This master should be used by designers working on Port of Portland construction projects and by designers working for PDX tenants (“Tenants”). Usage notes highlight a few specific editing choices, however the entire section should be evaluated and edited to fit specific project needs.

Select this section for temporary GA aprons, temporary roads, and vehicle parking lots.

SECTION 321238 – CAPE SEAL

PART 1 - GENERAL

1.1  DESCRIPTION

  1. This section describes the application of an asphalt-blended cape seal. Cape seal is a single layer of chip seal surface treatment application followed by an emulsion mix slurry seal application.

1.2  SUBMITTALS

Edit “21 days” as appropriate for the project.

  1. Submit the manufacturer’s certification of source and properties of sealer, latex additive, and gravel a minimum of 21 days prior to their intended use.
  2. Submit equipment information for Port approval.

PART 2 - PRODUCTS

2.1  ASPHALT SEALERS

  1. First Sealer Application Properties (prior to gravel application):
  2. Cationic asphalt emulsion base.
  3. 3 percent latex additive.
  4. Contains no aggregates.
  5. CRS-2P polymer modified emulsified asphalt, GSB-88 emulsion seal coat concentrate as manufactured by Asphalt Systems, Inc., of Salt Lake City Utah, or pre-bid approved equal.
  6. Second Sealer Application Properties (after the coarse aggregate application):
  7. Cationic asphalt emulsion base.
  8. 5 percent latex additive.
  9. Contains fine aggregates (sand).
  10. Armor Seal No. A-300 with 25 percent coal tar, or pre-bid approved equal.

2.2  LATEX ADDITIVE

  1. Copolymer containing 51-70 parts butadiene and 30-49 parts acrylonitrile, with a minimum solids content of 40 percent, a particle size less than 80manometers, and silicones at 4 percent of the latex additive content.
  2. Approved for use by the manufacturer of the bituminous material to ensure compatibility.
  3. Compatible with the coal-tar emulsion used by the Contractor and mix homogeneously with the coal-tar emulsion, water, and aggregate in the proportions specified to produce a mixture that will adequately suspend the aggregate during mixing and application.
  4. Armor Seal Maxi-Tuff Latex Additive No. A-600, or pre-bid approved equal.

2.3  COARSE AGGREGATES

  1. Consist of clean, sound, durable particles of crushed stone or crushed gravel, 1/4-inch - No. 10, and be free from coatings of clay, silt, vegetable matter, and other objectionable materials. Course aggregates shall contain no clay balls.

2.4  FINE AGGREGATES

  1. The fine aggregate material for the second seal coat application shall consist of hard durable particles of fragments of granular aggregates or dry, clean, dust-free slag, No. 16 - Pan, with a Mohs hardness value of 7.5 – 8.0. Slag shall be black boiler sanding slag as supplied by Tru-Grit Abrasives, Inc., of Danville, CA, or pre-bid approved equal.
  2. The material shall meet the following gradation requirements:

Sieve Size / Percent Passing /
U.S. No. 16 / 99-100
U.S. No. 20 / 99-100
U.S. No. 30 / 80-95
U.S. No. 40 / 35-60
U.S. No. 50 / 60-80
U.S. No. 60 / 0-5
U.S. No. 110 / 0-3
Pan / 0-2

PART 3 - EXECUTION

3.1  EXISTING SURFACE/PAVEMENT PREPARATION

  1. Remove all vegetation along with roots and topsoil within the work area limits.
  2. The existing surface shall be thoroughly cleaned and shall contain no loose material, dirt, dust, deicing chemical residue, grease, oils, or petroleum residue. Clean up loose material with a regenerative-air vacuum sweeper and dispose of material off Port property.

Edit or delete the following two paragraphs according to project requirements/location.

  1. Patch designated potholes and ponding areas prior to the first seal coat application. Patch these areas with a chip seal application of seal coat and 1/2"-0" aggregates.
  2. Cover existing features such as catch basins, manholes, aircraft tie downs, lights and light pads, etc., prior to each seal coat application.

3.2  EQUIPMENT

  1. Distributor trucks for the first seal coat shall be of the pressure type with insulated tanks and heaters, shall be self-propelled, and shall be capable of applying a uniform, constant, measurable shot over the entire length of spray bar. Properly calibrate the distributer and properly adjust nozzles and bar height. Spray bars shall have a minimum length of 9 feet and shall be the full circulating type.
  2. Calibrate chip spreader to deliver a uniform and constant spread of aggregate 1/4 inch deep.
  3. Roller compactors shall be 3- to 8-ton pneumatic tire rollers.
  4. The second seal coat application equipment shall be of a calibrated spray type and equipped with a power agitator, capable of applying a uniform, constant, measurable shot over the entire length of spray bar.
  5. All equipment shall meet the approval of the Port.

3.3  WEATHER LIMITATIONS

  1. Minimum atmospheric temperature shall be 55°F and rising.
  2. Do not apply within 24 hours after rain or if rain is expected within 8hours after application.
  3. Do not apply during windy conditions when wind is in excess of 10 mph, unless directed by the Port.

3.4  SEAL COAT AND AGGREGATE APPLICATIONS

  1. General:
  2. Mix sand into both the first and second coats.
  3. Mix sand into the blended sealer at 2 pounds per gallon of undiluted sealer.
  4. Add water to the undiluted sealer only at the work site just prior to application.
  5. Apply seal coat only when existing surface is clean and dry.
  6. Apply uniformly over the entire work area.
  7. First Seal Coat Mixing and Application:
  8. Mix 40 to 45 percent water with the undiluted emulsified sealer.
  9. Apply first coat of sealer at a rate of 0.40 gallons per square yard or 45 gallons per 1,000 square feet of undiluted material.
  10. Coarse Aggregate Application:
  11. Apply immediately after the first seal coat application.
  12. Apply one layer of coarse aggregate consistently throughout the designated area at the rate of 20 to 30 pounds per square yard.
  13. Operate the chip spreader at speeds which do not cause the aggregate chips to roll over after striking the bituminous-covered surface.

4.  Compact aggregate with a minimum of two pneumatic tire rollers. Initial rolling shall consist of one complete pass over the designated area and shall begin immediately behind the spreader. Do not spread asphalt emulsion and aggregate more than 2,500 feet ahead of completed initial rolling operations. Secondary rolling shall begin immediately after completion of the initial rolling. The amount of secondary rolling shall be sufficient to adequately seat the aggregate, and shall not be less than two complete passes.

  1. Keep all traffic off the surface during seal coat distribution and curing.
  2. Second Seal Coat Mixing and Application:
  3. Apply the second seal coat after curing the first coat for 5 to 7 days.
  4. Clean the chip seal surface with a regenerative-air vacuum sweeper just prior to the slurry seal application to remove all loose particles and aggregate chips. Dispose of material off Port property.
  5. Mix up to 20 to 30 percent water with the undiluted sealer. The amount of water added shall be based on workability of the seal coat on the existing pavement surface. Add water only at the work site just prior to application.
  6. Mix concentrated latex additive with water at a ratio of 1:1 before mixing it into the sealer.
  7. Add 3 percent by total volume concentrated latex additive to each undiluted gallon of sealer.
  8. Apply one coat of sealer at a rate of 0.40 gallons per square yard or 45 gallons per 1,000 square feet of undiluted material.
  9. The finished surface shall not contain any bumps or ridges.
  10. Keep all traffic off the surface during slurry distribution. Cure for a minimum of 24 hours before opening to traffic.

END OF SECTION 321238

2/5/2016 / CAPE SEAL
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