Characterisation of Groundnut Shell Ash as a Partial Cement Replacement in Concrete Production: A Case Study in Kano State

The construction industry in Nigeria faces persistent material cost challenges, and agro-industrial waste valorisation offers a practical path toward affordable alternatives. This study characterises groundnut shell ash generated from oil processing mills in Kano State, North West Nigeria, and evaluates its suitability as a partial Portland cement replacement. Representative ash samples were collected from three mills in Kano Municipal and subjected to X-ray fluorescence analysis, particle size distribution, loss on ignition tests, and Blaine fineness measurements. Concrete cubes were cast at ash substitution levels of 5%, 10%, 15%, and 20% by weight of cement, and compressive strength was assessed at 7, 14, and 28 curing days. Workability was measured via slump tests conducted at each substitution level. Preliminary characterisation confirmed appreciable silica and alumina fractions consistent with pozzolanic activity. Compressive strength results at 10% substitution met the minimum requirements of the Nigerian Industrial Standards for structural concrete at 28 days. Higher substitution rates produced marginal strength reductions, though workability improved incrementally. The findings suggest that groundnut shell ash can viably displace up to 10% of Portland cement without compromising structural integrity, offering cost and environmental benefits for construction in the North West zone. The study recommends further investigation into durability properties and long-term carbonation resistance before large-scale adoption. Keywords: groundnut shell ash, pozzolan, cement replacement, compressive strength, Kano State