Accelerated carbonation for the valorization of mineral by-products

In Europe, mineral waste represents the largest waste stream, yet it is seldom recycled and is primarily disposed of in landfills. This study aims to provide added value to certain types of mineral waste by exploring their potential use as partial replacements for cement in mortar mixtures. Given the environmental impact of cement production, finding sustainable alternatives for cement is crucial. By utilizing mineral waste, this approach could help reduce the volume of waste sent to landfills while also promoting more eco-friendly construction practices.
The mineral wastes are first crushed to produce particles with a size range of 0 to 100 μm. A portion of these fine particles is subjected to a carbonation treatment. Mortar mixtures are then prepared by partially replacing cement with either carbonated or non-carbonated fines, and their workability is assessed. Results reveal that, at a fixed substitution level, carbonation of the fines enhances the workability of the mortar by decreasing its porosity, thus improving its handling properties.
Additional tests are performed on hardened mortar samples to measure their mechanical strength. They indicate that carbonated fines improve the mechanical properties of the mortar specimens compared to those made with non-carbonated fines, although both types of fines lead to a reduction in mechanical strength when substituted to Portland cement.
In conclusion, carbonation improves the workability and mechanical performance of mortars, although it does not fully compensate for the loss of strength associated with substituting Portland cement. This suggests that carbonated mineral wastes could be a viable alternative for enhancing both the environmental impact and performance of cementitious materials, though further research is needed to optimize their use in construction applications.