Alternative Fatigue Cracking Resistance Assessment Criteria Of Asphalt Mixtures With Overlay Tester

The accumulation of damage due to cracking of hot mix asphalt (HMA) layers under repeated loading along with the climatic effects is known as fatigue cracking. The Overlay Tester (OT) has been implemented or considered by several highway agencies as an index to evaluate the cracking susceptibility and resistance to cracking of asphalt mixtures in the laboratory. The performance indicator used to measure the quality of the HMA mixes is the number of cycles that a specimen may resist during the test until the crack appears and fully propagates to the top of the specimen. The repeatability of the number of cycles to failure measured with the OT is expressed as a concern to reliably assess the potential of asphalt mixtures to cracking. The goal of this Thesis is to methodically evaluate the performance of the current OT test protocol. By addressing alternative cracking test methods and parameters a surrogate performance indicator may reliably estimate the fatigue cracking properties of HMA mixes. Fundamentally, cracking can be characterized in two stages: a) crack initiation and b) crack propagation. In this study, the focus was to analyze the data from the OT test considering these two stages. An alternative failure criteria to rank and screen the cracking resistance of asphalt mixtures was developed for the current OT tes