Influence Factors in the Wide Application of Alkali-Activated Materials: A Critical Review about Efflorescence

Abstract

Applications related to alkali-activated materials (AAMs) have received much attention due to their excellent mechanical properties and low-energy production. Although much research has focused on developing AAMs, their application is still limited. One of the primary reasons is the efflorescence. Not only does efflorescence affect the material aesthetics, but it also affects the mechanical performance, leading to a decrease in material quality. This paper first summarizes the current research on AAMs efflorescence. The formation process of efflorescence is divided into three parts: alkaline cation leaching, air carbonation, and efflorescence formation. Furthermore, the influences caused by different factors, including raw materials, curing conditions, AAMs modalities, etc., on the efflorescence are proposed. This paper highlights the solutions for efflorescence by avoiding free alkaline cation leaching and preventing air carbonation. The advantages and disadvantages of efflorescence are discussed in-depth, showing that it can be exploited under certain conditions, such as in wastewater treatment. This paper has important implications for the practical preparation and application of AAMs.

Dry Mix Slag—High-Calcium Fly Ash Binder. Part Two: Durability

“…Published studies demonstrate possibility of producing mortars and concretes based on alkali-activated GGBFSs that meet criteria of sulfate resistance, resistance to alkali-silica reactions, exposure to chlorides, and frost resistance. At the same time, certain disadvantages, such as efflorescence and shrinkage, are more common for some types of alkali-activated slag binders than for ordinary Portland cement materials [6] [7] [8]. However, all these characteristics are determined by quite a few parameters including binder composition, type of aggregate, water-to-binder ratio and others.…”