ABSTRACT
Today, research and technology have provided vast information about the strength, workability, performance, and cost of timber, which continues to be one of the most essential building materials.
The materials used for this investigation include timbers (stress graded according to BS 5268) and Polyvinyl Acetate glue. Three species of timber were used for this study, they include; Apa, Mahogany, and Iroko. The physical properties of the timber species including moisture content, specific gravity, and density were determined in accordance with BS373;1957. Mechanical properties of timber samples such as tensile strength perpendicular to grain, bending strength, and compression test parallel to grain were determined in accordance with ASTM D193 (2000), BS373;1957 with dimensions 30mm X 30mm X 120mm for flexural strength, and 30mm X 30mm X 500mm for compressive strength and tensile strength. Moisture content was determined based in accordance to BS373:1957.
This study showed that all of the species could be glued structurally, with Iroko having the highest density (0.119 g/cm3), maximum bending strength (147.92 N/mm2), and highest moisture content (10.62%) of the cross-laminated timbers. Mahogany, with a compressive strength of 21.57 N/mm2, was the species that produced the strongest material. Using the findings from the research done for this thesis, it was shown that these timber species can be engineered into load-bearing cross laminated structural elements and that the strength depends on the moisture content, specie type, the manner of arrangement—that is, whether it is parallel to grain (regular gluelam) or perpendicular to grain (crosslam)—as well as the type and quantity of binder.
