Potentials of Dialium guineense Endocarp Ash as a Cement Replacement Material

Abstract

Agricultural wastes such as Dialium guineense Endocarp are often generated in volumes that surpass disposal efforts. This concerns communities because improperly handled agricultural waste can lead to environmental challenges. Research on the use of agro-industrial or natural waste as cementitious materials tends to focus on the ashes from orange peel, locust bean pod, palm oil fuel, rice husk and sugarcane bagasse as partial replacements for cement. However, investigations are limited, focusing on Dialium guineense Endocarp ash (DEA) as an alternative cementitious material to reduce CO2 emissions and agricultural waste. This study explores the potential of DEA as a partial cement replacement material. Partial replacement of Portland limestone cement with DEA 1, 2, 3, 4, 5 and 6 wt.% for physical properties while mortar strength was varied from 0 -5 wt.%. Dialium guineense Endocarp pods were collected in Bauchi state- Nigeria, washed, dried, and grinded, followed by determination of thermal stability of the endocarp via Thermogravimetric Analyzer/ Differential Thermal Analyser (TGA/DTA). The resultant ground endocarp was calcined at 600 oC in a furnace for 4 hours, characterised by its chemical composition and functional groups via X-ray fluorescence (XRF) and Fourier Transform infrared (FTIR) spectrometer, respectively. The mortar strengths of 72 cubes for 3 days, 7 days, 28 days and 60 days were produced and determined with a mixing ratio of 1:2:4 (water: cement: sand) according to ASTM standards. The XRF analysis of DEA revealed that the composition of silicon, aluminium and iron oxides was less than 50 wt.% (24.84 wt.%), which did not meet the minimum requirement by standard to be considered a pozzolan with a high CaO content of 25.58 wt.% and possessed significant K2O content of 36.03 wt.%, an increase in the standard consistency and retardation of both setting times of DEA cement blends was experienced when the cement replacement with DEA was increased. The consistencies and setting time of the DEA-cement blends were higher than control. This prolonged setting times and higher consistency could be linked with the unburnt carbon presence in DEA. As the curing age progressed, the mortar strength experienced increments despite clinker diminution, suggesting pozzolanic activity. Most DEA cement blends produced enhanced strength at 28 days for cement replacement up to 4%, which led to diminished strengths that produced strength slightly lower than control despite clinker diminution. The optimum percentage of cement to be replaced with DEA was determined at four wt.%. DEA possesses properties that are useful as a partial cement replacement material.