Driven　by　the　scarcity　of　river　sand　and　accompanying　environmental　concerns,　sea　sand　is　emerging　as　an　alternative　material.　However,　the　durability　of　construction　products　can　be　jeopardized　by　chloride　ions　in　raw　sea　sand.　Alkali-activated　cementitious　materials　possess　high　chloride　binding　capacity,　alleviating　some　of　these　risks.　But　its　carbonation　resistance　is　weaker.　In　alkali-activated　sea　sand　slag　(AASS)　mortars,　the　interaction　effects　and　mechanisms　of　carbonation　and　chloride　ions　are　still　unclear.　To　address　this,　our　study　investigates　the　effects　of　alkali　equivalent　and　sea　sand　substitution　rates　on　carbonation　resistance　and　chloride　ion　distribution　in　AASS　mortar.　Mortar　specimens　were　prepared　with　varying　alkali　equivalents　(4–6%)　and　sea　sand　substitution　rates　(0–100%),　followed　by　mechanical　strength,　carbonation　depth,　chloride　ion　distribution,　and　microstructure.　Our　results　reveal　that　higher　alkali　equivalents　improve　mechanical　performance　and　carbonation　resistance.　Although　the　presence　of　shells　in　sea　sand　slightly　reduces　strength,　an　optimal　substitution　rate　of　30%　refines　pore　structure　and　thereby　enhances　durability.　Conversely,　higher　sea　sand　substitution　negatively　affects　resistance　due　to　poor　gradation.　Increased　alkali　equivalent　slightly　escalated　peak　chloride　concentration,　whereas　higher　sea　sand　amplified　the　concentration　gradient,　expediting　chloride　transport.　Through　TG　and　MIP　analyses,　optimal　resistance　was　verified　at　5%　alkali　equivalent　and　30%　sea　sand　substitution.　In　conclusion,　appropriate　sea　sand　incorporation　can　improve　AASS　mortar　durability,　making　sea　sand　a　feasible　alternative　material.　©　2023