This study investigates the remaining short-term mechanical properties and explores the reuse potential of spruce roundwood foundation piles that have been in service for approximately 100 and 135 years supporting two bridges in Amsterdam (NL). A total of 51 pile segments from constructions dated to 1886 and 1922 were examined. The load history of each pile was reconstructed and used to evaluate potential damage accumulation due to long-term loading. The analysis confirmed that no load-induced damage affected the remaining short-term compressive strength. Saturated compressive strength and modulus of elasticity values were determined for head, middle, and tip sections and compared with those of new spruce piles. Visual grading was conducted to confirm that this difference is consistent with the presence of defects within the grading limits specified in Annex Q of prEN 1995-1-1:2024. In addition, wood biodegradation was assessed using micro-drilling measurements to exclude the presence of decay and verified by X-ray computed tomography (CT) scans across pile cross sections and along their length. Only pile segments exhibiting negligible decay, within a tolerance of 2% of the cross-sectional area, were considered. Finaly, the aged piles exhibited mean strength and stiffness values approximately 5–10% lower than new material, a difference attributable to the natural variability of wood properties. The results demonstrate that historic timber piles can retain 90–95% of their original strength after more than a century of service, supporting their potential reuse in renovation or structural adaptation projects.
Pagella et al. (Tue,) studied this question.