Methods of forming asphalt pavement using foamed asphalt compositions
Foamed asphalt compositions, recycled asphalt compositions, asphalt pavement, and methods of forming asphalt pavement using the foamed asphalt compositions are provided herein. An exemplary foamed asphalt composition is in a cellular matrix form and includes a base asphalt component and oxidized high density polyethylene. An exemplary asphalt pavement includes a recycled asphalt layer that includes the foamed asphalt composition and a recycled asphalt component. An exemplary method of forming asphalt pavement includes combining a base asphalt component and an oxidized high density polyethylene to form an asphalt mixture. The asphalt mixture is foamed using water and compressed air to form a foamed asphalt composition. The foamed asphalt composition and a recycled asphalt component are combined to form a recycled asphalt composition. A recycled asphalt layer is formed with the recycled asphalt composition.
1 . A method of forming asphalt pavement, said method comprising the steps of:
combining a base asphalt component, an oxidized high density polyethylene, and an additional polyethylene different from the oxidized high density polyethylene and selected from non-oxidized polyethylene homopolymer, oxidized low density polyethylene, and a combination thereof to form an asphalt mixture, wherein the mixture has a viscosity of at least about 30,000 Pa·s at a temperature of 60° C. and a viscosity of less than about 150 cP at a temperature of 160° C., wherein viscosity is determined in accordance with ASTM D4402;
foaming the asphalt mixture using water and compressed air to form a foamed asphalt composition;
combining the foamed asphalt composition and a recycled asphalt component to form a recycled asphalt composition; and
forming a recycled asphalt layer with the recycled asphalt composition.
2 . The method of claim 1 , wherein the oxidized high density polyethylene has a density of from about 0.97 to about 1.01 g/cm 3 .
3 . The method of claim 1 , further comprising forming a hot mix asphalt layer over the recycled asphalt layer.
4 . The method of claim 1 , wherein the additional polyethylene is oxidized low density polyethylene having a density of from about 0.84 to about 0.95 g/cm 3 .
5 . The method of claim 1 , wherein the additional polyethylene is non-oxidized polyethylene homopolymer having a density of from about 0.87 to about 0.98 g/cm 3 .
6 . The method of claim 1 , where a combined amount of all polymeric species present in the foamed asphalt composition is from about 2 to about 10.5 weight % based upon a total weight of the foamed asphalt composition on a dry basis.
7 . The method of claim 1 , wherein the oxidized high density polyethylene and the additional polyethylene are present in the foamed asphalt composition in a weight ratio of from about 1:2 to about 2:1.
8 . The method of claim 1 , wherein the recycled asphalt layer is formed to have an indirect tensile strength of at least 0.45 Mpa as measured in accordance with ASTM D6391-12.
9 . The method of claim 3 , wherein the hot mix asphalt layer has a thickness of from 4 to less than 8 cm, the recycled asphalt layer has a thickness of from about 10 to about 18 cm, and the recycled asphalt layer has anti-rutting performance of at least 5000 cycles/mm at 60° C. in accordance with T0719-2011 of the Industry Standard JTG E20-2011 Specification and Test Methods of Bitumen and Bituminous Mixture for Highway Engineering, China.
10 . The method of claim 1 , wherein the steps of combining to form the asphalt mixture, foaming, combining to form the recycled asphalt composition, and forming the recycled asphalt layer are conducted at ambient temperatures of no greater than about 50° C.
11 . The method of claim 1 , wherein foaming the asphalt mixture comprises introducing the asphalt mixture to a foam nozzle.
12 . The method of claim 1 , wherein water is present in the asphalt mixture in an amount of from about 2 to about 5 weight % based upon a total weight of all components present in the asphalt mixture.