A total of four concrete mixtures were made. These included one control concrete without fly ash and three mixtures incorporating different percentages of fly ash. In addition to the standard compressive strength determination under normal moist-curing conditions the effect of curing and ambient temperature on the strength and some durability characteristics of the concrete were determined. Fly ash concretes having total cementitious materials content inferior to that of the control concrete and incorporating up to 45% fly ash as partial replacement for cement were produced and achieved compressive strengths that met the 28-day strength requirement that was specified for the potential demonstration project. The fly ash concretes performed better than the control concrete in a number of aspects more specifically for heat generation resistance to chloride-ion penetration and drying shrinkage. Although both the strength development and the resistance to chloride-ion penetration of the concretes investigated were strongly affected by the exposure to air drying at high temperature it appears that the fly ash concretes beneficiated from some acceleration of the pozzolanic reaction due to the higher temperature during the drying period and that this compensated at least partly for the lack of moist curing.
Technical Report Author: Alain Bilodeau, Nabil Bouzoubaa, R. Chevrier, Pierre-Claver Nkinamubanzi, CANMET Energy Technology Centre, Natural Resources Canada,