TM 5-822-12
value. The majority of the maintenance will consist of
Table 7. Gradation for aggregate surface courses.
periodic grading to remove the ruts and potholes that
will inevitably be created by the environment and traffic
Sieve Designation
No. 1
No. 2
No. 3
No. 4
25.0mm
1 in.
100
100
100
100
and to replace fines. Occasionally during the lifetime of
9.5 mm
3/8 in.
5-85
60-100
-
-
the road or airfield, the surface layer may have to be
4.7 mm
No. 4
35-65
50-85
55-100
70-100
scarified, additional aggregate added to increase the
2.00 mm
No. 10
25-50
40-70
40-100
55-100
thickness back to that originally required, and the
0.425 mm
No. 40
15-30
24-45
20-50
30-70
wearing surface recompacted to the specified density.
0.075 mm
No. 200
8-15
8-15
8-15
8-15
Note: The percent by weight finer than 0.02 mm
12. Dust control
shall not exceed 3 percent.
a. Objective. The primary objective of a dust
palliative is to prevent soil particles from becoming
provisions should be evaluated to determine if rerouting
airborne as a result of wind or traffic. Where dust
is needed to prevent water from other areas flowing
palliatives are considered for traffic areas, they must
across the road or airfield.
withstand the abrasion of the wheels or tracks. An
important factor limiting the applicability of the dust
palliative in traffic areas is the extent of surface rutting
road or airfield design, construction, and maintenance.
or abrasion that will occur under traffic.
Some
Therefore, drainage should be considered prior to
palliatives will tolerate deformations better than others,
construction, and when necessary, serve as a basis for
but normally ruts in excess of 1/2 inch will result in the
site selection.
virtual destruction of any thin layer or shallow-depth
penetration dust palliative treatment. The abrasive
action of tank tracks may be too severe for use of some
11. Maintenance requirements
The two primary causes of deterioration of aggregate
dust palliatives in a traffic area.
surfaced roads requiring frequent maintenance are the
environment and traffic. Rain or water flow will wash
b. A wide selection of materials for dust control is
fines from the aggregate surface and reduce cohesion,
available to the engineer. No one choice, however, can
while traffic action causes displacement of surface
be singled out as being the most universally acceptable
materials. Maintenance should be performed at least
for all problem situations that may be encountered.
every 6 months and more frequently if required. The
However, several materials have been recommended
frequency of maintenance will be high for the first few
for use and are discussed in TM 5-830-3.
years of use but will decrease over time to a constant
Table 8. Compaction requirements for roads, cohesive soils.
11
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