Soil　tuff,　an　industrial　solid　waste,　can　serve　as　a　sustainable　alternative　to　cement　for　modifying　iron　tailings　sand　(ITS).　To　substantiate　this　claim,　the　physical　properties,　durability　and　microstructure　of　soil　tuff　and　cement-modified　ITSs　were　analyzed　at　different　modifier　dosages,　compaction　degrees　and　maintenance　ages,　with　a　comprehensive　comparison　in　the　perspective　of　sustainable　built　environments.　The　results　indicate　that　the　physical　properties　of　soil　tuff-modified　ITS　(STM-ITS)　were　significantly　enhanced　in　subgrade　engineering　applications　compared　with　cement-modified　ITS　(CM-ITS).　In　addition,　compared　with　CM-ITS,　the　hydration　products　of　STM-ITS　possessed　a　smaller　amount　of　Ca(OH)2　and　were　cemented　with　surrounding　binding　products,　which　resulted　in　fewer　cracks.　STM-ITS　featured　a　more　stable　C-S-H　gel　than　CM-ITS　due　to　a　lower　Ca/Si　ratio,　contributing　to　its　higher　corrosion　resistance.　Notably,　a　sustainability　analysis　demonstrated　that　incorporating　STM-ITS　has　physical　properties　comparable　to　those　of　CM-ITS　and　can　be　obtained　at　a　significantly　lower　cost,　CO2　emission,　and　energy　consumption.　Therefore,　this　study　highlights　the　potential　of　soil　tuff　as　a　promising　eco-friendly　option　for　subgrade　engineering,　promoting　waste　usage,　improving　built　environments,　and　contributing　to　carbon-neutrality　goals.　These　findings　have　significant　implications　for　the　construction　industry　and　the　pursuit　of　sustainable　development.