Enhancement of the wet carbonation of artificial recycled concrete aggregates in seawater

This study aimed to improve the carbonation efficiency and reduce processing time of recycled concrete aggregates (RCAs). Different liquid mediums were used for wet carbonation and compared with dry carbonation. Reaction kinetics, phase assemblage, microstructure and performance of RCAs and recycled aggregate concrete (RAC) prepared with carbonated RCAs were evaluated. RCAs carbonated under seawater for 10 min achieved >9 % reduction in water absorption and 3 % increase in density, which were more efficient than dry carbonated samples. Compressive strength of RAC prepared with 1-h seawater carbonated RCAs was significantly improved. Formation of ettringite and calcite under wet carbonation increased density and strength by contributing to solid volume, also leading to improved bond strength in interfacial transition zone in RAC. Seawater presents several advantages as a medium for wet carbonation due to its abundant availability, CO2 capture capacity and accelerated hydration and carbonation, thereby enabling rapid improvement of RCA's and resulting concrete formulations' performance.

Automated summary

This study aimed to improve the carbonation efficiency and reduce processing time of recycled concrete aggregates (RCAs). Wet carbonation with seawater was found to be more efficient than dry carbonation, leading to significant reduction in water absorption and increase in density of RCAs. The compressive strength of recycled aggregate concrete (RAC) prepared with 1-hour seawater carbonated RCAs was also improved. The formation of ettringite and calcite under wet carbonation contributed to the increased density and strength, as well as improved bond strength in the interfacial transition zone of RAC. Seawater presents several advantages as a medium for wet carbonation, including its abundant availability, CO2 capture capacity, and accelerated hydration and carbonation.