Structural evolution of binder gel in alkali-activated cements exposed to electrically accelerated leaching conditions

[Display omitted] •Electrically accelerated leaching tests for alkali-activated materials are conducted for the first time.•Fly ash samples show significant dissolution of binder gel upon leaching, unlike other samples.•A low hydraulic property of fly ash prevents further hydration from occurring in contact with water.•C-A-S-H type gel remains more stable in comparison with N-A-S-H type gel.•Charge-balancing cations in alkali-activated materials have an important implication for the phase stability. The structural evolution of a binder gel in alkali-activated cements exposed to accelerated leaching conditions is investigated for the first time. Samples incorporating fly ash and/or slag were synthesized and were exposed to electrically accelerated leaching by applying a current density of 5 A/m2. The leaching behavior of the samples greatly depended on the binder gel formed in the samples. The N-A-S-H type gel abundant in fly ash-rich samples showed some extent of dissolution upon accelerated leaching, while slag-rich samples underwent hydration of the anhydrous slag after leaching. The obtained results are discussed in view of the degradation of the binder gel induced by accelerated leaching, and their potential performance under repository conditions where groundwater-induced leaching is the main durability concern.