Partial replacement of cement by fly ash in autoclaved products ? theory and practice

Abstract

Nine different fly ashes have been used in a study of autoclaved (216° C) cement-fly ash mixtures containing 50% fly ash (by weight). Paste samples for each fly ash were prepared at water-solid ratios of 0.22 to 0.45 and mechanical property-porosity relations were determined. The autoclaved products were characterized by several techniques. Linear correlations with a composition term, C/(S + A)−kF, were obtained for logarithms of zero-porosity modulus of elasticity and microhardness values. A linear correlation for modulus of elasticity of the porous solid and the composition term, 2 - C/S + A−kF, was also obtained for each water-solid ratio. Correlations for microhardness of the porous solid with a composition term, 2−C/S + A are reported, a different curve for each water-solid ratio. Impregnation of the porous products resulted in increased values for modulus of elasticity and microhardness and provided an alternate means of estimating zero-porosity values of these properties.