temperature differentials [46]. Temperature segregation can also be found in the accidental discharge of asphalt from a haul truck on the base surface to be later paved over. The dropped material will cool quickly and will not compact properly when fully paved over [48]. Asphalt pavement is one continuous material and therefore nonstop paving is preferred. However, mechanical or hauling issues can lead to the paver stopping for several minutes. Waiting too long between hauls can lead to a cyclic temperature segregation where the mat temperature has the potential to fluctuate up to 86°F (30°C) before paving continues [46]. This creates a strip of temperature differentials that may be significant enough to effect density if it is a long delay. A high-severity temperature segregation can reduce a pavement life by up to 50%. Cold spots in asphalt pavement causes nonuniform compaction which can lead to accelerated distresses (Figure 20) under traffic loading and environmental effects [47,48]. Common distresses that occur due to temperature segregation are oxidation and moisture damage caused by density differentials creating excess air and water exposure. There can also be a decrease in bond strength between pavement sections caused by the cooling caused by paver stoppage which can lead to transverse cracking [48]. Edges and joints are already especially susceptible to distresses due to the temperature differential created by being exposed to more air than just the surface [47]. This can result in a low density at the edges and joints, increasing the vulnerability of this location [49].
Figure 20: Distress due to temperature segregation causing inadequate compaction [50].
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