Portland cement concrete is the most heavily used manufactured material on the planet after clean water, and it is integral to modern life. However, the production of 4 billion tonnes of Portland cement per year is responsible for 8% of global man-made greenhouse gas emissions. With the growing threat of climate change, there is an urgent need to decarbonise cement production. Currently, the most viable approach to reduce cement's carbon footprint involve the widespread use of supplementary cementitious materials (SCMs), such as fly ash from electricity generation and ground granulated blast furnace slag from steel manufacture. However, with decarbonisation of electricity and the decline of UK steel manufacture, these materials are becoming increasingly scarce. Therefore, we need to develop low-carbon alternatives, without disrupting construction practice nor compromising on long-term performance. This is the ultimate goal of this project.

Recently, there has been growing interest in using clays as cementitious materials in the production of low-carbon concrete because they are practical, affordable, and scalable. The UK has abundant clay resources that can be easily obtained from overburdens of existing quarries and infrastructure development projects, where they are currently regarded as wastes. However, most of the clay in the UK and globally are low grade and are less reactive compared to high purity kaolinite clays. Therefore, there is a need to develop focussed solutions based on these low-grade clay deposits, rather than to depend on the importation of alternatives from thousands of miles. This project is timely since increased infrastructure activity, e.g. Crossrail, HS2, as well as driving increased demand for cement and concrete, will also lead to higher production of construction spoils that contain waste clays. Thus, we will develop new low-carbon cements from locally sourced clay-bearing construction and mining spoils. Using these in concrete production is a highly sustainable and circular solution; turning waste clays into valuable resources.

The development of low-carbon cements is vital, but if these new materials are not translated from the laboratory to the construction site, then the necessary change will not arise. To achieve this, we will examine the performance of these new low-carbon cements from manufacture, through site practice to understanding long-term durability. The research team will work with industry from all along the supply chain to ensure that the newly developed materials satisfy industry requirements and are adopted as wide as possible to maximise carbon reductions of our built environment.

In summary, the research team and their industrial partners will develop new cements from locally sourced low-grade waste clays to significantly reduce the carbon footprint of concrete and ensure performance along the entire lifetime of infrastructure. This will help the UK to deliver on its plans to decarbonise and achieve a net-zero economy.