Ferroaluminate　cement　(FAC),　characterized　by　low　CO2　emissions　and　enhanced　durability　due　to　iron-phase　minerals,　has　emerged　as　a　sustainable　alternative　to　ordinary　Portland　cement　(OPC).　However,　the　influence　of　supplementary　cementitious　materials　(SCMs)　on　the　performance　of　FAC remains　unclear.　This　study　systematically　investigated　the　effects　of　granulated　blast　furnace　slag　(GGBS)　and　fly　ash　(FA)　at　replacement　ratios　of　10,　20,　and　30%　on　the　workability,　mechanical　properties,　and　hydration　mechanisms　of　FAC　mortar.　Results　demonstrated　that　FAC　exhibited　a　slightly　lower　water　demand　and　about　~　25　and　36%　shorter　initial　and　final　setting　time　compared　to　OPC,　attributed　to　the　absence　of　C3A/C3S　and　rapid　AFt　formation.　GGBS　and　FA　could　accelerate　hydration　of　FAC　and　reduce　the　initial　setting　time　by　26–76%,　depending　on　the　replacing　ratio.　However,　the　compressive　strength　of　FAC　significantly　decreased　with　increasing　amount　of　GGBS　and　FA.　30%　replacement　of　GGBS　and　FA　caused　a　19.5%　and　24.8%　in　28 day　compressive　strength,　respectively.　This　was　mainly　caused　by　the　reduction　in　formation　of　AH3　and　C2ASH8　in　the　hydration　products　of　FAC　with　GGBS/FA.　Besides,　FA　promoted　ettringite　crystallization　but　introduced　unreacted　particles,　while　GGBS　increased　pore　connectivity.　©　The　Author(s),　under　exclusive　licence　to　RILEM　2025.