Comparative analyses of the compressive and flexural strength of glulam with different laminate configurations

Abstract The development of sustainable infrastructure in Nigeria requires the effective use of native timber species in designed constructions. This study assesses the structural integrity of glue-laminated timber (Glulam) made of five tropical hardwoods, namely, Ekki (Lophira alata), Baphia (Baphia spp.), Iroko (Milicia excelsa), Afara (Terminalia superba), and Opepe (Nauclea diderrichii). Polyvinyl acetate (PVA) adhesive was used to produce Glulam beams and short columns with 3-, 4-, and 5-laminate layers to determine the effect of the number of laminate layers on the mechanical performance. The physical tests indicated a density of Ekki (1.19 g/cm3) to Opepe (0.79 g/cm3), with Ekki having the highest moisture level (13.87–1). Mechanical testing revealed a positive correlation (p < 0.05) between laminate number and strength among all the species. For emphasis, the bending strength of Ekki increased by 32% from 21.44 N/mm2 to 28.39 N/mm2 when the number of laminate layers was increased to five. The layers also increased the uniformity of lower-density species such as Afara and minimized variability (CoV decreased from 8.50% to 2.89%). Density was a good predictor of bending strength (R2 = 0.71), although compressive strength was more sensitive to moisture, with Opepe (17.77 N/mm2) performing similarly to Ekki (17.62 N/mm2) in the five-laminate samples. The results show that increasing the number of laminates improves the material’s consistency, making species such as Ekki and Opepe suitable for high-load structural works.