18/11/2019
Richard Leese, MPA director of industrial policy, energy and climate change, considers some of the innovations in cement that have the potential significantly reduce the carbon emissions in concrete.
The mineral products industry has a long history of innovation. And with climate change climbing the global agenda, research into reducing the carbon impact of cement is showing ever-more promising signs.
From the sourcing of alternative raw materials and harnessing renewable energies, to optimising the manufacturing process and transforming the way products perform, there is no shortage of creative solutions in the mineral products sector. Even small refinements can be significant and collectively have a huge positive impact.
To increase confidence in the use of new materials, rigorous testing and field evidence is needed to influence the relevant standards and guidance that underpin decision-making. That takes time, money and persistence on the part of the industry, with no guarantee of success.
Undeterred, mineral products companies are steadily breaking new ground – in some cases over many years – to encourage customers to adapt their thinking and adopt innovations.
Today new innovations in carbon reduction are being pushed to the next level to drive another step change in the carbon impact of concrete. Here are just two examples of innovations designed to reduce the embodied carbon in concrete which could be coming to the market soon.
Multi-component cement
The CO₂ in cement is commonly reduced by substituting it with a percentage of a secondary component, such as fly ash or blast furnace slag. But companies are always looking for ways to optimise the use of such replacements to extend the performance and availability of low-carbon concretes.
MPA Cement and its research partners have identified that ground limestone could also be used to make new lower carbon ‘multi-component’ cements – or cements with more than one additional component.
Certain multi-component combinations have better material efficiency and therefore higher rates of substitution. Early indications suggest there could be CO₂ emissions savings of around eight per cent across the UK cement industry, with some multi-component products having emissions profiles up to 40% lower than conventional cement.
With funding from the Government’s Industrial Energy Efficiency Accelerator (IEEA) the MPA is spearheading a project with Hanson Cement, Forterra Building Products and the Building Research Establishment to develop new lower carbon multi-component cements and demonstrate they are fit for purpose in a wide range of UK concrete applications.
The research, testing and demonstration will provide crucial evidence and assurance for architects, specifiers and engineers to confidently use these new low carbon cements to deliver the Government’s plans for low carbon schools, housing and infrastructure.
Carbon-storing concrete
After investing heavily in research, US-based Solidia Technologies has launched a radically reformulated cement and concrete process which has the potential to reduce CO₂ by up to 70%.
It has done this by reformulating cement so that it contains less calcium. This reduces CO₂ emissions at the cement kiln – both because less CO₂ is released during the manufacturing and the cement can be produced at lower temperatures, so less energy is required.
Traditional Portland cement-based concrete reacts with water to produce calcium silicon hydrate – the glue that binds it together.
However, concrete that uses Solida’s low calcium cement is bound together by calcium silicon carbonate after being activated by the addition of warm CO₂ gas.
By activating the mix with CO₂ recovered from industrial processes it is incorporated permanently into the concrete. This means the carbon footprint of the end product is reduced to around 30% of traditional concrete.
If CO₂-cured concrete succeeds in gaining commercial traction, it could be used to bind up large quantities of CO₂.
By Richard Leese, MPA director of industrial policy, energy and climate change