Self healing salt water barrier
Geocomposite articles that can provide a barrier against high conductivity water e.g., ocean water, are described and their method of manufacture, for waterproofing surfaces that contact high conductivity water. The geocomposite article mat includes a woven or non-woven geotextile sheet or mat containing a powdered or granular partially cross-linked acrylamide/acrylate/acrylic acid copolymer across its entire major surface(s). The powdered or granular copolymer has an unexpectedly high free-swell when hydrated with High Conductivity water, such as ocean water. A liquid-impermeable cover sheet is adhered to the upper major surfaces of the filled copolymer-carrying geotextile to provide a primary high conductivity water barrier layer that, if ruptured, is sealed by the swell of an underlying layer of water-insoluble, partially cross-linked acrylamide/acrylic acid copolymer.
1. A method of manufacturing a geocomposite article that provides a barrier to water having a conductivity of at least 1 mS/cm comprising:
providing a woven or non-woven lower geotextile fabric;
contacting the lower geotextile fabric with a blend of a meltable adhesive and powdered or granular partially cross-linked, water-insoluble acrylamide/acrylate/acrylic acid copolymer, and causing at least a portion of the powdered or granular copolymer to flow into the geotextile fabric to fill at least a portion of the geotextile fabric within openings thereof;
disposing an upper geotextile fabric over the blend of meltable adhesive and copolymer and applying heat and pressure to melt and flux the adhesive around the copolymer and fuse the geotextile fabrics together and to seal the copolymer between the upper and lower geotextile fabrics; and
securing a liquid-impermeable cover sheet to a major surface of one of the upper or lower geotextile fabrics;
wherein the geocomposite article exhibits a self-healing performance index less than 0.1 when tested by placing a 1 inch slit through all layers of the geocomposite article sealed at its edges under 4 meters of water with a conductivity of 1 mS/cm or greater, and
wherein the copolymer is an acrylamide/potassium acrylate/acrylic acid copolymer (CAS #31212-13-2).
2. The method of claim 1 , wherein the meltable adhesive is a powder and the adhesive and copolymer are blended in a weight ratio of 55/45.
3. The method of claim 1 , wherein the lower and upper geotextile fabrics are needle-punched together.
4. The method of claim 1 further comprising adding a second powdered or granular material to said geotextile fabric, said second powdered or granular material being selected from the group consisting of sodium smectite clay; organophilic clay; activated carbon; coke breeze; zero-valent iron; apatite; zeolite; peat moss; polymeric ion-exchange resin; polymeric adsorbent; and a mixture thereof.
5. The method of claim 1 , wherein the lower geotextile fabric is a fiber locked woven (FLW) textile constructed by needle-punching a non-woven into a woven textile.
6. The method of claim 5 , wherein the lower geotextile fabric has tufts of the non-woven textile punched through the woven textile, said tufts being disposed against the adhesive/copolymer mixture.
7. The method of claim 1 , wherein the copolymer comprises a partially cross-linked, water-insoluble powdered or granular high conductivity-water absorbent copolymer particles, having 50 wt. % to 90 wt. % of the particles in the 200 μm to 800 μm size range, and about 10 wt. % to about 50 wt. % having a size of 50 μm to 200 μm, and capable of absorbing water having a conductivity of at least 1 mS/cm, said copolymer containing about 25-80 mole % acrylamide; about 15-40 mole % sodium or potassium or lithium or ammonium acrylate; and about 5-20 mole % acrylic acid;
wherein the geocomposite article exhibits a self-healing performance index less than 0.1 when tested by placing a 1 inch slit through all layers of the geocomposite article sealed at its edges under 4 meters of water with a conductivity of 1 mS/cm or greater, and
wherein said geocomposite article, further includes a water-impermeable membrane layer adhered to and essentially coextensive with an outer major surface of one of the geotextile fabrics.
8. The method of claim 7 , wherein the membrane layer comprises a polymeric sheet material.
9. The method of claim 1 , wherein the powdered or granular copolymer is included in the article in an amount in the range of 0.1 ounce to 5 pounds per ft 2 of a major surface area of the geocomposite article.
10. The method of claim 1 , wherein the copolymer has a free swell of greater than 35 mL/2 grams material in 4.5% sea salt in water solution.
11. The method of claim 9 , wherein the powdered or granular copolymer is included in the article in an amount in the range of 0.1 ounce to 3 pounds per ft 2 of a major surface area of the geocomposite article.
12. The method of claim 1 , further comprising adding a second powdered or granular material to said adhesive/copolymer mixture, the second powdered or granular material being selected from the group consisting of sodium smectite clay; organophilic clay; activated carbon; coke breeze; zero-valent iron; apatite; zeolite; peat moss; polymeric ion-exchange resin; polymeric adsorbent; and a mixture thereof.
13. The method of claim 12 , wherein the second powdered or granular material is included with the copolymer in an amount less than 50 wt. % based on the total weight of the copolymer and the second powdered or granular material.
14. A geocomposite article manufactured by the method of claim 1 .
15. The geocomposite article of claim 14 , wherein the meltable adhesive is a powder and the adhesive and copolymer are blended in a weight ratio of 55/45.
16. The geocomposite article of claim 14 , wherein the lower geotextile fabric is a fiber locked woven (FLW) textile constructed by needle-punching a non-woven into a woven textile.
17. The geocomposite article of claim 14 , wherein the lower geotextile fabric has tufts of the non-woven textile punched through the woven textile, said tufts being disposed against the adhesive/copolymer mixture.
18. The geocomposite article of claim 14 , wherein the copolymer comprises a partially cross-linked, water-insoluble powdered or granular high conductivity-water absorbent copolymer particles, having 50 wt. % to 90 wt. % of the particles in the 200 μm to 800 μm size range, and about 10 wt. % to about 50 wt. % having a size of 50 μm to 200 μm, and capable of absorbing water having a conductivity of at least 1 mS/cm, said copolymer containing about 25-80 mole % acrylamide; about 15-40 mole % sodium or potassium or lithium or ammonium acrylate; and about 5-20 mole % acrylic acid;
wherein the geocomposite article exhibits a self-healing performance index less than 0.1 when tested by placing a 1 inch slit through all layers of the geocomposite article sealed at its edges under 4 meters of water with a conductivity of 1 mS/cm or greater, and
wherein said geocomposite article, further includes a water-impermeable membrane layer adhered to and essentially coextensive with an outer major surface of one of the geotextile fabrics.