TM 5-830-3/AFM 88-17, Chap. 3
Types of bituminous materials, aggregate gradations,
blow over the area to be protected.) The best method of
application rates, and methods of placing surface
placement is for the fiberglass scrim material to be
treatments are described in TM 5-822-8/AFM 88-6,
placed immediately after the prewet water followed by
Chapter 9.
Single or double bituminous surface
the DCA 1295 (fig 3-1).
(7) Polypropylene-asphalt membrane. The
treatments should not be used where turf is to be
established.
polypropylene-asphalt membrane is recommended for
(5) Polyvinyl acetates (DCA 1295). DCA
use in all traffic areas. It has considerable durability and
1295 has a slight odor and an appearance similar to
will withstand rutting up to approximately 2 inches in
latex paint. The material is diluted 3 parts DCA 1295 to
depth. This system is a combination of a polypropylene
1 part water and cures in 2 to 4 hours under ideal
fabric sprayed with an asphalt emulsion. Normally a
conditions of moderate to high temperature and low
cationic emulsion is used; however, both cationic and
relative humidity. A clear, flexible, film forms on the
anionic emulsions have been used successfully. Several
treated surface. DCA 1295 can be sprayed with a
types of polypropylene fabric are commercially available.
(a) Application. Generally this system is
conventional asphalt distributor provided modifications
are made to the pump to permit external lubrication. The
placed in a three-step procedure. The first step consists
DCA 1295 can be used alone or over fiberglass
of placing a layer of asphalt (0.33 to 0.50 gal per sq. yd.)
reinforcement. The addition of fiberglass does not affect
on the ground and covering this with a layer of
the basic application procedures or the curing
polypropylene fabric. In most cases this is accomplished
characteristics of the DCA 1295. This material is
in a single operation. Normally, a rolling frame is
suitable for use on nontraffic, occasional traffic, and
fabricated, the roll of polypropylene is placed on the axle
traffic areas. This material has also been found to be
shaft of the frame and the frame is attached to the rear
effective when sprayed over grass seed to protect the
of a distributor. Figure 3-2 illustrates this assembly. The
soil until growth occurs. Uniform soil coverage is
second step is the placement of 0.33 gal per sq. yd. of
enhanced by sprinkling (prewetting) the surface with
asphalt on top of the polypropylene and the third step is
water.
the application of a sand blotter course. This system
(6) Polyvinyl acetate (DCA 1295) with
does not require any rolling or further treatment and can
reinforcement.
A fiberglass scrim material is
be trafficked immediately.
(b) Construction for traffic areas. Care
recommended for use with the DCA 1295 when a
should be taken during construction operations to assure
reinforcement is desired. Fiberglass scrim increases the
adequate longitudinal and transverse laps where two
expected life of the dust-control film by reducing the
pieces of polypropylene fabric are joined. Longitudinal
expansion and con- traction effects of weather extremes.
joints should be lapped a minimum of 12 inches. On a
The scrim material should be composed of fiberglass
super-elevated section the lap should be laid so the top
threads having a plain weave pattern of 10 by 10 (ten
lap end is facing downhill to help prevent water intrusion
threads per inch in the warp direction and ten threads per
under the membrane.
On a transverse joint, the
inch in the fill direction), having a greige finish, and
minimum overlap should be at least 24 inches.
should weigh approximately 1.6 ounces per square yard.
Additional emulsion should be on the top side of the
The use of scrim material does not create any health or
bottom lap to provide enough emulsion to adhere to and
safety hazards, and special storage facilities are not
waterproof the top lap.
Figure 3-3 illustrates this
required. Scrim materials can be applied under any
climatic conditions suitable for dispensing the DCA 1295.
(Under special conditions, continuous strands of fiber-
glass may be chopped into 1/2-inch-long segments and
3-8
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