In wood-concrete composite constructions (WCC constructions), the specific compressive and tensile strengths of concrete and wood are combined in a superb manner, e.g. as ceiling components. Furthermore, WCC elements exhibit not only improved properties as regards acoustic insulation and structural fire protection but also an increased load-bearing capacity with a low component height. In addition to its load-bearing function, the concrete also undertakes the construction-related protection of the wood and acts as a storage mass in connection with the building climate control. The use of wood strengthens moreover the growing desire for the application of renewable raw materials in the construction sector, which can also often be easily obtained locally.
Until now, the bonding of WCC elements has been primarily carried out through mechanical connection means (e.g. screws) or via a mechanical fitting (comb-like interlocking of directly wet-cast concrete in grooves of the wood construction). In addition to high costs for the necessary assembly work, the occurrence of moisture in adjacent components and the shrinkage of the concrete - which can even lead to tension and slippage in the area of the grooves - can be listed as possible disadvantages.
Bonded WCC elements for high-rise buildings represent an efficient and, in many respects, optimized construction component and would be a completely new product group. Amongst other things, this method of bonding enables a rigid bond, in contrast to mechanical joining. In addition, the application of the conductive rapid-bonding technique using special adhesive tapes, which is pursued in this research project, enables a fast, operationally simple and secure construction technique for on-site assembly. Re-usability following the end of the useful life of individual components and elements presents a further advantage; this can be graded as more valuable than the simple material recycling carried out until now with the down-cycling of concrete to concrete granules and the thermal utilization of wood.
This innovative joining technology can be applied across all sectors (wooden construction/solid construction) and is intended to benefit the construction sector - which is strongly characterized by medium-sized companies - in the relevant branches of wooden construction as well as the prefabricated reinforced concrete industry, adhesive manufacturers and installation companies.
The assessment bases developed within the research project and the testing methodology will be introduced into the discussion on the further development of normative rules at European level. As no comparable scientific studies are currently known, it can be assumed that the further development of normative rules for testing methodology and the provision of normative rules for the design and dimensioning of bonded WCC components will be significantly shaped by the research project.
Fraunhofer Institute for Wood Research 
