Recycled concrete aggregates (RCA) are a key resource for more circular construction, but their use is often limited by the residual cement paste attached to the particles. This adhered mortar can increase porosity and water demand and can lead to more variability compared with natural aggregates. Our project investigates a pre-treatment approach based on controlled carbonation to improve RCA quality while supporting the broader transition toward low-carbon, resource-efficient concrete.
In this work, RCA is subjected to a wet carbonation pre-treatment designed to promote the formation of stable carbonate phases and densify the microstructure of the adhered mortar. The central idea is to convert reactive calcium-bearing phases into carbonates and to fill pores and microcracks, thereby enhancing aggregate stability and reducing the pathways for water ingress. The research focuses on understanding how treatment conditions influence phase development and microstructural evolution, and how these changes translate into improved aggregate performance.
To evaluate the effectiveness of the pre-treatment, we combine complementary materials characterization techniques, including thermogravimetric analysis, X-ray diffraction, and electron microscopy. This integrated approach allows us to track carbonation products and microstructural features across scales and to quantify the extent of carbonate formation associated with the pre-treatment. The outcomes will support robust pre-treatment strategies and provide data for the design of more durable and sustainable concretes incorporating recycled aggregates.
