Deformation and tracking of bituminous sealants in summer temperatures: pseudo-field behaviour

The bituminous sealants used in the maintenance of roadways sometimes fail because of the excessive deformation or flow under the shearing action of tires in summer temperatures. This issue has yet to be studied and no data on sealant deformation and flow are available. To address this issue, a small-scale tracking test was developed and applied to 21 sealants held at temperatures between 46 and 82°C, typical pavement temperature maximums in North America. It was found that sealant shear deformation increased linearly or non-linearly with temperature, and that past a temperature threshold, sealants deformed excessively and tracked. The tracking failure temperature was readily identified. Some sealants showed a tracking failure at fairly low temperatures, 46–64°C, but most only failed at 76°C or beyond. The sealant flow characteristics, acquired under pseudo-field conditions, provide the basis for developing a performance-based method to assist in the selection of sealants with resistance to tracking.