Assessing changes in the mechanical properties of wood recovered from demolished buildings

Circular economy encourages the reuse of recovered demolition wood; however, the mechanical properties and reliability of this material are poorly understood. This study investigated the mechanical properties, performance, and failure behavior of demolition (aged) wood samples collected from the structural parts a demolished building’s roof, floor, and wall sections in comparison to fresh wood. The analysis focused on density, moisture content, modulus of elasticity (MOE), modulus of rupture (MOR) and work of fracture (WOF), complemented by chemical analyses using Fourier-Transform Infrared Spectroscopy (FTIR). The results revealed a trend of declining strength and stiffness in aged wood, with the lowest being aged roof wood with an MOE of 7190 MPa compared to fresh wood with an MOE of 7780 MPa, although aged wall samples have the highest MOE and MOR correlating with their high density. Aged wood samples with an MOE of 9900 MPa displayed brittle failure compared to the ductile failure observed in fresh wood. One-way analysis of variance (ANOVA), coefficient of variation and regression analysis was used to study the statistical significance of the results, highlighting the heterogeneity of aged wood especially in WOF results (p-value > 0.05). The results demonstrate both natural variability and aging effects, rather than absolute changes in strength, giving a benchmark for studying recovered wood for reuse. Overall, the results show that recovered wood still has the potential to be reused in new building structural and non-structural application, but more studies are needed at a molecular level to understand the fracture mechanisms brought on by aging. • Different aging patterns based on location and function in building; wall samples retained higher strength and stiffness. • Transition from ductile to brittle failure mode in aged wall wood samples. • Reduced work of fracture in aged wood samples compared to fresh wood.