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Publication Number: FHWA-HRT-11-021
Date: April 2011

Reclaimed Asphalt Pavement in Asphalt Mixtures: State of the Practice

508 Captions

Figures

Figure 1. Photo. Milled RAP. This photo shows a close-up view of milled reclaimed asphalt pavement (RAP) that has been milled and stockpiled from an existing roadway.

Figure 2. Graph. Estimated asphalt production cost categories. This bar graph shows the estimated distribution of percent cost for four asphalt production categories: material, plant production, trucking, and lay down. Percent of cost is shown on the y-axis. The data are as follows: 70 percent from materials, 10 percent from plant production, 15 percent from trucking, and 5 percent from lay down.

Figure 3. Graph. Approximate tons of RAP used in recycled asphalt in New Jersey per year. This graph shows the tons of reclaimed asphalt pavement (RAP) used in recycled asphalt. Tons of RAP is shown on the y-axis, and years is shown on the x-axis. The data are as follows: 89,000 tons in 2000, 60,000 tons in 2001, 65,000 tons in 2002, 105,000 tons in 2003, 140,000 tons in 2004, and 135,000 tons in 2005.

Figure 4. Graph. Usage and potential of various RAP percentages in the intermediate layer. This bar graph shows the number of State highway agencies that allow reclaimed asphalt pavement (RAP) in the intermediate layer of a pavement. The number of State highway agencies is shown on the y-axis. The data are as follows: 45 agencies permit up to 10 percent RAP, 43 agencies permit up to 19 percent RAP, 36 agencies permit up to 29 percent RAP, and 15 agencies permit 30 percent RAP and higher. The graph also depicts the number of agencies that use the following percentages of RAP: 41 agencies use up to 10 percent RAP, 37 agencies use up to 19 percent RAP, 10 agencies use up to 29 percent RAP, and 4 agencies use 30 percent RAP and higher.

Figure 5. Graph. Usage and potential of various RAP percentages in the surface layer. This bar graph shows the number of State highway agencies that allow reclaimed asphalt pavement (RAP) in the surface layer of a pavement. The number of State highway agencies is shown on the y-axis. The data are as follows: 43 agencies permit up to 10 percent RAP, 35 agencies permit up to 19 percent RAP, 20 agencies permit up to 29 percent RAP, and 5 agencies permit 30 percent RAP and higher. The graph also depicts the number of agencies that use the following percentages of RAP: 40 agencies use up to 10 percent RAP, 31 agencies use up to 19 percent RAP, 2 agencies use up to 29 percent RAP, and zero agencies use 30 percent RAP and higher.

Figure 6. Map. States with increased RAP use since 2007. This map of the United States shows which of the 50 States as well as the District of Columbia and Puerto Rico increased their reclaimed asphalt pavement (RAP) use from 2007 to 2009. The following States did not increase their RAP use: Alaska, Arkansas, California, Delaware, Indiana, Iowa, Kansas, Louisiana, Massachusetts, Michigan, Minnesota, Mississippi, Nebraska, New Jersey, New York, North Dakota, Oklahoma, Oregon, Puerto Rico, Rhode Island, South Carolina, South Dakota, Washington, Wisconsin, and Wyoming. The following States increased their RAP use: Alabama, Arizona, Colorado, Connecticut, the District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Kentucky, Maine, Maryland, Missouri, Montana, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Tennessee, Texas, Utah, Vermont, Virginia, and West Virginia.

Figure 7. Map. States that permit more than 25 percent RAP in HMA layers. This map of the United States shows which of the 50 States as well as the District of Columbia permit more than 25 percent reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) and in which layers. The following States do not permit more than 25 percent RAP in any layer: Alaska, Connecticut, Delaware, Iowa, North Dakota, and Washington. The following States permit 25 percent RAP in the base layer only: California, Hawaii, Louisiana, Michigan, Nevada, and New York. The following States permit 25 percent RAP in base and intermediate layers only: Arizona, Colorado, Florida, Indiana, Maine, Massachusetts, Mississippi, New Jersey, New Mexico, Ohio, Oklahoma, South Carolina, Rhode Island, Tennessee, Texas, and Wisconsin. The following States permit 25 percent RAP in all layers: Alabama, Arkansas, District of Columbia, Georgia, Idaho, Illinois, Kansas, Kentucky, Maryland, Minnesota, Missouri, Montana, Nebraska, New Hampshire, North Carolina, Pennsylvania, Oregon, South Dakota, Utah, Vermont, Virginia, West Virginia, and Wyoming.

Figure 8. Map. States that use more than 20 percent RAP in HMA layers. This map of the United States shows which of the 50 States as well as the District of Columbia and Puerto Rico use 20 percent or more reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) and in which layers. The following States do not use more than 20 percent RAP in any layer: Alaska, Arizona, Arkansas, Colorado, Connecticut, Delaware, Idaho, Illinois, Iowa, Kentucky, Maine, Missouri, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Pennsylvania, Puerto Rico, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming. The following States use 20 percent or more RAP in the base layer only: California, Hawaii, Nevada, Tennessee, and Virginia. The following States use 20 percent or more RAP in base and intermediate layers only: the District of Columbia, Florida, Maryland, Massachusetts, Michigan, Mississippi, Montana, Nebraska, New Mexico, Ohio, Oklahoma, Rhode Island, and South Carolina. The following States use 20 percent or more RAP in all layers: Alabama, Georgia, Indiana, Kansas, Minnesota, Oregon, South Dakota, and Texas. Louisiana did not respond to this question in the survey.

Figure 9. Map. States that have experimented with or routinely use high RAP mixtures. This map of the United States shows which of the 50 States as well as the District of Columbia and Puerto Rico have either experimented with or routinely use high reclaimed asphalt pavement (RAP) or that do not use high RAP. The States that experimented with or routinely use high RAP include Delaware, Florida, Georgia, Illinois, Kansas, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, and Wyoming. The States that do not use high RAP include Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, District of Columbia, Idaho, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Nevada, New Hampshire, New Jersey, Oklahoma, Pennsylvania, Puerto Rico, Rhode Island, Vermont, Washington, West Virginia, and Wisconsin.

Figure 10. Map. Ownership of RAP by State highway agency. This map of the United States shows the ownership of reclaimed asphalt pavement (RAP) by State highway agency. Within the following States, both the agency and the contractor retain ownership of RAP: Arizona, Arkansas, Connecticut, Delaware, Georgia, Kansas, Kentucky, Louisiana, Minnesota, Montana, Nebraska, Nevada, New Hampshire, New York, Oklahoma, Oregon, Pennsylvania, South Dakota, Texas, and Vermont. Within the following States, the contractor owns RAP: Alabama, Alaska, California, Colorado, Florida, Idaho, Illinois, Indiana, Iowa, Maryland, Massachusetts, Michigan, Mississippi, Missouri, New Jersey, North Carolina, North Dakota, Ohio, South Carolina, Tennessee, Utah, Virginia, Washington, West Virginia, and Wisconsin. Within the following States, the agency owns RAP: Maine, New Mexico, and Wyoming.

Figure 11. Graph. Quantification of the use of different methods for determining the AC of RAP mixtures. This bar graph shows the different methods used for determining the asphalt content (AC) of reclaimed asphalt pavement (RAP) mixtures. The number of State highway agencies is shown on the y-axis, and the four methods are shown on the x-axis (ignition oven, solvent/chemical extraction, both ignition and/or extraction, and none). In total, 14 agencies used the ignition oven, 7 agencies used solvent/chemical extraction, 3 agencies used both ignition oven and/or extraction, and 3 agencies used no method for determining asphalt content of RAP mixtures.

Figure 12. Photo. Stockpile of unprocessed RAP millings. This photo shows a stockpile of unprocessed reclaimed asphalt pavement (RAP) millings of various sizes.

Figure 13. Photo. Specialized fractionation equipment. This photo shows fractionation equipment from a distance including the conveyors.

Figure 14. Photo. Close-up view of specialized fractionation equipment. This photo is a close-up shot of the conveyor and sieves.

Figure 15. Photo. Fine fractionated RAP stockpile. This photo shows fine fractionated reclaimed asphalt pavement (RAP) being added to the fine RAP stockpile.

Figure 16. Photo. Coarse fractionated RAP stockpile. The photo shows coarse fractionated reclaimed asphalt pavement (RAP) being added to the coarse RAP stockpile.

Figure 17. Photo. RAP stockpile being maintained. This photo shows a front-end loader picking up reclaimed asphalt pavement (RAP) material from a RAP stockpile to maintain the stockpile.

Figure 18. Graph. Percent RAP content versus high temperature PG. This graph depicts the linear relationship between the increase in percent reclaimed asphalt pavement (RAP) content by weight of mix, which is on the y-axis, versus the increase in high temperature performance grade (PG) of the virgin binder, which is on the x-axis. The linear relationship is represented by the equation y equals 3.57 times -228.48, where y is the percent RAP content by weight of mix and x is the high temperature performance grade.

Figure 19. Photo. Sampling RAP from the stockpile. This photo shows a Federal Highway Administration Mobile Asphalt Laboratory technician using a shovel to collect reclaimed asphalt pavement (RAP) in a bucket from a RAP stockpile for testing.

Figure 20. Photo. Scalping screen for RAP feed. This photo shows the scalping screen at a mobile hot mix asphalt plant from a distance for reclaimed asphalt pavement (RAP) feed.

Figure 21. Photo. Smaller scalping screen for large RAP particles. This photo shows a close-up shot of the conveyor belt and a smaller screen used for preventing large-sized reclaimed asphalt pavement (RAP) particles from entering the plant.

Figure 22. Photo. Placement of a high RAP mixture. This photo shows a crew checking to ensure that a high reclaimed asphalt pavement (RAP) is level.

Figure 23. Photo. Compaction of a high RAP mixture. This photo shows a vibratory roller compacting a high reclaimed asphalt pavement (RAP) mixture on a project.

Figure 24. Graph. Pavement age in years versus percent RAP for FDOT projects with greater than 5,000 tons of asphalt mix. This graph shows the pavement age (in years) on the y-axis versus the percentage of reclaimed asphalt pavement (RAP) used in randomly selected pavement projects for the Florida Department of Transportation (FDOT) on the x-axis. The average age for zero and 30 percent RAP is 11 years, the average age for 35 percent RAP is 10 years, and the average age for 40, 45, and 50 percent RAP is 13 years.

Equations

Equation 1. Binder replacement. Binder replacement in percentage equals parenthesis A times B end parenthesis divided by C times 100 percent.

Equation 2. G subscript se superscript RAP. G subscript se superscript RAP equals 100 minus P subscript b divided by 100 divided by G subscript mm minus P subscript b divided by G subscript b.

Equation 3. G subscript sb superscript RAP. G subscript sb superscript RAP equals G subscript se superscript RAP divided by bracket P subscript ba minus G subscript se superscript RAP divided by 100 times G subscript b plus 1 end bracket.

Equation 4. T subscript virgin. T subscript virgin equals T subscript blend minus parenthesis percent RAP times T subscript RAP end parenthesis divided by parenthesis 1 minus percent RAP end parenthesis.

Equation 5. Percent RAP. Percent RAP equals T subscript blend minus T subscript virgin divided by T subscript RAP minus T subscript virgin.

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