King County Environmental Purchasing Program
According to a report issued by the Federal Highway Administration and the United States Environmental Protection Agency, 80 percent of the asphalt pavement that’s removed each year during widening and resurfacing projects is reused as part of new roads, roadbeds, shoulders and embankments.
As landfill costs for Construction, Demolition, and Landclearing debris (CDL) continue to rise and the landfills become more heavily regulated, it makes economic sense to seek alternative means of disposal of asphalt that is taken up during construction and demolition. More disposal sites are becoming available and contractors are routinely incorporating recycling into their operations to decrease disposal costs.
Recycled asphalt can be an economical alternative to new asphalt. Project managers can ensure that contractors are aware of opportunities to recycle this material and to use recycled material in construction.
A frequently stated concern is that asphalt will leach into groundwater. According to the Asphalt Institute, asphalt does not create a leachate problem. That is, the petrochemical base of the asphalt does not move into groundwater in a way that presents a hazard. Asphalt can thus be used as a "clean-fill" material without restriction.
Recycled asphalt is commonly incorporated into new asphalt mixes by contractors. Department of Transportation regulations permit ANY level of recycled material to be used in mixes, provided that normal performance requirements are satisfied. The level of recycled asphalt that will perform adequately depends on the specific requirements of the job and the characteristics of the recycled material used. In many cases, recycled asphalt will reduce costs significantly.
Asphalt paving contractors typically use up to 20 percent recycled material in mixes, although mechanisms are not yet in place to measure and report the level of recycled material used.
The King County Roads Maintenance Section has been purchasing asphalt cold patch that reduces the amount of volatile organic compounds (VOCs) released to the environment, since 2001. This product is a dry, odorless, ready-to-use asphalt-based compound used to repair potholes, cracks, and other defects in paved surfaces. It contains 75% post-consumer asphalt and works by compaction. Traditional cold patch hardens through a combination of compaction and evaporation of a petroleum-based carrier, such as kerosene. This evaporation releases large amounts of VOCs, which are not present in this product. It can also be used in all weather and can be overlaid with new asphalt without the special steps needed to overlay conventional patching compounds with new paving. In the past year, King County Roads Maintenance Operations purchased over 1,000 fifty-pound bags, approximately 25tons, of this product, at a cost of over $11,000. For more information about cold patch, please see the program bulletin onLow VOC Cold Patch.
Rubberized Asphalt
For more information about this project, please see the product summary sheet.Asphalt made with recycled rubber was used in an overlay project by Roads Division in 1998. It had been suggested that using “rubberized asphalt” might reduce traffic noise in this 6.3 mile overlay project. The project included noise measurement on the existing deteriorated concrete pavement, the new pavement with a typical asphalt surface, this surface laid on a “rubblized” base, and 3,600 linear feet (1,804 tons) of “rubberized asphalt.” No significant differences in noise-levels were found between the asphalt surfaces, though all were quieter than the deteriorated concrete surface, with noise reduced from between 2.6 to 4.8 decibels. The cost of the rubberized section was approximately 35% higher than conventional asphalt.
Bid and Contract Specifications
WSDOT Standard Specifications - excerpts
Hot Mix Asphalt: 5-04 Asphalt Concrete Pavement 5-04.2 Materials
The Contractor may choose to utilize recycled asphalt pavement (RAP) in the production of HMA. If utilized, the amount of RAP shall not exceed 20 percent of the total weights of aggregate in the mix. the RAP may be from pavements removed under the contract, if any, or pavement material from existing stockpile.
9-03.8(3)C Gradation — Recycled Asphalt Pavement and Mineral Aggregate
Asphalt concrete planings or old asphalt concrete utilized in the production of asphalt concrete shall be sized prior to entering the mixer so that a uniform and thoroughly mixed asphalt concrete is produced in the mixer. If there is evidence of the old asphalt concrete not breaking down during the heating and mixing of the asphalt concrete, the Engineer may elect to modify the maximum size entering the mixer. No contamination by deleterious materials will be allowed in the old asphalt concrete used.
The gradation for the new aggregate used in the production of the asphalt concrete shall be the responsibility of the Contractor, and when combined with recycled material, the combined material shall meet the gradation specification requirements for the specified Class ACP as listed in Section 9-03.8(6) and 9-03.8(6)A or as shown in the Special Provisions. The new aggregate shall meet the general requirements listed in Section 9-03.8(1) and shall meet the appropriate fracture and sand equivalent requirements as listed in Section 9-03.8(2).
The project used recycled concrete aggregate and recycled asphalt from the demolition for backfill, general fill, pipe-bedding and as aggregate base course for pavement construction in new construction. The paragraphs below are excerpted from contract documents related to this project.
For a product performance summary, please see Recycled Concrete Aggregate at the Regional Justice Center and Recycled Asphalt Road BaseThe County wants to recycle as much material as possible during demolition and the demolition schedule has been planned to maximize the amount of recycling, reuse, and salvage that can be achieved during demolition.
Base Contract Work Includes:
- Demolish building and foundations. Crush and stockpile concrete rubble and dispose of all rebar. Do not mix asphalt with concrete in stockpile. Remove drives, parking areas, walks and pads. Segregate different material types (concrete and asphalt) load, haul, crush, consolidate and stockpile material on site. Backfill pits, holes and excavations with clean recycled crushed concrete. Backfill to surrounding grades.
- Recycled crushed materials of differing material types are not to be mixed. Segregate concrete and asphalt stockpiles. Concrete which has been overlaid with asphalt shall be kept separate from other stockpiles.
- The County requires the Contractor to recycle, reuse, and salvage as much material as possible. The demolition schedule was planned to allow for selective removal and sorting of materials. The County requires the Contractor to submit a waste handling plan detailing how the waste streams will be separated and managed.
- The Contractor is responsible for removing and reusing, recycling, or salvaging all other materials associated with the demolition of the buildings, pavement, vegetation, utilities, and any other site improvements.
Part 1-GENERAL Concrete including concrete and cement shall be crushed on site. Crushed concrete shall
be stockpiled separately on site. Crushed concrete shall be used as backfill as specified
in Section 02200, Earthwork. Asphalt and Concrete Asphalt mixtures shall be crushed on
site. No asphalt or combination of asphalt products shall be used as fill by the
Demolition Contractor. Crushed asphalt shall not be mixed with crushed concrete.1.02 Description of Work
This section pertains to work involving recycled crushed concrete, crushed asphalt, and
crushed concrete/asphalt materials produced on site during demolition operations.
Potential sources of recycled crushed materials on site include (but are not limited to)
existing foundations, floor slabs, reinforced concrete walls, and pavements. Mixed crushed
recycled concrete/asphalt may occur as a result of demolishing concrete slab areas
overlain by asphalt surfacing. All reinforcing steel shall be removed from concrete
elements prior to crushing, and exported from the site. Recycled crushed concrete may be used on site as backfill in the parking garage over
excavation zone identified on the project plans, or as general backfill to fill
depressions produced during demolition or within low areas. Recycled crushed concrete will
also be stockpiled on site for use during future site work, as backfill in future footing
over excavation zones, as general fill, pipe-bedding or backfill, and as aggregate base
course for pavement construction. Recycled crushed asphalt or mixed asphalt/concrete will
be stockpiled on site for use during future site work, as general fill or aggregate base
beneath paved areas. Brick, masonry, and CMU elements will be demolished as part of this
Contract. These materials will not be reused on site, but should be demolished and
exported from the site. 1.03 Description of Site Conditions:
- Part 2 - PRODUCTS
2.01 Crushed Recycled Concrete:- Crushed recycled concrete materials shall conform to the following gradation specification:
| Sieve Size U.S Standard |
Percent Passing by Dry Weight |
|---|---|
| 1-1/2 inch | 100 |
| 3/4 inch | 40-75 |
| 1/4 inch | 25-50 |
| No. 40 | 5-20 |
| No. 200 | 10 max |
Recycled concrete materials used or stockpiled on site shall be uniform in quality and free from wood, steel, roots, bark or other extraneous material. In addition, the recycled concrete materials shall meet the following requirements:
Los Angeles Abrasion ....... 500 rev ...... 35%max
Sand Equivalent ........................... 30 min
2.02 Crushed Recycled Asphalt Pavement:
Existing asphalt concrete pavement on site shall be pulverized by a method that limits damage or dislodging of the material below the pavement. The pulverized material shall conform to the following gradation:
| Sieve Size U.S Standard |
Percent Passing by Dry Weight |
|---|---|
| 1-1/2 inch | 100 |
| 3/4 inch | 40 min |
- 2.03 Mixed Crushed Concrete/Asphalt
- Any mixed crushed concrete/asphalt shall conform to the gradation specified above in Section 2.02.
The Contractor shall crush, haul and stockpile the crushed materials to a stockpile area on site designated by King County. Crushed recycled materials shall not be placed higher than Elevation 33 within the parking garage excavation, as shown on the project plans.
- Part 3 - EXECUTION
Where used as backfill in the parking garage over excavation zones, the recycled concrete shall be placed on properly-prepared subgrade. Where very soft, wet subgrade conditions are encountered, use a geotextile separator between subgrade soils and the recycled concrete. Evaluation of conditions requiring use of a geotextile separator, and monitoring of geotextile placement, shall be performed in the field by Hong West, King County's Representative.
- Where placed as compacted fill, recycled concrete materials shall be moisture conditioned to within 3 percent of the optimum moisture content, placed in horizontal lifts less than 8 inches in loose thickness, and compacted to at least 95 percent maximum dry density, determined using ASTM D 1557. Where used as general backfill in areas to be reloaded, the recycled concrete shall be compacted to at least 90 percent maximum dry density, and using the same criteria.
- PART 4 - QUALITY CONTROL
- The Contractor is responsible for the quality of the work and for complying with the specifications. Testing will be conducted by Hong West and King County.
- PART 5 - MEASUREMENT AND PAYMENT
- Crushing, placement, and stockpiling of crushed recycled materials shall be measured by lump sum as part of the base bid.
- Crushed recycled materials that do no meet gradation or other criteria specified herein shall be removed from the site and disposed of at the Contractor's expense.
- Unauthorized excavation consists of removal of materials beyond indicated subgrade elevations or dimensions, or beyond that level required for normal clearing and grubbing operations or removal of structural elements, without specific direction of King County. Unauthorized excavations within footing over excavation zones shall be backfilled in accordance with these specifications, at the Contractor's expense. Any unauthorized excavations in other areas of the site shall be backfilled as directed by Hong West.
- Any additional testing required due to recycled crushed materials failing laboratory or field density test specifications shall be at the Contractor's expense. In addition, testing related to backfilling of unauthorized excavations shall be at the Contractor's expense.
- No payment will be made for materials which has become mixed with other material or misplaced by the Contractor's action, or lack of action. Crushed recycled material which is contaminated by the Contractor by spills or mixing with other site soils, or by any other means, shall be tested, removed, and disposed of by the Contractor at the Contractor's expense.
County of Los Angeles Rubberized Asphalt Concrete Technology Center (RACTC)
Asphalt Recycling & Reclaiming Association - ARRA
(produces US Cold Patch)
- Y.K. Products
E-mail
Updated: May, 2007
King County
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