458
3.Check whether measured deflections are within the following limits:
0.56 < Dj or D < 2.92 mil
0.27 < D3 < 2.07 mil
0.15 < D, < 1.50 mil
0.05 < D5 <1.00 mil
and also the following criteria are met:
0.09 < Dj + D2 2D3 < 0.85 mil
0.12 < D3 D4 < 0.57 mil.
These criteria conform approximately to the following range of layer
moduli and thicknesses:
65.0
< Ei
<
400
ksi
1.5
<
8.5 in.
26.0
E2
<
130
ksi
6.0
<
*2 <
24.0 in.
18.0
< E3
<
90.0
ksi
12.0
<
s<
36.0 in.
5.0
< E*t
<
105
ksi
%
=
semi
-infinite
Note that for the prediction equations, E.¡ is in ksi, t.¡ in inches,
and D.j in mils. Also extremely high or low D5 values, outside the
stipulated range, may be used for estimates of E4 from 1.0 to 200
ksi.
4. If the above conditions are satisfied, proceed to step 5. If not,
check deflection measurements and then go to step 3. If the checked
deflections do not meet conditions in step 3, proceed to step 5
considering that the predictions may be approximate or significantly
in error.
5. Obtain pavement layer thicknesses from construction drawings or by
coring.