Evaluation of the suitability of plantain peel ash as a secondary cementitious material/ filler in mortar

The possibility of using Plantain Peel Ash (PPA) as a cementitious or filler material in partial replacement of cement for mortar and concrete was investigated in this research work. Plantain peels were collected in Idah in Kogi state and carbonated in the open air to reduce the carbon content after which it was calcined in a muffled furnace at 600­oC for 3 hours. Samples were taken for oxide composition using XRF analysis. Ordinary Portland cement was partially replaced with PPA at 0, 5, 15, 20 and 25% replacement levels and the OPC-PPA mix used as binder material to produce mortar cubes at 0.5% Water to binder ratio and binder – aggregates ratio of 1:6, which were cured for 7, 14 and 28 days respectively and tested for compressive strength. Durability of the PPA blended mortar was evaluated using water absorption, Sorptivity and apparent porosity tests. The result shows that while specific gravity decreased with increasing percentage replacement from 3.1 to 1.2 for 0 to 25% PPA replacement respectively, standard consistency and setting times increased with increasing percentage replacement. The oxide composition of PPA gives a combined SiO­­2+Al­­2O­­3+Fe­­2O­­3 of 22.44%, which is less than the 50% required for pozzolanas. The compressive strength at 7, 14 and 28 days curing all increased with curing age but decreased as the percentage of ash increases, with only the mortar with 0% ash meeting the strength requirement for a class M mortar; and while the sorptivity increases with curing age and percentage replacement, water absorption and apparent porosity decreases with age but increases with percentage replacement. However, PPA blended mortars showed higher performance in acidic curing environment as compared to normal OPC mortars. It can be concluded on the basis of this research that while PPA does not meet the requirement of ASTM C618 for pozzolanas, it can be used as a filler material in concrete and mortar at up to 10% replacement of OPC to increase concrete durability when in acidic environment.