Concrete is a mixture of cement, an aggregate such as gravel, and water. For added strength, steel fibers are sometimes added. Now, scientists are claiming that a new type of fiber-reinforced concrete could soon serve as a lighter and greener alternative.

The experimental building material was developed by Amir Hajiesmaeili, a PhD student working in the Structural Maintenance and Safety Laboratory of Switzerland's EPFL research institute.

In place of the usual steel fibers, it incorporates fibers made of a very stiff type of polyethylene. These not only provide the same amount of structural support as steel fibers, but they also adhere very well to the cement. As a result, approximately half as much cement is required, with readily-available limestone making up the difference.

This is quite noteworthy, as the production of traditional Portland cement is a major source of greenhouse gas emissions. In fact, Hajiesmaeili claims that the manufacturing of his ultra high-performance fiber-reinforced concrete (UHPFRC) releases 60 to 70 percent less CO2 than that of regular steel-fiber equivalents. And as an added bonus, the material is also reportedly 10 percent lighter.

A view inside the polyethylene-fiber concrete Alain Herzog/EPFL

Plans now call for the new UHPFRC to see its first real-world application next year, when it will be used to reinforce a bridge. "With this material, we can add value to age-old structures by ensuring they will last for a long, long time," says lab leader Eugen Brühwiler. "This solution is also much more financially and environmentally sound than razing and rebuilding existing structures like bridges and historical monuments."

And for an even more eco-friendly approach, the EPFL concrete could conceivably be used along with a new polymer rebar developed at Australia's Deakin University, the production of which requires only one quarter as much energy as that of conventional steel rebar.

Source: EPFL