Temperature control of hot-poured sealants during the sealing of pavement cracks

Bituminous sealants are applied to asphalt concrete roadways to prevent the ingress of water, brine and debris in the road structure. This delays degradation and extends the pavement service life. Sealants are applied hot, yet little is known about temperature control and temperature variations during typical sealant installations and its affect on sealant properties and performance. To address this issue, sealant temperatures were measured at various points in three common kettles melters during sealant installations. Kettle temperature gauge readings were compared to true sealant temperatures and to recommended application temperatures. The results indicate a mismatch between the suggested and the true installation temperatures due to the lack of kettle gauge calibration, the contractors' attention to and control of the sealant temperature, and the characteristics of the stirring system. To improve temperature control, it is suggested that installation specifications require a certificate of temperature calibration, that kettles with variable speeds be operated at the fastest and safest practical speed, and that the next generation of kettle be equipped with automated temperature controls.