Bending and compressive properties of glued-laminated timber composed of Japanese white birch wood using casein adhesive

Size-reduced model glued-laminated timber (GLT) (1/8 cross-sectional size, six layers, 11 by 18 by 430 mm) was manufactured using birch (Betula platyphylla) wood and a casein adhesive to evaluate the possibility of producing the structural GLT without petrochemical-based adhesives in Mongolia. The same-sized solid lumber and GLT using aqueous vinyl polymer solution-isocyanate adhesives (API) that can be used for structural GLT production in Japan was prepared to evaluate the mechanical performance of GLT using casein adhesive. The effects of lamination configuration and patterns on the mechanical properties (dynamic Young's modulus, modulus of elasticity [MOE], modulus of rupture [MOR], bending work [energy until broken, W], and compressive strength [CS]) were also evaluated using mixed-effect model. Almost no significant differences in the bending and compressive properties were found between GLT using casein and API adhesives, suggesting that, in dry conditions, the bonding performance of casein adhesives closely matches that of API. Modeling results showed that lamina configuration influenced the W and CS even in the Young's modulus was almost the same, suggesting that the basic wood properties, such as load and deflection characteristics, are important to enhance the mechanical properties of birch GLT with casein adhesive by laminae configurations.