(117). The following equations (98,117) were used in the computations:
For n < 9.18 E8 Pa.s:
100
log E = 7.18659 + 0.30677 log(n ) Eqn. 6.1
1 100
For n > 9.19 E8 Pa.s:
100
log E = 9.15354 + 0.04716 log(n ) Eqn. 6.2
1 100
Equations 6.1 or 6.2 were used to compute E1 values for the various
layers (lifts) in the AC layer. The average El value for the total AC
layer was computed using the weighted average technique. Where lift
thicknesses were not known, a common averaging technique was employed.
The computed asphalt concrete moduli for the various test sections are
listed in Table 6.5, and compared with those determined from the theo-
retically developed NDT prediction equations.
Table 6.5 shows significant differences between the NDT and rheo-
logy methods. It will be shown in Section 6.5 that the indirect method
which uses modulus-temperature-viscosity relationships is reliable in
modeling NDT deflection basins. Therefore, the other El values deter-
mined from the NDT prediction equations could'be doubtful.
Higher differences occur with the FWD than the Dynaflect El predic-
tions. The discrepancy in the Dynaflect predictions could be attributed
to the estimated E2 values exceeding the limits of developed equations
and also the use of a single D, measurement in most of the test sites.
When two sensor deflection measurements are used (sensors placed next to