THE INFLUENCE OF CEMENT BYPASS DUST ON THE PROPERTIES OF CEMENT CURING UNDER NORMAL AND AUTOCLAVE CONDITIONS

Abstract

This paper analyses the properties of cement binders composed with cement CEM I 42.5R and cement bypass dust in amount of 0.5, 1.0 and 5.0% by mass of binder, curing under standard and additionally autoclave conditions. The bypass dust increases the water content for standard consistency and delays the initial setting time of binder. The cement paste containing 5% of dust reveals the change in volume by 6 mm according to Le Chatelier test. After 2 days, the compressive strength of cement mortar containing bypass is comparable to that of Portland cement mortar, but at later time the strength development of this cement binder is slower. The addition of cement bypass dust in amount to 1% can obtain the cement of strength class of 42.5R according to standard The autoclave curing improves the compressive strength of cement mortar. The SEM/EDS observations confirm the presence of low crystalline C-S-H gel and well-formed tobermorite fibres in autoclaved cement mortar containing 5% of cement bypass dust.