Hygro-mechanical behavior of thermally treated beech subjected to compression loads

The physical and mechanical properties of beech wood (Fagus sylvatica L.) were determined after industrial thermal treatment in a steam atmosphere. Parallel clear uniaxial compression specimens (20 × 20 × 20 mm) were made from control and thermally treated wood, conditioned in a series from an oven dry to saturated atmosphere (20 °C) and compression loaded parallel and transverse to the grain. The reduced density of thermally treated beech was reflected in the decreased stiffness and, especially, strength of wood transverse to the grain. No impact of thermal treatment on the longitudinal compression strength of wood was confirmed. Lower hygroscopicity was additionally detected with thermo-modified wood, whereas the relationship between wood moisture content and stiffness (MOE/MOE0), as well as strength (σ/σ0), along and transverse to the grain of the beech wood remained identical.