Self-nanocrystallisation of cement for CO2 emissions reduction

Concrete, the most widely used man-made material, builds modern society, while also generating massive CO2 emissions. The cement and concrete sector emitted 2.9Gt CO2, over 7% of global emissions. As highlighted in the GCCA Net Zero Roadmap, reducing cement use offers significant mitigation potential. Nanofillers show comprehensive advantages in modifying concrete performance, but some critical shortcomings are related to the complex production process, low production capacity, and high cost of nanofillers. This project proposes a self-nanocrystallisation of cement (SNC) approach. The SNC approach involves producing homogenous nano Ca(OH)2 in cement solution by controlling hydration conditions, followed by its conversion into nano-CaCO₃ through controlled CO2 bubbling. This process enhances cement efficiency and reduce CO2 emissions through improving concrete performance. For this purpose, this project will initially develop, validate, and optimise the SNC approaches, while revealing their underlying mechanisms, thus establishing reproducible and efficient SNC approaches. Then, the modification effect and mechanisms of SNC-derived nanofillers on the mechanical, durability and microstructural properties of concrete will be investigated. Finally, the project will evaluate the load-bearing performance of structures constructed with SNC-modified concrete, and conduct life-cycle assessments, emphasizing the potential benefits of SNC approach in reducing concrete cost and CO2 emissions. The SNC approach is designed based on the hydration characteristics of cement and carbonation process, and it does not require complex preparation processes, large amount of energy, or extra catalysts. Benefiting from the nano-core effect, SNC-derived nano-CaCO₃ can increase concrete compressive strength by 1–3 grades without extra cement, thereby reducing CO2 emissions by 10–40% and costs by 10–26%, while advancing the development of net zero concrete in line with the GCCA 2050 roadmap.