How can we make concrete greener (and cheaper)?

Global production of cement – the 'glue' that holds concrete together – accounts for 8% of the world's CO₂ production. Adding tiny amounts of graphene to concrete dramatically increases its strength – meaning much less material is needed, and CO₂ emissions are significantly cut.

Manchester engineers have now gone from lab to market by pioneering a new CO₂-busting building material: Concretene.

Liquid concrete sets in solid form through chemical reactions known as hydration and gelation, where water and cement react to form a paste, drying and hardening over time.

Engineers at The University of Manchester's Graphene Engineering Innovation Centre (GEIC) have discovered that using graphene, which acts as both a mechanical support and catalyst for the initial hydration reaction, results in improved bonding at microscopic scale – offering improved strength, durability and corrosion resistance.

A solid start

Concretene can be used in the same way as standard concrete, meaning no new equipment or training is needed in the batching or laying process. The improved binding means less material is required, making the process greener and cheaper, with cost savings passed directly to the client.

Laying the foundation

Initial trials at lab scale showed significant improvement in compressive and tensile strength, with small amounts of graphene added to concrete. This work led to Innovate UK funding Nationwide Engineering — a UK construction firm co-founded by Manchester graduate Alex McDermott — the GEIC and The University of Manchester's Department of Mechanical, Aerospace and Civil Engineering in establishing large-scale pilot trials.

Nationwide Engineering has also been supported in its work developing graphene-enhanced concrete by the EU-funded ERDF Bridging the Gap programme at the GEIC, which aims to help small-to-medium-sized enterprises (SMEs) successfully commercialise innovative products using graphene and other 2D materials

In May 2021 the development team scaled-up and successfully laid a 700m2 Concretene floor slab for a new gym in Amesbury, Wiltshire. Using conventional equipment and labour, the team used 30% less material for comparable performance to standard, and removed all steel reinforcement, further reducing costs and emissions.

Subsequently, the GEIC and Nationwide Engineering laid two more Concretene slabs in Manchester with contrasting functions: one as part of an access road to the GEIC building, allowing for monitoring of outdoor performance; the other a suspended floor at the Mayfield Depot brownfield regeneration site, for use as a roller disco.

From these trials, the engineering team estimates saving of 25-30% in CO2 emissions and 15-20% in cost, depending on the size of project.

The success of these programmes could lead to a standards and testing programme centred in Manchester, aimed at certification of Concretene for building regulations and roll-out to the wider construction supply chain.