CONCERTO · CarbOn Negative CemEnt fRom ulTra-mafic rOcks

The majority of CO2 emissions associated with Portland clinker production originate from the calcination of limestone, a process necessary to extract calcium, the key element required for forming the main binding hydration phases. Unfortunately, most of the calcium found in nature is embedded in limestone. This project aims to explore hydraulic binders based on magnesium (instead of calcium) since this element is abundant in silico-magnesian ultramafic rocks, which are widely available. This approach thus eliminates the CO2 emissions associated with the decarbonization of raw materials during the production process. We have developed a groundbreaking, scalable process for producing silico-magnesian CO2-free cements from ultramafic rocks (CNRS pending patent). If decarbonized energy is used during production, the overall carbon footprint of this binder could be net-negative, as magnesium hydroxide formed during hydration could sequester atmospheric CO2 throughout the service life of the cementitious product via carbonation. The main goal of this project is to optimize the manufacturing process and performances of this hydraulic binder and to develop various applications based on it.