### **ITEM P-630 REFINED COAL TAR EMULSION WITHOUT ADDITIVES, SLURRY SEAL SURFACE TREATMENT**

**630-1.1 GENERAL.** This item shall consist of a mixture of refined
coal tar emulsion, mineral aggregate, and water properly proportioned,
mixed, and applied as a slurry seal on new or existing (aged) asphalt
concrete pavement.

MATERIALS

**630-2.1 Refined Coal Tar Emulsion.** A refined coal tar emulsion
prepared from a high temperature refined coal tar conforming to the
requirements of ASTM specification D 490 for grade 11-12. The use of oil
and water gas tar is not allowed. Base refined coal tar emulsion must
conform to all requirements of Federal Specification R-P-355.

**630-2.2 Aggregate.** The aggregate shall be washed dry silica sand or
boiler slag free of dust, trash, clay, organic materials or other
deleterious substances. The aggregate shall meet the gradation
requirements of Table 1, when tested in accordance with ASTM C 136.

**TABLE 1. GRADATION OF AGGREGATES**\*

+-----------------+------------------+---------------+---------------+
| **Sieve Size**  |                  | ###### Per    |               |
|                 |                  | cent Retained |               |
+-----------------+------------------+---------------+---------------+
|                 |                  | **Minimum**   | **Maximum**   |
+-----------------+------------------+---------------+---------------+
| #20 or coarser  | (0.850 mm)       | 0             | 2             |
+-----------------+------------------+---------------+---------------+
| #30             | (0.600 mm)       | 0             | 12            |
+-----------------+------------------+---------------+---------------+
| #40             | (0.425 mm)       | 2             | 60            |
+-----------------+------------------+---------------+---------------+
| #50             | (0.300 mm)       | 5             | 60            |
+-----------------+------------------+---------------+---------------+
| #70             | (0.212 mm)       | 5             | 60            |
+-----------------+------------------+---------------+---------------+
| #100            | (0.150 mm)       | 5             | 30            |
+-----------------+------------------+---------------+---------------+
| #140            | (0.106 mm)       | 0             | 10            |
+-----------------+------------------+---------------+---------------+
| #200            | (0.075 mm)       | 0             | 2             |
+-----------------+------------------+---------------+---------------+
| Finer than #200 |                  | 0             | 0.3           |
+-----------------+------------------+---------------+---------------+

> \* Table 1 represents the maximum range of aggregate gradations.
>
> In all cases the refined coal tar emulsion supplier is to give written
> approval of the aggregate used in the mix design.

**603-2.3 Water.** Water for mixing shall be potable, free of harmful
soluble salts and at least 50ºF (10ºC).

**603-2.4 Crack Sealant.** Crack sealant shall be certified for
compatibility with the refined coal tar emulsion by the manufacturer of
the refined coal tar emulsion, and approved by the engineer.

**603-2.5 Oil Spot Primer.** Oil spot primer shall be certified for
compatibility with the refined coal tar emulsion by the manufacturer of
the refined coal tar emulsion, and approved by the engineer.

**603-2.6 Pavement Primer.** Pavement primer shall be certified for
compatibility with the refined coal tar emulsion by the manufacturer of
the refined coal tar emulsion, and approved by the engineer.

COMPOSITION AND APPLICATION

**630-3.1 Composition.** The refined coal tar emulsion seal coat is to
consist of a mixture of refined coal tar emulsion, water and aggregate,
and be proportioned as shown in Table 2. The composition must have
written approval of the coal tar emulsion manufacturer.

**630‑3.2 Job Mix Formula.** The contractor shall submit the recommended
formulation of water, emulsion, aggregate and application rate proposed
for use to a testing laboratory together with sufficient materials to
verify the formulation at least **\[ \]** days prior to the start of
operations. The mix design shall be within the range shown in Table 2.
No seal coat shall be produced for payment until a job mix formula has
been approved by the Engineer. The formulation shall pass the fuel
resistance test in Appendix A.

The job mix formula for each mixture shall be in effect until modified
in writing by the Engineer.

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> **Improper formulations of coal‑tar pitch emulsion seal produce
> coatings that crack prematurely or do not adhere properly to the
> pavement surface. A minimum of 5 days is recommended for job mix
> approval.**

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**TABLE 2.**

**COMPOSITION OF MIXTURE PER 100 GAL OF REFINED COAL TAR EMULSION**

+-----------+-----------+-----------+-----------+-----------+-----------+
| **Appl    | **Refined | **Water** | **Ag      | **Formula |           |
| ication** | Coal**    |           | gregate** | Rate of   |           |
|           |           |           |           | Ap        |           |
|           | **Tar**   |           |           | plication |           |
|           |           |           |           | of**      |           |
|           | **E       |           |           |           |           |
|           | mulsion** |           |           | **Mix per |           |
|           |           |           |           | Square    |           |
|           |           |           |           | Yard**    |           |
|           |           |           |           |           |           |
|           |           |           |           | **(Square |           |
|           |           |           |           | Meter)**  |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
|           | **        | **        | **LBS**   | **Minimum | **Maximum |
|           | Gallons** | Gallons** |           | Gallons** | Gallons** |
|           |           |           | **(Kil    |           |           |
|           | **(       | **(       | ograms)** | **(       | **(       |
|           | Liters)** | Liters)** |           | Liters)** | Liters)** |
+-----------+-----------+-----------+-----------+-----------+-----------+
| Prime     |           |           |           |           |           |
| Coat      |           |           |           |           |           |
| (where    |           |           |           |           |           |
| required) |           |           |           |           |           |
| as        |           |           |           |           |           |
| specified |           |           |           |           |           |
| by the    |           |           |           |           |           |
| coal tar  |           |           |           |           |           |
| emulsion  |           |           |           |           |           |
| manu      |           |           |           |           |           |
| facturer. |           |           |           |           |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1st Seal  | 100       | 25-30     | 300-500   | 0.12      | 0.17      |
| Coat      |           |           |           |           |           |
|           | \(379\)   | (95-114)  | (136-228) | (0.54)    | (0.77)    |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 2nd Seal  | 100       | 25-30     | 300-500   | 0.12      | 0.17      |
| Coat      |           |           |           |           |           |
|           | \(379\)   | (95-114)  | (136-228) | (0.54)    | (0.77)    |
+-----------+-----------+-----------+-----------+-----------+-----------+

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> **The numbers shown in Table 2 represent the maximum recommended range
> of values. In all cases, the refined coal tar emulsion supplier is to
> give written approval of specific composition numbers to be used in
> the mix design.**
>
> **Some specifications covering this type of coating have allowed sand
> loadings in excess of 10 pounds per gallon of refined coal tar
> emulsion. These coatings have not performed well in the field due to
> poor fuel resistance and loss of adhesion and are not recommended.**
>
> **Additional coats may be specified for greater wearability.**

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**630-3.3 Application Rate.** Application rates are not to exceed 0.17
gal/yd.^2^/coat (0.77 liters/m^2^/coat), and at no time are total coats
to exceed 0.51 gal/yd^2^ (2.3 liters/m^2^).

**630‑3.4 Test Section.** Prior to full production, the Contractor shall
prepare a quantity of mixture in the proportions shown in the approved
mix design. The amount of mixture shall be sufficient to place a test
section a minimum of 250 square yards at the rate specified in the job
mix formula. The area to be tested will be designated by the Engineer
and will be located on a representative section of the pavement to be
seal coated. The actual application rate will be determined by the
Engineer during placement of the test section and will depend on the
condition of the pavement surface.

The test section shall be used to verify the adequacy of the mix design
and to determine the application rate. The same equipment and method of
operations shall be used on the test section as will be used on the
remainder of the work.

If the test section should prove to be unsatisfactory, the necessary
adjustments to the job mix formula, mix composition, application rate,
placement operations, and equipment shall be made. Additional test
sections shall be placed and evaluated, if required. Full production
shall not begin without the Engineer\'s approval. Acceptable test
sections shall be paid for in accordance with paragraph 630‑7.1.

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> **The test section affords the Contractor and the Engineer an
> opportunity to determine the quality of the mixture in place as well
> as the performance of the equipment.**
>
> **The application rate depends on the surface texture.**
>
> **If operational conditions preclude placement of a test section on
> the pavement to be seal coated, it may be applied on a pavement with
> similar surface texture.**
>
> **The only test required on the composite mix placed in the field is
> the viscosity test. The fuel resistance test may be specified,
> however, this test takes 96 hours to run.**

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CONSTRUCTION METHODS

**630‑4.1 Weather Limitations.** The seal coat shall not be applied when
the surface is wet or when the humidity or impending weather conditions
will not allow proper curing. The seal coat shall be applied only when
the atmospheric or pavement temperature is 50°F (10 degrees C) and
rising and is expected to remain above 50°F (10°C) for 24 hours, unless
otherwise directed by the Engineer.

**630‑4.2 Equipment and Tools.** The Contractor shall furnish all
equipment, tools, and machinery necessary for the performance of the
work.

**a. Distributors.** Distributors or spray units used for the spray
application of the seal coat shall be self‑propelled and capable of
uniformly applying 0.12 to 0.55 gallons per square yard (0.54 to 2.5
liters per square meter) of material over the required width of
application. Distributors shall be equipped with removable manhole
covers, tachometers, pressure gauges, and volume‑measuring devices.

The mix tank shall have a mechanically powered, full‑sweep, mixer with
sufficient power to move and homogeneously mix the entire contents of
the tank.

The distributor shall be equipped with a positive placement pump so that
a constant pressure can be maintained on the mixture to the spray
nozzles.

**b. Mixing Equipment.** The mixing machine shall have a continuous flow
mixing unit capable of accurately delivering a predetermined proportion
of aggregate, water, and emulsion, and of discharging the thoroughly
mixed product on a continuous basis. The mixing unit shall be capable of
thoroughly blending all ingredients together and discharging the
material to the spreader box without segregation.

**c. Spreading Equipment.** Spreading equipment shall be a
mechanical‑type squeegee distributor attached to the mixing machine,
equipped with flexible material in contact with the surface to prevent
loss of slurry from the spreader box. It shall be maintained to prevent
loss of slurry on varying grades and adjusted to assure uniform spread.
There shall be a lateral control device and a flexible strike‑off
capable of being adjusted to lay the slurry at the specified rate of
application. The spreader box shall have an adjustable width. The box
shall be kept clean; coal‑tar emulsion and aggregate build‑up on the box
shall not be permitted.

**d. Hand Squeegee or Brush Application.** The use of hand spreading
application shall be restricted to places not accessible to the
mechanized equipment or to accommodate neat trim work at curbs, etc.
Material that is applied by hand shall meet the same standards as that
applied by machine.

e**. Calibration.** The Contractor shall furnish all equipment,
materials and labor necessary to calibrate the equipment. It shall be
calibrated to assure that it will produce and apply a mix that conforms
to the job mix formula. Commercial equipment should be provided with a
method of calibration by the manufacturer. All calibrations shall be
made with the approved job materials prior to applying the seal coat to
the pavement. A copy of the calibration test results shall be furnished
to the Engineer.

**630-4.3 Preparation of Existing Asphalt Pavement Surfaces.** Existing
asphalt pavements indicated to be seal coated shall be prepared as
follows:

-   Patch bituminous pavement surfaces that have been softened by
    petroleum derivatives or have failed due to any other cause. Remove
    damaged pavement to the full depth of the damage and replace with
    new bituminous concrete similar to that of the existing pavement. If
    a solvent containing cold-applied material is used, complete
    patching a minimum of 90 days prior to the planned application of
    the sealer to permit solvent to escape before sealing.

-   Remove all vegetation and debris from cracks to a minimum depth of
    1″. If extensive vegetation exists treat the specific area with a
    concentrated solution of a water-based herbicide approved by the
    engineer. Fill all cracks, ignoring hairline cracks (\< 1/4″ wide)
    with a crack sealant. Wider cracks (over 1½″ wide (38.4 mm)), along
    with soft or sunken spots, indicate that the pavement or the
    pavement base should be repaired or replaced as stated above.

-   Clean pavement surface immediately prior to placing the prime coat
    or seal coat by sweeping, flushing well with water leaving no
    standing water, or a combination of both, so that it is free of
    dust, dirt, grease, vegetation, oil or any type of objectionable
    surface film.

-   Remove oil or grease that has not penetrated the asphalt pavement by
    scraping or by scrubbing with a detergent, then wash thoroughly with
    clean water. After cleaning, treat these areas with the oil spot
    primer.

-   To insure adhesion to sound but oxidized pavements, mix and apply a
    prime coat of a type and at a rate recommended by the coal tar
    emulsion manufacturer, after all loose aggregate is removed.

**630-4.4 Preparation of New Asphalt Pavement Surfaces.** New asphalt
pavements indicated to be seal coated shall be prepared as follows:

-   Cure new asphalt pavement surfaces so that there is no concentration
    of oils on the surface.

-   A period of at least 60 days at +70ºF daytime temperatures must
    elapse between the placement of a hot mixed asphalt concrete surface
    course and the application of the seal coat.

-   Perform a water-break-free test to confirm that the surface oils
    have degraded and dissipated. (Cast one gallon of clean water out
    over the surface. The water should sheet out and wet the surface
    uniformly without crawling or showing oil rings.) If asphalt does
    not pass this test, additional time must be allowed for extra curing
    and retesting prior to sealing.

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-   Clean pavement surface immediately prior to placing the prime coat
    or seal coat by sweeping, flushing well with water leaving no
    standing water, or a combination of both, so that it is free of
    dust, dirt, grease, vegetation, oil or any type of objectionable
    surface film.

-   Where oil spot priming is needed, remove oil or grease that has not
    penetrated the asphalt pavement by scraping or by scrubbing with a
    detergent, then wash thoroughly with clean water. After cleaning,
    treat these areas with the oil spot primer.

**630-4.5 Mixing.** Blend the coal tar emulsion mixture in the equipment
described in paragraph 630-4.2 using the ingredients described in Table
2. The mixing must produce a smooth homogeneous mixture of uniform
consistency. (Consult coal tar emulsion supplier for its recommended
order of addition of the ingredients.) During the entire mixing and
application process, no breaking, segregating or hardening of the
emulsion, nor balling or lumping of the sand is to be permitted.
Continue to agitate the seal coat mixture in the mixing tank at all
times prior to and during application so that a consistent mix is
available for application.

Small additional increments of water may be needed to provide a workable
consistency, but in no case is the water content to exceed the specified
amount.

**630-4.6 Application of Slurry Seal Coat.** The aggregate filled slurry
seal coat shall be applied at a uniform rate determined in paragraph
630-3.4.

In order to provide maximum adhesion, the pavement shall be dampened
with a fog spray of water if recommended by the supplier. No standing
water shall remain on the surface.

If a prime coat is required, mix and apply the prime coat as specified
in paragraph 630-4.3 for existing pavements or paragraph 630-4.4 for new
pavements.

Apply the first coat uniformly to obtain the rate determined in
paragraph 630-3.4.

Each coat shall be allowed to dry and cure initially before applying any
subsequent coats. The initial drying shall allow evaporation of water of
the applied mixture, resulting in the coating being able to sustain
light foot traffic. The initial curing shall enable the mixture to
withstand vehicle traffic without damage to the seal coat.

Apply the second coat in the same manner as outlined for the first coat.

Additional coats shall be applied over the entire surface as directed by
the engineer.

The finished surface shall present a uniform texture.

The final coat shall be allowed to dry a minimum of eight hours in dry
daylight conditions before opening to traffic, and initially cure enough
to support vehicular traffic without damage to the seal coat.

Where marginal weather conditions exist during the eight hour drying
time, additional drying time shall be required. The length of time shall
be as specified by the supplier. The surface shall be checked after the
additional drying time for trafficability before opening the section to
vehicle traffic.

Where striping is required, the striping paint utilized shall meet the
requirements of P-620, shall be compatible with the seal coat and as
recommended by the coal tar emulsion manufacturer.

QUALITY CONTROL

**630‑5.1 CONTRACTOR\'S CERTIFICATION.** The Contractor shall furnish
the manufacturer\'s certification that each consignment of emulsion
shipped to the project meets the requirements of Federal specification
R‑P‑355, except that the water content shall not exceed 50 percent. The
certification shall also indicate the solids and ash content of the
emulsion and the date the tests were conducted. The certification shall
be delivered to the Engineer prior to the beginning of work. The
manufacturer\'s certification for the emulsion shall not be interpreted
as a basis for final acceptance. Any certification received shall be
subject to verification by testing samples received for project use.

The Contractor shall also furnish a certification demonstrating a
minimum of three years' experience in the application of coal‑tar
emulsion seal coats.

**630‑5.2 INSPECTION.** The Owner shall have an independent technical
consultant on the job site at the beginning of operations for
application of coal‑tar emulsion seal coats. The consultant shall have
knowledge of the materials, procedures, and equipment described in this
specification and shall assist the Contractor regarding proper mixing of
the component materials and application of the seal coat. The consultant
shall have a minimum of 3 years' experience in the use of coal-tar seal
coats. Documentation of this experience shall be furnished to the
Engineer prior to the start of operations. The cost of the technical
consultant shall be paid for by the Owner.

**630‑5.3 SAMPLING.** A minimum of one sample per day shall be tested
for the properties of Table 2. A random sample of approximately
one-quart of the composite mix will be obtained daily by the contractor
and stored in a glass container. The containers shall be sealed against
contamination and retained in storage by the Owner for a period of six
months. Samples shall be stored at room temperature and not be subjected
to freezing temperatures.

A sample of undiluted coal-tar emulsion shall be obtained from each
consignment shipped to the job.

**630‑5.4 ENGINEER\'S RECORDS.** The Engineer will keep an accurate
record of each batch of materials used in the formulation of the seal
coat.

METHOD OF MEASUREMENT

**630-6.1** The refined coal tar emulsion shall be measured by the
**\[gallon (liter)\] \[ton (kg)\]**. Only the actual quantity of
undiluted refined coal tar emulsion will be measured for payment.

**630-6.2** Aggregate shall be measured by the ton (kg) of dry
aggregate.

BASIS OF PAYMENT

**630-7.1** Payment shall be made at the contract unit price per
**\[gallon (liter)\] (ton (kg)\]** for the refined coal tar emulsion and
at the contract price per ton (kg) for aggregate.

These prices shall be full compensation for furnishing all materials,
preparing, mixing, and applying these materials, and for all labor,
equipment, tools, and incidentals necessary to complete the item.

Payment will be made under:

> Item P-630-7.1 Refined Coal Tar Emulsion for Slurry Coat---per
> \[gallon (liter)\] \[ton (kg)\]
>
> Item P-630-7.2 Aggregate---per ton (kg) of dry aggregate.

TESTING REQUIREMENTS

> ASTM C 67 Sampling and Testing Brick and Structural Clay Tile
>
> ASTM C 136 Sieve or Screen Analysis of Fine and Coarse Aggregates
>
> ASTM D 160 Practice of Sampling Bituminous Materials
>
> ASTM D 2939 Standard Test Methods for Emulsified Bitumens used as
> Protective Coatings.

MATERIAL REQUIREMENTS

> ASTM D 490 Standard Specification for Road Tar
>
> ASTM D 692 Standard Specification for Coarse Aggregate for Bituminous
> Paving Mixtures
>
> ASTM C 3699 Kerosene
>
> ASTM D 4866 Standard Performance Specification for Coal Tar Pitch
> Emulsion Pavement Sealer Mix Formations Containing Mineral Aggregates
> and Optional Polymeric Admixtures
>
> ASTM D 5727 Emulsified Refined Coal Tar (Mineral Colloid Type)
>
> FED SPEC R-P-355 Pitch, Coal-tar Emulsion (Coating for Bituminous
> Pavements) ASTM D 5727 Emulsified Refined Coal Tar (Mineral Colloid
> Type)

Appendix A

**FUEL RESISTANCE TEST**

ITEM P-630

**FUEL RESISTANCE TEST ITEM P‑630**

**TEST METHODS CRITERION**

**1. Scope**

This method determines the resistance of the coal tar emulsion seal coat
to kerosene.

**2. Apparatus**

2.1 2 6″ X 6″ square 16 gauge sheet metal masks with a 4″ 4″ square
center removed.

> 2.2 6″ X 6″ unglazed white ceramic tile with an absorption rate of
> 10‑18 percent (determined in accordance with ASTM C 67.

2.3 Brass ring, 2″ diameter and 2″ high.

2.4 Kerosene meeting requirements of ASTM D 3699.

2.5 Silicone rubber sealant.

**3. Procedure**

3.1 Immerse the ceramic tile in distilled water for a minimum of ten
minutes.

3.2 Remove excess water from the tile to produce a damp surface before
applying the seal coat.

3.3 Using the mask described in 2.1 apply one layer of the coal tar
emulsion mixture to the tile. Spread even with the top of the mask using
a spatula or other straight edge.

3.4 Allow the sample to cure for 96 hours at 77 [+]{.underline} 2
degrees F. and 50 [+]{.underline} 10 percent relative humidity.

3.5 Position a second mask on top of the first mask.

3.6 Apply a second coat of coal tar emulsion mixture. Spread even with
the top of the second mask.

3.7 Cure as in step 3.4.

3.8 After curing, affix the brass ring to the seal coat on the tile with
silicone rubber sealant.

3.9 Fill the brass ring with kerosene.

3.10 After 24 hours, remove the kerosene from the brass ring, blot dry
and immediately examine the film for softness and loss of adhesion.
Immediately after the film is examined, break the tile in half, exposing
that part of the tile whose film was subjected to the kerosene.

3.11 Evaluate for penetration of kerosene through the sealer and loss of
adhesion.

**4. Report**

4.1 Report the results as pass or fail. Visible evidence of leakage or
discoloration shall constitute failure of the test.

**Criterion:** A "pass" rating in the fuel resistance test is required.

**END OF ITEM P-630**