ETL 1110-1-189
14 Feb 03
reinforcement recommended as shown in Table 5. A minimum aggregate thickness of 6 inches
is recommended for aggregate-surfaced pavements. Aggregate-surfaced design examples are
provided in Appendix A. Note that standard frost design procedures should be used for regions
in which significant frost penetration occurs.
Table 5
Reinforced Bearing Capacity Factors, Nc1, for Aggregate-Surfaced Pavements
Step 1: Determine Design Subgrade Soil Strength and Geosynthetic Applicability
CBR < 0.5
0.5 < CBR < 2.0
2.0 < CBR < 4.0
CBR > 4.0
A geotextile is required for
Use a geotextile
Both a geogrid and a
Perform a
fine-grained subgrades. A
and a geogrid at
cost analysis.
geotextile are
geogrid may also be cost-
Consider
subgrade-base
recommended. Use this
effective. Perform a life
interface. No
design procedure for
"hidden"
cycle cost analysis.
benefits.
aggregate
aggregate thickness
Inadequate
thickness reduction
reduction.
recommended.
data is
Geotext Geogri
Geotextil
Bot
Both2
Use TM 5-822-12
available to
ile
d
e
Geogrid
h
determine
for thickness
5.03
5.03
5.8
5.8
5.8
5.8
design
bearing
1
The unreinforced bearing capacity factor, Nc, is 2.8.
2
Both a geotextile and a geogrid are recommended. The geotextile serves primarily as a
separation fabric.
3
Use a factor of 3.6 for conservative geotextile-reinforced pavement designs.
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