Since the 1990s the Leutner shear test has become the most important device for testing the interlayer shear bond of asphalt pavements. The test device was originally designed by R. Leutner in the late 1970s, but since different countries and laboratories have made modifications or have built their own equipment. Besides others the gap width between the shearing rings has been a matter of modification. Recently this question also appeared in the process of European standardization. This paper shows the results of a laboratory study in which the gap distance was varied between 0 and 5mm. It was found that the influence of the gap width depends on the asphalt concrete type of the two layers (mixture type, max. aggregate size, and binder content). In most cases the gap width is negligible, in some cases maximum shear force and stiffness value decreases with increasing gap width. In addition to the shear values at the interface, shear tests were conducted in the material itself. Therefore, the difference between in-layer and interlayer shear properties and behavior is also discussed in more detail.

Additional Metadata
Keywords Gap width, Interlayer shear bond, Leutner test
Journal International Journal of Pavement Research and Technology
Raab, C. (Christiane), Parti, M.N. (Manfred N.), & Halim, A.O. (2010). Effect of gap width on interlayer shear bond results. International Journal of Pavement Research and Technology, 3(2), 79–85.