Concrete is a mixture of cement, aggregate such as gravel and water. For added strength, steel fibers are sometimes added. Now scientists claim that a New type of fiber-reinforced concrete could soon serve as a lighter and greener alternative.
The experimental construction material was developed by Amir Hajiesmaeili, a doctoral student working at the Structural Maintenance and Safety Laboratory of the Swiss Research Institute of EPFL.
Instead of the usual steel fibers, it incorporates fibers made of a type of very rigid polyethylene. These not only provide the same amount of structural support as steel fibers, but they also bond very well to cement. As a result, about half the amount of cement is needed, with the readily available limestone making the difference.
This is quite remarkable, as the production of traditional Portland cement is a major source of greenhouse gas emissions. In fact, Hajiesmaeili claims that manufacturing its Ultra High Performance Fiber Reinforced Concrete (UHPC) releases 60-70% less CO2 than that of regular steel fiber equivalents. And as a bonus, the material would also be 10% lighter.
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 centuries-old structures by ensuring that they will last a very long time,” says Eugen Brühwiler, lab manager. “This solution is also much more financially and environmentally sound than tearing down and rebuilding existing structures like bridges and historic landmarks.”
And for an even more eco-responsible approach, EPFL concrete could possibly be combined with a new polymer reinforcement developed at Australia’s Deakin University, the production of which requires only a quarter of the energy of a conventional steel frame.