During the week of June 14, 1982, Donohue & Associates, Inc. performed an infrared thermographic scan of 19 bridges and 1 section of continuously reinforced concrete pavement. The bridges and pavement were located throughout the northwest quarter and central portion of. Iowa. The scanning was undertaken under various environmental conditions to evaluate the technique under typical conditions. During the data collection phase surface temperatures were measured with a digital contact thermometer. Temperature measurements were taken in delaminated and solid areas. The ability to detect delaminations accurately is dependent upon the temperature differential between the solid and delaminated pavement. The larger the temperature differential the easier it will be detected by the infrared scanner. The temperature differential is dependent upon the depth of the delamination, amount of separation at the delamination, and environmental conditions. The environmental conditions under which the data was collected is summarized on Table 2 along with the temperature differentials between the solid and delaminated pavement. The environmental conditions varied on each of the five days that data was collected. These conditions together with the range of temperature differentials are shown in Table 3.
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