New sustainable material that will replace steel in reinforced concrete

A new technique that involves replacing steel with polyethylene in reinforced concrete has been developed.

The new material was created in the Structural Maintenance and Safety Laboratory (MCS) of the École Polytechnique Fédérale de Lausanne (EPFL) from Amir Hajiesmaeili, a Ph.D. researcher. MCS laboratory is currently focusing on two purposes: 1) Introducing a concrete mixture that will be more environmental-friendly and 2) Assessing the performance of existing infrastructure in Switzerland and all over the world.

Reducing building materials' environmental footprint is crucial as the construction industry is responsible for about 40% of the total carbon emissions worldwide. Therefore, the technology and materials used in infrastructure should develop to become environmentally sustainable. 

The material that is the next generation of UHPFRC (Ultra High-Performance Fiber-Reinforced Concrete), will have the same strength and durability of steel concrete but will result in about 60-70% fewer carbon emissions.

Hajiesmaeili tried various types of mixtures and conducted laboratory tests to derive the compressive and tensile strength of the produced materials for 3 years before discovering the perfect combination. Finally, he managed to develop a mixture using polyethylene to replace steel fiber and limestone to replace half of the cement's quantity, with the same characteristics as reinforced steel concrete and also 10% lighter. “After three years of this trial-and-error, we finally found the right recipe – one that also meets stringent building standards. The trick was to find a material that’s very strong and produces the right consistency,” Hajiesmaeili, stated.

During the last 15 years, similar materials, known as the first generation of UHPFRC, have been developed in the MCS laboratory and have been used in the reinforcement of more than 100 structures in Switzerland. According to Eugen Brühwiler, Professor of Structural Engineering at the EPFL and head of MCS, repairing existing infrastructure is more efficient than rebuilding them. “This solution is also much more financially and environmentally sound than razing and rebuilding existing structures like bridges and historical monuments," Prof. Brühwiler, stated.

The new material is going to be used for the first time to reinforce a bridge in 2020.

Sources: EPFL Theengineer.co.uk