Physicochemical and Mineralogical Characterisation of Nigerian Rice Husk Ash and a Portland Limestone Cement-Based Binder Containing 30% Rice Husk Ash

Koku-Ojumu B. E., Raheem A. A., Ajamu S. O., Oguntola I. O.

Abstract


Rice husk ash (RHA) is a potential supplementary cementitious material whose suitability depends on its chemical composition, mineralogical structure and physical characteristics. This study characterises RHA obtained from Imota Rice Mill, Ikorodu, Lagos State, Nigeria, and compares the chemical, mineralogical and physical properties reported for a control Portland limestone cement (PLC) and a binder designated as containing 30% RHA. X-ray fluorescence analysis indicated that the ash contained 91.84% SiO₂, while the combined SiO₂, Al₂O₃ and Fe₂O₃ content was 92.94%. The supplied X-ray diffraction interpretation estimated an amorphous fraction of 88.6% and identified quartz, graphitic carbon, calcite and hematite. Compared with the control PLC, the 30% RHA blend had higher Blaine fineness (4,179 versus 3,992 cm²/g), lower specific gravity (2.80 versus 3.15), higher standard consistency (33% versus 27%) and longer initial and final setting times (230 and 290 min, respectively, compared with 130 and 200 min). Soundness was reported as 0 mm for both binders. These findings show that the investigated ash was silica-rich and that its incorporation was associated with measurable changes in binder properties. They do not independently demonstrate pozzolanic reactivity or improved strength and durability. 


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References


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