ETL 1110-l-139
22 Jun 90
Analysis and Asphalt Selection
The climatological data allow classification of the site by temperature
region and allow an estimate of pavement temperature. According to Table 4 of
Enclosure 1, the pavement temperature index classifies the site as a cold
region where the PVN method should be used to select the grade of asphalt
cement, The DFI allows the use of Figure 2 (Enclosure 1) to estimate a mini-
mum pavement temperature at a 2-in. (5 cm) depth. From Figure 2, a minimum
anticipated pavement temperature is about -22" F (-30" C).
Table 5 of Enclosure 1 shows that this cold region can be further classi-
fied as a moderately cold region since its DFI is less than 3,000
Fahrenheit-days. Table 5 also indicates that the required PVN of the asphalt
selected must be greater than -0.5 for a design index of 10. This will mini-
mize low temperature pavement cracking.
Now, PVN values must be determined for the available asphalt cements.
This can be done by either plotting penetration and viscosity at 275" F
in Figure 1 of Enclosure 1 or by using PVN equations. If the details
(135"
of Figure 1 are not sufficient to accurately determine PVN values, equations
should be used.
The general PVN equation1 is as follows:
X)(-1.5)
PVN
where
L
logarithm of viscosity in centistokes at 275" F
C) for a PVN
of 0.0 at the given penetration
logarithm of viscosity in centistokes at 275" F
C) of a given
X
asphalt
logarithm of viscosity in centistokes at
F
C) for a PVN
of -1.5 at the given penetration
Values of X can be determined directly from asphalt cement viscosity data as
provided in this example, but values of L and M are a function of the
penetration values of each asphalt. Equations for the values of L and M
are:
0.79674
(PEN)
L
4.25800
LOG
1
N. W., "Using Paving Asphalt Rheology to Impair or Improve Asphalt
Pavement Design and Performance", Asphalt Rheology: Relationship to Mixture,
ASTM STP 941, 0. E. Briscoe, Ed., American Society for Testing and Materials,
Philadelphia, 1987.
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