here’s how it works Step 1 Prepare the molds by pouring the heated binder into the ring and letting it rest at room temperature for an hour prior to hooking up sensors in the cooling chamber.
Step 2 Align sensors on the mold in the cooling chamber.
Step 4 Sensors inside the ABCD ring measure and record temperatures and strains, sending the data to the software.
Step 5 When the strain is abruptly relieved, the ABCD cracking temperature is recorded.
Step 3 The temperature in the chamber steadily decreases.
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).
T
62 // may 2020
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. SangSoo Kim at EZ Asphalt Technology at (740) 707-6817.
SHOW US HOW IT WORKS If you’re an original equipment manufacturer with a complex product, let us help you explain its inner workings to asphalt professionals. There’s no charge for this news department, but our editorial staff reserves the right to decide what equipment fits the parameters of a HHIW feature. Contact our editor at sandy@theasphaltpro.com.
