Development of a Predictive System for Estimating Fatigue Life of Asphalt Mixtures Using the Indirect Tensile Test

Fatigue cracking is a major problem in asphalt pavement. It would be beneficial for predictions of the fatigue life of asphalt mixtures to be made with minimal effort and time, both at the design stage and the operating stage of pavement. For practicality, the indirect tension (IDT) test has widely been used for testing both laboratory-made and field-cored mixtures; however, a fatigue test using the IDT test needs to be performed in the stress-controlled mode rather than in the strain-controlled mode. Results may not be comparable to those from other mixture tests, such as the flexural beam fatigue or uniaxial tension test, so this study employed the viscoelastic continuum damage (VECD) model. The C-1-S-1 curve, which is a final product of the VECD model, is known as a single-characteristic curve of an asphalt mixture and is independent of loading types. Three C-1-S-1 curves obtained from two fatigue tests and one monotonic strength test using the IDT test were similar when superimposed into a single C-1-S-1 curve, indicating that the VECD model can be applicable both to the IDT fatigue test and the strength test. This also indicates that the fatigue life of a mixture subjected to sinusoidal strain loading can be determined through the model's damage principles using the IDT test results. Consequently, a system for predicting the fatigue life of asphalt mixtures was developed. It is expected that the predictive system will be useful in estimating the fatigue life of asphalt mixtures fabricated in the laboratory and those cored from field pavements. DOI: 10.1061/(ASCE)TE.1943-5436.0000452. (C) 2012 American Society of Civil Engineers.