New challenges in Concrete Construction
The building industry is facing major challenges in terms of the current climate crisis. New strategies must be developed to reduce the carbon footprint and to establish a more sustainable thinking. The building industry is responsible for approx. 11% of global carbon emissions, with a large portion ascribed to structural concrete, which is by far the most utilised material worldwide. A more sustainable handling of concrete can be achieved by a variety of ways. One possible approach followed by researchers at TU Wien is the implementation of high performance materials, as for example textile-reinforced concrete (TRC), which allow for a crucial material reduction if efficiently used.
What is textile-reinforced concrete?
TRC is a composite material consisting of a combination of textile reinforcement and a high-performance concrete. The reinforcement consists of high-performance fibres (in general carbon or AR-glass) and is manufactured mostly by means of warp knitting (see Figure 1).
Figure 1: Textile reinforcement made of high-performance fibres.
The reinforcement is characterized by a high strength of up to 3000MPa (carbon reinforcement) while simultaneously exhibiting an outstanding durability, as there is a high resistance against corrosion. These characteristics allow for a reduction of the necessary concrete cover, enabling the construction of filigree and lightweight, but still very durable structures.
Research at TU Wien
The functionality of a composite material is guaranteed by the bond between its individual components. Since the geometric and mechanical properties of textile reinforcement differ to those of ordinary steel reinforcement, currently existing models on the load-bearing behaviour of structural concrete cannot be transferred directly to TRC. Researchers at the Institute of Structural Engineering at TU Wien are therefore investigating the bond and anchorage behaviour of TRC. In the course of the research innovative methods of investigation are applied in interdisciplinary collaborations. The geometric properties of the textile reinforcement, for instance, were examined by conducting optical measurements with a laser scanner. A pronounced regularly repeating variation in cross-sectional dimensions was depicted (see Figure 2) through the detailed analysis of the digital 3D model.
Figure 2: 3D-model of a fibre strand: Cross section (left), top view (middle), side view (right).
On the basis of these observations experimental and numerical investigations were carried out focusing on the splitting failure mode in TRC, which has been observed in several tests on structural TRC components in the past. The findings of these investigations led to the establishment of a model, which enables the calculation of the occurring splitting forces in TRC. Further investigation, which are currently taking place, deal with the anchorage behaviour of TRC which is derived from the bond behaviour, on the one hand, and the concrete resistance against a splitting failure, on the other. More investigations on this topic in regard to the different types of textile-reinforcement and different concretes are necessary and are currently being planned.