Evaluating the recyclability and efficacy of seawater during the wet carbonation of recycled concrete aggregates

Ning Li, Cise Unluer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Seawater has emerged as a promising medium for enhancing recycled concrete aggregates (RCAs) through wet carbonation, with a limited focus on its disposal after carbonation. This paper evaluates the feasibility and efficiency of recycling carbonated seawater for the continuous wet carbonation of RCAs. Initial carbonation of RCAs in seawater was followed by the repeated use of the carbonated seawater in the wet carbonation of new RCAs. After repeating this process 10 times, results indicated that the quality of wet carbonated RCAs was improved regardless of the number of cycles. As the number of carbonation cycles involving the same seawater increased, a reduction in RCA’s hydration reaction was accompanied with an enhancement of the carbonation reactions. This was primarily linked to the depletion of available sulphur and chlorine in seawater, limiting the formation of ettringite; whereas increased carbonate saturation in solution improved carbonation. Finally, the compressive strength of recycled concrete containing carbonated RCAs increased by at least 60 % compared to non-carbonated RCAs, even after 10 cycles of seawater carbonation. These findings demonstrated the feasibility of repeatedly using seawater for continuous wet carbonation of RCAs, highlighting its potential for carbon sequestration and sustainable reutilisation in the concrete industry.
Original languageEnglish
Article number139774
JournalConstruction and Building Materials
Volume459
DOIs
Publication statusPublished - 2 Jan 2025

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