In the second phase, 31 laboratories participated in a study to evaluate the repeatability, accuracy, and simplicity of the testing system. The volunteers included 18 State and Federal government labs, one Superpave Center, one Canadian Ministry of Transportation lab, five universities, and six private facilities.
Technicians at each lab set up the ABCD testing system and conducted a series of three test runs on three sets of asphalt binder specimens. Despite limited experience using the device, almost all participating labs were able to complete the tests without major difficulty. Results of the tests showed that the standard deviation of the temperature was within an acceptable range of precision.
Ten labs also conducted a Bending Beam Rheometer (BBR) test, the current Superpave test for low-temperature grading, on the asphalt binder samples. The results indicated that the precision estimates of ABCD cracking temperature and BBR critical temperature were comparable.
Users provided feedback on their ABCD testing experience, which was used to further refine the test procedure. Several reported that trimming the poured asphalt sample was difficult, so the test procedure was simplified to eliminate that step without affecting the test’s accuracy. User comments from the survey included the following:
- “ABCD unit was very user friendly, software was excellent, and I personally would recommend this to anyone into binder testing.”
- “Easy to use. The instructions were well written and easy to follow. The setup did not take long and the macro ran great to get the cracking results.”
- “Easy-to-understand concept. Simple results.”
- “I was impressed on how easy the ABCD was to use. Once you get the sample prep technique down, the rest of the procedure was simple to use.”
- “Easy test to perform with a very simple test procedure. Relatively easy to clean up. I think this is great test with the potential to replace the BBR [Bending Beam Rheometer] and DT [Direct Tension] tests in the future.”
“Most labs reported that the ABCD was an easy test to run,” said Kim. “Engineers and technicians liked the fact that they could see the performance of the tested binder directly without additional analysis.”
Now that the Technology Partnerships project is completed, EZ Asphalt plans to develop a range of ABCD models to satisfy industry’s different needs. “We plan to address the feedback of the participating labs, and we already have significantly refined the test equipment and procedures,” Kim said.
To learn more
For more information on Technology Partnerships, visit www.fhwa.dot.gov/hfl/tech.cfm or contact Julie Zirlin at firstname.lastname@example.org or (202) 366-9105. For details on ABCD, go to www.ezasphalttechnology.com or contact Sang-Soo Kim at (740) 597-3230 or email@example.com.