IlliTC – low-temperature cracking model for asphalt pavements

Low-temperature cracking (LTC) is a major distress and cause of failure for asphalt pavements located in regions with cold climate; however, most pavement design methods do not directly address LTC. The thermal cracking model (TCModel) utilised by American Association of State Highway and Transportation Officials Mechanistic-Empirical Pavement Design Guide relies heavily on phenomenological Paris law for crack propagation. The TCModel predictions are primarily based on tensile strength of asphalt mixture and do not account for quasi-brittle behaviour of asphalt concrete. Furthermore, TCModel utilises a simplified one-dimensional viscoelastic solution for the determination of thermally induced stresses. This article describes a newly developed comprehensive software system for LTC prediction in asphalt pavements. The software system called ‘IlliTC’ utilises a user-friendly graphical interface with a stand-alone finite-element-based simulation programme. The system includes a preanalyser and data input generator module that develops a two-dimensional finite element (FE) pavement model for the user and which identifies critical events for thermal cracking using an efficient viscoelastic pavement stress simulation algorithm. Cooling events that are identified as critical are rigorously simulated using a viscoelastic FE analysis engine coupled with a fracture-energy-based cohesive zone fracture model. This article presents a comprehensive summary of the components of the IlliTC system. Model verifications, field calibration and preliminary validation results are also presented.