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Reclaimed calcined clay cements (Re-C3)

Innovator and industrial partner/s:

Mineral Products Association Ltd (MPA), Hanson Cement, Imerys Aluminates, Forterra Building Products, Tarmac, University College London, University of Dundee

Expected impact:

• 20 - 40% reduction in CO2 emissions vs CEM I (the market leader)
• Multiple clays from UK sources to be investigated for calcining and used as secondary cementitious materials in low carbon cements
• UK standards to be updated to include the new cement formulations

Sectors likely to benefit:

Construction, cement, concrete

The innovation

An MPA-led consortium co-funded by Innovate UK, has begun to investigate the potential of new cements containing UK-sourced calcined clays. The project partners will assess the feasibility of producing calcined clays from reclaimed clays, specifically those obtained from extraction or other manufacturing processes.

For the experimental programme a total of 10 clays have been sampled (from Hanson, Imerys and Tarmac quarries) where parameters such as kiln temperature and particle size will be optimised to allow the highest-possible clinker substitution in low carbon cement formulations. The project is also investigating the potential of a brick powder sample – an already calcined material – as a clinker substitution material.

It has been well documented that the reduced workability of cements containing calcined clays restricts the level of clinker replacement. It is therefore necessary to develop and investigate new water-reducing admixtures which are compatible with calcined clays, and the project will include working closely with the Cement Admixtures Association to achieve this.

The demonstration

Of the 10 quarry-sourced clays in the project, three will be selected for pilot scale production using two industrial heating processes: (1) rotary and (2) flash. A production run of brick powder will also be demonstrated. Following this, low-carbon cements will be formulated and tested for conformity against current standards. The calcined materials from the pilot trials will be sent to the University of Dundee for rigorous strength and durability testing in concrete, with the aim of establishing their suitability as supplementary cementitious materials (SCMs) for concrete.

Thermogravimetric data obtained for one of the UK clays after heating to different maximum temperatures

The potential

Currently 79% of the UK cement market sales is CEM I, with a total market of 10 million tonnes per annum. Of the new cements trialled in the project - one has a CO2 profile 40-60% lower than CEM I. If fully deployed this would result in a reduction in direct emissions from cement production of over 4 million tonnes of CO2 every year. On completion of the testing, the cements will need adoption and deployment.


This project was part funded by Innovate UK through the Industrial Strategy Challenge Fund (ISCF) Transforming Foundation Industries (TFI) large collaborative R&D projects competition. This funding is aimed at improving the productivity and competitiveness of foundation industry companies and supply chains, by funding cross-sector collaborative research and development projects.