PROCESS FOR COLD-IN-PLACE RECYCLING USING FOAMED ASPHALT AND LUBRICATION ADDITIVE
Cold-in-place asphalt recycling is disclosed. A foamed asphalt may be produced by injecting water and optionally compressed air into a hot asphalt stream. A lubricating surfactant may be added to the hot asphalt stream to improve performance. The foamed asphalt may be mixed with reclaimed material to provide a uniformly coated paving material that can compacted to a desired density.
1 . A method for forming a foamed asphalt binder, which method comprises:
injecting water and optionally a lubricating surfactant or compressed air into a hot stream of an asphalt binder containing a lubricating cationic surfactant, to form the foamed asphalt binder.
2 . The method of claim 1 , further comprising:
milling an existing pavement surface to a desired depth to provide milled bituminous material on-site;
combining the milled bituminous material with the foamed asphalt binder to produce a paving material; and
compacting the paving material on-site to provide a recycled pavement surface.
3 . The method of claim 2 , wherein the recycled paving surface has a density, measured two days after compacting, of at least about 88 percent of the theoretical maximum density.
4 . The method of claim 2 comprising combining virgin aggregate and the milled bituminous material with the foamed asphalt binder.
5 . The method of claim 2 , comprising laying the paving material using a paver.
6 . The method of claim 2 , comprising laying the paving material using a grader.
7 . The method of claim 2 , wherein the lubricating cationic surfactant reduces the temperature needed for construction, including laying and compacting the paving material, by as much as 60° F.
8 . The method of claim 1 , comprising combining the milled bituminous material with the foamed asphalt binder in an amount of about 0.5 to 4 percent asphalt binder by weight of milled bituminous material.
9 . The method of claim 1 , wherein compressed air is injected into the hot stream of asphalt binder containing lubricating cationic surfactant.
10 . The method of claim 1 , wherein lubricating surfactant is injected into the hot stream of asphalt binder containing lubricating cationic surfactant.
11 . The method of claim 1 , wherein the lubricating cationic surfactant comprises an alkyl amine, alkyl quaternary ammonium salt, heterocyclic quaternary ammonium salt, amido amine or non-nitrogenous sulfur or phosphorous derivative.
12 . The method of claim 1 , wherein the lubricating cationic surfactant comprises an ethoxylated di amine.
13 . The method of claim 1 , wherein the lubricating cationic surfactant comprises an ethoxylated tallow amine.
14 . The method of claim 1 , wherein the lubricating cationic surfactant comprises tris(2-hydroxyethyl)-N-tallow-alkyl-1,3-diaminopropane.
15 . The method of claim 1 , wherein the lubricating cationic surfactant is an ethoxylated diamine or an ethoxylated tallow amine in an amount of about 0.05 to about 3 weight percent of the asphalt binder.
16 . The method of claim 1 , wherein the foamed asphalt binder is formed from about 0.5 to about 5 weight percent water and about 0.05 to about 3 weight percent ethoxylated diamine or ethoxylated tallow amine.
17 . The method of claim 1 , wherein the hot stream of asphalt binder containing lubricating cationic surfactant is at a temperature greater than about 300° F.
18 . The method of claim 17 , wherein the hot stream of asphalt binder containing lubricating cationic surfactant is at a temperature of about 300° F. to about 380° F.
19 . The method of claim 17 , wherein the hot stream of asphalt binder containing lubricating cationic surfactant is at a temperature of about 320° F. to about 360° F.
20 . The method of claim 1 , wherein the foamed asphalt binder produces a uniformly coated paving material.
21 . A cold-in-place asphalt recycling method to prepare a recycled asphalt pavement surface, which method comprises:
producing a foamed asphalt binder by injecting water and optionally a lubricating surfactant or compressed air into a hot stream of an asphalt binder containing a lubricating cationic surfactant;
in a continuous mixing process, milling an existing pavement surface to provide milled bituminous material and combining the foamed asphalt binder with the milled bituminous material to produce a recycled bituminous mix;
conveying the recycled bituminous mix into a paver;
laying the recycled bituminous mix onto an existing grade; and
compacting the recycled bituminous mix to form a recycled asphalt pavement surface.
22 . The method of claim 21 , wherein the foamed asphalt binder comprises about 0.5 to about 5 weight percent water and about 0.05 to about 3 weight percent lubricating cationic surfactant.
23 . The method of claim 21 , wherein the hot stream of asphalt binder containing lubricating cationic surfactant is at a temperature greater than about 300° F.
24 . The method of claim 23 , wherein the hot stream of asphalt binder containing lubricating cationic surfactant is at a temperature of about 300° F. to about 380° F.
25 . The method of claim 23 , wherein the hot stream of asphalt binder containing lubricating cationic surfactant is at a temperature of about 320° F. to about 360° F.
26 . The method of claim 21 , wherein the lubricating cationic surfactant is an ethoxylated diamine or an ethoxylated tallow amine.
27 . The method of claim 21 , wherein the lubricating cationic surfactant comprises tris hydroxyethyl)-N-tallow-alkyl-1,3-diaminopropane.
28 . The method of claim 21 , comprising combining virgin aggregate and the milled bituminous material with the foamed asphalt binder.
29 . The method of claim 21 , further comprising crushing the milled bituminous material.
30 . The method of claim 21 , wherein the lubricating cationic surfactant reduces the temperature needed for construction, including laying and compacting the recycled bituminous mix, by as much as 60° F.
31 . The method of claim 21 , further comprising placing a hot mix asphalt layer on the recycled asphalt pavement surface.