Enhancing　the　flame　retardancy　of　cable　tape　coatings　while　maintaining　low　electrical　conductivity　during　fire　incidents　remains　a　significant　challenge.　In　this　study,　we　address　this　issue　by　incorporating　waste　aluminum　sludge　(AS)　into　an　intumescent　flame　retardant　(IFR)/vinyl　acetate–ethylene　(VAE)　coatings,　thus　optimizing　the　flame　retardancy,　mechanical　properties,　and　electrical　insulation　of　fiberglass　tapes.　AS,　composed　of　boehmite　and　bayerite　phases　with　a　sheet-like　structure,　interacts　chemically　with　IFR/VAE　during　combustion,　yielding　thermally　stable　minerals　(Al(PO3)3　and　AlPO4).　Concurrently,　its　layered　morphology　promotes　the　formation　of　a　compact　and　well-ordered　carbonaceous　char.　The　resulting　hybrid　mineral/carbon　char　acts　as　a　robust　physical　barrier,　effectively　impeding　heat　and　mass　transfer,　while　disrupting　the　conductive　carbon　network.　This　dual　mechanism　leads　to　a　remarkable　enhancement　in　fire　safety　and　electrical　insulation　performance,　including:　a　77.2　%　reduction　in　peak　heat　release　rate,　a　29.0　%　decrease　in　total　heat　release,　a　58.5　%　suppression　in　total　smoke　production,　a　759.2　%　increase　in　surface　resistivity,　a　45.7　%　improvement　in　tensile　strength,　and　a　2.4　%　rise　in　limiting　oxygen　index.　This　work　not　only　presents　a　sustainable　strategy　for　upcycling　industrial　waste　into　high-performance　flame　retardants　but　also　elucidates　the　mechanistic　role　of　aluminum　oxides/hydroxides　in　modifying　the　combustion　behavior　of　IFR　systems.　©　2025　Elsevier　Ltd