Producing　steel　slag　(SS)　bricks　using　carbonation　technology　holds　significant　potential　for　improving　the　utilization　of　SS,　as　carbonation　enhances　both　the　mechanical　strength　and　CO2　sequestration　capacity.　This　study　uses　Response　Surface　Methodology　(RSM)　to　investigate　the　effects　of　water-to-binder　ratio　(w/b),　binder-to-sand　ratio　(b/s),　and　molding　pressure　on　the　compressive　strength　of　carbonated　SS　bricks.　The　optimal　mix　design　was　determined　through　predictive　modeling,　and　characterization　techniques　such　as　Mercury　Intrusion　Porosimetry　(MIP),　X-ray　Diffraction　(XRD),　and　Thermogravimetric　Analysis　(TGA)　were　employed　to　analyze　the　pore　structure,　mineral　composition,　and　microstructure.　A　Life　Cycle　Assessment　(LCA)　was　conducted　to　evaluate　the　environmental　impact　of　the　process.　The　RSM　analysis　revealed　that　both　w/b　and　b/s　ratios　significantly　influenced　the　carbonation　of　SS　bricks,　while　the　effect　of　molding　pressure　was　less　pronounced.　The　predictive　model　suggested　that　the　optimal　compressive　strength　of　36.53　MPa　is　achieved　with　a　w/b　of　0.19　and　a　b/s　ratio　of　2.25,　which　closely　matches　the　experimentally　measured　strength　of　36.88　MPa.　The　results　indicate　that　SS　paste　samples　and　those　with　low　b/s　ratios　negatively　affect　both　the　carbonation　efficiency　and　mechanical　performance　of　SS　bricks.　Specifically,　SS　paste　bricks　inhibit　CO2　diffusion　due　to　the　formation　of　calcite　on　the　surface,　while　samples　with　low　b/s　ratios　exhibit　excessive　porosity　and　a　loose　structure.　TGA　results　showed　that　WB20　and　BS53　samples　contained　higher　calcite　contents,　at　6.21　%　and　4.53　%,　respectively.　The　LCA　of　WB20　revealed　that　its　carbon　footprint　(kg·CO2·eq)　is　81.41　%　lower　than　that　of　concrete　bricks　and　85.02　%　lower　than　that　of　fired　shale　bricks.　The　Global　Warming　Potential　(GWP)　of　WB20　was　also　significantly　lower,　showing　reductions　of　84.61　%,　115.7　%,　and　112.7　%　compared　to　its　own　CO2　emissions,　concrete　bricks,　and　fired　shale　bricks,　respectively.　This　study　provides　a　valuable　reference　for　the　feasibility　of　producing　carbonated　SS　bricks,　offering　optimal　mix　parameters　through　RSM　and　demonstrating　the　superior　physical　properties　of　carbonated　SS　bricks.　The　LCA　comparison　with　conventional　concrete　and　fired　shale　bricks　confirms　that　carbonated　SS　bricks　are　a　promising　carbon-negative　building　material.　©　2025　Elsevier　Ltd