Table 4. Frost-susceptibility in current FAA specifications.
FAA
Material and
Frost-susceptibility
designation
layer type
specifications
Yes < 3% finer than 0.02 mm
P-154
Subbase course
P-155
Lime-treated subgrade
Not available
P-208
Aggregate base course
No
Yes < 33% finer than 0.02 mm
P-209
Crushed aggregate base course
P-210
Caliche base course
No
P-211
Lime rock base course
No
P-212
Shell base course
No
P-213
Sandclay base course
No
P-301
Soilcement base course
Not available
P-304
Cement-treated base course
Not available
P-306
Econocrete subbase course
Not available
sified as non-frost-susceptible. There were only
heave tests, Kaplar (1974) found that for gravels the
two materials in the reviewed FAA specifications
amount finer than 0.02 mm was approximately half
where a limit was established for minimizing frost
the amount passing the no. 200 sieve as long as the
heave (Table 4). We also found that there were no
amount passing the no. 200 sieve was less than
data for the remaining base course materials on
18% (Fig. 2). This relationship was used to esti-
the amount finer than 0.02 mm in the FAA-specifi-
mate the amount finer than 0.02 mm in the FAA
cations. The gradation stopped at the no. 200
specifications.
sieve. Therefore, an alternative was needed to clas-
From laboratory frost heave tests on noncohe-
sive soils (4-in.-diameter 6-in.-long samples [10
sify the frost-susceptibility of the FAA specified
15 cm]), Croney and Jacobs (1967) found a rela-
materials.
In his review, Chamberlain reported that other
tionship between the percentage passing the no.
agencies have used the amount passing no. 200
200 sieve and frost heave (Fig. 3). The criterion
sieve for estimating the frost-susceptibility of the
used by Croney and Jacobs for differentiating lev-
soil. Chamberlain cited a study by Townsend and
els of frost-susceptibility is shown in Table 5. The
Csathy (1963), in which they found that the grain
table shows the amount of frost heave at the end
size criterion (passing no. 200 sieve) was conserva-
of 10 days. The results (Fig. 3) clearly indicate that
tive, i.e., although the criterion was good for find-
as the amount passing the no. 200 sieve increases,
ing frost-susceptible soils, it sometimes classified
so does the amount of frost heave. Croney and
non-frost-susceptible material as frost-susceptible.
Jacobs also found a relationship between the
Reviewing some of the laboratory results of frost
amount of frost heave and the PI of cohesive soils
Figure 2. Relationship between percentage passing the no. 200 sieve and
the percentage finer than 0.02 mm for coarse-grained gravel soils.
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