Determination of Low Temperature Thermal Cracking of Asphalt Binder by ABCD
Sang-Soo Kim
Department of Civil Engineering, Ohio University
Athens, Ohio 45701
Zachary D. Wysong
CON/SPAN, Dayton, Ohio
Formerly, Graduate Assistant, Ohio University
An Asphalt Binder Cracking Device (ABCD) is proposed to determine the low temperature cracking potential of an asphalt binder. ABCD is a simple test method whose operating principle is based on the differential thermal contraction between the metal ABCD ring and an asphalt binder placed outside of the ring. As the temperature is lowered, the test binder shrinks more rapidly than the ABCD ring placed inside, which results in development of thermal stresses. When the developed thermal stress exceeds the strength of the binder, the binder specimen cracks. Strain gauges installed inside of the ABCD ring detect the fracture, and the temperature is recorded as the ABCD cracking temperature. Using a number of modified and unmodified binders, ABCD repeatability was studied. Based on this study, the ABCD and its test procedures were modified to produce repeatable results. From laboratory tests, ABCD showed the better correlation with Thermal Stress Restrained Specimen Test (TSRST) results than with the MP1 and MP1a procedure. When the strength data determined by ABCD were used in the MP1a procedure, its correlation with TSRST was significantly improved.