UFC 3-250-03
15 May 2001
(1) Joints. Whenever possible, joints should be made while the slurry-seal mixture applied in
the first pass is still semifluid and workable. If operations preclude fresh working joints, the previously
laid pass must be allowed to set and cure sufficiently to support the spreader box without scarring,
tearing, or being scraped from the pavement surface.
(2) Hand application. Close attention should be given to spreading of the slurry-seal mixture
by hand squeegee. Overworking will sometimes cause partial breaking of the emulsion before the final
spreading is completed which results in a non-uniform material that will have poor appearance and
durability.
h. Curing. Slurry seals, depending upon the emulsion characteristics in relation to the aggregate
with which it is used, may cure primarily by evaporation of water from the surface, by deposition of
asphalt on the aggregate which frees the water, or by a combination of both. If curing is from the surface
downward, the surface may present a cured appearance but the material below may be uncured.
Thorough curing of the slurry seal must be assured before traffic is permitted.
i. Rolling. Rolling is advantageous in reducing voids in the slurry seal, smoothing out surface
irregularities, and increasing the resistance to water. Rolling should begin as soon as the slurry seal has
cured enough to support the roller without any pickup of the slurry seal mixture. A rubber-tired roller
should be used for rolling the slurry seal mixture.
4.
FUEL-RESISTANT SEALER.
a. General. Fuel-resistant sealer (FRS) material is a combination of coal-tar emulsion, fine
aggregate, water, and occasionally other additives. These materials are mixed in batches and applied
to hot-mix asphalt surfaces by hand or mechanical squeegees. The coal-tar emulsion binder provides a
fuel-resistant surface and the fine aggregate provides suitable skid resistance. The FRS is placed in thin
layers usually around 2 millimeters (1/16 inch) or less. Particle size will effect the minimum thickness
that can be applied by squeegee. A FRS will not significantly enhance the structural strength of the
pavement structure.
b. Areas of application. FRS should be applied to any hot-mix asphalt surface subjected to fuel
drippage or spillage. This includes vehicle maintenance and parking areas.
c. Considerations for use. Some important factors that should be considered before using a FRS.
(1) FRS should only be used where a fuel-resistant surface is required.
(2) FRS's generally do not have as long a service life as surface treatments with asphalt
cement binder, but they may last up to 4 years or more depending on traffic and climate conditions.
(3) Parking areas with low vehicle turnover or low usage (therefore lower instances of fuel
spillage) rates may be better served with a single or double bituminous surface treatment or a slurry
seal.
(4) FRS's will provide a seal to protect the underlying hot-mix asphalt pavement to retard
oxidation and weathering.
(5) The pavement must be closed to traffic during the curing of FRS layers (usually 4 to
8 hours).
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