Performance buildup of reactive magnesia cement (RMC) formulation via using CO2-strengthened recycled concrete aggregates (RCA)

Reactive magnesia cement (RMC) is gaining research interest as a low-carbon cement, yet the impacts of recycled concrete aggregates (RCA) on the performances of RMC formulations are rarely researched. In this study, the carbonated/un-carbonated RCA was involved in preparing RMC samples, and three w/c ratios (similar to 0.55, 0.6 and 0.65) were also adopted. The mechanical performances, mineral phases and pore structures of samples are also unveiled. The results indicate that irrespective of curing conditions, RMC samples with carbonated RCA reveal the best 28 d strength (similar to 46.79 MPa), and a faster strength gaining was also seen. The improved mechanical performances of RMC samples with carbonated RCA are related to the refined microstructure owing to their smaller number of large pores. The above findings highlight the benefits of the pre-carbonation process in RCA treatment. In addition, using carbonated RCA in RMC samples could increase their hydration degree, but their carbonation process is slowed down, resulting from their denser internal microstructure. Finally, concerning the strength development of RMC samples, their pore structures could be more important than other factors (e.g., carbonation degrees of samples).

Automated summary

This study investigates the impact of recycled concrete aggregates (RCA) on the performances of reactive magnesia cement (RMC) formulations. The results suggest that RMC samples with carbonated RCA show the best 28-day strength and a faster strength gain, which is attributed to the refined microstructure.