A　comprehensive　investigation　concerning　the　mechanical　properties　and　microstructural　characteristics　of　ultra-high-performance　concrete　(UHPC)　using　different　dosages　of　limestone　calcined　clay　cement　(LC3)　and　recycled　fine　aggregate　(RFA)　was　conducted.　Results　demonstrated　that　the　compressive　strength　using　15%　LC3　and　30%　RFA　is　comparable　to　the　control　group,　and　the　tensile　strength　of　UHPC　using　30%　LC3　is　comparable　to　the　control　mix-ID.　Incorporation　of　LC3　generates　additional　hydration　products.　The　addition　of　LC3　improved　the　pore　size　distribution　and　reduced　porosity.　The　results　of　nanoindentation　testing　showed　that　using　LC3　and　RFA　improved　the　performance　of　interfacial　transition　zone,　contributing　to　the　achievement　of　considerable　mechanical　resistance.　Finally,　life　cycle　analysis　revealed　that　using　LC3　and　RFA　could　reduce　the　environmental　impact.　©　2023　Elsevier　Ltd