Characterizing viscoelastic properties of asphalt mixtures utilizing loaded wheel tester (LWT)

Abstract

The performance of asphalt mixture is governed by its viscoelastic properties, especially those in tension mode. However, due to the difficulties in performing tests in direct tension mode, the test methods commonly used are in either compression or indirect tension (diametrical compression) mode. Previous studies show that loading mode has a significant effect on the viscoelastic properties of asphalt mixtures, especially at high temperatures. It is of great importance to develop a testing method to effectively and efficiently characterize the tensile properties of asphalt mixtures. In this study, a flexural tension test was proposed to utilize a loaded wheel tester (LWT) to characterize the viscoelastic properties of asphalt mixtures. In this test, beam specimens were subjected to constant or cyclic loads provided by moving wheels of a LWT. With transducers mounted on the beam, flexural bend deformations are measured. In addition to the LWT test, uniaxial tests in tension mode, tension-compression mode, and compression mode as well as indirect tension creep test were conducted on the same asphalt mixtures for comparison and validation. The results showed that the LWT test was able to characterize the viscoelastic properties of asphalt mixtures made with different aggregates and asphalt binders. The results from the LWT tests were found to be in general accordance with those from other tests. Compared to uniaxial and indirect tension tests, the LWT test could better represent the stress state in pavements and thus was more suitable for characterizing the viscoelastic properties of asphalt mixtures.