UFC 3-260-03
15 Apr 01
Table 7-1
Frost Susceptibility Soil Classification
Percentage
Percentage
Finer than
Finer than
Typical Soil Types
Frost
0.02 mm
#200 Sieve
Under Unified Soil
by Weight1
Group
Kind of Soil
by Weight
Classification System
NFS2
(a)
Gravel
0 - 1.5
0-3
GW, GP
Crushed Stone
Crushed Rock
(b)
Sands
0-3
0-7
SW, SP
PFS3
(a)
Gravel
1.5 - 3
3-7
GW, GP
Crushed Stone
Crushed Rock
(b)
Sands
3 - 10
SW, SP
S1
Gravelly Soils
3-6
7 - 15
GW, GP, GW-GM. GP-GM
S2
Sandy Soils
3-6
7 - 15
SW, SP. SW-SM, SP-SM
F1
Gravelly Soils
6-10
GM, GW-GM, GP-GM
F2
(a) Gravelly Soils
10-20
GM, GW-GM, GP-GM
(b) Sands
6-15
ASM, SW-SM, SP-SM
F3
(a) Gravelly Soils
Over 20
GM, GC
(b) Sands, except very fine
Over 15
silty sands
SM, SC
(c) Clays, PI > 12
--
CL, CH
F4
(a) Silts
--
ML, MH
(b) Very fine silty sands
Over 15
SM
(c) Clays, PI < 12
--
CL, CL-ML
(d) Varved clays and other
fine grained, banded
CL, ML, and SM,
sediments
--
CL, CH, and ML,
CL, CH, ML, and SM
1
These are rough estimates. If there are surface indications of frost action, then frost susceptibility tests
should be conducted.
2
Nonfrost susceptible.
3
Possibly frost susceptible, requires lab test to determine frost design soil classification.
12. EVALUATE PAVEMENT FOR LIMITED SUBGRADE FROST PENETRATION. Determine if the
combined base thickness under the evaluated pavement structure (x) is sufficient for limited frost pene-
tration into the subgrade.
a. For limited frost penetration into the subgrade, estimate the average moisture content of the
subgrade during nonfrost conditions. Compute water content ratio r . Use the same base-course water
content as that assumed in frost penetration calculations
ωsubgrade
r'
(eq 7-3)
ωbase
b. If the computed r exceeds 2.0, use 2.0 for type A or primary B traffic areas. If r exceeds 3.0,
use 3.0 for all pavements except those in type A, B, or primary traffic areas. Either use figure 7-5, with c
7-6
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