Durability　of　alkali-activated　slag　cement　(AAS)　against　combined　freeze-thaw　and　sulfate　attack　was　studied　in　this　paper.　AAS　which　is　activated　by　CaO-Na2CO3　activators　(CNS)　was　used　to　prepare　mortar　with　the　strength　of　35　MPa　(CNS35)　and　50　MPa　(CNS50)　respectively　and　ordinary　Portland　cement　was　used　to　prepare　mortar　with　the　strength　of　35　MPa　(PC35)　as　a　comparison.　The　rapid　freeze-thaw　test　was　performed　to　investigate　the　extent　of　deterioration　in　CNS　and　PC　mortar　exposed　to　freeze-thaw　cycles　in　various　media,　including　clear　water　and　sodium　sulfate　solution.　The　relative　dynamic　modulus,　microhardness,　pore　structure　evolution,　microstructure,　and　hydration　products　were　analyzed　using　experimental　and　microscopic　tests.　The　results　show　that　the　durability　of　CNS　mortar　under　water　freeze-thaw　and　sulfate　freeze-thaw　cycles　is　higher　than　that　of　PC　mortar.　The　CNS　hydration　product　is　a　low　Ca/Si　ratio　C-A-S-H　gel,　hydrotalcite,　hydrotalcite-like,　calcium　carbonate,　and　no　calcium　hydroxide.　While　the　PC　mortar　hydration　product　is　a　high　Ca/Si　ratio　C-S-H(II)　gel　and　calcium　hydroxide.　The　hydration　product　of　CNS　mortar　was　denser　than　that　of　PC　mortar　and　had　no　obvious　interfacial　transition　zone.　Furthermore,　sodium　sulfate　does　not　destroy　the　hydration　product　structure　of　CNS　mortar,　in　contrast,　it　has　a　certain　excitation　effect.　However,　sodium　sulfate　reacts　with　the　hydration　product　of　PC　mortar　forming　ettringite　to　destroy　its　internal　structure.　©　2025　Elsevier　Ltd