Factors controlling carbonation resistance of alkali-activated materials

Although notable advances have been made in recent years in elucidating the relationship between the nature of the precursor and the activation conditions used for production of alkali-activated materials (AAMs), it remains largely unknown whether these materials can withstand various environmental threats during their service life. The interaction between a cementitious material and the CO2 present in the air is referred to as carbonation, and while this is largely a well understood phenomenon for portland cement systems, its long-term effects in AAMs are unknown. This is a consequence of the large number of variables controlling microstructural development and therefore macro-scale properties of AAMs, and the lack of standardized methodologies for testing their carbonation resistance. This study reports an overview of recently identified factors inducing microstructural changes in AAMs upon exposure to CO2, and the influence of carbonation on the corrosion resistance of some steel reinforced AAMs.