In 2016, the general volume of waste wood in Germany was determined to be around 10 million tonnes. A share of 40% can be attributed to construction and demolition waste. (BMUV, 2023) However, according to the German Waste Wood Ordinance, waste wood from load-bearing construction, such as roof trusses, is categorized as A IV and has to be incinerated (AltholzV, 2002). This loss of large quantities of material is contradictory to the intended transition towards a circular bio-based economy with wood cascading as key concept to increase efficiency of wood utilization. However, a better understanding of the material properties of recovered wood is necessary to implement cascading and develop secondary wood products.
Both, utilisation scenarios and material properties of recovered wood are currently well-lit topics (Ui Chúláin et al., 2023; Fridley et al., 2001; Klinge et al., 2019; Llana et al., 2022; Nguyen et al., 2023). Plenty of research investigates the use of recovered wood in structural timber products, especially CLT (Arbelaez et al., 2020; Ui Chúláin et al., 2023; Llana et al., 2022; Rose et al., 2018). Furthermore, the material recovery rate for the reprocessing of lamellae for the production of GLT from the general flow of recovered wood was investigated for France (Irle et al., 2019). However, most studies focus on the mechanical properties of recovered wood or derived products while little is known about the material recovery rate during reprocessing in relation to different deconstruction methods. Moreover, the existing studies do not refer to the geographical reference of Germany.
The aim of this research is to contribute to the cascading use of recovered wood, giving preference to material recycling over thermal recycling. Therefore, the material recovery rate and material properties for salvaged rafters from building demolition in comparison to selective deconstruction in southern Germany are determined.
Keywords: salvaged timber, recovered wood, rafter, material recovery rate
Authors
Florian Böhm
Technical University of Munich, Chair of Wood Science, Germany
Michael Risse
Technical University of Munich, Chair of Wood Science, Germany
Klaus Richter
Technical University of Munich, Chair of Wood Science, Germany
Login to download the PDF