Characterisation of temporal variations of alkali-activated slag cement property using microstructure features and electrical responses

Relatively few studies currently exist concerning temporal variation of the overall performance of alkali-activated slag (AAS) cement; a topic essential for quality control in practice. This study uses microstructural characteristics and electrical responses to reflect performance variation of AAS cement. To achieve this, four key performance parameters were assessed, pore formation factor, chloride transport coefficient, permeability coefficient and compressive strength. Classical theories used for PC-based materials were applied to estimate the performance of AAS paste. It is found that the formation factor of AAS can be assessed by combining bulk conductivity and pore solution conductivity and the permeation properties of AAS cement cannot be reliably assessed by the Katz-Thomoson (KT) model, while the Millington-Quirk (MQ) model works better. To assess the relationship between compressive strength and permeable porosity, the Balshin and Ryshkevitch equations performed best in terms of describing the relationship between these two parameters. Meanwhile, AAS cement is more sensitive to the mix proportions and additional care is needed to ensure its quality. It is the first time to use electrical response to predict the chloride transport coefficients of AAS cement, which would provide a powerful tool for its quality control and service life prediction.