Effects of asphalt rejuvenator on thermal and mechanical properties of oxidized hot mixed asphalt

Asphalt Rejuvenator;Acoustic Emission

Farace, Nicholas Anthony ; Reis ; Henrique

关键词: Asphalt Rejuvenator;    Acoustic Emission;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/88046/FARACE-THESIS-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The utilization of asphalt rejuvenator, and its effectiveness for restoring thermal and mechanical properties was investigated via Disk-shaped Compact Tension (DC(T)) testing and acoustic emission (AE) testing for determining the embrittlement temperature of the mixtures. During the DC(T) testing the fracture energies and peak loads were used to measure the resistance of the rejuvenated asphalt to low temperature cracking. The AE testing monitored the emissions generated while the specimens were cooled from room temperature to -40°C to estimate the temperature at which thermal cracking began (i.e. the embrittlement temperature). The purpose of this research was to determine if the rejuvenator restored the low temperature performance of highly oxidized hot mixed asphalt (HMA).The study was divided into three parts. Part 1 set a baseline for comparison of the low temperature performance by using DC(T) testing and AE testing on virgin HMA samples and HMA samples that had been aged and oxidized for 36 hours at 135°C. The results showed the virgin samples had much higher peak loads and fracture energies than the 36 hours aged samples. Acoustic Emission showed similar results with the virgin samples having embrittlement temperatures 10°C cooler than the 36 hours aged specimens. Part 2 of the study evaluated the effect of varying amounts of rejuvenator (10%, 15%, and 20% by weight of binder content) on HMA mixtures when left for different dwell times. The dwell times were varied from 1 week to 8 weeks. The testing was done at 0°C instead of the standard -12°C as the standard was too close to the original 36 hours aged embrittlement temperature, and could have caused variance in the results. It was found that the rejuvenator lowered peak loads, and kept the fracture energies near the same level from the DC(T) testing. The AE results showed an improvement of embrittlement temperature, with increasing improvement with the dwell times. The 8 weeks specimens had cooler embrittlement temperatures than the virgin specimens. Part 3 of the study investigated lower temperature effects on fracture energy and peak load of the rejuvenated asphalt. Rejuvenator was applied (10% by weight of binder) to specimens aged 36 hours at 135°C, and the dwell time was varied from 1 to 4 weeks. The results from this testing showed the peak loads being restored to levels of the virgin specimens, and the fracture energies improved to a level beyond that of the virgin specimens. The results showed a general trend of improvement for the AE testing of the embrittlement temperature, but further testing at different rejuvenator levels and dwell times would be required to ensure the mechanical results.