Assessment of the physicochemical properties of alkali-activated slag blended with belite-rich cement subjected to carbonation attack

The present study investigated the physicochemical transformation of alkali-activated slag (AAS) under CO2 exposure. The belite-rich cement (BRC) used as an additive up to 30 wt% of GGBFS and Ca(OH)2 was used for alkali activation. The threshold ratio of lime/slag and BRC/binder was 4.5% and 20%, respectively, for the improvement in strength and the physicochemical properties. The residual strength after CO2 exposure was higher for an AAS mix prepared with 30% BRC/binder and a 6% lime/slag ratio. Due to the additive (BRC) in AAS, the unreacted β-C2S and portlandite act as a buffer during CO2 exposure. The additional supply of Ca2+ ions provided via Ca(OH)2 contributed to promoting the reactivity of AAS. The decrease in critical pore diameter by 51.6% as the prepared AAS with the higher BRC/binder ratio was exposed to CO2 increased the solid-phase assemblage per unit volume, which also contributed to the physicochemical properties. •Properties of alkali-activated slag (AAS) after carbonation attack were examined.•Belite-rich cement (BRC) was added as the binder, while hydrated lime was employed as the activator.•Amounts of BRC and hydrated lime affect the resistance to carbonation attack of AAS.•The increase in BRC content significantly mitigated the decrease in strength of AAS caused by carbonation attack.