This　study　investigated　the　bond　behavior　of　ultrahigh-strength　steel　bars　with　spiral　grooves　(UHSSBs)　embedded　in　high-strength　recycled　aggregate　concrete　(RAC).　Forty-five　pullout　specimens　under　monotonic　loadings　were　designed　to　evaluate　the　effect　of　several　parameters　on　the　bond　strength.　The　variables　included　concrete　strength　(50　MPa–60　MPa);　recycled　concrete　aggregate　(RCA)　replacement　ratio　(0　%,　50　%,　and　100　%);　embedment　length　(5db,　10db,　and　20db);　concrete　cover　(25　mm,　45　mm,　and　68.7　mm);　surface　treatment;　volume　fraction　of　steel　fibers　in　RAC　and　stirrup　ratio.　The　failure　modes　of　these　tests　mainly　concentrated　on　two　types,　pullout-type　bond　failure　and　splitting-type　bond　failure.　According　to　the　typical　bond　stress-slip　curves　and　trendlines　of　plotted　values,　the　bond　strength　increased　with　increasing　of　concrete　compressive　strength.　For　specimens　with　splitting-type　bond　failure,　the　higher　normalized　bond　strength　was　observed　in　higher　RCA　replacement　ratio　and　concrete　cover　thickness.　The　factors　of　embedment　length　and　surface　treatment　were　also　proven　to　be　effective　for　bond　strength.　For　specimens　with　pullout-type　bond　failure,　the　presence　of　steel　fibers　and　stirrups　substantially　restricted　the　splitting　crack　growth　and　improved　the　bond　failure　modes.　Combined　with　previous　experimental　results,　simple　empirical　equations　for　the　average　bond　strength　and　bond　stress-slip　relationship　between　UHSSBs　and　RAC　under　different　types　of　bond　failure　were　developed　by　regression　analysis,　which　can　capture　the　experimental　data　with　high　accuracy.　©　2023　Elsevier　Ltd