It　is　environmentally　friendly　to　crush　waste　concrete　as　recycled　aggregate　for　cyclic　utilization,　and　it　also　can　solve　the　shortage　of　natural　aggregate.　However,　the　performance　of　the　recycled　aggregate　concrete　was　poor　caused　by　the　surface　adhesion　of　old　cement　mortar　on　the　aggregate　and　the　micro　crack　properly　generated　during　the　crushing　process.　The　pressure　pretreatment　on　recycled　coarse　aggregate　by　CO2　was　used　to　improve　its　basic　performances.　The　variables　carbonization　time　(0h,　6h,　12h,　24h,　48h,　72h)　and　CO2　carbide　gas　pressure　(0.1MPa,　0.4MPa,　0.8MPa)　were　studied,　and　the　basic　properties　of　recycled　coarse　aggregate　before　and　after　carbonization　were　compared　and　analysed,　and　the　degree　of　improvement　on　recycled　aggregate　concrete　were　also　investigated　to　determine　the　optimal　scheme　for　carbonation,　which　was　in　the　container　with　0.4MPa　pressure　for　24h.　Based　on　the　optimum　carbonation　scheme,　the　influence　of　recycled　coarse　aggregate　on　mechanical　properties　of　recycled　aggregate　concrete　was　studied　with　the　substitution　rate　of　recycled　coarse　aggregate　(30%,　50%,　70%　and　100%)　before　and　after　carbonization　respectively.　The　results　showed　that　the　CO2　reinforced　recycled　coarse　aggregate　water　absorption　rate　and　crushing　index　was　decreased,　apparent　density　was　increased.　At　the　same　substitution　rate,　the　compressive　strength　and　elastic　modulus　of　carbonized　recycled　aggregate　concrete　was　higher　than　that　of　non-carbonized　recycled　aggregate　concrete.　©　Published　under　licence　by　IOP　Publishing　Ltd.