A cable is provided which is longitudinally waterproof and has improved fire protection characteristics. The cable contains a composite material with a first substance which can be expanded by water being supplied to it, and a second substance which can be foamed by heat being supplied to it and is suitable for production of a glass layer. The composite material also has a substrate to which the first substance and the second substance are bonded. The composite material can be produced by dissolving the first substance and the second substance in a solvent, and by introducing the solvent into the support material, or by applying it to the support material.