Table 4-6. Viscosity-temperature regression coefficients for unaged and
RTFO aged PG 67-22 (AC-30) asphalt
Results Based on Viscosities Obtained Results Based on Viscosities
Regression From Brookfield Rotational Viscometer Obtained From Dynamic Shear
Constants Test Rheometer Test
Unaged Binder RTFO Aged Binder Unaged Binder RTFO Aged
B___inder
A -5.6362 -3.4655 -5.7817 -3.0165
VTS 16.207 10.407 16.63 9.0824
Table 4-7. Typical viscosity-temperature regression coefficients for AC-30 (PG 67-22) at
different hardening states (Witzcak and Fonseca, Transportation Research
Record 1540, 1996, pp. 15-23)
Regression Constants Original Conditions Mix/Laydown
(Unaged Binder) Conditions
A -3.6666 -3.56455
VTS 10.928 10.6768
interest are obtained from: (a) Brookfield Rotational Viscometer testing of RTFO aged
AC-30 asphalt, (b) Dynamic Shear Rheometer testing of RTFO aged PG 67-22 (AC-30)
asphalt, and (c) Mix/Laydown conditions from Witzcak and Fonseca (1996). Table 4-8
summarizes the results of the calculated viscosities for condition and test temperature.
Table 4-8. Calculated viscosity at four complex modulus test temperatures
Test and Aging Condition Calculated Viscosity (in Poise) Complex Modulus
Test and Aging Condition T Tepeat r
Test Temperature
10 C 25 C 30 C 40 C
Brookfield test 3.89E+08 7.17E+06 2.29E+06 2.95E+05
RTFO
DSR test 1.73E+06 1.12E+05 5.08E+04 1.20E+04
RTFO
From Witzcak and Fonseca (1996) 4.57E+08 7.39E+06 2.28E+06 2.79E+05
Mix/lay down condition
Comparison of Predicted and Measured Dynamic Modulus
The predictive regression equation by Witczak et al. (2002) is used to obtain
predicted dynamic modulus values for all test temperature and frequencies for all
mixtures tested, except the Superpave P5 mix for which a total volumetric description