The current means of evaluating the low temperature cracking resistance of HMA relies on extensive test methods that require assumptions about material behavior and the use of complicated loading equipment. The purpose of this project was to develop a simple test method to directly measure the cracking resistance of hot mix asphalt.
In this project two devices were created that utilized the low thermal expansion coefficient of Invar steel to induce tensile stresses in a HMA sample as the device is cooled. The first setup used a cylindrical sample epoxied to a fixed frame. The results of this test showed high variability. The second setup was a notched ring shaped specimen compacted around an Invar ring. After testing several mixes it was found that this method showed good repeatability and correlated well with BBR and TSRST results. Finally, a finite element analysis was performed to visualize the stress distributions present in the samples of both test setups. The results from the second setup were promising and it is recommended that it be researched further to refine and validate this test method.