Assessing the Impact of Test Conditions on Indirect Tensile Test Results for Evaluating Rutting Potential in Asphalt Mixtures

This study investigates how variations in testing procedures and conditions of the indirect tensile at high temperature (IDT-HT) test affect the assessment of rutting potential in asphalt mixtures. Specifically, it explores the effects of specimen conditioning environments, loading rates, device types, and storage (lag and dwell times) on the IDT-HT test results. Four dense-graded asphalt mixtures with varying rutting potentials were evaluated. The results indicated significant differences in specimen conditioning times between water bath and environmental chamber, with water bath-conditioned specimens consistently showing lower strength values. Additionally, the repeatability characteristics of the test were not significantly affected by conditioning environment, loading rate, loading frame, or storage. Furthermore, loading rate (50±4 mm/min), loading frame, or storage did not significantly affect the test results, particularly in the context of single-operator precision estimates. A preliminary performance criterion was established for the IDT-HT test, requiring a minimum strength value of 100 kPa for specimens conditioned in a water bath at 54.4°C for 1 h.