This　paper　presents　experimental　investigation　on　the　post-fire　performance　of　geopolymeric　recycled　aggregate　concrete　filled　steel　tube　(GRACFST)　columns　and　temperature　field　of　GRAC　cubes.　A　total　of　10　GRACFST　column　specimens　were　tested　to　investigate　their　post-fire　performance.　A　total　of　10　GRACFST　column　specimens　were　tested　to　evaluate　their　performance　after　exposure　to　fire,　considering　various　parameters:　(a)　cross-section　type　(circular　and　square);　(b)　testing　conditions　(ambient　temperature　test,　post-fire　test　without　initial　load,　and　full-coupled　post-fire　test);　(c)　target　temperatures　(20　℃,　600　℃,　and　800　℃);　and　high-temperature　exposure　durations　(30　min　and　180　min).　The　study　examined　failure　modes,　temperature　evolution,　deformation　and　strain　patterns,　and　post-fire　ultimate　bearing　capacities.　The　test　data　revealed　the　commendable　post-fire　performance　of　GRACFST　columns,　as　evidenced　by　the　residual　strength　index　typically　falling　within　the　range　of　0.83　to　1.11.　To　calibrate　the　thermal　properties　of　GRAC　materials,　a　series　of　temperature　field　tests　of　GRAC　cubes　at　different　target　temperatures　(200　℃,　400　℃,　600　℃　and　800　℃)　were　conducted.　These　tests　provided　data　on　temperature　distribution　within　the　cubes　and　mass　loss　due　to　high　temperatures.　Using　back　analysis　of　these　temperature　field　tests,　thermal　property　models　for　GRAC,　including　thermal　conductivity,　specific　heat,　and　density,　were　developed　and　validated　by　simulating　temperature　data　from　existing　fire　and　post-fire　tests　of　GRACFST　columns.　The　proposed　thermal　property　models　are　crucial　for　designing　this　novel　composite　column　type　for　fire　resistance　applications.　©　2024　Elsevier　Ltd