Carbonation　is　a　primary　factor　driving　the　continuous　improvement　of　the　long-term　performance　of　natural　hydraulic　lime　(NHL).　This　research　systematically　examines　the　impact　of　accelerated　carbonation　(3　%　CO2)　on　the　carbonation　depth,　phase　composition,　microstructure,　and　compressive　strength　of　hardened　natural　hydraulic　lime　(NHL)　pastes　mixed　with　different　amounts　of　ground　granulated　blast　furnace　slag　(GGBFS),　termed　as　S-NHL.　The　findings　show　that　the　hydration　reaction　products　of　GGBFS　and　Ca(OH)(2)　(CH),　such　as　C(3)AH(10),　C4ACH(11),　and　C-S-H,　densify　the　microstructure　of　S-NHL,　resulting　in　a　decrease　in　carbonation　depth　with　increasing　GGBFS　content.　Accelerated　carbonation　(AC)　promotes　the　rapid　transformation　of　a　significant　quantity　of　CH　into　calcite　in　S-NHL,　with　the　carbonation　of　CH　occurring　more　readily　than　the　carbonation　of　hydration　reaction　products.　Throughout　the　AC　process,　NHL　contains　only　calcite-type　calcium　carbonate.　In　contrast,　after　28　days　of　AC,　the　carbonation　of　hydration　reaction　products　such　as　C3AH10　and　C-S-H　in　S-NHL　produces　a　minor　amount　of　aragonite　and　vaterite.　AC　continuously　reduces　the　total　pore　volume　and　porosity　of　S-NHL,　but　the　average　pore　diameter　and　most　probable　pore　diameter　initially　decrease　and　then　slightly　increase.　AC　significantly　reduces　the　large　pores　in　S-NHL,　ultimately　resulting　in　pores　predominantly　composed　of　capillary　pores　(50-1000　nm).　AC　facilitates　the　development　of　compressive　strength　in　S-NHL　paste,　with　the　increase　in　compressive　strength　being　positively　correlated　with　its　CH　content.