Enhanced properties of recycled concrete aggregates through liquid-solid carbonation treatment

This study investigates the effectiveness of a liquid–solid carbonation technique for treating commercially sourced recycled fine and coarse aggregates using a modified reactor that has been optimized for resource-efficient and large-scale production. To examine the role of an additional calcium source, a batch of aggregates was presoaked in Ca(OH)2 before carbonation. The process resulted in notable improvements in the physical properties of the aggregates, including reduced water absorption and improved aggregate crushing value. When incorporated into concrete, treated aggregates enhanced mechanical performance by 14.2–15.5% across multiple indices. Additionally, reduced drying shrinkage and increased ultrasonic pulse velocity indicated improved volumetric stability and structural integrity. Aggregates subjected to 3-hour carbonation without presoaking showed similar performance to those treated for 1 h with presoaking. The experimental results of this study were compared with those in existing studies showing comparable or superior results by the proposed simplified setup, highlighting its practicality and replicability.