UFC 3-250-03
15 May 2001
monthly maximum temperature and the difference above 23.9EC (75EF) for Site A and Site B are given
below.
The temperature index at these sites is the sum of the increments of average monthly maximums above
23.9EC (75EF); therefore, the pavement temperature index for each site is as follows:
Site A = 54.2, cumulative EC (98.0, cumulative EF)
Site B = 1.1, cumulative EC (2.0, cumulative EF)
Based on the criteria shown in table 2-3, Site A is a hot region, and Site B is a cold region.
Site A
Site B
Average Maximum Difference Above
Average Maximum Difference Above
Month
Temperature EC
23.9EC
Temperature EC
23.9EC
January
15.8
--
-1.2
--
February
20.3
--
-2.3
--
March
23.2
--
6.1
--
April
26.6
2.7
14.6
--
May
31.4
7.5
19.6
--
June
34.7
10.8
21.3
--
July
36.4
12.5
25.0
1.1
August
33.3
9.4
23.4
--
September
32.3
8.4
19.4
--
October
26.8
2.9
14.2
--
November
23.3
--
6.3
--
December
15.7
--
2.7
--
Cumulative total
54.2
1.1
(c) Cold region requirements.
[1] Determining the design air freezing index. When it is determined that a project
will exist in a cold region, as defined in table 2-3, additional climate data are required. For the project
area under consideration, a design air freezing index (DFI) is also required to further satisfy cold region
requirements. (Reference TI 825-01/AFM 32-1124(I)/NAVFAC DM 21.10 for determination of DFI.)
DFI's are used to differentiate between climates in cold temperature regions. A DFI of 1,667 degree-
Celsius-days or 3,000 degree-Fahrenheit-days (degree-days) is used as the delineation between
moderately cold and severely cold (extremely cold) climates. Moderately cold climates have DFI's up to
1,667 degree-days, and severely cold climates have DFI's greater than 1,667 degree-days.
[2] Penetration-viscosity number. Cold regions are areas where the penetration-
viscosity number (PVN) method is used to aid in selecting an asphalt cement. Site B in the previous
example would require the use of the PVN method to select an asphalt cement. Asphalt cement factors
considered in the original correlation were penetrations at 25EC (77EF), viscosity at 135EC (275EF), and
penetration index. The PVN method is used to quantify temperature susceptibility of an asphalt cement
and estimate its ability to resist low-temperature cracking. Required input data are penetration at 25EC
(77EF) and kinematic viscosity at 135EC (275EF). Figure 2-3 allows estimation of PVN for asphalt
cements in cold regions. Table 2-4 provides minimum PVN selection criteria for asphalts in cold regions.
Table 2-4 and figure 2-3 should always be used when selecting asphalts for use in cold regions unless
performance graded asphalt cements are used. Table 2-4 also shows requirements for airfields and
2-8
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