TM
5-822-14/AFJMAN
32-1019
obtain adequate proportioning and mixing. With
LCF, it also should be noted that the presence of
cement requires that the stabilized mixture be
compacted as soon as possible.
4-4. Construction with Bitumen. Bituminous
stabilization can involve either hot-mix or cold-mix
materials. Bitumen and aggregate or soil can be
blended in place or in a central plant. Construc-
tion procedures presented in this manual are for
cold-mix materials mixed in place or in a central
plant. Construction procedures for hot-mix hot-laid
materials are similar to those used for asphalt
Figure 4-42. Pneumatic roller completes compaction
concrete and applicable standard construction pro-
of LCF base.
cedures should be followed when these materials
are involved.
a. Equipment for Mixed-in-Place Materials. Some
pieces of equipment used for mixed-in-place bitu-
minous stabilization are similar to those used in
standard construction and will not be described
here. These include water distributors, compaction
equipment, and windrow sizers. Only equipment
especially associated with or having special fea-
tures applicable to bituminous stabilization will be
discussed.
(1) Mixing equipment.
(a) Travel plants. Travel plants are self-
propelled pugmill plants that proportion and mix
Figure 4-43. Vibrating roller completes compaction of subgrade.
aggregates and asphalt as they move along the
road. There are two general types of travel plants:
the moisture content of the compacted layer and is
one that moves through a prepared aggregate
an adequate medium for curing. Two types of
windrow on the roadbed, adds and mixes the
curing can be employed: moist and asphaltic
asphalt as it goes and discharges to the rear a
membrance. In the first, the surface is kept damp
mixed windrow ready for aeration and spreading
by sprinkling with light rollers being used to keep
(fig 4-44) and one that receives aggregate into its
the surface knitted together. In membrane curing,
hopper from haul trucks, adds and mixes asphalt,
the stabilized soil is either sealed with one shot of
and spreads the mix to the rear as it moves along
cutback asphalt at a rate of about 0.10 to 0.25
the roadbed (fig 4-45). Certain features and perfor-
mance capabilities are common to all travel
gallons per square yard within 1 day after final
plants, enabling them to operate effectively and to
rolling, or primed with increments of asphalt
produce a mix meeting design and specification
emulsion applied several times during the curing
criteria. To begin, the tracks or wheels on which
period. A common practice is to apply two shots
the machine moves must be so sized, designed, and
the first day and one each day thereafter for 4
positioned that they do not damage or rut the
days at a total rate of 0.10 to 0.25 gallons per
surface on which it operates when the plant is
square yard. The type of membrane used, amount,
fully loaded. The basic purpose of the travel plant
and number of shots vary considerably. Usually, it
is to mix asphalt and aggregate. Some machines
is difficult to apply more than 0.2 gallons of
are equipped with devices that maintain the
asphalt prime because the lime-stabilized layer is
proper proportions automatically. Others, however,
relatively impervious after compaction.
require that a uniform speed be maintained to
4-3. Construction with Lime-Fly Ash (LF) and
ensure uniform proportioning. Regardless of the
Lime-Cement-Fly Ash (LCF). Construction proce-
type, the manufacturer's recommended procedures
dures for LC and LCF are similar to those used for
for calibrating and operating the travel plant
lime stabilization. Although both field in place and
should be followed carefully. Finally, the efficient
central plant mixing may be used with LF and
travel plant should be capable of thoroughly mix-
ing the asphalt and aggregates, uniformly dispers-
LCF, the latter procedure is recommended to
4-20
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