Structural wood building materials

Climate change is one of the key factors driving an adaptation of species composition of Austrian forests, diminishing the proportion of softwood in favour of hardwood, particularly beech and oak, which are more resistant to drought and ensuing calamities. Since beech and oak are fundamentally different from the currently dominating softwood spruce in terms of their technological properties, new approaches to boost high-value hardwood utilisation are urgently needed. The present proposal suggests splitting as a means to minimise fibre deviations on hardwood from low-quality branch-wood. Furthermore, split macro-fibrous elements will be straightened with the aid of thermally assisted plasticisation in steam and densified to form high-value, straight fibre beam elements capable of serving as structural elements e.g. in construction or automotive. This highly material-efficient utilisation concept for low-value hardwood provides numerous benefits in that it enables a high proportion of bio-based material utilisation also in future, supporting the continuous competitiveness of the forest-based sector in times of climate change.

Contact: Maximilian Pramreiter

In recent years, timber construction has been able to demonstrate its suitability for multi-storey buildings through various lighthouse projects (e.g. HoHo, LCT ONE, etc.). The utilization of wood in the construction sector not only leads to a substitution of energy-intensive raw materials with simultaneous carbon storage, but can also satisfy the enormous additional demand for building materials. A significant increase in the utilization efficiency of the resources used is just as inevitable as efficient construction methods and dimensioning of the components. Currently, successful timber construction products such as cross laminated timber (CLT) are predominantly based on softwood lumber and have a low raw material yield (30-40%) due to the production process. The "UniStrand" project is intended to investigate the technological and design fundamentals for a (approx. 7-20cm) thick, panel-shaped, wood-based material for multi-storey, structural building applications. The starting material will be long, thin wood particles (strands), which can be produced with a high raw material yield (over 75%). Mainly hardwood assortments or combinations of softwood and hardwood are to serve as raw material. Unidirectionally oriented strands will be bonded together to form UniStrand boards of different densities, a predictable intermediate product with improved mechanical properties compared to already established strand-based products (oriented strand board, laminated strand lumber). Finally, the required stability and material thickness of the layered wall and ceiling elements will be achieved by crosswise layer bonding of the strand-boards. The combination of a numerical design optimization of the finished elements, coupled with an application-oriented cutting pattern, enables the production of targeted elements that use
high-performance panel material only where this is statically required. The results of the project are continuously evaluated by a process-oriented life cycle assessment (LCA) and a technology impact analysis. The overall vision of the project is to form the basis for a large-scale industrial implementation and pave the way for a resource-efficient wood building material of the next generation.

Contact: Maximilian Pramreiter und Johannes Konnerth