321214_slurry_sea1.pdf

SLURRY SEAL 321214-1

USDA FOREST SERVICE, R-4

VERNAL OFFICE PARKING LOT

SECTION 321214 – SLURRY SEAL TYPE 2

PART 1 - GENERAL

1.1 SUMMARY

A. This Section includes the following:

1. Slurry Seal.

1.2 QUALITY ASSURANCE

A. All work is to be completed according to applicable Federal, State and Local codes.

1.3 SUBMITTALS

A. Slurry Seal

1. Job-Mix Formula

2. Refinery Test Reports

3. Certificate of Compliance

B. Aggregate source, gradation, and material properties.

1.4 MEASUREMENT AND PAYMENT

A. Payment will be lump sum for Slurry Seal and will include all equipment, materials, work and incidentals necessary to complete the item.

B. Payment will be as listed for the following items:

1. Slurry Seal: Square Yards of slurry seal installed, completed and accepted, including all equipment, materials, work and incidentals necessary to complete the item.

PART 2 - PRODUCTS

2.1 SLURRY SEAL

A. Emulsified Asphalt: Ensure that quick-set emulsions conform to the following:

1. Viscosity: Saybolt Furol at 25°C - 20 to 100 seconds

2. Residue by Distillation: 57% min.

3. Sieve Test: 0.10% max.

4. Tests on Residue from Distillation:

a. Penetration: 25°C, 100 g, 5-second, AASHTO T49 - 40 to 100 mm

SLURRY SEAL 321214-2

b. Solubility in Trichloroethylene: AASHTO T44 - 97.5% min.

c. Ductility: 25°C, 50 mm per minute, AASHTO T51 - 40 mm min.

B. Mineral Filler: Furnish mineral filler that conforms to AASHTO M17.

C. Slurry Seal Aggregate: For slurry seals, furnish aggregate that is a natural or manufactured sand, slag, crushed fines, or other mineral aggregate conforming to Table 321214-1 and the following:

1. Los Angeles Abrasion: AASHTO T96 - 35% max.

2. Sand Equivalent Value: AASHTO T176, alternate method number 2 - 45 min.

3. Sand content by weight of total combined aggregate with < 1.25% water absorption

- 50% max.

4. Sodium Sulfate Soundness Loss: AASHTO T104 - 12% max.

5. Fine Durability Index: AASHTO T210 - 60% max.

D. Table 321214-1 - Slurry Seal Aggregate Gradation Requirements and Application Rates

Sieve Size

Percentage(%) by Weight Passing Designated Sieve

(AASHTO T27 and T11) Type of Slurry Seal

I II III

3/8” - 100 100 #4 100 90-100 70-90 #8 90-100 65-90 45-70 #16 65-90 45-70 28-50 #30 40-65 30-50 19-34 #50 25-42 18-30 12-25 #100 15-30 10-21 7-18 #200 10-20 5-15 5-15

Application rate (Lbs/Sq.Yd.)

0.66-1.10

1.10-1.64

≥1.64

E. Water

1. Do not use water from streams, lakes, ponds, or similar sources without prior approval. Use water that is free of substances detrimental to the work.

PART 3 - EXECUTION

3.1 COMPOSITION OF MIXTURE (JOB-MIX FORMULA)

A. Furnish a slurry seal mixture of aggregate, water, emulsified asphalt, and additives in accordance with ASTM D3910 and ISSA T114. Ensure that the mixture meets the applicable aggregate gradation shown in table 321214-1 and has the following residual asphalt contents, based upon weight of dry aggregate:

1. Type I - Residual asphalt between 10.0 percent and 16.0 percent.

SLURRY SEAL 321214-3

2. Type II - Residual asphalt between 7.5 percent and 13.5 percent.

3. Type III - Residual asphalt between 6.5 percent and 12.0 percent

B. Submit a written job-mix formula for approval at least 21 days before production that includes the following:

1. Aggregate Gradation Values: Provide the representative value for each sieve size for the aggregate blend.

2. Emulsified Asphalt Content: Provide the residual asphalt content, as a percent by weight of dry aggregate.

3. Samples: Provide samples of the aggregate, emulsified asphalt, and mineral filler when shown on the Drawings.

4. Laboratory Test Reports & Mix Design Data: Provide copies of all laboratory test reports and mix design data verifying that the material meets the requirements of paragraph 2.1 and the job-mix formula. The job-mix formula will be evaluated for approval.

3.2 EQUIPMENT

A. Slurry Seal Mixer

1. Self-propelled.

2. Continuous-flow mixing.

3. Calibrated controls.

4. Easily readable metering devices that accurately measure all raw material before entering the pugmill.

5. Automated system for sequencing in all raw material to ensure constant slurry mixture.

6. Mixing chamber to thoroughly blend all ingredients together.

7. Fines feeder with an accurate metering device for introducing additive into the mixer, where the aggregate is introduced into the mixer.

8. A pressurized water system with a fog-type spray bar capable of fogging the surface immediately ahead of the spreading equipment at a rate of 0.003 gal/ft2 to 0.007 gal/ft2 .

9. Proportioning system that is accurate for measuring all material independent of the engine speed.

10. Minimum speed of 65 feet/min and maximum speed of 180 feet/min.

11. Minimum storage capacity of 6.6 T.

12. Capability in accordance with ISSA A105

B. Mechanical-Type Single Squeegee Spreader

1. Attaches to the slurry seal mixer.

2. Flexible squeegee in contact with the surface to prevent loss of slurry.

3. Adjustable to assure a uniform spread over varying grades and crowns.

4. Adjustable in width with a flexible strike-off.

5. Augers for uniform flow to edges.

C. Auxiliary Equipment

SLURRY SEAL 321214-4

1. Furnish hand squeegees, shovel, and other equipment necessary to perform the work. Provide cleaning equipment that includes, but is not limited to, power brooms, air compressors, water-flushing equipment, and hand brooms for surface preparation.

D. Pneumatic-Tire Roller (If Required)

1. Smooth tread tires of equal size.

2. Minimum ground pressure of tire greater than 50 psi.

3.3 SURFACE PREPARATION

A. Immediately before placing the slurry seal, clean the existing surface of loose or deleterious material.

3.4 WEATHER LIMITATIONS

A. Apply slurry seal when the air temperature in the shade and the surface temperature are at least 60°F and rising, and when the weather is not foggy, rainy, or overcast.

3.5 AGGREGATE STOCKPILES

A. Obtain site approval before stockpiling aggregates. Make the stockpiles neat and regular in shape. Side slopes shall be not flatter than 1:1.5.

B. Build the stockpiles in layers not to exceed 3 feet in thickness. Complete each layer before depositing aggregates in the next layer. Construct stockpile layers by spreading aggregates with trucks or other approved pneumatic-tired equipment. Do not push aggregates into piles.

C. Do not dump the aggregate such that any part of it runs down and over the lower layers in the stockpile. Do not drop aggregates from a bucket or spout in one location to form a cone-shaped pile.

D. When operating trucks on stockpiles, avoid tracking dirt or other foreign matter onto the stockpiles material.

E. Space stockpiles far enough apart to prevent different aggregate gradations from mixing, or use suitable walls or partitions to separate stockpiles.

3.6 SLURRY SEAL APPLICATION

A. Mix the slurry seal using a slurry seal mixer. Fog the surface with water immediately preceding the spreader.

B. Blend the additive with the aggregate using the fines feeder. Prewet the aggregate in the pugmill immediately before mixing with the emulsified asphalt.

C. Mix the slurry seal for a maximum of 4 minutes. Ensure that the slurry seal mixture is of the desired consistency as it leaves the mixer, and that it conforms to the approved job-mix formula.

SLURRY SEAL 321214-5

D. If approved by the Contracting Officer, the mineral filler and the emulsified asphalt content may be adjusted during construction to conform to variations in field conditions.

E. Carry sufficient slurry seal mixture in the spreader to completely cover the surface.

F. Spread the mixture with a mechanical-type single squeegee spreader box. In areas not accessible to the spreader box, use hand squeegees to work the slurry seal mixture.

G. Apply slurry coat in a uniform thickness according to ASTM D 3910 and allow to cure.

H. Roll slurry seal to remove ridges and provide a uniform, smooth surface. Provide a minimum of five coverages, to completely cure it prior to opening to traffic. Cure is complete when clear water can be pressed out of the slurry mixture with a piece of paper without discoloring the paper.

I. Remove or repair ridges or bumps in the slurry surface.

3.7 ACCEPTANCE

A. Asphalt materials

1. Asphalt materials are defined as all types and grades of asphalt cement, cutback, and emulsified asphalt.

2. The refinery test reports and the Certificate of Compliance will be reviewed and used to support acceptance of the asphalt material incorporated into the project.

3. If materials are found not to be in conformance with the specified tolerances or within the specification limits, the Contracting Officer will determine an equitable adjustment in payment.

4. If the Contracting Officer elects to test field samples, the test results may be used for acceptance.

B. Aggregate

1. Submit test results and a Certificate of Compliance that states that the aggregate meets the contract requirements. Submit test results within 16 hours of obtaining samples. Take additional samples, if required by the Contracting Officer, to validate the certification.

2. Before incorporating material into the work, ensure that sampling and testing of material conform to AASHTO requirements, and occur at the producer’s plant or stockpile.

3. Provide the minimum number of samples and tests specified in Table 321214-2.

Table 321214-2 – Sampling and Testing

SLURRY SEAL 321214-6

Type of Acceptance

Material or Product

Property or Characteristic

Test Method or Specification

Frequency Sampling Point

Production Certification

Emulsified Asphalta

Contract requirements

AASHTO M140

or M208, as ap-plicable Each shipment -

Tested Conformance

Material sourceb (Contractor-lo-cated source)

Los Angeles abrasion AASHTO T 96

Three times for each undeveloped source,c or once for all other sources

Material source

Slurry Seal Aggregate

Gradation table 02618-1

AASHTO T 27

and T 11 Once for each 2000

SqYd, but not more than three times per day Sand equivalent value

AASHTO T

176, alternate method number 2 (referee method)

Emulsified as-phalt Sample Paragraph 2.1(a) Each tanker, including all trailers

At point of shipment delivery

a. Use in work permitted before sampling and testing for conformance.

b. Testing not required when using Government-provided material source.

c. An undeveloped source is a source that has not supplied slurry seal aggregate within 365 days of the start of producing slurry seal aggregate for this project.

END OF SECTION 321214

May 2020