Laboratory evaluation of aging for asphalt-aggregate mixtures

2.1.5 Moisture Damage (Loss of Adhesion)
Numerous studies and A-003B in particular have demonstrated that moisture
damage causing loss of adhesion is primarily associated with aggregate.
Classification of moisture damage susceptibility from the chemistry of only the
binder is probably a minor effect at best. None the less, a highly speculative
classification is shown in Table 2.4 based on the carbonyl content, with emphasis
on the free acid content, as determined by FTIR. Note that aging affects the 8
core asphalts differently.
2.2 Physical Properties Pennsylvania State University (PSU)
The Penn State rankings (see Robertson, 1994) consider three distress
modes: low-temperature thermal shrinkage cracking, load associated fatigue, and
rutting caused by plastic deformation in the upper layers of the hot-mix asphalt
concrete. The actual rankings are presented in the attached set of tables. In some
instances, where multiple parameters were selected for the ranking, the better
understanding of the failure mechanisms and better models were developed by the
other SHRP research programs.
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