Concrete Step in the Right Direction

Finding a replacement for energy intensive concrete would make massive inroads into our net zero targets, so could new ‘super-material’ geopolymer cement be the answer?

When it comes to inspiration on ways we can save the planet, we really don’t need to look much further than the walls around us, the roads we drive, or the paths we walk.

The global construction industry is responsible for a whopping 39% of global CO2 emissions, their processes consuming 40% of raw materials. The production of concrete is highly carbon intensive. It’s the second most used material in the world. Water is the first. It’s also the biggest source of CO2 after fossil fuels, generating 8% of global CO2 emissions, mostly because the creation of Portland cement is a heat intensive, high energy process. Tackling our rigid attachment to concrete will make a significant dent in our net-zero targets.

Roisin Hyde is an architect and PhD researcher at Queens University at Belfast. She is working on ground-breaking research into geopolymer cement. A product that presents a real opportunity for the construction industry to cut their global emissions significantly. Geopolymer cement uses a much lower carbon intensive process, but it is also an ideal ‘circular economy’ product, with cement easily made from a wide array of readily available waste materials and by-products.

This specialist research team was formed following a climate emergency summit held in 2020 by the Royal Scottish Geographical Society on the theme of construction. RSGS was subsequently asked to convene a more detailed event specifically on geopolymer cement. They mobilized attendance from industry reps, angel investors, the Scottish Construction Innovation Centre, circular economy experts and water companies, alongside senior managers from leading construction firms. Hyde outlined the opportunity for low carbon alternatives like geopolymer cement, and the need for innovation. The excitement in the room was palpable, leading to a successful joint bid to the Innovate UK fund to progress further research.

Hyde commented: “Geopolymer is a real opportunity to cut emissions significantly but, in order to gain acceptance for the production of this high-performance cement-free concrete we needed to rapidly invest in more trials and research.”

The NoMAD (Novel Materials Architecture and Design) research team, led by Hyde, is run out of Queen’s University Belfast. They are working with the UK’s largest construction company, Balfour Beatty, whose senior management team are all alumni of the RSGS Climate Solutions course and members of the Climate Solutions Network, engineering consultants AKTII and architects MamouMani. Their objective is to develop high performance pre-cast and 3D printed geopolymer concrete components using locally available by-product and waste materials.

“Balfour Beatty are a unique company,” explains Hyde. “They have real vision, are innovation friendly and embrace disruptive technologies. After engaging with literally hundreds of companies I feel I am now working with my dream team to demonstrate the potential of this amazing product.”

She continued, “Conventional cement is a made through the extraction, crushing, heating, and milling of limestone. This is a process during which more than 40% of the materials is converted to CO2. Combined with the fossil fuels used in transportation and processing this amounts to between 0.75 – 1.00 tons of CO2 per ton of cement. This all adds up to over 3.2 billion tons annually, the equivalent to the combined annual emissions from every car in Europe, America and China put together. It’s a staggering amount.”

“Geopolymer binders, by contrast, are created using waste by-products such as incinerator waste, waste-water purification sludge, or recycled glass, ceramics and aluminium. It’s a commercial game changer for the waste management industry, creating a new and valuable market for their waste by-products, as well as boosting the planet friendly practices of the world’s construction industry.”

“It is stronger, more chemically resistant, more stable at extreme temperatures and more durable than conventional cement materials. It sets rapidly, meaning it saves construction time too – a win for the industry and their clients. I can’t begin to underline enough that this is one of the most significant innovations that the industry has ever seen. In short, we can do it better and faster, with less impact on the planet.”

This summer the team developed a prototype ultra-high performance geopolymer concrete pontoon which was built at the Construction Scotland Innovation Centre. This will be on display as part of the centre’s upcoming BE@COP26 exhibition, showcasing innovations which specifically tackle construction industry challenges and stimulate sustainable economic growth.

Their industry leading research demonstrates how the current “take-make-dispose” model of concrete production can be easily transformed to a circular economic model, reducing reliance on imported raw materials and the need to dispose solid waste in landfill.

“This is it,” explains Hyde. “Geopolymer is a high performance, low impact super-material. It is undoubtedly part of the solution for the de-carbonisation of the concrete industry. This is not a futuristic hypothesis, it’s current viability and, crucially for our planet, we can start doing it today.”
Hyde said, “I probably don’t feel as negative about the future as a lot of people. When you are involved in this type of work you know there are thousands of people all over the world doing remarkable things. There are solutions. We have the technology, the resources, the expertise and knowledge. We just need to do it!”

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