Investigation on admixtures applied to alkali-activated materials: A review

Alkali activated material (AAM) is recognized as a potential alternative to Portland cement due to its excellent performance and low-carbon characteristics. In this paper, the latest research progress in the application of admixtures in AAM was reviewed, and the effects on AAM properties, hydration, microstructure and surface/solution chemistry were summarized. The interaction between high salt and alkali AAM solution and admixture causes changes in the surface/solution chemistry of the system, such as pH, composition concentration and admixture stability. The inhibition of retarding admixtures on AAM hydration is influenced by the effective concentration and raw material composition. The decreases in solubility and adsorption of plasticizer are the key reasons for their ineffectiveness in improving AAM fluidity. In addition, the incorporation of nanoparticle admixture can improve the properties and promote the hydration of AAM. Future research should focus on the careful design-synthesis of new admixtures to achieve significant improvements rather than direct use of conventional admixtures, while providing new opportunities to promote the sustainable application of AAM.