DETERMINATION OF THE STRENGTH AND TOUGHNESS OF GRANITE IN IKARE AKOKO, SOUTHWESTERN NIGERIA

The strength and toughness of crystalline rocks are the two geomechanical parameters often considered when evaluation geomaterials applications in tunnels, roads, foundation, bridge and dam construction. There is paucity of location specific data on these two parameters for the Ikare-Akoko granite. This study therefore aimed to determine these paramaters using their Uniaxial Compressive Stregth (UCS), Point Load Index (PLI), Los Angeles Abrasion (LAA), Aggregate Impact Test (AIV) and Water Absorption Capacity (WAC). Three granite samples were obtained from outcrops in the field and taken to laboratory testing. The results showed that the UCS values ranges between 173 – 185 MPa while the PLI has an average value of 20 MPa both falling on very strong rock category by ISRM classification. The very low water absorption percentages obtained (average 0.29%) indicate high durability and resistance to weathering. The LAA avearge of 5.03% indicates excellent abrasion resistance, since the value is well below the international maximum of 30% established for construction aggregates. However, the AIV value average of 40% falls on weak materials for road surce course category denoting poor impact resistance. The implication is that while Ikare-Akoko granite has high UCS and LAA, its resistance to sudden loading is weak. In general, granite from Ikare Akoko can be used as aggregates in concrete production, road base materials, railway ballast and other civil engineering applications requiring very low impact loadings. The study therefore provides credible geotechnical information that is relevant for sustainability considerations in infrastructure development while reaffirming the importance of site-specific investigations in guaranteeing the efficient harnessing of Basement Complex materials in Nigeria.