*3.3. Flexible-Wall Hydraulic Conductivity Test Results*

Figure 9 shows the results of hydraulic conductivity of amended compacted clay. During permeation with tap water, the *k* of the unamended, attapulgite amended, diatomite amended, and dual-additives-amended compacted clay were 8.3 × <sup>10</sup>−<sup>9</sup> m/s, 6.3 × <sup>10</sup>−<sup>9</sup> m/s, 7.4 × <sup>10</sup>−<sup>9</sup> m/s, and 5.9 × <sup>10</sup>−<sup>9</sup> m/s, respectively. Importantly, the *<sup>k</sup>* of compacted clay amended by attapulgite, diatomite, and dual-additives were lower than unamended compacted clay, which decreased by 25%, 11%, and 29%, respectively. These results indicate that the dual-additives-amended clay possessed better hydraulic performance than unamended clay.

**Figure 9.** The flexible wall penetration test results of amended compacted clay.
