Experimental Study on Shear Properties of Gmelina Arborea Cross-laminated Timber Panels by Short Span Bending

Abstract

This study examines the shear strength properties of cross-laminated timber (CLT) panels fabricated from Nigerian-grown Gmelina arborea using polyurethane (PUR) and epoxy resin (ER) adhesives. Eight CLT panels were produced and tested according to ANSI/APA PGR 320 and BS EN 16351 standards, with rolling shear strength assessed through short-span testing configurations across span-to-depth (S/d) ratios of 4, 5, and 6, per BS EN 408 guidelines. Results showed that PUR-bonded specimens had superior rolling shear strength, with mean values of 2.85 N/mm², 2.38 N/mm², and 2.14 N/mm² across S/d ratios 4, 5, and 6, respectively, compared to 1.97 N/mm², 1.74 N/mm², and 1.59 N/mm² for ER-bonded specimens. Rolling shear strength values decreased as S/d ratios increased, indicating typical structural responses. The ER-bonded specimens exhibited an increasing trend in MOR as the S/d ratio increased from 4 to 6, though the MOR values were consistently lower than those of PUR-bonded panels. These findings contribute essential data on Gmelina arborea CLT's mechanical properties, supporting its potential as a sustainable, high-performance material in the Nigerian timber industry. The study establishes a foundation for the development of value-added timber products, promoting sustainable construction practices in Nigeria.