The Use of X-Ray Computed Tomography to Characterize Microdamage in Asphalt

X-ray Computer Tomography (CT) has been used to quantify the damage induced during constant strain rate and fatigue tests on asphalt. Using image analysis techniques grading of the aggregate was carried out from the X-ray images of compacted asphalt specimens. It was found that particles larger then 5mm can be seen in comparison to the mix design curve of the asphalt mixture. It was observed from X-ray scanning of the specimens tested in mechanical testing that the increase in the volume of void content is not uniform throughout the specimen. It was found from the constant strain rate tests that the damage (air voids) were found to increase with increasing strain as damage accumulates in the specimen. It was also found that there is a greater increase in damage (void content) for the specimens tested at the higher temperatures and lower strain rates. Similar behaviour was observed from the fatigue tests with the greatest increase in damage at the higher test temperature.