Thermal segragation of asphalt material in road repair

Abstract

This paper presents results from a field study of asphaltic pavement patching operations performed by three different contractors working in total of ten sites. Thermal imaging technology was used to record temperatures of the patching material throughout the entire exercise, from the stage of material collection, through transportation to repair site, patch forming and compaction. Practical complications occurring during patch repairs were also identified. It was found that depending on the weather condition and duration of the travel, the temperature of the asphalt mixture can drop as much as 100oC over the entire period of patching work. Cold spots and temperature differentials were also identified between the new and old surfaces as well as along the edge of the pavement. In addition, the temperature loss at various locations on the asphalt mat was found to vary despite the material being laid at the same temperature. For example, over a five minute period, the temperature at one point was reduced by 33% whereas the temperatures of nearby areas were decreased by 65% and 71%. A return visit to the repair sites, three months later, revealed that locations where thermal segregation was noted during the patching operation had failed prematurely.