Effect of carbonation on recycled concrete aggregates microstructure by X-ray tomography

Recycled concrete aggregates carbonation is one of the key solutions to trap CO2 emitted during concrete production back into the material, aiming to approach carbon-neutrality. However, it is a complex process, that depends on several factors, such as the carbon dioxide transport within the material, the moisture content in the pore network and other environmental conditions. These effects are still poorly understood since all current theories rely on point-wise, macroscopic measures, neglecting the intrinsically heterogeneous nature of the process. We seek instead to quantify, in-situ, the spatial distribution of the absorbed carbon by tracking the progressive concrete density variation along with occupancy of the pore-space over a range of conditions to understand the micro-scale processes underlying the macroscopic response. The high contrast and fast X-ray microtomography available at the ID19 of ESRF is the perfect tool to quantify these processes in situ.