No. 4 or larger sieve No. 4 to No. 200 sieve Inert Inert
Particle attraction, water absorption
Source: J.E. Bowles, 1988, Foundation analysis and design, 4th ed. (McGraw-Hill).
the type of cations that are adsorbed to the clay. If the layer of adsorbed cation (such as C*+) is thin and the clay particles can be close together, making the attractive van der Waals forces dominant between the particles, then the clay is flocculated. If the clay particles are kept some distance apart by adsorbed cations (such as Nt,), the repulsive electrostatic forces are dominant, and the clay is dispersed. Since clay particles are negatively charged, which can adsorb cations from the soil solution, clay can be converted from a dispersed state to a flocculant condition through the process of cation exchange (e.g. N* ® C*+) which changes the adsorbed ions. The reverse, changing from a flocculated to a dispersed clay, can also occur. Clay structure change is used to handle some groundwater problems in clay because the hydraulic properties of soil are dependent upon the clay structure.
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