The laying of too cool a mixture may result in a course with a considerably large amount of air voids (see Section 11.6). That is an obvious matter; however, quite often the accelerated cooling of a mixture takes place in particular areas during its laying. Such places have been defined as having porosity of different types.
The figures in the sections that follow are photos taken with an infrared camera. The Fahrenheit scale of temperature has been placed on each of them. They show various causes of mixture cooling, followed by thermal differences resulting in poor quality.
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FIGuRE 11.12 Distribution of asphalt mixture temperature after transport to the work site during discharge into the paver. (Photo courtesy of Kim A. Willoughby, WSDOT, United States.) |
