To　assess　the　potential　for　substituting　foam　concrete　with　low-carbon　foamed　geopolymer　(FG)　in　the　field　of　structural　protection,　a　series　of　quasi-static　and　dynamic　compression　tests　were　conducted.　These　tests　aimed　to　examine　the　mechanical　performance　and　energy　absorption　of　FG　while　considering　the　factors　of　FG　density,　granulated　blast　furnace　slag　(GBFS)　replacement　rate,　and　water–solid　ratio.　Additionally,　supplementary　investigations　involving　XRD　analysis,　indentation　tests,　X-CT　scanning,　and　3D　reconstruction　techniques　were　conducted　to　explore　the　influence　of　GBFS　replacement　rate　on　the　energy　absorption　of　FG　in　terms　of　base　material　properties　and　internal　pore　structure.　The　results　of　the　quasi-static　compressive　tests　showed　that　increasing　the　FG　density　and　reducing　the　water–solid　ratio　had　a　positive　effect　on　energy　absorption,　however,　it　also　resulted　in　a　notable　increase　in　peak　strength.　Increasing　the　GBFS　replacement　rate　not　only　enhanced　the　load-bearing　capacity　but　also　increased　the　extent　of　spalling　damage,　thus　FG　with　a　moderate　GBFS　replacement　rate　of　20%　demonstrated　superior　performance　in　terms　of　energy　absorption　and　load　transfer.　Under　dynamic　compression,　all　specimens　predominantly　experienced　vertical　splitting　failure.　However,　with　increasing　loading　velocity,　crushing　failure　emerged　at　the　two　ends　of　the　specimens,　particularly　in　the　case　of　low-density　specimens.　As　the　loading　velocity　increased,　the　specimen　exhibited　a　significant　increase　in　peak　strength,　demonstrating　a　notable　strain　rate　effect,　however,　the　energy　absorption　of　the　specimen　remained　relatively　stable　without　significant　alterations.　In　addition,　a　simplified　DIF　was　proposed　to　predict　the　peak　strength　of　FG　with　varying　densities　and　two　distinct　GBFS　replacement　rates　under　different　strain　rates.　It　provided　some　valuable　insights　into　the　potential　application　of　FG　in　the　field　of　structural　protection.　©　2023　Elsevier　Ltd