Hassan Darwish, M. R. Abo El-Suoud

The effect of the substitution of palm ash (PA) on the physico-chemical and mechanical properties of Portland cement pastes (OPC) was clearly evaluated. Results showed that as the PA content increased, the fineness as well as the heat of hydration of the whole mix increased too.  The water of consistency (WC) and set times (ST) decreased with the increase of PA content due to the presence of the water reducing admixture. The bound water content (BWn), bulk density (BD) and compressive strength (CS) improved and enhanced up to 20 % PA content, and then decreased onward at all hydration periods, while the total porosity decreased and then increased. Above 20 % PA content, all properties were adversely affected. The free lime content (FLn) of the OPC increased continuously up to 90 days, but decreased with PA content. The FTIR spectra illustrated that there is a large amount of free lime content with P0 (OPC), but it gradually decreased with PA content. The SEM microscopy demonstrated the formation of ettringite phase and aggregates of CSH in addition to free lime. In the case of PA blended cement pastes the ettringite was disappeared completely and well-defined crystals were detected


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