EFFECTS OF SPECIES, DENSITY, MOISTURE CONTENT AND SIZE ON SHEAR PROPERTIES OF SELECTED TIMBER IN SOUTH-WEST NIGERIA
DOI:
https://doi.org/10.11113/mjce.v38.25733Keywords:
Timber, Shear strength, Moisture content, Density, SustainabilityAbstract
Timber remains a renewable and environmentally sustainable construction material, yet its variations in shear strength are not well understood, particularly with respect to species, density, moisture content, and size. This study was conducted to investigate these variations in four hardwood species commonly used in Southwestern Nigeria: Ayin (Anogeissus leiocarpus), Eru (Ricinodendron heudelotii), Ayere (Pterocarpus erinaceus), and Alakrity (Albizia ferruginea). Timber samples were obtained from Johnson Sawmill, Ikole Ekiti, Nigeria, and prepared in accordance with British Standard (BS 373). A total of 36 control samples and 192 test samples were analyzed for moisture content, density, and shear strength using a universal testing machine. Initial moisture content ranged from 17% to 25%, while post-drying values stabilized between 11% and 12%. Density values varied from 676.87 kg/m³ for Ayere to 971.33 kg/m³ for Ayin. Analysis of variance (ANOVA) confirmed that, at 12% moisture content, Ayere exhibited the lowest density, whereas Ayin recorded the highest. Shear strength results revealed that oven-dried samples demonstrated significantly higher values than wet samples. A positive correlation was observed between density and shear strength, with higher-density timbers exhibiting greater resistance. Cross-sectional analysis indicated a general decrease in shear strength with increasing area, largely reflecting the influence of defects. This study highlights the relationship between moisture content, density, size, grain orientation, and shear strength, and practical recommendations for the selection and application of hardwoods in structural engineering.
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