Maximising value of construction Waste and CO2 capture for low-carbon CEMent: In situ hydration imaging with SYNchrotron X-ray

Portland cement (PC) production is responsible for 7% of global CO2 emissions, and construction and demolition waste represent the largest waste stream in the EU, accounting for over one-third of all waste. These factors pose significant threats to sustainable development. To address these challenges, the Syn4WCO2-Cem project aims to align with the European Green Deal by promoting a circular economy within the construction sector. The primary objective of the project is to treat recycled concrete powder (RCP) by capturing CO2 from cement plant flue gases and to develop low-carbon cement composites using carbonated RCP (CRCP). One of the main challenges of low-carbon cement is its slow hydration kinetics within the first three days, which impedes the development of early strength. Currently, the particle dissolution rates in PC-CRCP blends and their C-S-H gel shell feature are not well understood. Gaining insight into the interactions between these parameters and strength-enhancing admixtures is crucial for accelerating the hydration process in a more mechanistic and scientifically grounded manner, rather than relying on the current trial-and-error approaches. The project seeks to address this critical knowledge gap by training fellow at the host institution (UMA) and utilizing advanced X-ray tools, including laboratory and synchrotron-based in situ X-ray imaging and diffraction, to visualize the hydration process of this low-carbon cement family. This comprehensive approach will help clarify the underlying mechanisms of the slow hydration process and develop effective strategies to accelerate it. The interdisciplinary innovation in this project will ensure that this low-carbon cement can achieve a 60% reduction in CO2 emissions compared to traditional PC-based binder while maintaining competitive performances. The project offers a unique opportunity for fellow to gain a competitive edge in the emerging field of “sustainable and green building materials”.