At the International Composites Congress in Stuttgart this autumn, the ZHAW researchers received the AVK Innovation Award in the category “Products and applications” for their light CPC panels. This award is given every year by the Industrievereinigung Verstärkte Kunststoffe (AVK). “Four carbon fibre cables could carry the weight of a car, but as soon as they are stressed laterally or joined together, they break immediately”, says Josef Kurath, head of the ZHAW’s research group for fibre-reinforced plastics. “This is why prestressed carbon fibres and concrete complement each other perfectly. Carbon absorbs the tensile forces and concrete absorbs pressure and lateral forces.” Moreover, while conventionally reinforced concrete panels develop cracks, the CPC panels spring back undamaged. 

The greatest potential which Kurath sees in the newly developed CPC panels, however, is that they can be produced industrially and cut to any size, and that they don’t rust. Finally, since the concrete panels can be made much thinner without reinforcement steel, valuable resources such as water and sand can be saved and energy consumption reduced. 

For one thing, these thin panels offer architects entirely new design possibilities, as they can be cut to any shape at all – with millimetre precision thanks to CNC (Computerised Numerical Control) machines using digital data. Apart from that, time can be saved on the construction site, as semi-finished carbon concrete products can be produced industrially, saving the time-consuming reinforcement work on site. “Besides use in new structures, they are also very well suited to the renovation of existing structures, enabling their lifespan to be extended considerably”, says ZHAW researcher Antje Sydow. For example, a bicycle bridge in Winterthur has recently been renovated with a CPC panel. Specifically, it was done with an almost eight-metre-long panel that is only four centimetres thick. Glued firmly to the supporting frame underneath, it carries the handrails and all the payloads. No additional coating is needed. With a total weight of 3200 kilogrammes, the delicate carbon concrete bridge weighs about five times less than a conventional structure. “That makes it the lightest concrete bridge in the world”, says Sydow. “What’s more, it’s rust-proof, which is an important issue in bridge construction.”