The Effects of SCB test support configurations on different fracture mechanic parameters in asphalt mixtures

Today, the semi-circular bending (SCB) test has become a common method and used in studying the mechanical behavior of asphalt mixtures. According to the regulations, this test has specified laboratory conditions such as sample geometry, test temperature and a certain loading rate. However, in addition to providing these conditions for SCB testing, the shape and type of supports used in the experiment are less considered and they do not have an integrated type and shape, which may cause differences in laboratory results. Therefore, in this study, the effects of 5 different support configurations on important parameters of fracture mechanics at intermediate temperatures was investigated by considering the coefficient of variation (CV). The used loading rate was selected 5 mm/min in which the asphalt samples were subjected to uniform static loading under mode I. The experimental results showed that the selection of support type has a direct influence on the fracture mechanic parameters, while the selection of the wrong support type may cause significant error in the test results. Nevertheless, the friction between the sample and the support causes more dispersion in the test results and could reduce its repeatability. For this purpose, it could be recommended not to use rigid supports that have considerable friction with the sample. Finally, considering specific laboratory conditions for the SCB test (i.e., sample geometry, test temperature and specific loading rate), support No. 1 was selected as the most suitable support with high repeatability of the results.