Marshalls is injecting carbon into its concrete facing bricks to eliminate it from the environment.
And in a separate project it is making concrete with zero cement content – not just cement-reduction additives, but none at all.
Marshalls declares that it has become the first precast concrete manufacturer in the UK to use CarbonCure technology, a process that permanently locks captured carbon into concrete. The technology is being used on facing bricks manufactured at the Marshalls plant in Grove, South Wales, where around 50 million bricks are made each year. The carbon is injected into the brick during the manufacturing process and has no impact on its performance or appearance.
Marshalls technical director Nick Jowett said: "We’re continually testing and trialling product and manufacturing innovations, and to be able to introduce something which also has a sustainability benefit is a double win.
“Whilst our customers will see no difference in our products' look and performance, we expect that, from this manufacturing site alone, we’ll prevent 30 tonnes of carbon from entering the atmosphere every year.”
CarbonCure is a company offering technologies that reduce and remove carbon dioxide across the concrete manufacturing process. CarbonCure’s technologies inject CO2 directly into concrete as it is being mixed. The CO2 immediately reacts with cement in the mix and mineralises to create calcium carbonate (CaCO3). Once the CO2 is mineralised, it is permanently locked into the concrete forever — never to be released into the atmosphere, even if the concrete is demolished, it is claimed.
Marshalls has also been working on finding a viable alternative to carbon-intensive cement and late last year produced its first full-scale production run of cement-free concrete blocks. For commercial reasons, it is vague about the details.
“On this project, we’re working with several suppliers to use by-products from other industrial processes and waste materials that, when activated, give similar chemical reactions and properties to cement-based systems,” Nick Jowett explained.
“The ‘glues’ that hold it all together are activators that are based on a blend of raw materials that, when used in conjunction with the cement replacement materials, react chemically and produce concrete with the strength and durability performance of conventional concrete,” he added.
Michael Edwards, group head of sustainability at Marshalls, said: “Cement can account for over 80% of the total carbon footprint of a concrete product, so it’s no surprise that customers have been asking for cement-free materials for a while. However, as a business known for its high-quality materials, we need to ensure that in removing the cement, we’re not compromising on the quality, appearance or longevity of our products, so we’re refining the materials and process before a full launch later in 2023.”
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