Report makes recommendations to drive carbon from concrete

The report’s most optimistic scenario suggests the concrete industry could become a carbon sink – absorbing more greenhouse gases than it emits – in the 2040s.

The Low Carbon Concrete Routemap, a collaboration between experts across the concrete and construction sector, has been published by the Green Construction Board and the Institution of Civil Engineers (ICE). The report lays out three decarbonisation routes to 2050 based on what action the industry takes and how fast carbon sequestration in concrete advances. Even under the most modest route, emissions are expected to fall from 10 million tonnes CO₂e in 2022 to five million tonnes in 2035.

In a statement, Andrew Mullholland, chair of the Low-Carbon Concrete Group and co-author of the report, said: “The next 10-15 years are critical in driving the carbon out of concrete. There are steps we can all take immediately to minimise the quantity of concrete we use and the carbon intensity of production, and this change should be driven by clients. This will require motivation and substantial effort from across the industry.”

Concrete accounts for 1.5 per cent of all UK carbon emissions, due largely to the process of making of cement, which binds the concrete and involves heating limestone and clay to very high temperatures and a chemical reaction that produces greenhouse gases. Every year

Approximately 11.7 million tonnes of cement is used in the UK annually and the report makes a series of recommendations for clients, designers, contractors and suppliers to help drive carbon out of concrete.

Recommendations to drive carbon from concrete:

• An industry-wide carbon rating system for concrete, similar to the energy efficiency ratings for homes
• Options for reducing the cement content, especially by using limestone and calcined clays as fly ash and blast furnace slag become less available
• Design approaches that use less concrete or lower-carbon concrete
• Greater collaboration and updates to standards so that lower-carbon concrete can be used wherever possible

Andy Mitchell, co-chair of the Construction Leadership Council, said: “This report pulls together a wealth of practical advice and best practice from across the industry. But more importantly, it charts a route forward to net zero which must increasingly be the guiding principle of every construction project. I call on peers across the industry to read this report and take up its recommendations as soon as possible.”

Many of the recommendations in the report are already being deployed, such as the main flood gate in the Environment Agency’s Boston Barrier which used low carbon concrete and saved over 1,300 tonnes of CO₂e. It also raised a control room above the flood level which avoided the need for deep piled foundations and saved a further 360 tonnes CO₂e.

An informal survey of 178 industry professionals found that education and a tendency of industry standards to recommend more traditional concrete blends and practices were major barriers to decarbonisation. More than half of respondents said they struggled to find data on the carbon embodied in concrete products, so the rating system could help address this.

The report also sees a major role for carbon sequestration from locking carbon dioxide into concrete and capturing the carbon that arises from cement production. The report acknowledges that these techniques are not yet commercially viable and calls for large-scale industry and government support for research and trials. Sequestration should be seen as an ‘end-of-pipe solution’ once other opportunities to cut carbon have been taken.

A new UK Concrete Decarbonisation Taskforce, convened by the ICE, will oversee the delivery of the Low Carbon Concrete Routemap. This group will update the report each year and monitor progress across the industry.

Mark Hansford, director of Engineering Knowledge at ICE, said: “We have the solutions and a clear route forward. The UK Concrete Decarbonisation Taskforce has a vital role to play in unlocking funding and working across the industry and government so that we can drive a step change in the decarbonisation of concrete.”