To establish a clear understanding of the behavior of hot-poured bituminous-based crack sealants at low service temperature and to predict their field performance, the constitutive stress-strain relationship must be described. The description of this relationship would allow accurate prediction of crack sealants' field responses to thermal and traffic loading. The objective of this paper is to describe crack sealant constitutive behavior at low temperature by linear viscoelastic modeling (Prony series expansion). The suggested model was fitted to creep measurements obtained from a modified bending beam rheometer test setup. The experimental program included testing of three soft crack sealants having a relatively high level of polymer modification content at a temperature ranging from -28°C to -40°C. A Prony series expansion was fitted to the experimental results. To determine the time-dependent responses of crack sealants to a constant creep load, the fitted material parameters were incorporated into a three-dimensional finite element model. Measured and calculated deflections were in good agreement. This finding suggests that the constitutive behavior of crack sealants can be accurately described by the linear viscoelastic regime at low service temperatures.