Carbon reduction

Innovating to reduce carbon

Nick Jowett
Tuesday 17th October, 2023

A few months ago, we revealed some exciting news about what we’re doing at Marshalls when it comes to taking real action on carbon reduction. I’m really proud of what we’re achieving – because I know it’s not been easy and it’s part of a much longer journey.

Reducing carbon is something we’ve been doing for a long time. Year on year, we hit our targets and we continue to push ourselves to be as efficient as we can be. We have lots of different projects at our manufacturing sites that are specifically aimed at reducing energy – for example the solar arrays that have been installed at our St Ives dual block plant or the plastic packaging reduction we started at our Sittingbourne site. This is all part of our plan to tackle climate change.

As a manufacturer, we know the role we have to play in innovating in our industry. We know we’ve got to do our bit and do the hard work. And that’s what we’ve been doing with cement reduction. The tricky thing is that it’s not easy to replace cement in concrete. Cement is a binder and binders have properties that are crucial to the manufacturing of concrete – a bit like flour to a loaf of bread, you can’t replace it with any material. We’ve looked at replacing cement for many years, but we have to be really strict on what we replace it with – we’ve got to think about the impact on the strength, durability, safety, and aesthetic of the product.

We tend to replace cement with GGBS (ground granulated blast furnace slag), PFA (pulverised fly ash) or limestone powder, or a combination of the three. Sometimes our trials haven’t worked because some blends just don’t mix well. Other times it might have been that we’ve tried a different substitute material which just didn’t work. Or sometimes the mix we were using affected the curing time of the product, so that was impacting on our efficiency. But we persevered and last year, we introduced Tri-blend powder technology to our Ramsbottom site. This has reduced the carbon footprint of concrete block paving products and more importantly, it’s a technology we are going to be rolling out across more of our sites.

I have to say our technical team is second to none – they’ve been working hard to look at lots of different ways to remove cement completely from the production of concrete. So, it’s a real achievement to have produced our first full-scale production run of cement-free concrete blocks. But that’s just the start. We’re now refining our materials and processes to be able to fully launch in 2024.

It’s the same with carbon sequestration – we’ve been developing this for some time and finding the right partner was fundamental to the success of the project. We’re working with CarbonCure Technologies to permanently lock captured carbon into our concrete facing bricks. This is really exciting for Marshalls because through this process, we’re using carbon from the waste industry and injecting it directly into our concrete as it’s being mixed. The CO2 immediately reacts with cement in the mix and mineralises. Once that’s happened, the carbon is permanently locked into the concrete – never to be released into the atmosphere, even if the concrete is demolished. We’ve trialled this at our Grove manufacturing site and the aim is to use this technology at more of our sites in the UK.

So, our journey continues, and I think it’s clear that we’re committed to innovating in the manufacture of our products. There is still a lot to do, but we’re in a good place and I look forward to sharing more updates in the future.

Injecting waste carbon into concrete bricks at Marshalls:

Capturing carbon in concrete:


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