Replacing　natural　aggregate　concrete　with　recycled　aggregate　concrete　(RAC)　can　effectively　solve　aggregate　shortage　problems.　However,　application　of　recycled　aggregate　in　engineering　structures　requires　analysis　of　the　interaction　between　steel　bars　and　RAC.　The　bond　behavior　under　flexure　is　similar　to　the　actual　state　of　stress　in　structural　members.　15　beam　specimens　were　designed　and　tested　to　investigate　the　RAC-reinforcement　bond　behavior　and　the　constitutive　relationship　at　the　interface　between　them.　Test　parameters　include　water-binder　ratio,　recycled　coarse　aggregate　(RCA)　replacement　percentage,　recycled　fine　aggregate　(RFA)　replacement　percentage,　bar　surface　shape,　and　anchorage　length　of　reinforcements.　The　influence　of　the　above　variables　on　the　load　to　slip　curves,　bond　strength,　and　the　bond　efficiency　coefficient　is　discussed.　Bond　strength　between　reinforcements　and　concrete　decreases　with　increasing　RCA　replacement　percentage,　however,　the　rate　of　decrease　is　reduced　for　specimens　with　low　water-binder　ratio.　The　addition　of　RFA　significantly　degrades　bond　behavior.　The　bond　strength　between　deformed　reinforcements　and　RAC　is　approximately　2　times　of　that　of　plain　reinforcements.　With　increasing　anchorage　length,　the　interface　bond　behavior　between　the　reinforcements　and　RAC　decreases.　(C)　2019　Published　by　Elsevier　Ltd.