Achieving instantaneous activation of recycled concrete powder by hyper-gravity carbonation

Abstract

In this study, a hyper-gravity environment was used for carbonation, aiming at achieving rapid carbonation for activating recycled concrete powder (RCP). The degree of carbonation, mineralogical changes, and microstructural evolution of the RCP during hyper-gravity carbonation (HGC) were monitored and compared with normal carbonation (NC). The results showed that HGC exhibited a carbonation rate 30 times higher than that of NC in 10 min, including the precipitation of 71.1 % calcium carbonate (Cc) and 95.08 % fully polymerized Q4 silicate. In HGC, RCP developed a unique structure characterized by a Cc shell and a silica core. HGC could overcome the gas/solid-liquid limiting steps in NC with its ultra-high mass transfer rates and shear forces, allowing for simultaneous and efficient dissolution and carbonation. The proposed HGC method provides a significant advancement in the joint fields of industrial CO2 capture and waste concrete recycling.