Geopolymer　has　received　widespread　attention　due　to　their　excellent　mechanical　properties　and　more　environmentally　friendly　characteristics.　Studying　the　bonding　performance　between　geopolymer　and　concrete　is　of　great　significance　for　the　development　of　a　building　material　for　repairing　damaged　concrete.　The　paper　studied　the　effects　of　slag　and　alkaline　solution　contents　on　bonding　strength　of　geopolymer-concrete　composites　(GCC).　Firstly,　15　groups　of　geopolymer　concrete　mix　proportions　with　5　groups　slag　contents　and　3　groups　alkaline　solution　contents　were　designed.　GCC　specimens　were　prepared　by　casting　geopolymer　concrete　on　cement　concrete　substrates.　Secondly,　the　splitting　tensile　test　was　conducted　on　GCC　specimens.　The　strain　field　during　the　testing　process　of　GCC　specimens　was　analyzed　based　on　the　digital　image　correlation　(DIC)　technique.　Thirdly,　the　effects　of　slag　and　alkaline　solution　contents　on　the　splitting　tensile　strength　of　GCC　specimens　were　discussed.　Finally,　the　optimal　mix　proportion　of　geopolymer　concrete　which　has　the　highest　bonding　strength　with　cement　concrete　was　proposed.　The　results　show　that　the　splitting　tensile　strength　of　GCC　specimens　increases　first　and　then　decreases　as　the　slag　content　increases.　The　splitting　tensile　strength　of　GCC　specimens　decreases　linearly　as　the　alkaline　solution　content　increases.　In　addition,　the　crack　growth　rate　of　GCC　specimens　increases　with　the　increase　of　slag　content　during　the　splitting　processing.　The　geopolymer　concrete　with　50.0　%　slag　content　and　0.7　alkaline　solution-binder　ratio　shows　the　highest　bonding　strength　with　cement　concrete,　which　is　recommended　for　the　potential　application　in　the　pavement　repair　works.　©　2023　Elsevier　Ltd