Effects of salt specific gravity on the post-dissolution mechanical behaviours of gap-graded soils

The salt dissolution method is an effective approach for simulating internal salt dissolution by replacing eroded fines particles with the same mass of salt. This method allows precise control of the amount of fines loss, enabling its effects to be studied on the post-dissolution mechanical behaviour of soil materials. In this study, three different salts with different specific gravities were selected to investigate their impact on soil deformation characteristics during dissolution and the post-dissolution mechanical behaviour of sand-salt mixtures in triaxial tests. Additionally, the influence of initial density was considered. During salt dissolution, volumetric strain generally increases with the amount of fines loss. This effect is more pronounced in specimens with salts of lower specific gravity, as a higher volume of salt is lost. Consequently, the soil structure is more severely disrupted, leading to looser specimens compared to those with higher specific gravity salts. In post-dissolution undrained monotonic triaxial tests, salt specific gravity has a minimal impact on the friction angle, although specimens with higher specific gravity salts exhibited slightly higher strength. While internal salt dissolution shifted the critical state line upward, the position of the critical state line is found to be independent of salt specific gravity.