Asphaltic sheet materials including expandable graphite

1. An asphaltic sheet comprising:

(i) an asphaltic component including an asphalt binder and a flame retardant, other than expandable graphite, dispersed within the asphalt binder, said asphaltic component including first and second planar surfaces;

(ii) a release film removably secured to said first planar surface;

(iii) a polymeric sheet adhesively secured to said second planar surface; and

(iv) a concentrated region of expandable graphite at or near at least one of said first and second planar surfaces, where said concentrated region is in the form of a concentration gradient, where the concentration of expandable graphite within the gradient changes from a plane of maximum concentration to a plane of minimum concentration.

2. The asphaltic sheet of claim 1 , where said concentrated region of expandable graphite is at or near said second planar surface and is sandwiched between said asphaltic component and said polymeric sheet.

3. The asphaltic sheet of claim 1 , where said asphaltic component includes from about 0.5 to about 40 parts by weight flame retardant, other than expandable graphite, per 100 parts by weight asphalt binder.

4. The asphaltic sheet of claim 1 , where said asphaltic component includes from about 3 to about 20 parts by weight flame retardant, other than expandable graphite, per 100 parts by weight asphalt binder.

5. The asphaltic sheet of claim 1 , where the asphaltic component further includes a polymeric modifier dispersed within the asphalt binder.

6. The asphaltic sheet of claim 5 , where the polymeric modifier is selected from the group consisting of polybutadiene, polyisoprene, styrene-butadiene rubber, styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, random styrene-isoprene, styrene-isoprene block copolymer, styrene-isoprene-butadiene block copolymer, random styrene-isoprene-butadiene, styrene-isoprene-styrene block copolymer, and chloroprene rubber.

7. The asphaltic sheet of claim 1 , where the polymeric sheet is a polypropylene sheet.

8. The asphaltic sheet of claim 1 , where said flame retardant, other than expandable graphite, is colemanite.

9. The asphaltic sheet of claim 1 , where said polymeric sheet is a polyolefin sheet.

10. A method forming an asphaltic composite, the method comprising:

(i) providing an asphaltic sheet, where the asphaltic sheet includes an asphaltic binder and a flame retardant dispersed within said asphaltic binder, and where said asphaltic sheet includes first and second planar surfaces;

(ii) dropping expandable graphite on to the first planar surface of the asphaltic sheet to form a concentration gradient of the expandable graphite, wherein the concentration of the expandable graphite decreases from said first planar surface to said second planar surface of said asphaltic sheet;

(iii) laminating a polymeric sheet to the first planar surface of the asphaltic sheet; and

(iv) removably securing a release film to the second planar surface of the asphaltic sheet.

11. The method of claim 10 , where said step of providing an asphaltic sheet includes submerging a fabric into molten asphalt binder.

12. The asphaltic sheet of claim 1 , where said step of laminating a polymeric sheet includes contacting a polymeric sheet to the first planar surface and allowing the adhesive properties of the asphaltic sheet to mate the asphaltic sheet and the polymeric sheet.

13. The method of claim 12 , where said step of laminating sandwiches at least a portion of the expandable graphite between the polymeric sheet and the asphaltic binder.

14. The method of claim 10 , where the flame retardant is colemanite.

15. The asphaltic sheet of claim 1 , where said concentration gradient is formed by dropping expandable graphite onto a molten asphaltic sheet.

16. The method of claim 10 , where said step of dropping includes dropping expandable graphite in particulate form.