Research　on　durability　of　alkali-activated　slag　concrete　(AASC)　has　received　great　attention　but　there　are　considerably　few　studies　on　the　effect　of　carbonation　on　steel　corrosion.　In　this　paper,　effects　of　activator　types　(waterglass　and　sodium　hydroxide)　and　exposed　concentrations　of　CO2　(0.03%,　3%　and　20%　by　volume)　on　steel　corrosion　have　been　investigated,　in　both　AASC　and　ordinary　Portland　cement　concrete　(OPCC).　The　latter　was　used　as　the　control　group　for　comparative　purposes.　X-ray　photoelectron　spectroscopy　(XPS)　was　used　to　confirm　the　composition　of　passive　film　of　AASC　and　OPCC.　Pore　structure　of　specimens　before　and　after　carbonation　were　measured　with　mercury　intrusion　porosimetry　(MIP).　The　corrosion　state　of　steel　rebars　were　monitored　by　open　circuit　potential　(OCP),　potentiodynamic　polarization　(PP),　and　electrochemical　impedance　spectroscopy　(EIS).　The　results　illustrate　that　AASC　shows　a　thicker　passive　film　with　higher　Fe2+/Fe3+　compared　to　OPCC.　These　two　activators　have　similar　effects　on　steel　corrosion　under　the　accelerated　CO2　environment,　showing　the　similar　degrees　of　corrosion　after　140　days　of　accelerated　carbonation.　This　may　be　attributed　to　the　same　carbonation　resistance　of　the　AASC　with　two　different　activators.　In　addition,　AASC　shows　worse　corrosion　resistance　in　comparison　with　OPCC.　Higher　concentrations　of　CO2　could　accelerate　the　corrosion　rate　of　steel　rebars　embedded　in　AASC.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.