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During compaction of asphalt hot mix three very important factors that will affect pavement performance take place. The asphalt coated aggregate particles are pressed together, air voids are reduced, and mix density (weight to volume ratio) increases.<ref>http://www.trb.org/news/blurb_detail.asp?id=3405</ref>
During compaction of asphalt hot mix three very important factors that will affect pavement performance take place. The asphalt coated aggregate particles are pressed together, air voids are reduced, and mix density (weight to volume ratio) increases.<ref>http://www.trb.org/news/blurb_detail.asp?id=3405</ref>
# This squeezing together of the aggregates increases their surface to surface contact and interparticle friction, resulting in higher mix stability and pavement strength.
#The reduction of air voids to the optimum level in the mix produces a pavement that is nearly impermeable. In an under compacted mix the voids tend to be interconnected thereby permitting the intrusion of air and water into the pavement structure. The air oxidizes the asphalt binder, making it brittle and causing the mix to crack under the repeated deflections due to traffic loads. Water permeating into and through the pavement can lead to stripping of the asphalt from the aggregate, weakening of the base and subgrade soils under the pavement, or freeze-thaw damage in colder climates. Premature pavement distress can occur in any of these situations.
#Finally, if a high level of compaction (concurrently with items 1 and 2 above) is not achieved during construction, subsequent traffic will further consolidate the mix. This will occur principally in the wheel paths and the resulting ruts could be a safety hazard to traffic using the road.
==References==
==References==