The study examines the relationship between the weakening factors of the potassium-magnesium salt massif in the Palashersky section of the Verkhnekamsk deposit – specifically, the content of clay material in the form of halopelitic interlayers and the impact of technogenic brines on the strength characteristics of rocks in the productive strata during backfilling operations in mined-out areas. The results of laboratory studies on the influence of insoluble residue content and moisture on the strength properties of salt rocks are presented. Dependencies of changes in strength, moisture, and ultimate deformations on the duration of exposure to brines were established. Based on the test results, it was found that saturated brine does not significantly affect the compressive strength of sylvinite and rock salt but influences the intensity of deformability.