The Project C3 team hopes that publicity about the CUBE will help draw attention to the many advantages of carbon fiber-reinforced concrete as a building material. “Carbon-reinforced concrete is sustainable, environmentally friendly, saves material and weighs less,” Curbach says. “This offers a wider variety for architectural designs. Carbon is four times lighter and up to six times more durable than steel. It can be recycled, and the material cycle is a closed one.” In a closed material cycle, post-consumer or post-production waste can immediately be recycled back into the production cycle.
The hope is that carbon fiber-reinforced concrete will someday replace steel-reinforced concrete in structures like bridges and façades. It can also be used as a supplemental material for strengthening intact steel-reinforced concrete structures, including silos, bridges and buildings.
The initial cost of carbon fiber-reinforced concrete is a concern; 1 kilogram of carbon costs 16 euros, while 1 kilogram of steel costs 1 euro. But this equation does not take into account the many other advantages that carbon has over steel.
“Carbon is four times lighter and six times more durable than steel,” says Curbach. “When renovating silos or building ceilings, for example, the lightness of carbon means that reinforcements can be laid much faster. Because of its corrosion resistance, we need much less material and save costs here, too.” In addition, Curbach says that the predicted durability of carbon fiber-reinforced concrete is 200 years, while steel-reinforced concrete constructions last 40 to 80 years. Costs can also be reduced with applications suitable for mass production.
The Project C3 team is currently using carbon fibers derived from PAN, but Curbach says that some researchers are exploring ways to produce them from lignin, from carbon dioxide in the air and from algae oil. When lignin carbon fibers do become available, they should be about 50% cheaper than PAN carbon fibers, making carbon fiber-reinforced concrete an even more attractive option.
The light weight of carbon fiber-reinforced concrete will make it easy for contractors to handle. It is easier to transport, and fewer people are needed to perform the work, so builders will be able to reduce installation time by 50% compared to steel-reinforced concrete. Curbach says, however, that production does have to be more precise when the application calls for thin layers and components.
After the introduction of the CUBE next summer, the C3 Project network will drive a broad market introduction of different carbon fiber-reinforced concrete applications. “By 2025, a noticeable market impact and the so-called irreversible process should be initiated, so that market penetration can be achieved by 2030,” Curbach says.