We are investigating timber-concrete composite systems (TCC systems) as an alternative to reinforced concrete. They are particularly suitable for use under bending loads, in which high tensile stresses occur on the underside of the composite system, for example in beams or floor slabs. Instead of steel, timber is used to absorb the tensile forces occurring in the composite.
For example, we develop ceiling slabs in which a beam structure is first installed with a top layer of wood-based panels. The top layer is an integral part of the structure and also serves as formwork and possible support for the ceiling. It is coated with an adhesive and then filled with fresh concrete. The concrete layer provides high strength in the compression zone, while the wood absorbs tensile forces. This results in a high bending strength within the compound. Compared with reinforced concrete floors, large amounts of tensile reinforcement and concrete are saved. In addition, TCC systems facilitate processing on the construction site as, in contrast to conventional construction methods, the formwork is not removed after the concrete has hardened.
Fiber-reinforced polymer-timber composite
Wood has a relatively high strength-to-weight ratio and additionally offers high adaptability and workability. However, the tensile and compressive strengths of wood vary considerably, which means that its use in load-bearing structures has been limited until now. This disadvantage can be compensated for by combining it with fiber-reinforced plastic. We develop suitable fiber-reinforced plastics and manufacturing processes for fiber-reinforced polymer-timber composite systems (wood-FRP).
One research approach is to incorporate several layers of polymer matrix and reinforcing fabric as a tension component in a wooden structure. We are testing various manufacturing methods for this purpose. High quality and reproducibility can be achieved by vacuum infusion. The hand lay-up process enables in-situ applications. Thus, fiber-reinforced polymer can even be used to reinforce existing wooden constructions, provided that the wooden components are accessible.