Mechanical properties and damage mechanisms of woods under extreme environmental conditions

Wood, a widely used eco-friendly material in ancient architecture, has endured for thousands of years. However, environmental changes over time cause varying degrees of internal damage, degrading mechanical properties and compromising overall building safety. Investigating wood's mechanical properties and damage mechanisms in ancient structures is crucial. This study simulates real conditions of ancient wooden structures by subjecting three common fresh woods (beech, maple, sylvestris pine) to extreme environments: high-temperature treatments (100, 150, 200, and 250 °C for 15, 30, 45 min), water immersion, and exposure to acidic/alkaline environments. Using the MTS instrument, longitudinal compression and bending tests are conducted, analyzing compressive strength and flexural performance. DIC tracks both test processes, and SEM provides a microscopic analysis of damage mechanisms. Results show that beech and maple outperform sylvestris pine under high temperatures and acidic/alkaline conditions. In extreme environments, wood's mechanical strength correlates with moisture content and hemicellulose decomposition. High temperatures enhance wood's mechanical properties through dehydration reactions, but prolonged exposure leads to continuous hemicellulose, cellulose, and lignin decomposition, ultimately reducing wood's mechanical performance.