Effects of chloride salts on strength, hydration, and microstructure of cemented tailings backfill with one-part alkali-activated slag

•Chloride salts’ effects on strength, hydration and microstructure of CTB were studied.•The influence of chloride salts is highly dependent on their cation type.•NaCl slightly weakens CTB’s strength due to the C-(A)-S-H decalcification.•CaCl2 promotes slag hydration and thus improves the CTB’s microstructure and strength.•MgCl2 inhibits slag dissolution due to the reaction between Mg2+ and OH–, markedly lowering CTB’s strength.