Hot applied tack coat
A method of applying building a pavement structure using a polymer modified hot-applied tack coat is disclosed. This polymer modified tack coat is non-adhesive at ambient temperatures, and, thus, also non tracking. The tack is applied while hot, but cools quickly. The subsequent application of hot mix asphalt results in a superior bond between the asphalt layer and the tack layer. It is particularly well suited to bonded friction course applications since it removes the necessity of specialized spray paving machinery and allows the use of conventional asphalt distributors and pavers.
1. A method for bonding a hot mix asphalt layer to a substrate pavement layer comprising:
(a) heating a non-aqueous tack coat composition to a temperature above its softening point until it is liquid, said non-aqueous tack coat composition comprising a low pen petroleum based asphalt ingredient, said low pen petroleum based asphalt ingredient having a pen value of less than about 40 dmm at 25° C. and a softening point greater than about 140° F., which is sprayable and adhesive when heated to temperatures exceeding 212° F.;
(b) applying said non-aqueous tack coat composition to the substrate pavement layer to form a tack coat layer, said non-aqueous tack coat composition being non-adhesive at ambient temperatures and having a pen value less than 30 dmm at 25° C.; and
(c) applying a heated hot mix asphalt layer on top of said non-aqueous tack coat layer.
2. The method of claim 1 further comprising heating the non-aqueous tack coat composition over 212° F.
3. A method of constructing a multiple layer pavement structure comprising:
(a) applying a liquefied non-aqueous tack coat layer to a substrate pavement layer, said non- aqueous tack coat layer being non-adhesive at ambient temperatures and adhesive when heated to temperatures exceeding 212° F. and having a pen value of less than 30 dmm at 25° C., said non-aqueous tack coat layer comprising a mixture of an asphalt ingredient and at least one additive ingredient, the asphalt ingredient having a pen value of less than about 40 dmm at 25° C. and a softening point greater than about 140° F.;
(b) allowing said non-aqueous tack coat layer to cool below its softening point; and
(c) applying an asphalt layer on top of said non-aqueous tack coat layer that has cooled, said asphalt layer heated to a temperature sufficient to liquefy said non-aqueous tack coat layer that has cooled.
4. The method of claim 3 wherein the asphalt layer is a bonded friction course.
5. The method of claim 3 wherein said non-aqueous tack coat layer further comprises an anti-stripping agent.
6. A method for bonding a layer of asphalt pavement material to a substrate pavement layer comprising:
(a) heating a non-aqueous tack coat composition to over 212° F. until it is liquid, said non-aqueous tack coat composition comprising a low pen petroleum based asphalt ingredient having a pen value of less than about 40 dmm at 25° C. and a softening point greater than about 140° F., wherein said non-aqueous tack coat composition is sprayable and adhesive when heated to temperatures exceeding 212° F.;
(b) applying said non-aqueous tack coat composition to the substrate pavement layer to form a tack coat layer, said non- aqueous tack coat composition being non-adhesive at temperatures below said non-aqueous tack coat's softening point, and wherein said non-aqueous tack coat composition has a pen value less than 30 dmm at 25° C.; and
(c) applying a layer of asphalt pavement material onto said tack coat layer.
7. The method of claim 6 further comprising heating the layer of asphalt pavement material to a temperature above the softening point of said non-aqueous tack coat composition before applying the layer of asphalt pavement material.
8. The method of claim 6 wherein said non-aqueous tack coat composition has a pen value of 18 dmm or less at 25° C.
9. The method of claim 6 wherein said non-aqueous tack coat composition includes at least one additive ingredient comprising SBS, SB, SEBS, XSB, EVA, polyolefins, acrylic polymers, Ground Tire Rubber, natural wax, synthetic wax, Gilsonite, Trinidad Lake Asphalt, plastomers, elastomers, hardeners, softeners, and any combination thereof.
10. The method of claim 6 wherein said non-aqueous tack coat composition includes at least one additive ingredient comprising Ground Tire Rubber.
11. The method of claim 6 wherein said non-aqueous tack coat composition includes at least one additive ingredient comprising natural wax or synthetic wax.