This Directive was Canceled June 23, 1999.

Notice
Subject
HOT AND COLD RECYCLING OF ASPHALT PAVEMENTS
Classification Code	Date
N 5080.93	October 6, 1981

 

1. PURPOSE

   To present the Federal Highway Administration's (FHWA) position on recycling of asphalt pavements.

2. CANCELLATION

   The FHWA Technical Advisory T5040.9 dated February 16, 1979, Hot Recycling of Asphalt Pavement Materials, is cancelled.

3. BACKGROUND

   The pressing need to conserve energy and minimize costs in highway construction requires that special effort be made to identify and make the maximum use of procedures that will result in reduced energy usage and minimum cost. Because recycling of asphalt pavements has the potential to be an effective method of conserving energy and materials and reducing costs, it is FHWA's policy that recycled asphalt concrete, defined as asphalt concrete containing salvaged paving materials including the use of suitable reclaimed material from other projects, be allowed for use on all projects. States with insufficient experience to properly evaluate the reuse of these materials should take immediate steps to initiate experimental projects.

4. DEFINITIONS
   1. Recycled hot asphalt concrete is an asphalt concrete mix, processed hot in a central plant, which consists of sized salvaged asphalt material, new asphalt, and/or recycling agents and new and/or salvaged aggregates, and meets all standard material and mix specifications for the type of mix being produced.
   2. Recycled cold mix is an asphalt concrete mix, processed in a central plant or on the grade which consists of sized salvaged asphalt material, some type of stabilizing agent and new and/or salvaged aggregates. This material meets specifications of an asphalt aggregate base and generally requires that an asphalt surface course or surface seal be used.
5. PAVEMENT DESIGN
   1. Recycling should be one of the options considered at the design stage of all rehabilitation projects. Material testing of the old pavement may be necessary to determine that recycling is a practical option. The decision to recycle or to overlay should be based on cost and performance on a life cycle basis rather than initial cost and should be specified by the contracting agency. It is emphasized that alternate bids between recycling and overlay are not recommended.
   2. Cracks and material deficiencies in the overlaid pavement will cause reflective cracks and points of weakness to occur in an overlay. Cracks can be eliminated and material deficiencies can be corrected by recycling.
   3. Recycled mixes placed experimentally as base layers, top structural layers, and wearing surfaces are still being evaluated and it would be premature to offer definite conclusions on life cycle performance. However, the earliest of those pavements are 5 years old or older and are performing as well as pavements constructed with new materials. While there is limited experience with recycled mixes, it appears that reasonable performance can be obtained.
   4. It is reasonable to assume that a recycled layer is structurally equivalent to an equal thickness of new hot mix pavement provided the mix meets all of the laboratory design criteria for a new mix intended to perform the same functions.
   5. Only proven methods and materials with which there has been adequate experience to assure success should be used on large projects with high traffic or heavy loading.
6. MIX DESIGN
   1. Recommendations for detailed mix design procedures are contained in NCHRP Report 224. Gradation and other material requirements should be the same for a recycled mix as those developed for mixes using all new materials for the same type of pavement.
   2. Distress observed on a few projects is directly attributable to improper or poor mix designs represented by low stabilities, uncorrected aggregate stripping problems, and low job achieved densities. These problems emphasize the need for proper mix design and construction control. Research results indicate that testing for water susceptibility is especially important for recycled mixes.
   3. Variation in material properties of the pavements to be salvaged should be identified by sampling and a sufficient proportion of new material provided to reduce the variation to an acceptable level. Major changes in mix characteristics for various sections along the same route usually demand separate mix designs.
   4. Removal and sizing of salvaged pavement materials have at times created additional minus 200 sieve material. The amount depends on the type and operation of the sizing process and aggregate properties. Final mix design should always be corrected to final properties of the material processed by the actual equipment used on the project. Large amounts of minus 200 sieve material or other gradation deficiencies can be compensated for by limiting the amount salvaged material used in the recycled mix and varying the gradation of the added new material. Experience has indicated that in most cases crushing the recycled material to a maximum particle size of 2 inches is adequate for hot mix. Additional crushing may result in excess fines.
   5. A soft asphalt alone has been used successfully to restore the penetration and viscosity of the reclaimed asphalt binder. A number of commercial recycling agents have also been used when salvaged asphalt binder in the salvaged material was severely hardened. Any proposed softening agent should be tested with the salvaged asphalt for the specific project, in the ratio to be used, to assure the desired properties of the combination are realized.
7. REMOVAL AND SIZING

   The type and degree of deterioration in a pavement to be constructed and/or the type of material underlying the pavement will usually determine whether a full or partial depth removal technique is utilized. Full-depth pavement removal and sizing can be accomplished using standard construction equipment such as dozers and loaders and portable or stationary crushers or by milling machines. The latter process, although generally more expensive, allows removal of one lane without disturbing traffic movement on adjacent lanes. Excessive dropoffs can be minimized by milling successive levels to a specificdepth. While milling machines usually are specified for partial depth removal, the choice of the method used for full-depth removal will be influenced by economics and maintenance of traffic through construction.

8. EQUIPMENT

   Virtually all equipment manufactured today for the production of asphalt concrete can be built to produce acceptable recycled mixes and meet all air quality standards. Existing equipment can be modified at reasonable cost. In hot mix recycling, batch plants are generally limited to the reuse of a maximum amount of 50 percent salvaged asphalt material in a recycled mix, while an upper limit of approximately 70 percent is attainable in some drum plants.

9. SAVINGS

   Materials savings are realized from the reduction in new asphalt and aggregate. Energy savings result primarily from reduced aggregate haul and drying, and asphalt transportation. Cost savings are greatly influenced by length of aggregate haul and distance from the plant to the job site. Other factors which have a major influence on bid prices are the degree to which contractors in the area are familiar with and equipped for recycling, the size of the State's present and projected recycling program, and State contract procedures.

10. RECOMMENDATIONS
    1. Allow the contractor the use of salvaged asphalt materials and aggregates in the production of asphalt concrete.
    2. Allow the contractor to determine the source and amount of salvaged material to be used as long as the mix produced meets all standard material and mix specifications called for in the contract.
    3. Require that a revised mix design be submitted and approved prior to changing either the source or amount of salvaged material originally approved.
    4. Serious consideration should be given to transferring ownership of all material to be removed to the contractor. This allows the owner agency to receive instant credit, in the form of lower bids, for the value of the salvaged material removed.
    5. Do not specify how to remove sand size a pavement scheduled for full-depth reconstruction; what type of hot mix plant (batch, continuous or drum) to use; the use of recycling agent--but allow it to be used; and what percentage of salvaged material to be used. All of these will be determined by economics resulting from the competitive bidding process.
    6. Recycled hot asphalt concrete should be paid for on the basis of a bid price per ton regardless of the percentage of salvaged material used. This price per ton is also to include the costs of all new additional asphalt, recycling agent, and aggregate.
11. DISCUSSION OF RECOMMENDATIONS

    These recommended practices will allow the production of recycled asphalt concrete, if economically feasible, at any time in any location. Because no restrictions are placed on percentages of used salvaged material, a batch owner can economically compete with owners of drum plants. If across the board use of salvaged materials is allowed in the production of asphalt concrete, the contracting industry can better justify gearing up for such production and write off the additional plant modification cost over a much larger tonnage basis over a longer period of time than on only one or two projects.

    Transferring ownership of all removed salvaged material to the contractor encourages recycling because surplus material can be used in private work at additional savings to the contractor.

12. EVALUATION

    Most highway agencies have successfully constructed one or more hot recycling projects and are continuing to develop new projects. These projects have been constructed under NEEP Project 22, Pavement Recycling, distributed by Notice N 5080.64 dated June 3, 1977. Many projects have also been constructed with technical and financial assistance from the Demonstration Projects program. It is recommended that the evaluation of these projects be continued to validate long-term performance projections. Broad participation is needed to provide the data base necessary to require additional projects to be programmed experimental. The projects under evaluation should be representative of recycling procedures adopted by a State which have become routine. When a significantly new or innovative feature is contemplated, or when a project is in a significantly different environment, the highway agency should e urged to designate the project as experimental.

    A recycling data bank is being developed under a contract through the FHWA Office of Research that will provide a means of long term evaluation of pavement recycling. The contract is scheduled to be completed in 1982.

 

/s/
R. D. Morgan
Associate Administrator for
Engineering and Traffic Operations

Attachments

 

REPORT FROM WISCONSIN DIVISION, April 13, 1981
WISCONSIN
1981 RECYCLING PROGRAM

During the first 6 months of 1981, Wisconsin Department of Transportation (WISDOT) let 42 contracts involving recycling of the existing bituminous pavement. The dollar amount of these contracts totaled $40.4 million and included 52 Federal-aid projects. Contractor competition for these contracts has been good with only 1 out of the 26 successful contractors having more than three contracts.

The contracts let of date have provided 696,700 tons of recycled bituminous pavement for paving 418 lane miles. The average bid price for this recycled bituminous pavement has been $8.84 per ton. This is significantly less than the $14.24 per ton average for virgin bituminous concrete pavement. When the savings in asphalt and shoulder aggregate are considered, the savings are almost $8.00 per ton.

In addition to the above tonnage, eight contracts totaling 34,800 tons of single aggregate bituminous surface have been let with the contractor having the option to use recycled or virgin aggregate. Most (6) of these projects were relatively small and provided less than 3,500 tons of bituminous pavement per project. The two larger projects provided 8,800 and 13,350 tons of single aggregate bituminous surface. Five of these contracts with optional recycling were in Milwaukee County.

The contracts let in FY 1981 have also provided for salvaging 496,000 tons of existing bituminous pavement. The average cost of salvaging bituminous pavement has been $4.41 per ton.

In addition to the "normal" recycling type of project, Wisconsin's 1981 recycling program has included three contracts that provide for recycling as part of a sulfur extended asphalt pavement. The cost of the sulfur for these projects has averaged $149 per ton.

One of the major accomplishments in WISDOT's recycling program isthe savings in energy, natural resources, and cost. It is estimated that the energy savings this fiscal year is equivalent of 915,000 gallons of gasoline; the aggregate savings is 574,700 tons of aggregate, and the cost savings is $4.8 million.

Reports Dealing with Recycling

NCHRP Synthesis of Highway Practice 54, "Recycling Materials For Highways, " 1978.

NCHRP Report 224, "Guidelines for Recycling Pavement Materials," 1980.

American Society of Testing Materials, STP 662, 1976.

Association of Asphalt Paving Technologists, Volume 46, 1977; Volume 48, 1977; Volume 49, 1980.

Proceedings of the national Seminar on Asphalt Pavement Recycling, Dallas-Ft Worth, Texas, 1980 - Transportation Research Record 780.

The above reports are available at a charge from:

The National Technical Information
Service (NTIS)
Springfield, Virginia 22161

Evaluation of Selected Softening Agents used in Flexible Pavement Recycling, FHWA-TS-79-204, 1978.

Hot Recycling - Minnesota - Modified Dryer Drum, FHWA-TS-80-233, 1980.

Hot Recycling - Wyoming Dryer Drum, FHWA TS-80-234, 1980.

The above reports are available free of charge from:

Federal Highway Administration
Region 15
Demonstration Projects Division (HDF-15)
1000 North Glebe Road
Arlington, Virginia 22201

 

REPORTS PREPARED
FOR
DEMONSTRATION PROJECT NO. 39
RECYCLING ASPHALT PAVEMENTS

FHWA-DP-39-1 - IN-PLACE RECYCLING OF ASPHALT PAVEMENT - REPUBLIC COUNTY, KANSAS - CONSTRUCTION REPORT - Clarence W. Smith - August 1978 - 30 pages

FHWA-DP-39-2 - SURFACE RECYCLING ASPHALTIC CONCRETE PAVEMENT - MC ALLEN, TEXAS - CONSTRUCTION REPORT - Wade D. Barnes and Jack T. Trammell - September \1877 - 58 pages

FHWA-DP-39-3 - WASHINGTON STATE DEPARTMENT OF TRANSPORTATION'S FIRST ASPHALT CONCRETE RECYCLING PROJECT - ELLENSBURG, WASHINGTON - CONSTRUCTION REPORT - R. V. LeClerc, R. L. Schermerhorn and J. P. Walter - July 1978 - 52 pages

FHWA-DP-39-4 - RECYCLING OF ASPHALT CONCRETE-OREGON'S FIRST HOT MIX PROJECT - WOODBURN, OREGON - INTERIM REPORT - James Dumler and Gordon Beecroft - November 1978 - 56 pages

FHWA-DP-39-5 - PAVEMENT SURFACE RECYCLING ON PARKS HIGHWAY BETWEEN LITTLE SUSITNA RIVER AND WILLOW CREEK - ANCHORAGE, ALASKA - INTERIM REPORT - John W. Henry - February 1978 - 31 pages

FHWA-DP-39-6 - BLEWETT PASS RECYCLING PROJECT - BLEWETT PASS, WASHINGTON - PRELIMINARY REPORT - September 1979 - 57 pages

FHWA-DP-39-7 - MILLING BITUMINOUS SURFACE - ELLENDALE, NORTH DAKOTA - CONSTRUCTION REPORT - September 1978 - 32 pages

FHWA-DP-39-8 - EVALUATION OF RECYCLED BITUMINOUS PAVEMENTS -ELKHART COUNTY , INDIANA - FINAL REPORT - Barry L. Elkin - August 1978 - 60 pages

FHWA-DP-39-9 - RECYCLING OF ASPHALTIC CONCRETE PAVEMENTS -LARAMIE, WYOMING - INITIAL REPORT - Wyoming State Highway Department, Materials Division - February 1979 - 89 pages

FHWA-DP-39-10 - EVALUATION OF RECYCLED ASPHALT CONCRETE PAVEMENTS - KOSSUTH COUNTY, IOWA - CONSTRUCTION REPORT - Richard P. Henely - February 1979 - 52 pages

FHWA-DP-39-11 - RECYCLING ASPHALTIC CONCRETE PAVEMENT - ROSCOE, TEXAS - CONSTRUCTION REPORT - Bobby R. Lindley - March 1979 - 142 pages

FHWA-DP-39-12 - EXPERIMENTAL PROJECT SURFACE RECYCLING OF ASPHALT CONCRETE PAVEMENT - NATCHEZ, MISSISSIPPI - PROGRESS REPORT -James D. Webb, Gayle E. Albritton, and Thomas L. Chance

FHWA-DP-39-13 - COLD RECYCLING - MENOMINEE INDIAN RESERVATION WISCONSIN - CONSTRUCTION REPORT - Steve Beckett and Roy J. Calbo - February 1979 - 45 pages

FHWA-DP-39-14 - EVALUATION OF RECYCLED ASPHALTIC CONCRETE -CHESTER, VIRGINIA - CONSTRUCTION REPORT - C. S. Hughes - August 1977 - 26 pages

FHWA-DP-39-15 - INTERIM REPORT ON HOT RECYCLING - Douglas J. Brown - April 1979 - 99 pages (English or Spanish)

FHWA-DP-39-16 - PAVEMENT RECYCLING PROJECT - GILA BEND, ARIZONA - CONSTRUCTION REPORT - Arizona Department of Transportation Research Division - October 1978 - 59 pages

FHWA-DP-39-17 - RECYCLING ASPHALT CONCRETE ON INTERSTATE 80 -GOLD RUN, CALIFORNIA - INTERIM REPORT - R. N. Doty and T. Scrimsher - April 1979 - 134 pages

FHWA-DP-39-18 - RECYCLING OF BITUMINOUS SHOULDERS - FERGUS FALLS, MINNESOTA - INTERIM REPORT - Ronald H. Cassellius and Roger C. Olson - March 1979 - 31 pages

FHWA-DP-39-19 - RECYCLING OF ASPHALT CONCRETE PAVEMENTS - PALM BEACH COUNTY, FLORIDA - INITIAL REPORT - Charles F. Potts and Kenneth H. Murphy - January 1980 - 35 pages

FHWA-DP-39-20 - COLD RECYCLING ASPHALT PAVEMENT - SHERVURNE, VERMONT - INITIAL REPORT - R. I. Frascoia and D. N. Onusseit - January 1979 - 42 pages

FHWA-DP-39-21 - SURFACE RECYCLING OF ASPHALT CONCRETE PAVEMENT - OHIO - PROGRESS REPORT - Willis B. Gibboney - November 1979 - 23 pages

FHWA-DP-39-22 - SURFACE RECYCLING OF ASPHALT CONCRETE PAVEMENTS - FORT MYERS, FLORIDA - INITIAL REPORT - Charles F. Potts and Kenneth H. Murphy - September 1979 - 62 pages

FHWA-DP-39-23 - RECYCLING OF ASPHALT CONCRETE PAVEMENTS - PANAMA CITY, FLORIDA - INITIAL REPORT - Charles F. Potts and Kenneth H. Murphy - December 1979 - 53 pages

FHWA-DP-39-24 - COLD RECYCLING OF PAVEMENT USING THE HAMMERMILL PROCESS - MAINE - FINAL REPORT - David W. Rand - December 1978 -41 pages

FHWA-DP-39-25 - COWHERD ROAD COLD ASPHALT RECYCLING PROJECT - JACKSON COUNTY, MISSOURI - CONSTRUCTION REPORT - Kirk Phillips -November 1979 - 99 pages

FHWA-DP-39-26 - COLD BITUMINOUS PAVEMENTS RECYCLING - WIBAUX, MONTANA - CONSTRUCTION REPORT - John J. Wright - May 1979 - 75 pages

FHWA-DP-39-27 - COLD RECYCLING OF A SOIL-ASPHALT ROADWAY - BEAVER COUNTY, OKLAHOMA - INTERIM REPORT - Jack C. Stewart - April 1980 - 52 pages

FHWA-DP-39-28 - HOT MIX RECYCLING - DURANGO, COLORADO - INTERIM REPORT - Robert F. LaForce - May 1980 - 61 pages

FHWA-DP-39-29 - BITUMINOUS CONCRETE PAVEMENT RECYCLING - INTERIM REPORT - Edgar J. Hellriegel - NORTH BRUNSWICK, NEW JERSEY - July 1980 - 61 pages

FHWA-DP-39-30 - HOULTON - LITTLETON HOT RECYCLING PAVING PROJECT - HOULTON, MAINE - PRELIMINARY & CONSTRUCTION REPORT - D. W. Rand - MARCH 1980 - 61 pages

FHWA-DP-39-31 - HOT RECYCLING OF ASPHALTIC CONCRETE PAVEMENT -BEAVER, UTAH - INTERIM REPORT - Wade B. Beteson - October 1980 -170 pages

FHWA-DP-39-32 - 1980 PAVEMENT RECYCLING PROGRAM - SPRINGFIELD, MISSOURI - INTERIM REPORT - prepared by Anderson Engineering, Inc. - January 1981 - 75 pages

 

OTHER RELATED RECYCLING REPORTS

DEMONSTRATION PROJECT NO. 39 - RECYCLING ASPHALT PAVEMENTS -PROJECT STATUS REPORT - February 1979 - 66 pages

RECYCLING OF ASPHALTIC CONCRETE - ARIZONA'S FIRST PROJECT - James A. McGee and A. James Judd - 28 pages

MINNESOTA HEAT TRANSFER METHOD FOR RECYCLING BITUMINOUS PAVEMENT - REPORT ON MAPLEWOOD, MINNESOTA, RECYCLING PROJECT - Richard C. Ingberg, Richard M. Morchinek, and Ronald H. Cassellius - 1977 -43 pages

EVALUATION OF AIR POLLUTION CONTROL DEVICES FOR ASPHALT PAVEMENT RECYCLING OPERATIONS - PROGRESS REPORT - Richard P. Henely -December 1977 - 47 pages

RECYCLING ASPHALT CONCRETE PAVEMENT - DEPARTMENTAL RESEARCH REPORT NO. 524-1-F - DHT 1-9-76-524-1F - Charles H. Hughes -August 1977 - 145 pages

COLD RECYCLING OF ASPHALT CONCRETE PAVEMENT - EXPERIMENTAL PROJECTS - REPORT NO. 613-1 - B. R. Lindley - October 1975 - 27 pages

RECYCLED ASPHALTIC CONCRETE PAVEMENT - SR-26, SR-100 TO HOLDEN RS-0303(3) - Wade B. Betenson - February 1979 - 94 pages

COLD RECYCLING OF PAVEMENT BY HAMMERMILL PROCESS - INTERIM REPORT - David W. Rand - August 1977 - 82 pages

RECYCLING OF SUBSTANDARD OR DETERIORATED ASPHALT PAVEMENTS - A GUIDELINE FOR DESIGN PROCEDURES - Donald D. Davidson, William Canessa, and Steven J. Escobar - February 1977 - 51 pages

FHWA-DP-PC-1000-1 - PRODUCTION EFFICIENCY STUDY ON PAVEMENT PLANING EQUIPMENT - INTERIM REPORT - David R. Lewis - March 1979 - 58 pages

HOT RECYCLING IN HOT-MIX BATCH PLANTS - National Asphalt Pavement Association - 5 pages

PRODUCING A BITUMINOUS WEARING COURSE BY DRUM MIX RECYCLING (MICHIGAN) - R. B. Moore and R. A. Welke - January 1979 - 51 pages

BATCH PLANT RECYCLING (MICHIGAN) - John E. Norton - April 1979 -USE OF RECYCLED ASPHALT SURFACE MATERIAL IN THE CONSTRUCTION OF A BITUMINOUS STABILIZED BASE (MICHIGAN) - J. H. DeFoe and G. F. Sweeney - April 1978 - 21 pages

MIXED-IN-PLACE STABILIZATION OF HIGHWAY BASE AGGREGATES AND PULVERIZED BITUMINOUS SURFACING USING ASPHALT STABILIZERS (MICHIGAN) - J. H. DeFoe - March 1977 - 39 pages

RECYCLING OF BITUMINOUS MAINLINE AND SHOULDERS (MINNESOTA) -Roger C. Olson - February 1979 - 26 pages

RECYCLING OF ASPHALTIC CONCRETE PAVEMENTS NO. 2 (WYOMING) -Materials Division of Wyoming State Highway Department - 86 pages

RECYCLED COLD-MIX ASPHALT BASE CATOCTIN MOUNTAIN PARK (REGION 15, FHWA) - William F. Bensing - December 1978 - 34 pages

HOT MIX RECYCLING GEORGE WASHINGTON MEMORIAL PARKWAY (REGION 15, FHWA ) - Reynaldo Cortez - 31 pages

EXPERIMENTAL TEST SECTION NEAR COVE FORT (UTAH) - \Uath Department of Transportation - 59 pages

RECYCLING ASPHALTIC CONCRETE PAVEMENT (TEXAS) - FINAL REPORT (I-20 PROJECT) - Bobby R. Lindley - January 1980 - 4 pages

EVALUATION OF RECYCLED ASPHALT CONCRETE PAVEMENTS (KOSSUTH COUNTY, IOWA) - FINAL REPORT - Richard P. Henely - 30 pages