The parameter Do was take as constant, as it has been determined that this leads to greater
consistency in fitting master curve parameters. As mentioned in Chapter 2, Do for all
binders, which is defined as the minimum compliance (or the inverse of the elastic
stiffness) is:
Do = 1/3GPa = 3.33 x10 Pa
The parameters D1 and m were then fit by performing linear regression on binder data
shifted to a reference temperature of 20"C. Table 4.23 gives the resulting power model
parameters for the master curves.
Table 4.5 Power Model Parameters for Master Curve
Binder Type Do D1 m
PG 67-22, 6.1% asphalt content 3.33 xl0-10 1.321 x10-6 0.524
PG 67-22, 7.2% asphalt content 3.33 x10-10 1.474 x10-6 0.527
PG 76-22, 6.1% asphalt content 3.33 xl0-10 1.070 x10-6 0.488
PG 76-22, 7.2% asphalt content 3.33 x10-10 1.238 x10-6 0.487
PG 67-22, RTFOT aged 3.33 xl0-10 1.140 x10-6 0.507
PG 76-22, RTFOT aged 3.33 x10-10 1.380 xl0-6 0.493
The creep compliance at any other temperatures was obtained by using shift factors in
the method of reduced time (equation 2.29).
4.4 Binder-to-Mixture Stiffness Relationship
This section describes how the binder-to-mixture stiffness relationships were
developed and used.