LAUSR

Abstract Hybrid alkaline cement (HAC) is regarded as a new binder which is composed of more than 70% supplementary cementitious materials (SCMs), less than 30% Portland cement and a small dosage of alkali activator. This cementitious material possesses the advantages of Portland cement and alkali-activated materials (AAMs) and provides more compact microstructure, high early strength and excellent resistance to sulfate attack and chloride penetration. This paper provides an overview on the hydration mechanisms of HACs and durability, including resistance to aggressive solutions and high temperatures, carbonation and efflorescence, chloride ion penetration and alkali-aggregate reaction. It is evident that HAC is more durable than Portland cement in a number of environments; however, the lack of long- term track records in field is the barrier for application. This paper also discusses the knowledge gap to facilitate the future research and development of HAC materials.