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 . An asphalt recycling method, which method comprises:
milling an existing pavement surface to a desired depth to provide milled bituminous material on-site;
combining the milled bituminous material with a foamed asphalt binder formed from a lubricating surfactant, water, and liquid asphalt binder heated to a temperature sufficient to produce the foamed asphalt binder, to produce a recycled, asphalt-coated paving material on-site, wherein the use of the lubricating surfactant provides a reduction in the temperature of the asphalt binder needed for paving by 60° F. or more;
conveying the recycled, asphalt-coated paving material to a paver on-site; and
paving the recycled, asphalt-coating the paving material on-site to provide a recycled pavement surface.
2 . The method of claim 1 , comprising combining virgin aggregate and the milled bituminous material with the foamed asphalt binder.
3 . 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.
4 . The method of claim 1 , further comprising adding the lubricating surfactant to the heated liquid asphalt binder prior to forming the foamed asphalt binder.
5 . The method of claim 1 , further comprising adding the lubricating surfactant to the water prior to forming the foamed asphalt binder.
6 . The method of claim 1 , further comprising separately adding the lubricating surfactant and water to the heated liquid asphalt binder prior to forming the foamed asphalt binder.
7 . The method of claim 1 , further comprising adding compressed air to the heated liquid asphalt binder.
8 . The method of claim 1 , wherein the lubricating surfactant comprises a cationic surfactant, an anionic surfactant or a nonionic surfactant.
9 . The method of claim 1 , further comprising adding a chip seal or an overlay to the recycled pavement surface.
10 . The method of claim 1 , wherein the heated liquid asphalt binder is at a temperature greater than 300° F.
11 . The method of claim 1 , wherein the foamed asphalt binder produces a uniformly coated paving material.
12 . The method of claim 1 , wherein the amount of lubricating surfactant used in the foamed asphalt is about 0.05 to about 3 weight percent of the heated liquid asphalt binder.
13 . An asphalt recycling method to prepare a recycled asphalt pavement surface, which method comprises:
producing a foamed asphalt binder by combining about 0.5 to about 5 weight percent water and about 0.05 to about 3 weight percent lubricating surfactant, and optionally compressed air, with a liquid asphalt binder heated to a temperature greater than about 300° F. to provide a foamed asphalt binder in a continuous mixing process, milling an existing pavement surface to provide milled bituminous material;
combining the foamed asphalt binder with the milled bituminous material to produce a recycled bituminous mix, wherein the use of the lubricating surfactant provides a reduction in the temperature of the asphalt binder needed for paving by 60° F. or more;
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.
14 . The method of claim 13 , further comprising adding the lubricating surfactant to the liquid asphalt binder prior to producing the foamed asphalt binder.
15 . The method of claim 13 , comprising combining virgin aggregate and the milled bituminous material with the foamed asphalt binder.
16 . The method of claim 13 , further comprising crushing the milled bituminous material.
17 . The method of claim 13 , wherein the foamed asphalt binder produces a uniformly coated paving material.
18 . The method of claim 13 , further comprising placing a hot mix asphalt layer on the recycled asphalt pavement surface.