Field and Theoretical Evaluation of Thermal Fatigue Cracking in Flexible Pavements (05-2328)
Imad L. Al-Qadi, University of Illinois, Urbana-Champaign
Marwa M. Hassan, Louisiana State University
Mostafa A. Elseifi, Louisiana State University

Thermal cracking in flexible pavement occurs when the tensile stress exceeds the tensile strength of hot-mix asphalt at a given temperature or when fluctuating stresses and strains caused by temperature variation leads to a build-up of irrecoverable deformations over time. The objective of this study was two-fold: 1) to quantify the measured strain magnitude associated with thermal fatigue through field measurements and 2) to present a three-dimensional finite element (FE) model that accurately simulates thermal fatigue in flexible pavement. Results of the experimental program indicated that pavement response to thermal loading was associated with a high strain range, reaching a maximum recorded value of 350ƒİm/m. This finding confirms the hypothesis that the criticality of thermal fatigue arises from the high stress/strain level exhibited in each cycle rather than its frequency, which is usually the critical factor in load-associated fatigue cracking. Moreover, the developed FE model accurately simulated pavement response to thermal loading by conducting a sequential coupled heat-transfer analysis. Results of the developed FE model were in agreement with field measurements and demonstrated the model¡¦s capability to simulate both the temperature and stress fields associated with thermal loading. This model may be used to evaluate pavement performance against transverse cracking.