EZ Asphalt’s ABCD Tester
The Asphalt Binder Cracking Device (ABCD), invented by Sang-Soo Kim, was developed alongside its low-temperature cracking potential test under the National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) project 99. In 2011, the ABCD test method was adopted as the American Association of State Highway and Transportation Officials (AASHTO) TP 92 test method and then AASHTO T387 in 2019. Here’s how it works.
The laboratory device consists of round molds, cooling chamber, sensors and software. Using proper safety protocol, a lab technician first pours a heated binder sample of 14.38 +/- 0.5 grams into a circular mold outside of a 2-inch diameter Invar ring. Invar is a steel alloy with a near-zero coefficient of thermal expansion (CTE).
The filled molds should rest at room temperature for an hour prior to testing. If the technician has overfilled the mold, trim the sample with a heated spatula.
She then places the ring with the specimen in the cooling chamber, lining up sensors that will collect data from the specimens.
As the temperature within the chamber steadily decreases, the binder specimen contracts and compresses the ABCD ring. Sensors inside the ABCD ring measure and record the temperatures and strains throughout the test, feeding information to the “data acquisition” software on a computer desktop. The technician can monitor progress with the computer software real-time plots.
When the binder specimen cracks, the strain is abruptly relieved. The temperature recorded at the instant of that relief is the ABCD cracking temperature.
According to Alaska Department of Transportation Northern Region Materials Lab (NRML) Supervisor Heidi Schaefer, the test takes about one day to perform and was relatively easy to perform.
For more information, contact Dr. Sang-Soo Kim at EZ Asphalt Technology at (740) 707-6817.