AASHTO T 315:2012(2016) Standard Method of Test for Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer (DSR).
4.4. The test specimen is maintained at the test temperature to within ±0.1°C by positive heating and cooling of the upper and lower plates or by enclosing the upper and lower plates in a thermally controlled environment or test chamber.
4.5. Oscillatory loading frequencies using this standard can range from 1 to 100 rad/s using a sinusoidal waveform. Specification testing is performed at a test frequency of 10 rad/s. The complex modulus (G*) and phase angle are calculated automatically as part of the operation of the rheometer using proprietary computer software supplied by the equipment manufacturer.
5.1. The test temperature for this test is related to the temperature experienced by the pavement in the geographical area for which the asphalt binder is intended to be used.
5.2. The complex shear modulus is an indicator of the stiffness or resistance of asphalt binder to deformation under load. The complex shear modulus and the phase angle define the resistance to shear deformation of’ the asphalt binder in the linear viscoelastic region.
5.3. The complex modulus and the phase angle are used to calculate performance-related criteria in accordance with M 320.
6.1.1. Test Plates—Stainless steel or aluminum plates with smooth ground surfaces. One 8.00 ± 0.02 mm in diameter and one 25.00 ± 0.05 mm in diameter (Figure 1). The base plate in some rhcomctcrs is a flat plate. A raised portion, a minimum of 1.50 mm high, with the same radius as the upper plate is required. The raised portion makes it easier to trim the specimen and may improve test repeatability.
Note 1—To obtain correct data, the upper and lower plates should be concentric with each other. At present there is no suitable procedure for the user to check the concentricity except to visually observe whether or not the upper and lower plates are centered with respect to each other. The moveable plate should rotate without any observable horizontal or vertical wobble. This operation may he checked visually or with a dial gauge held in contact with the edge of the moveahie plate while it is being rotated. There are two values that determine the operating behavior of a measuring system: centricity (horizontal wobble) and runout (vertical wobble). Typically, wobble can be detected if it is greater than ±0.02 mm. For a new system. a wobble of ±0.01 mm is typical. If the wobble grows to more than ±0.02 mm with use, it is recommended that the instrument be serviced by the manufacturer.AASHTO T 315 pdf download.