Soil　cement　bentonite　(SCB)　is　a　common　material　for　constructing　vertical　cutoff　walls　to　prevent　groundwater　migration　at　contaminated　industrial　sites.　However,　site　contaminants　can　degrade　the　durability　of　the　cutoff　wall.　To　enhance　its　performance,　this　study　developed　a　silica　fume-SCB　(SSCB).　The　macroscopic　and　microscopic　properties　of　SSCB　were　assessed　by　unconfined　compressive　strength　test,　variable　head　permeability　test,　X-ray　diffraction　(XRD),　scanning　electron　microscopy　(SEM)　and　nuclear　magnetic　resonance　(NMR)　spectroscopy.　The　correlation　between　its　multi-scale　properties　was　analyzed　based　on　pore　characteristics.　The　results　indicate　that　increasing　the　silica　fume　substitution　ratio　improved　SSCB　strength,　especially　in　the　middle　and　late　curing　stages.　Moreover,　increasing　the　substitution　ratio　decreased　SSCB　permeability　coefficient,　with　a　more　pronounced　effect　in　earlier　curing　stages.　Silica　fume　addition　also　refined　SSCB　pore　structure　and　reduced　its　porosity.　The　fractal　dimension　was　used　to　quantify　SSCB　pore　structure　complexity.　Increasing　silica　fume　content　reduced　small　pore　fractal　dimension　in　SSCB.　Concurrently,　SSCB　strength　increased　and　SSCB　permeability　coefficient　decreased.　The　findings　of　this　research　will　demonstrate　the　great　potential　of　SSCB　backfill　for　practical　applications.　©　Central　South　University　2025.