Process for cold-in-place recycling using foamed asphalt and lubrication additive

Abstract

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 - 20 . (canceled) 
     
     
         21 . A cold-in-place 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 in an amount of about 0.05 to about 3 weight percent of the foamed asphalt binder, water, and liquid asphalt binder heated to a temperature sufficient to produce the foamed asphalt binder, to produce a paving material on-site; and   compacting the paving material on-site to provide a recycled pavement surface.   
     
     
         22 . The method of  claim 21 , wherein the recycled paving surface has a density, measured two days after compacting, of at least about 88 percent of the theoretical maximum density. 
     
     
         23 . The method of  claim 21 , comprising combining virgin aggregate and the milled bituminous material with the foamed asphalt binder. 
     
     
         24 . The method of  claim 21 , 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. 
     
     
         25 . The method of  claim 21 , further comprising adding the lubricating surfactant to the heated liquid asphalt binder prior to forming the foamed asphalt binder. 
     
     
         26 . The method of  claim 21 , further comprising adding the lubricating surfactant to the water prior to forming the foamed asphalt binder. 
     
     
         27 . The method of  claim 21 , further comprising separately adding the lubricating surfactant and water to the heated asphalt binder prior to forming the foamed asphalt binder. 
     
     
         28 . The method of  claim 21 , further comprising adding compressed air to the heated liquid asphalt binder. 
     
     
         29 . The method of  claim 21 , wherein the lubricating surfactant comprises a cationic surfactant, an anionic surfactant or a nonionic surfactant. 
     
     
         30 . The method of  claim 21 , further comprising adding a chip seal or an overlay to the recycled pavement surface. 
     
     
         31 . The method of  claim 21 , comprising laying the paving material using a paver. 
     
     
         32 . The method of  claim 21 , comprising laying the paving material using a grader. 
     
     
         33 . The method of  claim 21 , wherein the heated liquid asphalt binder is at a temperature greater than 300° F. 
     
     
         34 . The method of  claim 21 , wherein the foamed asphalt binder produces a uniformly coated paving material. 
     
     
         35 . A cold-in-place 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 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.   
     
     
         36 . The method of  claim 35 , further comprising adding the lubricating surfactant to the liquid asphalt binder prior to producing the foamed asphalt binder. 
     
     
         37 . The method of  claim 35 , comprising combining virgin aggregate and the milled bituminous material with the foamed asphalt binder. 
     
     
         38 . The method of  claim 35 , further comprising crushing the milled bituminous material. 
     
     
         39 . The method of  claim 35 , wherein the foamed asphalt binder produces a uniformly coated paving material. 
     
     
         40 . The method of  claim 35 , further comprising placing a hot mix asphalt layer on the recycled asphalt pavement surface.