Laboratory evaluation of aging for asphalt-aggregate mixtures

Table 2.2. Ranking of SHRP asphalts in terms of their resistance to low
temperature cracking
Carbon Number at
Asphalt the Max of SFC Peak Ranking
AAA-1 32 Least likely to low temp. crack
AAD-1 32 "
AAK-1 32
AAG 42 Moderate probability to low temp.
crack
AAB 43 "
AAF 48 Most likely to low temp. crack
2.1.3 Fatigue Cracking
Fatigue cracking is typically associated with aged pavement, although it can
occur in relatively new pavements. In relatively new pavement fatigue cracking, to
any extent that it occurs, should be somewhat the opposite of rutting. That is,
asphalts that have the smallest amounts of SEC II should have the greatest
propensity to crack under stress of traffic. The matrix developed by a large SEC I
would be expected to be too rigid. This is highly speculative and the best ranking
available is the reverse order of the early rutting list. (Table 2.3)
Problems of fatigue cracking in aged asphalts are more likely than fatigue
cracking in unaged binders. Based on Figure 2.2 the rankings were developed for
3 temperature regimes for the 8 core asphalts that are shown in Table 2.3. Each
ranking also has a qualitative descriptor.
9