Cyclic interlayer testing in bituminous pavements

Interlayer bonding in bituminous pavements is assessed by measuring the interface shear strength (ISS) of double-layered specimen, using monotonic tests. However, dynamic shear testing better simulates the actual traffic loads. The RILEM Technical Committee “Phase and Interphase behavior of bituminous Materials” (PIM) organized an interlaboratory test aimed at comparing different equipments employed to obtain the dynamic shear characterization of multilayer bituminous systems. This paper describes the experimental activities carried out at Università Politecnica delle Marche, specifically organization of the interlaboratory test, preparation of the double-layered samples to be tested by the participating laboratories and development of a new device for performing cyclic interface testing. The results include the ISS of the double-layered samples measured with the ASTRA and Leutner devices. Moreover, the results of the cyclic Leutner device are presented along with the preliminary outcomes obtained with the new cyclic ASTRA device, both in terms of stiffness and cumulative damage.