Table 3. Cumulative damage models used.
B. Flexible pavement subgrade strain criteria
A. Flexible pavement horizontal strain criteria
1) The Asphalt Institute (1982):
1) The Asphalt Institute (MS-1, 1982):
[Ea -0.854 ]
-3.291
Na = 18.4 C (4.325 10 -3 ) ε t
Ns = 10[1 / m (log l - log ε v )]
where Ns = allowable traffic based on subgrade
where Na = number of load applications to 45%
strain
m = a constant (0.25)
C = a function of the volume of the voids and
l = a constant (2.8 102)
the volume of asphalt, 10z
εv = vertical strain at the top of the subgrade,
z = 4.84 [(Vb/Vv + Vb) 0.69]
in./in.
Vb = volume of the asphalt, percent (11%)
Vv = volume of the voids, percent (5%)
2) The Corps of Engineers (U.S. Army 1987):
εt = tensile strain at the bottom of the asphalt
layer, in./in.
Ns = 10000 ( A / ε v ) B
Ea = modulus of the asphalt layer, lb/in.2
A = 0.000247 + 0.00245 log Es
where
2) Witczak (1972) (also Asphalt Institute MS-11):
B = 0.0658 Es0.559
d
Na = abq (1 / ε t )c
Es = subgrade resilient modulus, lb/in.2
1.86351 1017
C. Rigid pavement horizontal stress criteria
where a
=
b
=
1.01996
1) The Corps of Engineers (U.S. Army 1990):
c
=
4.995
Nh = 10 [(df - adon)/bdon]
d
=
1.45
pavement temperature, F
q
=
where: Nh = allowable traffic based on horizontal
3) The Corps of Engineers (U.S. Army 1988):
stress
df = Rcon/σh
(2.68-5 log ε t -2.66 log Ea )
Na = 10
Rcon = flexural strength of the concrete, lb/in.2
σh = horizontal stress at the base of the
4) Coetzee and Connor (1990):
concrete, lb/in.2
Na = a ε tb Eac
adon = 0.2967 + 0.002267 SCI
where, when Ea ≥ 1,500,000
lb/in.2:
a, b, c
bdon = 0.3881 + 0.000039 SCI
= 3.364 106, 7.370, 4.470
SCI = surface condition index of the pavement
and when Ea < 1,500,000 lb/in.2: a, b, c
when failed
= 6.565 106, 5.764, 3.640
were also determined in both the frozen and thawed
emphasis on tests to provide input to the Mecha-
(or unfrozen) condition. Modeling materials with
nistic Pavement Design Procedure (Table 4). Tests
the CRREL design procedure requires data from
to generally characterize physical properties in-
the following tests: moisture retention, hydraulic
cluded grain-size distribution, specific gravity,
conductivity, unfrozen moisture content, and re-
Atterberg limits, organic content, hydraulic prop-
silient modulus.
erties (moisture retention and hydraulic conduc-
This report provides a brief summary of the
tivity), and compaction. Tests more specifically
testing results; a complete presentation is found in
related to freeze/thaw processes were frost sus-
Bigl and Berg (1996a, b) and Berg et al. (1996).
ceptibility and unfrozen moisture content at sub-
The Mn/ROAD test sections include four base
freezing temperatures. Resilient modulus values
9
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