Bending tests are widely used for measuring the stiffness modulus and assessing the fatigue resistance of asphaltic paving materials. The two-point bending test on trapezoidal specimens is, arguably, the most repeatable and reproducible bending test method detailed in the relevant EN12697 standards. In this test the specimen is mounted as a vertical cantilever. The base is fixed and the top is moved sinusoidally with a constant displacement amplitude. The trapezoidal shape ensures that the maximum values of bending stress and strain occur away from the ends of the specimen where there are likely to be stress concentrations.
With the James Cox equipment, two trapezoidal specimens are tested simultaneously and stiffness modulus can be determined at a range of frequencies and temperatures. In the fatigue test the specimens are subjected to a constant strain amplitude at a selected frequency and temperature until the stiffness modulus decreases to a user-selected target level (normally 50 percent of its initial value).