Researching adhesive-free timber systems

While engineered wood products such as CLT and Glulam offer significant sustainability benefits, their recyclability and reuse potential are often limited due to the use of adhesives between layers. An alternative to that is the use of Dowel-Laminated Timber (DLT) which is a fully biobased timber system in which individual timber lamellae are connected using hardwood dowels instead of adhesives or steel fasteners.

At RESED, the research group led by Professor Arjan Habraken within the Structural Engineering and Design unit at Eindhoven University of Technology, Bonno Van der horst investigates how Dowel-Laminated Timber (DLT) beams can be applied to improve both structural and environmental performance. More specifically, the research explores how the distribution and sizing of these dowels can be optimized along the beam length to achieve the required stiffness.

Using a multi-scale analysis, this study combines pull-out testing, slip modulus determination, analytical modelling, full-scale six-point bending experiments (shown in the video) and Life Cycle Assessment (LCA). The results show that the bending stiffness of DLT beams is strongly influenced by the production tolerances, the embedment of the dowel and of course the stiffness of the dowel itself. Also optimized dowel layouts can reduce dowel volume by approximately 45% with only a limited reduction in structural performance.

Beyond the structural investigations, the environmental assessment demonstrates that DLT systems achieve a substantially lower global warming potential than comparable Glulam, NLT and steel beam solutions. Although the structural capacity does not equal gluing, the findings highlight the potential of DLT as both a structurally efficient and highly circular alternative for future timber construction.

Supervisors: Arjan Habraken, Rudi Roijakkers, Vincent Staat