In order to overcome the aforementioned obstacles that limit the potential of a high C-sink in concrete, we developed a method for up-cycling carbon-rich biochar into functional lightweight-aggregates (LWA) for concrete. We propose to produce carbon-rich LWA (C-LWA) by granulation (pelletization) followed by a coldbonding process. Cold bonding pelletization has been previously proposed for synthetic concrete aggregates (without biochar) e.g. in . In this paper we propose a method of production and present a basic physical characterization of the carbon-rich LWA. The C-LWA can be used in concrete much like conventional (sintered) LWA . The CO 2 emissions of the C-LWA are estimated by accounting for the negative emissions thanks to the C-sink and the related emissions involved in the production process.