The Climate Challenge: Taking cement ‘2 Zero’


Will Lavelle of Atkins and Dr Philippa Horton from University of Cambridge discuss the world’s first zero emissions cement trial and the aim of developing net-zero cement for the construction industry.

The decarbonisation of the built environment presents a phenomenal challenge to the construction industry, as the global 2050 deadline looms large. And with an estimated 80% of 2050’s buildings already in use today, there has rightly been considerable political and public attention given to the operational decarbonisation of existing UK homes through improved insulation, installation of heat pumps and the rapid shift towards a renewable domestic electricity supply.

But there is also a keen focus on the carbon footprint of construction itself and a real need to ensure ‘embodied carbon’ is not left behind. Which is why the recent launch of zero-emissions cement trials is such an important step in the construction industry’s net zero journey.

Cement 2 Zero (C2Z) is a UK-based demonstrator project to trial the world’s first zero-emissions cement on an industrial scale. This innovative project, which secured £6.5m of Government funding from UKRI as part of the Transforming Foundation Industries Challenge, aims to further advance the construction, cement and steel sectors’ decarbonisation journey to net zero industries of the future, to help meet the UK Government’s commitment of achieving Net Zero by 2050.  

Led by the Materials Processing Institute, supported by the University of Cambridge, and in collaboration with key players in the supply chain, Cement 2 Zero is the first collaborative trial of its kind, to address the global construction industry’s biggest challenge of decarbonisation, in response to the climate emergency. 

Concrete is the most widely used material on earth, after water, and it is fundamental to our way of life, our economy and shaping our world. However, the chemical and thermal combustion processes involved in the production of cement are a significant source of CO2 emissions – with more than four billion tonnes of cement produced each year – accounting for around 7% of global CO2 emissions, according to the Global Cement and Concrete Association (GCCA). 

Cement-based products can easily contribute more than 50% of the CO2e emitted during construction of a traditional new-build home and is found in many of the key elements including foundations, mortar and screed, but also blockwork and plasterboard. 

In the UK, concrete and cement account for 1.5% of CO2 emissions and the Cement 2 Zero project will investigate both the technical and commercial aspects of upscaling the production of Cambridge Electric Cement (CEC) to produce 20 tonnes of what’s thought to be the world’s first zero emissions cement.  

The first phase of trial melts is being carried out by the Materials Processing Institute, initially in a 250 kg induction furnace, before being scaled up to 6T in an Electric Arc Furnace (EAF). Once the process has been substantially trialled, developed and de-risked effectively, industrial scale melts will follow in CELSA’s EAF in Cardiff. 

The two-year industrial trial will test each stage of the production process and brings together the expertise of the Materials Processing Institute, the University of Cambridge and key supply chain partners – Atkins, Balfour Beatty, CELSA, Day Aggregates and Tarmac – before using the innovative product in a live UK construction project.  

If successful, it could not only further advance the cement, steel and construction industries, but influence how we recycle, construct and maintain our built environment and transport infrastructure, shaping the future of towns and cities, while simultaneously boosting economic development, and most importantly, reducing CO2 emissions to help tackle global warming.  

If Cambridge Electric Cement lives up to the promise it has shown in early laboratory trials, when combined with other innovative technologies, it could be a pivotal point in the journey to a zero-emissions society.  The Cement 2 Zero project is an invaluable opportunity to collaborate across the entire construction supply chain, to expand CEC from the laboratory to its first commercial application.

It also has the potential to make a significant contribution to achieving a zero-carbon society, secure and increase jobs in the UK cement and steel sectors and challenge conventional production processes, creating high-value materials from demolition waste.

The science behind Cambridge Electric Cement (CEC) is truly innovative. Three researchers at the University of Cambridge, Dr Cyrille Dunant and Professor Julian Allwood along with Dr Philippa Horton, invented a process that converts construction and demolition waste to cement over molten steel, using an EAF used to recycle scrap steel. 

The Cement 2 Zero project aims to demonstrate that concrete can be recycled to create a Slag Forming addition which could, when cooled rapidly, replace Portland cement.   

Dr Dunant has discovered that the chemical composition of used cement is virtually identical to that of the lime-flux used in the conventional EAF steel recycling process.  

Traditional Portland clinker, one of the main ingredients in cement, is produced by firing limestone and other minerals in a kiln at extremely high temperatures (1,450°C), which is the process accounting for more than 50% of the cement sectors’ emissions. 

By contrast, Cement 2 Zero will use recycled cement as the flux in the electric steel recycling process (EAF powered by renewables), the by-product of which, when cooled and ground, produces Portland cement clinker, which is then blended to make ‘zero-emissions’ cement.  

Therefore, this innovative cement product (CEC) could be made in a virtuous recycling loop, that not only eliminates the significant emissions of cement and steel production, but also saves raw materials.  

It is a project that aims to be transformational for the cement and steel industries, creating a zero-emission supply chain from demolition to construction. 

So, when it comes to housebuilding, CEC represents a huge opportunity to massively reduce the impact of our industry. And when you combine this with the lower carbon steel technology which is also enabled by this trial, there is a real sense that we’re well on our way to real net-zero homes.

Will Lavelle is Atkins’ embodied carbon lead & Dr Philippa Horton is Use Less group business manager at University of Cambridge