The performance of multi-layered pavement systems strongly depends on interlayer bonding. Thus, to guarantee good bonding, during pavement construction or overlay, tack coats (also indicated as bond 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. The paper shows how interlayer shear resistance may be evaluated through ASTRA device. The ASTRA results, expressed in terms of maximum interlayer shear stress (peak), highlight the effects of various influence parameters such as type of interface treatment, curing time, procedure of specimen preparation, temperature, applied normal load. Moreover, the paper compares the peak 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 for Materials Testing and Research). Both test methods provide different but comparable results showing the same ranking of shear resistance for different interface treatments.
Advanced testing and characterization of interlayer shear resistance / Canestrari, Francesco; Ferrotti, Gilda; M., Partl; E., Santagata. - In: TRANSPORTATION RESEARCH RECORD. - ISSN 0361-1981. - STAMPA. - 1929:(2005), pp. 69-78. [10.3141/1929-09]