Table 15. Summary of effective resilient modulus for New
Hampshire subgrade soils.
Effective resilient modulus, MPa (psi)
Soil type
Interstate/Primary
Secondary
Silt, some fine sand.
44 (6351)
47 (6757)
Some coarse to fine gravel,
trace coarse to medium sand
(glacial till) NH1
Fine sand, some silt NH2
61 (8917)
61 (8865)
Coarse to fine gravelly,
coarse to medium sand,
trace fine sand NH3
259 (37,535)
280 (40,678)
Coarse to medium sand,
little fine sand NH4
22 (3227)
31 (4490)
Clayey silt (marine deposit) NH5
20 (2931)
21 (3078)
determine the effective resilient modulus as a func-
the tables are calculated using eq 4: and the effec-
tion of moisture. It is also recommended that the
tive resilient modulus (Meff, psi) is calculated us-
remaining shear and hydrostatic compression tests
ing eq 6:
be completed for prediction of pavement rutting
1
during thaw periods.
2.32
uf
Meff =
.
(5)
1.18 108
RECOMMENDATIONS/CONCLUSIONS
Table 16. Recommended effective moduli for
subgrade soils.
This report describes the results of resilient
modulus tests conducted on five subgrade soils
Effective subgrade
commonly found in the state of New Hampshire.
Subgrade type
modulus, MPa (psi)
Based on the results from these tests, the effective
Silt, some fine sand.
45 (6500)
resilient modulus was determined for use in de-
Some coarse to fine
sign and evaluation of pavement structures. The
gravel, trace
effective resilient modulus of the subgrade soil
coarse to medium
under the interstate system was found to be
sand (glacial till) NH1
similar to that of the secondary pavements.
Fine sand, some silt NH2
62 (9000)
The recommended values are presented in
Table 16.
Coarse to fine gravel, coarse
265 (38,500)
It must be noted that these effective resilient
to medium sand, trace fine
moduli were obtained for soils at one moisture
sand NH3
content and density, i.e., at the optimum density
Coarse to medium sand,
26 (3800)
and moisture content. These values should be used
little fine sand NH4
with reservation at other densities and moisture
contents. It is recommended that for general use
Clayey silt (marine deposit) NH5
21 (3000)
within the state, additional tests be conducted to
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