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Where:
• Gr = theoretical maximum specific gravity of the particular HMA in question
• Ga = bulk specific gravity of the HMA in question.
Figure 6-45. Two cores – the core on the right has significantly higher air void. ©
Copyright 2006 University of Washington
5.2. Compaction Importance
This is because high air void content (above 8%) or low air void content (below
3%) can cause the following pavement distresses (this list applies to dense-graded
HMA and not open-graded HMA or SMA):
1. Decreased stiffness and strength.
2. Reduced Fatigue Life.
3. Accelerated Aging/Decreased Durability.
4. Raveling.
5. Rutting.
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