Threshold Identification and Field Validation of Performance-Based Guidelines to Select Hot-Poured Crack Sealants

Abstract

Hot-poured bituminous crack sealing has been widely accepted as a routine preventative maintenance practice. With proper installation, the sealing is expected to extend pavement service life by 3 to 5 years. However, current specifications for selection of crack sealants correlate poorly with field performance; hence, a set of new testing methods, based on sealant rheological and mechanical properties, was developed recently. Measurements of the mechanical properties of crack sealant at low temperatures are among the criteria introduced as part of the developed performance-based guidelines. The main purpose of this study was to identify and validate the low-temperature selection thresholds for the newly developed performance-based guidelines for selecting hot-poured bituminous crack sealants. In this study, selection criteria for crack sealant bending beam rheometer (CSBBR) and crack sealant direct tension tester (CSDTT) tests were identified. Two performance parameters for CSBBR test were used for the selection criteria: stiffness at 240 s and average creep rate (ACR). Both parameters were identified by comparing laboratory testing results with known sealant field performance, obtained from a long-term study in Canada. The selection criterion for the CSDTT test was extendibility, on the basis of field values reported in the literature. The recommended selection criteria were used to predict the field performance of 12 sealants evaluated by the National Transportation Product Evaluation Program (NTPEP). Results showed good correlation between the proposed selection thresholds and NTPEP field sealant performance.