Estimation of asphalt binders’ resistance to permanent deformation with application of the MSCR and multiple shear creep long recovery (MSCLR) tests

The main goal of introducing the MSCR test was to estimate the rheological properties of pen grade and modified binders using the same measure. The conditions for this test were chosen at random (the length of creep and recovery period, the stress levels, as well as the test temperature). In most applications, the test temperature value was equal to 64 or even 70°Celsius. It is clear that for such high temperature values for softer binders the test interpretation is not always possible or burdened with a significant statistical error. Some time ago authors of this paper proposed a certain very similar test, but with different test parameters and with different interpretation of the test results. The test may be called a multiple shear creep long recovery (MSCLR) test and the main differences are the test temperature assumed as 10°Celsius and duration of creep and recovery period. In the first part of test, 10 cycles of creep-recovery periods are applied in the stress shearing mode on an asphalt binder sample. This part of the test ends with a long-term recovery period. The test is interpreted through the permanent deformation ratio determined on the basis of the maximum shearing strain observed during the test and the strain value after the long recovery period. In the paper the MSCR and MSCLR tests are conducted on highly-modified binders currently produced in Polish market. The obtained results are statistically analyzed, compared with each other and correlation functions between the results from MSCR and MSCLR tests are determined. Selected results are then presented in relation to results of modified and pen binders produced 8 years before (or some archival binders used for analysis in the paper [1]). Based on the analysis of the results, it is possible to observe some advantages of MSCLR test over MSCR test. One of them is a higher test sensitivity in distinguishing resistance to permanent deformations of individual binders and another one is the simplicity of interpretation of the test data.