. Phase and microstructural changes were investigated by X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy (SEM). It was found that the CBPD hydration process is primarily associated with the presence of free lime. It is characterized by a significant initial heat emission, which is accompanied by swelling the paste as a result of calcium hydroxide and calcium chloride salts formation.