August 10, 2005

Dear Industry Representative:

Federal Aviation Administration (FAA) Draft Engineering Brief 68,
*Four-Component Coal Tar Sealer Rejuvenator,* is being circulated to
interested industry associations and individuals to obtain comments and
recommendations of actions to be taken. Please review this draft
(enclosed) and submit comments as appropriate.

This draft engineering brief provides information and guidance for the
use of a four-component coal tar based material as a fuel resistant
pavement sealer and pavement rejuvenator. The draft contains detailed
material formulation requirements. Please note that Engineering Brief
No. 44 *Coal-Tar Sealer/Rejuvenator* is active and will not be cancelled
as a result of this review.

Comments received by September 30, will be considered for inclusion in
the final action to be taken.

The document may be obtained in Microsoft Word DOC format and Adobe
Acrobat PDF format from the FAA Airports Internet site at
http://www.faa.gov/arp/engineering/briefs/index

Sincerely,

![](media/image2.png){width="1.8854166666666667in" height="0.46875in"}

Rick Marinelli, P.E.

Manager, Airport Engineering Division

Enclosure

DRAFT ENGINEERING BRIEF NO. 68 Four Component Coal-Tar Sealer
Rejuvenator

I. [PURPOSE]{.underline}

This engineering brief provides information and guidance for the use of
a four-component coal tar based material as a fuel resistant pavement
sealer and pavement rejuvenator

II\. [BACKGROUND]{.underline}

Asphalt hardening in pavements is an oxidation process that is a
function of exposure to air on the surface and within the pavement. This
hardening contributes to the loss of fines and aggregate from the
surface, a pavement distress commonly referred to as weathering and
raveling. If circulation of air through the void spaces in a pavement
can be interrupted, the rate of hardening of the asphalt will be reduced
and the life of the pavement may be extended. Materials that meet the
requirements of this brief have demonstrated an ability to delay
weathering and raveling. Part of the material penetrates into the
asphalt and lowers the viscosity while the other portion remains on the
surface and protects the pavement against fuel spill damage and the
intrusion of air and water.

The material in this brief also meets the requirements of Engineering
Brief No. 44 Coal-Tar Sealer/Rejuvenator, issued November 2, 1989. When
Engineering Brief No. 44 was issued, the Federal Aviation Administration
(FAA) was aware of one manufacturer that produced material meeting the
requirements of the specification contained in the brief. Since that
time, comparable coal tar based mixtures have been introduced and used
on airport pavements with generally satisfactory results. However, the
consistent performance of the original material is such that the
specifying of the following detailed material formulation by airport
sponsors and engineers is acceptable.

WARNING: THERE IS A PATENT ON ONE FORMULATION OF THE SEALER REJUVENATOR
THAT WILL MEET THE REQUIREMENTS OF THIS ENGINEERING BRIEF. THIS
ENGINEERING BRIEF AND THE SPECIFICATION ATTACHED TO THIS ENGINEERING
BRIEF DO NOT CONSTITUTE A LICENSE TO PRACTICE THE PATENT.

III\. [APPLICATION]{.underline}

This material can be considered for use on all bituminous pavement
surfaces at an airport. There may be a temporary reduction in the
frictional characteristics of surfaces tested with this material. It is
recommended that project-specific skid resistance testing be included
whenever this material is applied to runway pavements and pavements
where traffic exceeds airplane taxiing speed.

IV\. [DESCRIPTION]{.underline}

Attached is a specification for a four-component coal-tar penetrating
sealer/rejuvenator.

SPECIFICATION

Four Component Coal-Tar Sealer Rejuvenator

1.0 [GENERAL.]{.underline} This item consists of an application of a
four-component coal-tar sealer/rejuvenator, applied to a previously
prepared bituminous surface, in accordance with these specifications, as
shown on the plans or as directed by the Engineer.

The purpose of this sealer/rejuvenator material is to provide a fuel
resistant surface and to rejuvenate oxidized or otherwise aged asphalt
binder without causing damage to the surface and without causing an
unacceptable reduction in the friction characteristics of the pavement.

WARNING: THERE IS A PATENT ON ONE FORMULATION OF THE SEALER REJUVENATOR
AND THIS SPECIFICATION DOES NOT CONSTITUTE A LICENSE TO PRACTICE THE
PATENT.

2.0 [MATERIALS.]{.underline}..The sealer/rejuvenator must consist of
only the following materials, proportioned within the ranges indicated.

  ----------------------------------------------- ----------- ------------
  COMPONENT MATERIALS                             MINIMUM     MAXIMUM

  1\. Refined Coal-tar (Grade RT-12)              30%         50%

  2\. Light aromatic solvent naptha or coal tar   30%         40%
  solvent naptha                                              

  3\. Blend of tar oils as described below        15%         40%
  meeting requirements of Table 1                             

  4\. Elastomer                                   0.01%       13%
  ----------------------------------------------- ----------- ------------

Coal-tar pitch must conform to the requirements of ASTM D 490, Grade
RT‑12 .

The light aromatic solvent naptha must be a solvent having an API
(American Petroleum Institute) Gravity @ 60 degrees F of 11-30, Specific
Gravity 60/60 degrees F of 0.876-0.993, Distillation Range degrees F of
310-450 IBP (initial boiling point) to 350-550 DP (dry point), and a
Flash point degrees F TCC (tag closed cup) of 110-250. The coal-tar
solvent naptha must have a Specific Gravity 60/60 degrees F of
0.94-0.99, distillation range degrees F of 250-385 IBP and Flash point
degrees F TCC of 92-108.

The coal-tar oils must be a composition for rejuvenating asphalt paving
comprising a mixture of di-, tri- and tetracyclic aromatic compounds and
their alkyl homologs containing lower alkyl groups together with
phenolic and hydroxy derivatives, said mixture being derived from the
distillation of coal tar, said mixture having a specific gravity at
25/25 degrees C of at least l.06, a maximum Brookfield viscosity at 25
degrees C of 60 cps., and an IBP of at least 180 degrees C and a
continuous boiling range to at least 300 degrees C and conform to the
requirements of Table 1.

A compatible elastomer must be used.

When all component materials are combined, the combined material must
meet the requirement of Table 2.

  ------------------------------------ ----------------------------------
  TABLE 1. BLEND OF COAL-TAR OILS      
  PROPERTIES AND DISTILLATION          
  REQUIREMENTS                         

  Specific Gravity @ 25/25 degrees C   1.06 minimum (min.)

  Water % by weight                    2.0% maximum (max.)

  Brookfield Viscosity @ 25 degrees C  60 cps. max.

  Soluble in Carbon Disulfide by       95% min.
  weight                               

  Flash Point C.O.C. min.              82 degrees C (180 degrees F) min.

  ASTM D-86 Distillation               

  Initial Boiling Point (IBP)          160 degrees C (320 degrees F)

  180 degrees C (356 degrees F)        0-2%

  190 degrees C (374 degrees F)        0-3%

  200 degrees C (392 degrees F)        0-4%

  210 degrees C (410 degrees F)        0-5%

  220 degrees C (428 degrees F)        0-6%

  230 degrees C (446 degrees F)        0-8%

  240 degrees C (464 degrees F)        0-12%

  250 degrees C (482 degrees F)        0-20%

  260 degrees C (500 degrees F)        5-30%

  270 degrees C (518 degrees F)        10-40%

  280 degrees C (536 degrees F)        15-50%

  290 degrees C (554 degrees F)        20-60%

  300 degrees C (572 degrees F)        25-60%
  ------------------------------------ ----------------------------------

  ----------------------------------- --------------------- ----------------------------
  TABLE 2. COMBINED MATERIAL PROPERTY                       
  REQUIREMENTS.                                             

  [Test Property]{.underline}         [Test                 R[equirements]{.underline}
                                      Method]{.underline}   

  Specific Gravity @ 25/25 degrees C  ASTM D 70             1.04 min.
  (77/77 degrees F)                                         

  Viscosity Engler 50 cc @ 50 degrees ASTM D 1665           4.5 max.
  C (122 degrees F)                                         

  Water % by volume                   ASTM D 95             2.0 max.

  [Distillation % by                  ASTM D 20             
  weight]{.underline}                                       

  170 degrees C (338 degrees F)                             20 max.

  270 degrees C (518 degrees F)                             25-45

  300 degrees C (57 degrees 2 F)                            30-55

  Flash Point                         PMCC (PENSKY-MARTENS  125 degrees F min. (51.7 C)
                                      CLOSED CUP)           

  Softening Point of residue from     ASTM D 36             40-55 degrees C (104-131
  distillation test                                         degrees F)
  ----------------------------------- --------------------- ----------------------------

2.1 [Verification of Materials]{.underline}. The materials listed in
paragraph 2.0 must be verified by the contractor by submitting a sample
of the combined product to the Engineer along with the results of an
independent material testing lab that confirm full compliance with each
individual component property requirement, and a statement from the
manufacturer that the sample tests by the independent lab and the sample
provided to the Engineer are an accurate representation of the materials
to be used on the project.

2.2 The Contractor must supply independent test results of the
sealer/rejuvenator, showing a minimum 40% reduction in viscosity of
treated pavement when compared to an untreated control section after 3
years. The binder extracted (ASTM D 2172) from samples of the upper 3/8
inch of the surface of the treated pavement must show this decrease in
viscosity when compared to the binder extracted from untreated control
section pavement as measured by ASTM D 2171. The RT‑12 and the solvent
naptha components will not be considered as binder for the purposes of
this test.

3.0 [TEST SECTION REQUIREMENTS]{.underline}.

[3.1 Test Section]{.underline}. Prior to full production, the Contractor
must place a series of one square yard test sections at rates between
0.05 and 0.10 gallons per square yard in integrals of 0.01 gallons per
square yard as necessary and as determined by the Engineer to develop
the proper application rate. The area to be tested will be approved by
the Engineer and will be located on the existing pavement. Test sections
must be constructed in accordance with the weather limitations,
equipment, surface preparation, and application temperature requirements
under paragraph CONSTRUCTION METHODS. The Contractor must examine the
test sections 24 hours after placement and recommend to the Engineer the
application rate to be used for the remainder of the project. A test
section will be required for each different type and category of
pavement surface. The Engineer will have the final decision, including
approvals, of the application rate for each pavement type.

[3.2 24-Hour Penetration]{.underline}. The Engineer or Owner must
examine the test sections 24 hours after treatment to determine if all
of the sealer/rejuvenator has penetrated into the surface. Application
rates that have not allowed full penetration into the pavement surface
after 24 hours will not be permitted to be used for full production.

[4.0 CONSTRUCTION METHODS.]{.underline}

4.1 [Weather Limitations]{.underline}. The sealer/rejuvenator must be
applied only when the existing surface is dry and the air temperature is
at least 50 degrees F and rising or higher.

4.2.. [Equipment]{.underline}. The Contractor must furnish all equipment
and hardware necessary for the performance of the work. The product must
be delivered in dedicated tankers and/or containers with filters. The
distributor must be designed and equipped as follows:

\(a\) Heating capability for rapid heating of the sealer/rejuvenator to
the proper application temperature;

\(b\) A positive displacement pump capable of pumping low viscosity
material and providing a pre-selected constant pressure of 20-60 psi to
deliver the specified rates of application;

\(c\) A full circulation spray bar and applicator which maintains proper
nozzles which provide the specified rate of application;

\(d\) A hooded spray bar and applicator which maintains proper nozzle
height;

\(e\) A positive shut-off for the spray bar;

\(f\) A hand spray, with hose, equipped with a positive shut-off at the
spray gun;

\(g\) A thermometer installed in the distributor tank to measure the
temperature of the sealer/rejuvenator at the time of application;

\(h\) A tachometer calibrated to a minimum of tenths of miles per hour;

\(i\) A chart listing the capacity of the tank, in gallons, must be
carried in each unit. This chart must show gallons for each one (1) inch
of depth. A chart showing speed/pressure application rates will also be
included;

\(j\) The distributor must be equipped with filters which must be fully
functional during both the loading and unloading of the product.

[4.3 Surface Preparation]{.underline}. Unless otherwise shown on the
plans, prior to placing the sealer/rejuvenator, the Contractor,
utilizing a power broom or approved equal, must clean the surfaces of
the pavement to be treated and assure that it is free of all debris,
dust, dirt or other loose matter. The pavement surface must be properly
cleaned by the Contractor to the satisfaction of the Engineer or Owner.

[4.4 Application Rate.]{.underline} The sealer/rejuvenator must be
uniformly applied with a bituminous distributor at the approved
application rate determined from the test section. The application rate
must not be varied without the approval of the Engineer or Owner. The
temperature of the material at application must be between 70F and 120F.

[4.5 Protection]{.underline}. Following the application, the surface
must be allowed to cure without being disturbed until the sealer has
thoroughly dried. Suitable precautions must be taken by the Contractor
during this period, including actions necessary to blot up excess
materials. All materials used for blotting purposes must be thoroughly
removed from the site by the Contractor to the satisfaction of the
Engineer.

METHOD OF MEASUREMENT

[5.0 MEASUREMENT.]{.underline} The sealer/rejuvenator will be measured
by the \[gallon(liter) \]

\[square yard{square meter}\].

BASIS OF PAYMENT

6.  [PAYMENT.]{.underline} Payment will be made at the contract unit
    price per \[gallon(liter)\] \[square yard(square meter)\] for the
    coal-tar

TESTING AND MATERIALS REQUIREMENTS

ASTM D 20 Distillation of Road Tars

ASTM D 36 Softening Point of Bitumen (Ring-and-Ball Apparatus)

ASTM D 70 Specific Gravity and Density of Semi-Solid Bituminous
Materials (Pycnometer Method)

ASTM D 86 Distillation of Petroleum Products at Atmospheric Pressure

ASTM D 95 Water in Petroleum Products and Bituminous Materials by
Distillation

ASTM D 490 Road Tar

ASTM D 1665 Engler Specific Viscosity of Tar Products

ASTM D 2171 Viscosity of Asphalts by Vacuum Capillary Viscometer

ASTM D 2172 Quantitative Extraction of Bitumen From Bituminous Paving
Mixtures

End of Specification