The carbonation resistance of alkali-activated slag concrete under different curing regimes: macroscopic properties evolution and microscopic mechanisms

This study investigated the carbonation resistance of alkali-activated slag concrete (AASC) under different curing regimes. Two types of AASC, using water glass and CaO + Na2CO3 as activators, were prepared and respectively denoted as CNCC and WGC, with Ordinary Portland Cement Concrete (OPCC) serving as the control. Three types of concrete were all subjected to two different curing regimes, namely standard curing and autoclaved curing. Microscopic techniques were employed to characterize the evolution of hydration products and pore structure. The results indicate that the high temperature and pressure of autoclaved curing affect the hydration of different concrete types in distinct ways, leading to varied microstructural development, which in turn influences their subsequent carbonation progress. Under autoclaved curing, the carbonation depths of OPCC and WGC at the same carbonation ages are higher compared to standard curing, whereas that of CNCC is lower.