The Future of Construction

Urbanization | Carbon Concrete: Hard shell – lightweight core

With over 100 million cubic meters used each year, steel-reinforced concrete is the most important construction material in Germany – for now. There’s a modern alternative on the horizon: Instead of steel, reinforcement is provided by carbon fibers, which are four times lighter than steel, offer six times the load capacity and don’t rust.

C3 (Carbon Concrete Composite) is the name of the carbon fiber-reinforced concrete project which is now slowly moving out of its infancy. It is the biggest construction research project in Germany and has received government funding of around 45 million euros. The project team includes specialists from our TechCenter Carbon Composites. Christoph Klotzbach, head of the TechCenter, says: “Initial applications show we’re on the right track.”

But why does concrete need to be reinforced in the first place? Isn’t it rock hard as it is? That’s true – but only for so-called compressive loads. Under tensile loading the material breaks relatively quickly. That’s why concrete needs to be reinforced, achieved to date by casting it around a steel mesh.

The principle has been known since the 19th century, and since then steel-reinforced concrete has been used to construct roads, bridges, tunnels, buildings, masts, retaining walls, drains and much more besides. The problem is that steel rusts and needs to be encased in several centimeters of concrete just to prevent corrosion.

Non-rusting materials such as carbon don’t need this protection, so components can be made much thinner and require far less concrete. Carbon fiber-reinforced concrete thus offers advantages in terms of resource and energy consumption and carbon footprint that are virtually unrivaled by any other material in any other sector.

Building with carbon fiber-reinforced concrete not only extends the lifetime of the structures, it also allows more intricate architectural designs. This could significantly extend the range of applications for concrete. Lightweight building with concrete is no longer a contradiction in terms, it is the concept of the future.

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