Soil stabilisation

Soil stabilisation using integrated design of low CO₂ alternative cementitious binders

Heavy machinery cannot make it over wet, uneven ground, so one of the first jobs on a construction site is stabilising the ground. This is often done with compacted virgin aggregate, which depletes natural resources, or pouring on hundreds of tonnes of concrete made with high-carbon, high-emission cement.

A Teesside-based company is exploring a solution that is lower in carbon and utilises local industrial waste otherwise destined for landfill. With funding from the Transforming Foundation Industries (TFI) challenge, Material Evolution Ltd is drawing on its existing low-carbon cement technology – which incorporates 95% waste – to develop a soil stabiliser made with a by-product of Teesside’s historic steel industry.

“Our mission is to rapidly decarbonise the cement industry at scale,” says Material Evolution CEO and co-founder Dr Liz Gilligan. “Our advanced geopolymer technology and algorithms already reduce carbon consumption by 85% in our cement mix, but we need to look at feedstocks to get to zero emissions. UK industry is full of untapped, mineral-rich waste streams that we could potentially ‘mine’ for cement materials.”

The project explored the potential of 500,000 tonnes of Basic Oxygen Furnace (BOF) steel slag at demolished steel works that could be used in developing the Teesside freeport. “Slag heaps present a challenge as a feedstock because they are often inconsistent; weathering at the top of the pile can make the material very different from that at the bottom,” explains Sam Clark, Material Evolution CPO and co-founder. “We use algorithms to rapidly understand what’s in each of the layers so that we can adjust the mix or our approach to that material accordingly.”

The project team worked with Teesside University to test and characterise the BOF slag. “It was interesting because the material didn’t act in the way we expected. However, we could create a very stable cementitious product with some pre-processing and altering our existing chemistry.”

With current cement shortages, rising prices and construction projects increasingly considering carbon emissions in their decision-making, there is a significant market opportunity for low-carbon, locally sourced cement within the UK. The team are following the project with an industrial demonstrator that aims to take a step closer to commercialisation and, crucially, establish the product’s feasibility on site.

“Our next project is working with industrial partners, as what works in a lab can be very different in the real world, particularly on sites where materials can be contaminated or treated differently than you intended,” says Dr Gilligan. “Understanding how these industries operate will put us in the perfect position to create a truly carbon-negative cement that uses our advanced technology and waste material locally in a particular area.”