UFC 3-260-02
30 June 2001
(5)
Determine the compaction requirements from Table 6-5.
(6)
The design section is as follows:
50-mm (2-in.) AC surface
190-mm (7.5-in.) Base1
Top of Subgrade
152-mm (6.0-in.) 95 percent compaction
1
Base is compacted to 100 percent.
Since the existing subgrade has an in-place density of 90 percent, the compaction of the 152-millimeter
(6.0-inch) upper layer of the subgrade may be achieved by moistening and compacting in place.
c.
Example 3.
(1) Design a secondary traffic area pavement for a Navy single-wheel aircraft with a gross
weight of 31,750 kilograms (70 kips) and 2.75-MPa (400-psi) tire pressure for 300,000 passes. The
subgrade consists of a silty sand (SM) with a design CBR of 6 and an in-place density of 86 percent.
Subbase is a sand-shell mixture with a CBR rating of 30. Base is also a sand-shell mixture with a CBR
of 80.
(2) From Figure 10-8 (2.75-MPa (400-psi) tire pressure) for a design subgrade CBR of 6 and
a gross weight of 31,750 kilograms (70 kips) and 300,000 passes, the pavement section required is
635 millimeters (25 inches). The thickness of base and surface required above the 30 CBR subbase is
228 millimeters (9 inches).
(3) From Table 8-4, the minimum thickness requirements are 102 millimeters (4 inches) of
bituminous surface and 203 millimeters (8 inches) of base. Use 330-millimeter (13-inch) subbase.
(4) Determine the compaction requirements from Table 6-6. This table would require the top
102 millimeters (4 inches) of the subgrade to be compacted to 90 percent of maximum density.
However, there is an overriding requirement that the top 152 millimeters (6 inches) of the subgrade be
compacted to 95 percent of maximum density.
(5)
The design section is as follows:
102-mm (4-in.) AC surface
203-mm (8-in.) Base1
330-mm (13-in.) Subbase1
Top of Subgrade
152-mm (6-in.) 95 percent compaction
In situ density of 86 percent is satisfactory
1
Base and subbase compacted to 100 percent
maximum density.
10-4
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