Zero-carbon cement could be a reality by 2025

Partners in a new two-year industrial trial have claimed they will produce the world’s first zero-emission cement by transforming a byproduct of steel recycling.

The Cement 2 Zero consortium is led by the Materials Processing Institute (MPI) and includes £6.5m of government funding from UK Research and Innovation. Participants in the demonstration project include researchers from the University of Cambridge with industry input from Atkins, Balfour Beatty, Celsa, Day Aggregates and Tarmac.

The group aims to produce an initial 20 tonnes of Cambridge Electric Cement (CEC) for use in an unnamed modest construction project.

CEC is derived from a process invented by three Cambridge academics to convert construction and demolition waste to cement over molten steel, using the same type of furnace used in steel recycling.

Researchers discovered that using recycled cement as the flux in the electric steel recycling process created Portland cement clinker, which can be blended to make zero-emission cement.

One of the inventors, Dr Cyrille Dunant, claimed that CEC “offers a positive move in cement production and will support the industry response to the UK’s legally binding commitment to bring all greenhouse gas emissions to net zero by 2050”.

Production and testing of CEC will take place at the MPI in Darlington, County Durham, where the first pilot-scale melt was completed earlier this week in a 250kg induction furnace.

Celsa will undertake industrial production of CEC in an electric arc furnace after the process has been “substantially trialled, developed and de-risked effectively”, Atkins noted.

Cambridge researcher Dr Philippa Horton, who created the Cement 2 Zero consortium, said the project “is an invaluable opportunity to collaborate across the entire construction supply chain, to expand CEC from the laboratory to its first commercial application”.

Cement and concrete account for 1.5 per cent of UK carbon dioxide output, according to the Mineral Products Association and National Air Emissions Inventory – and more than half of this total comes from traditional methods of producing Portland cement.

Professor Paul Monks, chief scientific officer at the Department for Business, Energy and Industrial Strategy, described decarbonising cement as “essential to reducing construction emissions and achieving net-zero carbon by 2050”.

Other initiatives on the road to net-zero include a planned £400m upgrade to implement carbon-capture technology at the Hanson cement plant at Padeswood in North Wales.

Proposed Part Z changes to the Building Regulations would limit embodied carbon emissions on all building projects over 1,000 square metres from 2027. It would also require construction firms to assess and report on whole-life carbon, including the use of building materials such as cement, on all non-residential UK projects larger than 1,000 square metres from 2023, and on residential projects from 2025.

Part Z co-author Tim den Dekker told Construction News that he was interested to hear about the zero-emissions cement announcement, but he warned that recycling initiatives of this kind still require a supply of finite old material.

“You might need blast furnace fly ash to make low-carbon cement, for example, but that’s in limited supply,” he noted.