TM 5-830-3/AFM 88-17, Chap. 3
(c)
Concrete
curing
compounds.
Concrete curing compounds can be used to penetrate
3-4. Admix method
sands which contain little or no silts or clays. This
In the admix method, the dust palliative is blended with
material should be limited to areas of no traffic. The high
the soil to produce a uniform mixture. This method takes
cost of this material is partly offset by the low application
more effort, time, and equipment than the penetration
rate required (0.1 to 0.2 gallon per square yard).
and surface blanket methods, however, it also increases
Standard asphalt pressure distributors can be used to
soil strength.
apply the resin, but the conventional spray nozzles
a. Depth of treatment. A minimum treatment of 3
should be replaced with smaller opening spray nozzles to
inches will be satisfactory for all nontraffic areas. To
achieve a uniform distribution at the low application rate.
provide a dustproof surface in traffic areas, a minimum
treatment depth of 4 inches is recommended. Admixing
have been used with varying success as dust palliatives.
can be accomplished in-place or offsite and is adaptable
Dry calcium chloride is deliquescent and is effective
to a large variety of soil types, (The admix method is not
when the relative humidity is about 30 percent or greater.
particularly suitable for areas where a vegetative cover is
A calcium chloride treated soil will retain more moisture
to be established.)
than the untreated soil under comparable drying
b. Types of materials. Two types of admix
conditions. Its use is limited to occasional traffic areas.
materials may be used as dust palliatives:
Sodium chloride achieves some dust control by retaining
-Powders - Portland cement, hydrated lime
moisture and also by some cementing from salt
-Liquids - Bituminous materials including cutback
crystallization.
Both calcium chloride and sodium
asphalt, emulsified asphalt, and road tars.
chloride are soluble in water and are readily leached
c. In-place admixing. In-place admixing is the
from the soil surface; thus frequent maintenance is
blending of soil and dust palliative on the site. The
required. Continued applications of salt solutions can
surface soil is loosened (if necessary) to a depth slightly
ultimately build up a thin, crusted surface that will be
greater than the desired thick- ness of the treated layer.
fairly hard and free of dust. Most salts are corrosive to
The dust palliative is added and blended with the
metal and should not be stored in the vehicle used for
loosened surface soil, and the mixture is compacted.
application. Magnesium chloride will control dust on
Powders may be spread by hand or a mechanical
gravel roads with tracked vehicle traffic. Best results can
spreader, and liquids should be applied with an asphalt
be, expected in areas with occasional rainfall or where
distributor. Mixing equipment that can be used includes
the humidity is above about 30 percent. The dust
rotary tillers, rotary pulverizer-mixers, graders, scarifiers,
palliative selected and the quantity used should not
exceed local environmental protection regulations.
continue until a uniform color of soil and dust palliative
(4) Water. As a commonly used but very
mixture, both horizontally and vertically, is achieved. The
temporary measure for allaying; dust, a soil surface can
most effective compaction equipment that can be used
be sprinkled with water. As long as the ground surface
are sheepsfoot or rubber-tired rollers. The procedure for
remains moist or damp, soil particles will resist becoming
in-place admixing closely resembles the soil stabilization
airborne. Depending on the soil and climate, frequent
procedure for changing soil characteristics and soil
treatment may be required. Water should not be applied
strength
used
in
road
to clay soil surfaces in such quantity that puddles form,
since a muddy or slippery surface may result where the
soil remains-wet.
3-5
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