What is the Low Carbon Concrete Routemap and what does it mean for you?

This article was authored by Paul Astle, Associate at Ramboll, and was originally published on the Institute of Civil Engineers (ICE) website at this link.

What is the Low Carbon Concrete Group?

The Green Construction Board’s Low Carbon Concrete Group, formed by industry professionals on a voluntary basis, has been meeting regularly since early 2020 to discuss the issues surrounding the decarbonisation of concrete. Also discussed are the latest techniques and technology that can speed up the move to a zero-carbon future. The result of these meetings is the recently launched Low Carbon Concrete (LCC) Routemap. Read the routemap here

What is the Low Carbon Concrete Routemap?

This free-to-download document is published by the ICE and endorsed by the Construction Leadership Council, the Concrete Centre and the Institution of Structural Engineers. It provides objective advice on low carbon concrete, the actions that are necessary to get to a net zero future, and potential scenarios when they are implemented.

What makes the LCC Routemap different?

There are several route maps, or roadmaps, from the concrete industry, as well as broader documents that discuss the decarbonisation of concrete. The LCC Routemap differs in these following important ways:

1. There’s no agenda to promote the use of concrete or a particular technology.

The document has been prepared on a voluntary basis by a broad cross-section of the industry, with representation from clients, designers, contractors, academics, concrete producers, and concrete technologists. A core tenet of the document is that we use concrete more efficiently, i.e. achieving the same benefits with less.

2. The document emphasises the steps that can be taken now to make immediate savings.

These need not involve a reduction in performance or an increase in cost. They’re simply the result of a conscientious focus on reducing carbon.

3. Finally, the routemap scenarios don’t rely on carbon capture use or storage to provide the savings.

However, it’s recognised that carbon capture can play a significant role overall as long as the technology can be developed, funded and rolled out at a sufficiently large scale.

How the LCC Routemap can help

The document seeks to address the full supply chain of concrete from design and specification to batching, mixing and the use of different cements. There are therefore many areas which will be of use to different parts of the industry. If we consider just one part though, the embodied carbon rating certificate, how would this be used? Many clients and engineers have been looking for a benchmarking approach that would allow them to drive demand of lower carbon concrete by understanding what good looks like. The carbon rating certificate provides just that.

Carbon rating certificate
The carbon rating certificate operates similarly to energy ratings system we use for electrical appliances at home.

Providing a benchmark

While concretes with the lowest carbon ratings aren’t suitable for all uses, the benchmark provides a solid starting point from which to assess how our concretes measure up against industry usage. It can also help identify opportunities for improvement. As such, it’s expected that clients and specifiers may seek to mandate at least the reporting of concrete carbon intensity against the benchmark if not going further by mandating a specific intensity threshold. For example, ‘all concrete shall, on average, be less than a B rating according to the LCCG benchmark’. The act of focussing attention on the carbon intensity of concrete will in turn lead to better data, lower carbon concretes and a strong incentive for innovation in the sector. All of which are long overdue.

Keeping options open

It’s recognised that a focus on carbon intensity of concrete alone could lead to a dash to GGBS (Ground Granulated Blast-furnace Slag) blends, something already experienced in the industry. While the optimised use of GGBS is part of the puzzle, it’s important to drive other alternatives which may be at an earlier stage in their adoption. Some suppliers may seek to meet the demand for low carbon concrete solely through the use of GGBS, but this will rapidly become unsustainable given the overall supply limitations.

Encouraging competition for the benefit of the industry

Companies that can offer alternative blends, additions or technologies will be in a more competitive position in the coming years. Furthermore, while there’s a danger of unintended consequences associated with a simple carbon rating for concrete, one could argue there’s a far greater risk associated with not seeking to limit carbon in concrete at all. The LCC benchmark provides a catalyst to start discussion between clients, designers and suppliers and will hopefully help accelerate a shift in carbon intensity.

Carbon intensity ratings
Proposed carbon intensity ratings for different strength classes of concrete.

Not the end, but the end of the beginning

One would think that after two years of dialogue, the discussion on decarbonising concrete might have been exhausted, but we’ve only just started. This is due in part to the explosion of interest in the subject and the vast range of new ideas and technologies that are all contributing to potential solutions. This is as well as the recognised urgency due to climate change.

There will be many more discussions and further guidance as we obtain more data, uncover more knowledge, and learn of new discoveries. The routemap provides practical guidance to making the first steps in the transition to lower carbon concrete. But there’s much more work to be done and many opportunities for the industry to meet the challenge. The route ahead may be bumpy, but the journey is unavoidable. We hope you’ll join us in finding the quickest way there.