Experimental Investigation on the Thermo-Mechanical Properties of Pre-Heated Wood concerning Compression

The test report from the Technical University of Munich (TUM) investigates the thermo-mechanical properties of pre-heated wood under compression as part of a research project on wood behaviour in fire conditions, in collaboration with ETH Zurich and TALTEC University, aiming to revise design methods in EN 1995-1-2. The study involved preparing spruce and fir specimens, heating them to temperatures ranging from 20 °C to 210 °C, and testing their compressive strength and modulus of elasticity in three scenarios: immediately after heating, after cooling for 24 hours, and after re-moisturisation for 28 days. The results showed that compressive strength remained mostly unaffected up to 105 °C, increased slightly due to drying, but decreased after 180 °C due to slow pyrolysis. Cooling or re-moisturisation helped restore most of its properties. The modulus of elasticity, however, showed a significant decline at higher temperatures, with some recovery observed upon re-moisturisation.