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.

The following is claimed: 
     
         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.