A Fundamental Study on Enhancing the Recycling of Low-Quality Recycled Fine Aggregate Using Carbonated Nanobubble Water

다국어 초록 (Multilingual Abstract)

Recycling concrete and other aggregates is a sustainable approach, but it poses significant challenges in terms of energy efficiency, byproduct management, and aggregate performance during production. A straightforward crushing process is the simplest method for recycling aggregates; however, it results in a substantial amount of paste adhering to the original aggregates. This adhered paste increases the water absorption rate and decreases aggregate strength due to microcracks induced by the crushing process. When these aggregates are used in concrete, the increased water content exacerbates drying shrinkage, while the strength of the resulting recycled concrete is lower than that of conventional concrete, hindering its commercialization. This study focuses on utilizing low-quality recycled fine aggregates produced by a simple crushing process. A widely recognized method to address these challenges is accelerated carbonation, which fills the pores of the hardened adhesive paste on the aggregates. This research innovatively examines the use of carbonic acid nanobubbles to detach paste from recycled aggregates. Carbonic acid nanobubbles penetrate the aggregates, enabling rapid carbonation under water at room temperature and pressure. The chemical detachment of adhesive paste is significantly enhanced, and results are further improved through ultrasonic treatment and repeated cycles of chemical and physical processes. The findings reveal that quick carbonation facilitated by carbonic acid nanobubbles effectively detaches paste, improving the quality of recycled fine aggregates. The combination of ultrasonic treatment and repeated chemical-physical interventions presents a novel and scalable method for upgrading recycled aggregates, contributing to a more sustainable and efficient recycling process.