Development of crack sealant bending beam rheometer (CSBBR) testing to characterize hot-poured bituminous crack sealant at low temperature

Hot-poured bituminous crack sealants are used to protect pavement systems from the intrusion of water and help delay pavement degradation. Crack sealing is a widely accepted, cost-effective routine maintenance procedure that increases pavement service life. Current American Society for Testing Materials (ASTM) standards do not correlate the selection of crack sealants to their field performance. The development of performance-based guidelines will assist in selecting a sealant based on specific local needs, such as climate conditions. Several testing methods have been developed as part of the ongoing research to develop performance-based guidelines for hot-poured bituminous crack sealants. In this paper, a modified test using a bending beam rheometer (BBR) has been developed and identified as a reliable method to evaluate the Theological behavior of hot-poured bituminous crack sealants. In this test that uses the crack sealant bending beam rheometer (CSBBR), a double thickness of the standard bending beam was found to overcome excessive deflections during testing. The new beam geometry had a negligible effect on the resulting deflection caused by shear. In addition to changes in specimen geometry and preparation, a newly developed aging procedure, a validated testing period, and a time at which stiffness is determined were introduced. Nine sealants, with a wide range of Theological behaviors, were tested between 4°C and -40°C. Three performance parameters, the stiffness at 240s, the average creep rate, and the dissipated energy ratio were analyzed and successfully used to distinguish among sealant behaviors. A viscoelastic model using Prony series expansion to characterize crack sealant mechanical behavior at low temperatures and strain levels was developed. A three-dimensional finite element was used to determine the time-dependent deflection at the mid-span of the CSBBR specimen. A description of the linearity response of crack sealants at low temperature is also presented. The developed model was found to be capable of simulating deflection both during the loading and the unloading process for tested sealants.