Pure concrete suffers from a susceptibility to tensile forces. The invention of steel-reinforced concrete solved this problem but created a new one—to protect rust-prone steel from dangerous moisture, it must be encased in a centimeter-thick layer of concrete. That is why today’s concrete structures consume much more material than is strictly necessary.
Carbon fibers could help in this area. As a lattice-structured textile or formed into rods, they could potentially replace steel in many applications. The new material is more flexible and saves a huge amount of concrete since carbon fibers don’t rust—along with being lightweight and having a high tensile strength. Because of this, the encasing wouldn’t have to be as thick. Carbon fibers would basically put steel-reinforced concrete on a diet.
We’re still at the start of this development process, but the potential of carbon concrete is huge.
Dr. Frank Schladitz, Managing Director of the C³ - Carbon Concrete Composite initiative.
One of the networks of researchers and companies working on developing this new area of application is named C³ – Carbon Concrete Composite, the world’s largest research initiative into carbon concrete, headquartered in Dresden. SGL Carbon is contributing to the initiative with its expertise and the company’s own materials.
Facades, bridges, silos and more
The applications of carbon concrete are diverse. The construction company Goldbeck for example is already planning the first multistory parking garages with carbon concrete ceiling panels that are thinner and corrosion-resistant.
Another field of application is bridges. In Germany alone there are 40,000 river crossings and autobahn bridges that must support increasingly heavy loads and are besieged by salt and snow during the winter. Carbon-reinforced concrete can easily withstand both challenges. Right now, at the TU Berlin university, a bridge component measuring twenty meters in length and built with materials from SGL Carbon is undergoing continuous testing.
In practice, aside from making construction more efficient, carbon concrete also makes construction faster. In a pilot project, the walls of a sugar silo were refurbished with a layer of carbon-reinforced concrete just a centimeter thick. The silo’s capacity was almost completely preserved. And since the carbon textiles were delivered in convenient rolls instead of unwieldy steel mats, the workers were able to complete the renovation much more quickly and at a lower cost.
Yet there are a number of hurdles that must be cleared before carbon can be used in residential construction. In contrast to steel, it is less heat-resistant. The C3 initiative team is currently researching fiber coatings that can withstand temperatures of up to 500 degrees Celsius and simultaneously adhere well to concrete. The experiments thus far are promising. The foundations for the use of carbon concrete are being laid right now.