Cooling rates in hot-poured bituminous sealants

The performance of bituminous sealants applied to cracks and joints is partly governed by installation. An important installation parameter yet to be investigated is the sealant rate of cooling after it is poured hot. Cooling rates affect sealant microstructure and rheology, adhesion at the sealant-hot-mix asphalt interface, and the time during which traffic must be rerouted. To provide data on sealant cooling rates, the temperature change in three sealants was measured in the field and in the laboratory. Results indicated that sealant bulk temperatures were >50°C lower than the sealant application temperature, typically 180°C, almost immediately after pouring, and that sealant bulk temperatures reached 40°C or less within 15 min. This finding suggests that traffic could be rerouted for less time than the standard 30 mm. The instantaneous sealant temperature at the sealant-substrate interface was also measured to be below 100°C immediately after pouring of the sealant This finding emphasizes the need for sealants with good wetting propensity to maximize the potential for proper adhesion.