Field Validation of Laboratory-Predicted Low-Temperature Performance of Hot-Poured Crack Sealants

Abstract

When properly installed, hot-poured crack sealants are widely accepted as a cost-effective, routine preventive maintenance practice that extends pavement service life by 3 to 5 years. However, current ASTM specifications for selection of crack sealants correlate poorly with field performance. Therefore, an improved sealant specification and selection system is urgently needed. Recently, performance-based guidelines were developed by the pooled-fund North American Consortium expert group for selecting hot-poured bituminous crack sealants. The work proposed a sealant grade system for selecting hot-poured crack sealant on the basis of environmental conditions. A special effort was made to use the equipment originally developed by SHRP, which was used to measure binder rheological behavior as part of the performance grade system. The equipment and testing procedures used for performance grading of binders were modified in accordance with crack sealant behavior. The main objective of this study was to validate the low-temperature selection thresholds for the newly developed performance-based guidelines for selecting hot-poured crack sealants. Thresholds for the crack sealant bending beam rheometer, crack sealant direct tension test, and crack sealant adhesion test were validated. Nine hot-poured crack sealants were installed in four test sites experiencing low temperatures. The field performance of crack sealants was evaluated for 2 consecutive years by detailed field surveys. The field database consisted of 40 sections containing 647 cracks. Overall, results showed good correlation between the proposed selection thresholds and sealant performance in the field.