TM 5-822-5/AFM 88-7, Chap. 1
(3) Compute thickness of unbound base C
water content of
(fig 18-4) required for zero frost penetration into
(4) Compute ratio r =
subgrade
the subgrade as follows:
water content of base
(5) Enter figure 18-4 with C as the abscissa
C=a-p
and, at the applicable value of r, find on the left
scale the design base thickness b that will result in
where
the allowable subgrade frost penetration s shown on
a=frost penetration depth
the right scale. If r is greater than 3.0 use 3.0
p=thickness of portland cement concrete or bituminous
concrete
18-9
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