Green, Circular, and Smart Cement Manufacture

I will establish the underpinning scientific and technical knowledge to enable the UK cement industry and UK producers of alumina-containing waste to create new supply chains for the manufacture of high-performance low-CO2 cements. I will also develop a user-friendly process model that can optimise cement clinker manufacture from waste. Moreover, I will support the academic and industrial community by creating a much-needed centre for experimental thermodynamics in the UK and will become established and recognised as a leader in low-carbon cement production.

Cement is the most manufactured product on the planet and is essential to the development of infrastructure and economy. Cement manufacture is responsible for 2% of the UK's carbon emissions where more than 8 Mt p.a. of, the generally employed, Portland cement (PC) clinker are produced. Globally, the manufacture of 4 Gt of cement p.a. is responsible for 8% of man-made CO2 emissions.

Calcium sulfoaluminate (CSA) cements can achieve more than 30% reduction in CO2 emissions compared to PC, on a mass basis, when produced from virgin raw materials. The properties of CSA cements are often superior to those of PC and are therefore used in special applications such as fast-track rehabilitation of highways and airfields. Considering their savings in work-time and their higher performance, CO2 savings from CSA cement, compared to PC, are in fact greater. Moreover, CSA cement can be produced in existing PC plant configurations without major modifications; thus, low industrial capex. CSA cements are normally produced from bauxite, limestone, and clay. However, the use of CSA cements has been limited in the UK due to the lack of a raw alumina source (i.e., bauxite), which is required for CSA manufacture; any CSA cement currently used in the UK is imported.

On the other hand, the UK industry produces significant volumes of waste material containing alumina which this Fellowship research aims to valorise. Two major waste streams are potable aluminium water treatment sludge (aWTS), and aluminium oxide residue (AOR) from secondary aluminium production and recycling. The UK produces ~90 kt of aWTS (dry) and ~70 kt of ALS per year which can be used as alumina sources, replacing bauxite, to produce ~1M tonnes of CSA cement p.a., and replacing up to 50% of virgin raw materials with waste.

This translational research will create a new subindustry in the UK, by enabling CSA cement manufacture through an innovative process, valorising UK industrial residues, and creating new UK products. However, to develop and establish the manufacturing process for targeted cement clinkers, the presence and fluctuation of impurities in the wastes must be addressed.

Industrially, the proportions of cement clinker phases produced through thermal processing of the raw materials are designed using empirical equations. This approach is not suitable to produce CSA clinker, especially when alternative raw materials (containing foreign elements) are used. A more flexible approach is required. Therefore, this Fellowship research will also derive necessary fundamental material data for the phases involved in CSA clinkering from waste and use the data to build a user-friendly pyro-processing simulator that will allow for rapid raw material mix and process design, optimisation, and troubleshooting. This simulator will also enable identification of other potentially useful feed sources for clinker manufacture; thus, a reduction in future experimental clinkering tests.

As part of this Fellowship, I will also establish the first centre for experimental thermodynamics in the UK. I will leverage the successful completion of the Fellowship to lead research in low-carbon cement production and specialising in thermochemistry. I also aim to become an ambassador for CSA cement and concrete in the UK and to be involved in influencing policy and writing standards for CSA cement and concrete.