Chloride transport, binding, and microstructure in alkali-activated concrete with different types of precursor combinations

This paper presented the experimental results of investigating chloride resistance and the microstructure of alkali-activated concrete (AAC). To show the reliable and efficient chloride transport analyses for AAC, a modified rapid chloride penetration test using 10 V was validated, and the conventional chloride profile methods were compared with the newly developed micro X-ray fluorescence (μXRF) profile method. Six AAC mixtures incorporating different precursors were evaluated for mechanical strength, water absorption, chloride diffusion, and binding. At the same content of ground granulated blast furnace slag in mixtures, the precursor incorporating calcined bauxite tailings and rice husk ash increased porosity and reduced chloride resistance compared to that containing fly ash. This study revealed that chloride binding in all AAC used in this study was predominantly physical and reversible, contrasting with Portland cement systems. μXRF technique provided reliable and spatially resolved chloride profile data for AAC. This study provides valuable insights into AAC performance and testing, emphasising the importance of precursor selection for sustainable AAC.