Engineering-Geological Evaluation of Rock Materials from Bansara, Bamenda Massif Southeastern Nigeria, as Aggregates for Pavement Construction

In this work, the properties of some basement rocks in Bansara area in the Nigerian sector of the Bamenda massif which determine their suitability for the production of aggregate for construction works were assessed to evaluate their performance as pavement materials. The rock materials evaluated were from Biotite-Granite, Granite-Gneiss, Schist and Greenstone rocks. The Biotite-Granite gave Aggregate Abrasion Value (AAV) of 22.0%, Aggregate Crushing Value (ACV) of 23.3%, Aggregate Impact Value (AIV) of 18.5% and water absorption of 0.54% while Granite-Gneiss has 27.0%, 26.1%, 22.8% and 0.73% and the Greenstone has 45.2%, 55.9%, 49.6% and 3.90% respectively. Although the Biotite-Granite and Granite-Gneiss possess the necessary criteria for use as construction aggregates, the Biotite- Granite is of better quality because of its exceptionally high strength value and low water absorption. The high resistance of Biotite-Granite and its low water absorption could be attributed to its mineralogical composition with interlocked grain boundaries. Greenstone has no value as aggregate material due to its high pore volume.