The valorization of contaminated waste glass to produce locally sourced, low-carbon cement at the Cemex Rugby cement plant

The rapid decommissioning of coal power plants in the UK has inadvertently created a supply chain crisis in the construction industry, as most cement and concrete producers use coal fly ash as a staple supplementary cementitious material (SCM) in cements. The lack of local SCMs from the coal power and steel industries has led to increased imports from mainland Europe and elsewhere, further exacerbating the carbon emissions associated with the UK construction industry. Carbon Upcycling Technologies UK (CUT) is a subsidiary of Carbon Upcycling Technologies, an award-winning Canadian startup (e.g., Carbon X-Prize winner and Solar Impulse Efficient Solution Label owner) scaling a carbon utilization technology that can activate a range of abundantly available waste materials such as landfilled ash, glass, clays, and volcanic rocks to permanently store CO2 and produce reactive low carbon cements.

For this initiative, CUT will assemble a consortium primarily comprising partners from two pivotal foundation industries: the glass sector, represented by Glass Technology Services and MKD32, and the cement industry, represented by CEMEX. Together, this consortium aims to pioneer a circular economy solution, transforming local low-grade, contaminated glass cullets into high-performance Supplementary Cementitious Materials (SCMs).

Collaborating closely, CUT and its project partners will develop a groundbreaking CO2-enhanced glass pozzolan. This innovative material not only reduces the carbon footprint of cement and concrete but also repurposes contaminated post-consumer glass, diverting it from its current use as an inert filler in precast blocks. Recognizing the significance of quality control in the cement sector, the project will establish a robust quality control system for processing materials, including investigations into pre-processing to enhance material quality and output.

The designed plant is versatile, capable of processing various dry feedstocks with a particle size of approximately <4mm. This adaptability allows the demonstrator to validate alternative feedstock types for diverse foundational industries, promoting circularity and contributing to emission reduction efforts across these industries.

The CO2-enhanced glass pozzolan, along with other trial types, will be integrated into cement at the CEMEX Rugby plant. The resulting blend will be utilized in ready-mix and precast concrete for various infrastructure elements such as sidewalks, curbs, gutters, driveways, and foundations. This integration aims to significantly reduce the carbon footprint of UK-built infrastructure. The glass-derived pozzolan is expected to decrease the amount of cement in a concrete mix by over 25%, enhance strength performance, and improve concrete durability by up to 45%. These improvements contribute to increased resilience against environmental impacts related to climate change.

By directly aligning with the UK's circular economy goals and supporting the nation's commitment to an 80% reduction in carbon emissions by 2050, this project plays a crucial role. Given that the infrastructure sector accounts for almost one-sixth of total emissions, its participation is instrumental in achieving national carbon reduction targets. Currently, low carbon cement and concrete are projected to contribute a 12% reduction toward reaching a net-zero emissions target.