The FastCarb project results from two observations. On the one hand, cement production is a major source of CO2 emissions worldwide (5 to 7% of total emissions). About two-thirds of these emissions are due to the decarbonation of limestone during the manufacture of portland cement. On the other hand, natural resources must be preserved and a large amount of recycled concrete from deconstruction is available. Although recycled concrete aggregates (RCA) can already be used, their high porosity has an impact on concrete performance. Recycled aggregates contain, within their cement matrix, portlandite and C-S-H that can be carbonated. The aim of the FastCarb project is firstly to store CO2 in the RCA, in order to reduce the environmental impact of concrete in the structures and secondly to improve the quality of these aggregates by reducing their porosity. It has two main objectives: to optimize the RCA accelerated carbonation process and to show that this process can be used in an industrial context.