Assessing the Suitability of Different Testing and Specimen Preparation Approaches for Indirect Tensile Cracking Test (IDT-CT) Using a Simple Ranking Framework

ABSTRACT The advent of new additives such as polymers, rubber, and warm mix additives, as well as emphasis on the use of reclaimed asphalt materials, has rendered the traditional volumetric mix design of asphalt mixtures inadequate. As a result, the need for incorporating performance tests in the mix design process and adopting a balanced mix design (BMD) approach is now being widely recognized. One of the major challenges in adopting and implementing the BMD process is the selection of performance tests for rutting and cracking evaluation. Oregon is in the preimplementation phase of BMD. The Oregon Department of Transportation has been working on the development of a BMD method since 2015 and is now exploring the use of the indirect tensile cracking test (IDT-CT) (formerly called the IDEAL-CT), which is a simple, practical, and rapid cracking performance test. However, the results of this test have been found to be sensitive to the loading equipment, aging conditions, temperature conditioning methods, and specimen's air voids, among other factors. In this study, the IDT-CT results of the two mix types were compared for different aging conditions, temperature conditioning methods, sample sitting time (the time that lapsed between the production of the sample and the cracking test), and device type, and the most suitable testing approach was determined using a simple ranking approach. Among all the testing approaches, testing the samples in a low-cost load frame after conditioning them in a dry conditioning chamber can be considered the most suitable method.