Suitability of Aspen (Populus Tremula L.) for Cross-Laminated Timber (CLT)

Cross-laminated timber (CLT) CLT is an excellent material for building and high load-bearing structural applications, but its fabrication and use are limited to softwood only. The suitability of aspen (Populus tremula L) wood for manufacturing CLT was assessed by using two adhesives, one-component polyurethane (1C-PUR) and melamine adhesive (ME). Physical properties like water absorption (WA), thickness swelling (TS), delamination, and mechanical properties like bond shear strength, bending modulus of elasticity, bending strength, and rolling shear strength were evaluated to examine its suitability. Compared to ME-bonded CLT, 1C-PUR bonded CLT panels displayed superior physical characteristics, with 70% passing the delamination test. CLT panels bonded with 1C-PUR adhesive also have better mechanical properties than ME-bonded CLT. CLT panels experienced three types of bending failure: rolling shear, delamination, and tension. Aspen CLT has similar or higher mechanical properties than traditional softwoods, making it suitable for CLT manufacturing.

Defining of thermal bridges of wood building and their elimination

The thesis focuses on the matter of thermal bridges in case of wooden panel structures, both in case of low-energy and passive structure-standard. Thermography was used for localization of critical areas of structures – details of corner joints of external walls and ceiling connections. The values subject to comparison are the linear coefficient of heat penetration from the exterior and the lowest interior surface temperature. This results in the overall comparison of both the structures as well as elimination of the excessive heat flow, whereas the difference in detail of corner joints of external walls is 0.03 W.(m.K)-1 for both, and the difference in detail of the ceiling connections equals 0.07 and 0.08 W.(m.K)-1 respectively. The difference in the lowest interior surface temperature in detail of corner joints of external walls for both structures equals 1.34 and 2.99°C respectively, and in the detail of the ceiling connections the difference is 2.45°C.

Tensile-shear strength of layered wood reinforced by carbon materials

This article deals with the influence of selected factors (wood species, used adhesive type, carbon reinforcement) on tensile-shear strength of glued layered wood. Tensile-shear strength was investigated on samples of European beech (Fagus sylvatica L.) and European spruce (Picea abies L.). The laminated wood was modified with carbon polymer or carbon fabric, and the tensile-shear strength values were compared with non-reinforced wood. Polyurethane and epoxide adhesives were used for the experiment. The highest tensile-shear strength values were found on non-reinforced beech wood glued by epoxide adhesive. As far as the tensile-shear strength concerns, each monitored factor as well as their mutual interactions were proven to be statistically significant.