Development of Performance Test for Sealants for Asphalt Pavement Thermal Control Joints

In cold regions, the flexibility of asphalt mixtures is often insufficient to prevent low-temperature cracking caused by thermal contraction. To mitigate the resulting tensile stresses, several highway agencies considered cutting and sealing control joints at the surface layer of asphalt pavements. This process involves cutting a fixed-width joint through the top layer of pavement, then filling the joint with a sealant to prevent intrusion of moisture or incompressible materials. Although field implementations have shown promising results, issues such as premature sealant adhesion failure have been observed. This study introduces a new test, the “low temperature asphalt sealant tensile test,” which addresses the limitations of ASTM D5329 by incorporating asphalt substrates, extremely low temperatures, and a failure mechanism tailored toward thermal contraction events. A modified version of the overlay test was adopted, incorporating an asphalt substrate and joint filled with flexible sealants. This test frame was selected based on the similarities in the failure mechanism between cracking owing to thermal contractions and reflective cracking. The test temperature was reduced to as low as −40°C. Loading was applied at a fixed displacement of 0.5, 1, or 2 mm/min to evaluate the impact of loading rate. Specimens with varied joint widths and sealant types were evaluated using a servo-hydraulic testing machine. This enhanced procedure provides a more representative assessment of joint and sealant performance under thermal stress and offers insights for improving the durability of asphalt pavements in cold climates, such as reducing thermal stress accumulated at the joint by 50%.