Modified repeated load tri-axial test for the high-temperature performance evaluation of HMA

Abstract

A modified repeated load tri-axial (RLT) test, capable of simulating the lateral confinement and temperature gradient in real pavement, was developed to evaluate the high-temperature performance of asphalt mixture. Proper indenter size was determined to apply partial pressure to the specimen to produce varying lateral confining pressure. To generate temperature gradient of field pavement within the specimen, the side and bottom areas of the specimen were covered with thermal isolating materials so that only the surface transfers heat with the environment. This study then fabricated a three-layer mix as the specimen to examine the effectiveness of the modified RLT test. Testing elements include surface, middle and bottom mix types, binder types, temperatures as well as their interactive impacts. The flow number index, defined as strain/load cycle, is found to be able to differentiate the impacts of all the factors except for the surface layer mix. The developed test can readily utilise the current RLT test apparatus with minor modifications and better characterise the high-temperature performance of asphalt mix at the expense of additional specimen preparation work.

Keywords:

• repeated load tri-axial test
• confining pressure
• temperature gradient
• flow number
• hot mix asphalt

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge the funding support of the National Science Foundation of China at a [grant number 51408114].