Investigation of Cracking Resistance of Asphalt Mixtures and Binders

Project summary:

Researchers studied the viability of using three test methods for asphalt mixtures and one test method for asphalt binders. These test methods are: Bending Beam Rheometer (BBR) for creep and strength of asphalt mixtures; low temperature Semi-Circular Bend (SCB) test for fracture energy of asphalt mixtures; Dynamic Modulus (E*) test of asphalt mixtures using the Indirect Tensile Test (IDT) configuration; and BBR strength test of asphalt binders. The materials used in the experimental work were used in MnROAD cells constructed in the summer of 2016 as part of the MnROAD Cracking Group (CG) experiment, a 3-year pooled-fund project.

The results show that the testing methods investigated provided repeatable results that followed trends similar to the one observed using traditional methods. The results also showed that the properties are highly temperature dependent and the ranking observed at one temperature can change at a different temperature. In addition, it is observed that materials with similar rheological properties--such as complex modulus absolute value |E*|, creep stiffness S, and m-value--do not necessarily have the same fracture resistance. These results confirmed one more time the need for a fracture/strength test for correctly evaluating cracking resistance of asphalt materials.