Abstract: The invention discloses a composite material 1 comprising essentially a mixture of hydroexpandable powder and thermobonding powder, sandwiched between two flat solid supports, one at least of which is at least partially hydrosoluble.This material can be used in agriculture, medicine, surgery, in the hygiene field and in the cable, particularly electric cable, industry. In this application, when water penetrates into the cable, the at least partially hydrosoluble support or supports release the hydroexpandable powder which rapidly forms a pad preventing propagation of the water through the cable.