Verification of the applicability of the time–temperature superposition principle to interface shear stiffness and strength of GlasGrid-reinforced asphalt mixtures

This paper aims to verify the applicability of the time-temperature superposition (t-TS) principle to the interface shear performance of GlasGrid-reinforced asphalt specimens under monotonic and random cyclic shear loading. A double shear tester and a direct shear device, the Modified Advance Shear Tester that has the capability to apply confining loads, were used to fulfil this objective. Double-layered asphalt specimens were fabricated and reinforced using two types of fibreglass grids with 12.5-mm and 25-mm grid openings, respectively. PG 64-22 asphalt binder was used as the tack coat when the smaller opening grid was used, and SS-1 emulsion was applied as the tack coat when the larger opening grid was used. Approaches that employ the mixture dynamic modulus, tack coat residue complex modulus, and interface shear modulus shift factors for shifting the shear test results and constructing shear master curves were evaluated. The results show that the t-TS principle is applicable to the shear strength and shear stiffness of GlasGrid-reinforced asphalt concrete specimens if the right shift factor function is used.