Modified asphalt hydraulic sealer

Cut-back asphalt, when modified by the addition of a small amount of a butadiene-styrene block copolymer, a hydrogenated butadiene-styrene copolymer, or mixtures thereof, or an ethylene-vinyl acetate copolymer, provides an effective hydraulic sealant when applied to a nonwoven fabric.

What is claimed is:

1. An improved hydraulic barrier system capable of withstanding a hydrostatic pressure at least equal to 35 feet of water at a temperature of 100.degree.F comprising at least one layer of a suitable fabric having applied thereto a sealant composition consisting essentially of an air-blown cut-back asphalt having incorporated therein from 1 to 10 weight percent of an additive selected from the group consisting of (a) a hydrogenated random butadiene-styrene copolymer containing from about 30 to about 44 parts by weight of butadiene per 100 parts by weight of total monomers with the remainder being styrene; (b) a butadiene-styrene block copolymer having the configuration S-B-S, containing about 70 weight percent butadiene and about 30 percent styrene; and (c) mixtures of (a) and (b) in a weight ratio of (a) to (b) in the range of 1:10 to 10:1.

2. The barrier system of claim 1 wherein the weight ratio of said mixture (c) is 1:1.

3. The barrier system of claim 1 wherein said fabric is a nonwoven fabric.

4. The barrier system of claim 3 wherein said fabric is formed of polypropylene fibers.

5. The barrier system of claim 1 wherein said fabric is a nonwoven fabric formed of polypropylene fiber fused on one side and capped with an additional layer of fibers selected from polypropylene and nylon and said sealant composition consists essentially of said asphalt and said copolymer mixture (c).

6. A reservoir comprising as a liner extending over its inner surfaces the barrier system of claim 1.

7. A method of sealing an essentially porous substrate which comprises forming an asphaltic gel composition consisting essentially of an air-blown cut-back asphalt and from 1 to 10 weight percent of a mixture of (a) a hydrogenated random butadiene-styrene copolymer containing from about 30 to about 44 parts by weight per 100 parts by weight of total monomers with the remainder being styrene and (b) a butadiene-styrene block copolymer having the configuration S-B-S, containing about 70 weight percent butadiene and about 30 weight percent styrene, wherein the weight ratio of said (a) to said (b) is in the range of 1:10 to 10:1; heating said gel to a temperature sufficient to render said gel substantially liquid; applying said heated liquid to said substrate; and allowing said asphaltic composition to cool upon contacting said substrate, thus forming a gel and thereby sealing said substrate.

8. The method of claim 7 wherein said substrate is a nonwoven fabric.