To　address　the　dual　challenges　of　improving　strength　and　reducing　permeability　in　solidified　soils　produced　from　excavated　waste　mud,　this　study　develops　a　sustainable　stabilization　method　using　industrial　by-products.　A　ternary　solid　waste-based　cementitious　material　(SWC),　consisting　of　ground　granulated　blast　furnace　slag　(GGBS),　steel　slag　(SS),　and　desulfurization　gypsum　(DG),　was　optimized　through　an　extreme　vertex　mixture　design.　The　results　demonstrate　that,　under　appropriate　mix　proportions,　the　solidified　soil　using　SWC　can　achieve　comparable　unconfined　compressive　strength　(UCS)　at　7　d　and　superior　strength　at　28　d　compared　to　ordinary　Portland　cement　(OPC).　Specifically,　the　mixture　containing　60　wt%　GGBS,　30　wt%　SS,　and　10　wt%　DG,　referred　to　as　G60S30D10,　achieved　a　28　d　UCS　of　3.22 MPa,　representing　an　increase　of　approximately　105%　over　OPC,　and　a　permeability　coefficient　of　1.94　×　10⁻⁸　m/s,　an　order　of　magnitude　lower　than　that　of　OPC,　which　indicates　excellent　water　resistance.　Microstructural　analysis,　including　X-ray　diffraction,　thermogravimetric　analysis,　scanning　electron　microscopy,　and　mercury　intrusion　porosimetry,　reveals　that　the　primary　hydration　products　in　the　SWC　solidified　soil　include　ettringite　(AFt),　C-S-H,　C-A-H,　and　C-A-S-H.　Compared　to　OPC,　the　AFt　content　increased　by　22–83%,　and　the　combined　action　of　expansive　AFt　crystals　and　dense　C-(A)-S-H　gels　effectively　fill　interconnected　pores,　leading　to　a　substantial　reduction　in　detrimental　macropores　(＞　1 μm)　from　15%　in　OPC　to　2–3%　in　the　SWC　matrix.　This　refined　pore　structure　substantially　contributed　to　the　observed　reduction　in　permeability.　These　findings　offer　valuable　insights　into　the　performance　and　mechanisms　of　low-carbon,　high-efficiency　solidified　soils　using　industrial　by-products.　©　The　Author(s)　2025.