Carbonation of recycled concrete: a way to reduce the CO2 footprint of cement industry

The use of concrete has been growing continuously in the 20th and 21st centuries. The manufacture of cement, the ‘glue’ in concrete, is associated with significant CO2 emissions accounting for ~ 7% of the anthropogenic CO2 emissions in the world. The current global warming crisis have pushed the building industry to search for new and sustainable solutions. New breakthrough technologies for lowering the CO2 footprint include a circular utilization of demolished concrete. This technology, currently under development by the cement industry, consists in the reactions between the hydraulic cement components and their hydration products with carbonate ions (from the injected CO2) in an aqueous medium, which lead to the formation of carbonate minerals and therefore to the permanent storage of the CO2 in solid form. Here, we aim to understand the carbonate mineral formation pathways in the complex environment of a recycled cement paste using in situ PDF analyses of total scattering data.