Akira KOMINAMI
The Research of the Asphalt Concrete of the Crack Evaluation Method by Using Indirect Tension Test
Osamu TAKAHASHI
A Direct Tension Test and a Bending Test are done as a crack evaluation method of the asphalt mixture in our country at the research level. A Direct Tension Test is very complicated because it is necessary to bond directly to the test equipments with a resin such as an epoxy, and this test method is still not standardized and is few executed. The Bending Test is standardized only in case of the temperature ?10”ī and load speed 50mm/min, but in case of high temperature and low load speed, the test is not suitable.As for these two tests, since the specimen is needed to prepare separately from one of mix design, it takes a lot of time and money.
In this study, the author took a notice of the Indirect Tension Test and considered it as a more simple test for evaluating crack. This test is a test that the load is put from the side of the cylinder specimen, and makes the tensile stress inside the specimen occur indirectly. In this test method, an application for the asphalt concrete is examined, but because the asphalt concrete is visco-elasticity material, and the whole material is not uniform, it is difficult to measure a strain at the time of the destruction. That”Ēs why, in our country, the test method to evaluate the crack resistance is not established. In this study, the author sought for a strain at the time of the destruction by the Indirect Tension Test, then used the test as a crack resistance evaluation test and examined the establishment of the standard of crack resistance evaluation.
First, the author measured a strain that occur in the specimen by the image processing, and grasped the tension performance of the specimen in the Indirect Tension Test. Then, the author compared the results of the Indirect Tension Test with ones of Direct Tension Test and Bending Test by using the specimens which have 4 different crack resistances. The author grasped the tension deformation performance by using the image processing in the Indirect Tension Test. In addition, the author made it clear that the applicability of the Indirect Tension Test was high by monitoring the horizontal strain.
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