Performance-based selection guidelines for roadway bituminous-based crack sealants

The long-term performance of pavements depends in good part on the quality and frequency of maintenance. Appropriate maintenance protects the pavement from deterioration, corrects deficiencies, and ensures safe and smooth riding. Crack sealing is practiced on a routine basis as preventive maintenance and as part of corrective maintenance prior to an overlay or a greater rehabilitation project. A timely and properly installed sealant adds several years of service life to the pavement at a relatively low cost. As a consequence, the selection of an appropriate sealant in a maintenance project becomes an important issue. Current sealant selection is based on ASTM standards that consist of quality control tests, not of performance indicators. These standards do not consider the changes in mechanical properties due to aging or the differences in local service temperatures. Given the breadth of temperatures in North America and its yearly variation, there is an urgent need for performance-based indicators of sealant performance. In this paper, a series of tests that provides a systematic approach to help highway agencies selecting proper sealants is proposed. These include an accelerated aging test, an apparent viscosity test performed at sealant application temperatures, a dynamic shear rheometer (DSR) test to assess flow in summer temperature, a crack sealant bending beam rheometer (CSBBR) and a crack sealant direct tension test (CSDTI') for cohesive properties at sub-zero temperature, and a blister test for adhesive properties. Using identified thresholds for these tests, performance-based guidelines for the selection of hot-poured crack sealants were developed.