Advanced Testing and Characterization of Interlayer Shear Resistance (05-1201) - MP-55
Francesco Canestrari, Universita Politecnica delle Marche, Italy
Gilda Ferrotti, Universita Politecnica delle Marche, Italy
Manfred N. Partl, Swiss Federal Laboratories for Materials Science and Technology

The performance of multi-layered pavement systems strongly depends on interlayer adhesion. Thus, to guarantee good adhesion, during pavement construction or overlay bond coats (also indicated as tack coats) are usually applied at the various interfaces. The effectiveness of the tack coat can be assessed by making use of several devices which are arranged by different laboratories to evaluate interlayer shear resistance. In this paper it is shown how interlayer shear resistance may be evaluated by using the ASTRA device the results of which, expressed in terms of maximum interlayer shear stress, highlight the effects of various influence parameters such as type of interface treatment, curing time, procedure of specimen preparation, temperature, applied normal load. Another aim of this paper is to compare the results obtained by two different shear test devices: the ASTRA tester designed and developed in the Università Politecnica delle Marche (Italy) and the LPDS tester created by EMPA (Swiss Federal Laboratories). Both test methods provide different but comparable results showing the same ranking of shear resistance for different interface treatments (without tack coat, with conventional emulsion and with modified emulsion).