Evaluation of Strength Classes of Two Selected Less-used Nigerian Timber Species for Structural Applications

Abstract

As a result of increase in population growth and urbanization, the demand for timber in construction industry has exponentially increased. Common and popular timber in the industry do not meet up with the high demand and attention has been shifted to unpopular timber species such as Bush mango (Irvingia gabonensis) and Ire (Funtumia elastica) but their properties are yet to be fully researched and documented. This research therefore aimed at characterizing and grading of two less-used timber species in Kwara State, Nigeria for structural applications. The selected timber species were obtained from Irewolede Sawmill in Ilorin, Kwara State and various test specimens were prepared according to the BS 373: 1957 using Small Clear Size Specimens of Timber. A total of 200 specimens free from visible defects were used for the determination of the strength properties using the Universal Testing Machine of 300 kN capacity at the Department of Agricultural and Biosystems Engineering, University of Ilorin in accordance with BS 373: 1957 (revised in 1999). It was revealed that Bush mango and Ire had average moisture contents of 13.95 and 12.71%, respectively. For density classification, Bush mango and Ire were classified as medium and light wood, respectively. Bush mango and Ire were therefore graded according to NCP 2 (1973) and BS 5268 (2002) and assigned to their corresponding strength classes. Hence, Bush mango can be applied as bridge beam and railway sleepers while Ire can be used for lightweight furniture.