Assessment of Aggregate Quality from Granite Quarries in Ogun State

Granite aggregates produced from quarrying operations in Ogun State, South West Nigeria, supply a significant proportion of the construction material demand for Lagos and its environs, yet quality consistency across different quarry operations requires independent evaluation for standards compliance. This study assesses the engineering quality of crushed granite aggregates sourced from three quarry operations in Ogun State, evaluating their suitability for use in road base, concrete production, and railway ballast applications. Representative bulk samples of coarse aggregate were collected from each quarry's product stockpile following stratified random sampling protocols. The following tests were conducted in accordance with BS 812 standards: aggregate impact value, aggregate crushing value, Los Angeles abrasion value, flakiness index, elongation index, water absorption, and specific gravity. Petrographic examination of thin sections from parent rock samples characterised the mineralogy, texture, and degree of microcracking in the granite to assess intrinsic material quality before crushing. Results from the three quarries were compared against minimum specification requirements from the Federal Ministry of Works and the Nigerian Industrial Standards for construction aggregates. Statistical analysis identified significant inter-quarry variability in aggregate crushing value attributable to differences in parent rock foliation intensity and feldspar alteration. Recommendations are made for quality assurance protocols that quarry operators should implement. Keywords: aggregate quality, granite quarry, Ogun State, Los Angeles abrasion, construction materials.