2.2.5. Direct Shear Tests

The size of the test specimen was *d*<sup>0</sup> = 64 mm and *h*<sup>0</sup> = 25 mm. Saturated specimens with 0.0% and 2.0% XG content were dried and wetted. The initial water content of the specimens was 22%. The drying and wetting paths of the specimens are shown in Figure 6 The specimens were uniformly dried to a state of 2% water content (drying path AB) and then wetted to a different water content (2%, 4%, 8%, 16%, or 22%). Fast shear tests were then carried out under vertical stresses of 50, 100, and 200 kPa. The automatic direct shear and residual shear test system is shown in Figure 7. The Shear Trac-II test system was operated by computer shear software and the control panel of the shear apparatus to receive immediate feedback on the loads and displacements monitored by the sensors.

**Figure 6.** Drying and wetting paths.

**Figure 7.** Shear Trac-II test system.
