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roads and other pavements; it is an index of traffic estimate and is defined
88-7, Chap. 3.
Temperature at a 2-in. depth of pavement can be estimated from a DFI for
a given project location or site as shown in Figure 2. This "minimum antici-
pated pavement temperature" and minimum PVN criteria of Table 5 can be used
with Figure 1 to select an asphalt cement.
An asphalt with given penetration and viscosity can be checked for satis-
fying PVN criteria of Table 5 by plotting in Figure 1. If its penetration and
viscosity point falls on or above the minimum PVN value and to the right of
the minimum anticipated pavement temperature, it is estimated that low temper-
ature contraction cracking of the asphalt concrete layer will be prevented.
If it plots to the left of the anticipated pavement temperature, the pavement
will likely crack at low temperatures. PVN values should be calculated for
more accurate results.
Examples of Asphalt Cement Selection
Enclosure 2 contains examples of asphalt cement selection by use of this
Engineer Technical Letter.