Clays structural stability

Landfills in wet areas. Because of the problems associated with contamination of local groundwaters, the development of odors, and structural stability, landfills must be avoided in wetlands. If wet areas such as ponds, pits, or quarries must be used as landfill sites, special provisions must be made to contain or eliminate the movement of leachate and gases from completed cells. Usually this is accomplished by first draining the site and then lining the bottom with a clay liner or other appropriate sealants. If a clay finer is used, it is important to continue operation of the drainage facility until the site is filled to avoid the creation of uplift pressures that could cause the liner to rupture from heaving. 

Mixtures of clay platelets and polymer chains compose a colloidal system. Thus in the melt state, the propensity for the clay to be stably dispersed at the level of individual disks (an exfoliated clay dispersion) is dictated by clay, polymer, stabilizer, and compatibilizer potential interactions and the entropic effects of orientational disorder and confinement. An isometric dimension of clay platelets also has implications for stability because liquid crystalline phases may form. In addition, the very high melt viscosity of polypropylene and the colloidal size of clay imply slow particulate dynamics, thus equilibrium structures may be attained only very gradually. Agglomerated and networked clay structures may also lead to nonequilibrium behavior such as trapped states, aging, and glassy dynamics. 

The primary mechanism for observed long term embankment movements relate to the poor conditions of the embankment clay core, both as an inadequate sub-grade for the track and for overall structural stability. The factor of safety of the clay bank often being quite low. 

Soil physical properties most likely to be altered by biomass burning are soil structure, soil wettability, and clay mineralogy (Table HI) (43). The destruction of organic matter results in losses of soil structure, increases in bulk density, diminished aggregate stability and decreases in macropore space (44). 

The properties of filtrate reducers contribute to their different molecular structures. Nonionic filtrate reducers work by completely blocking the filter-cake pore, and anionic ones work by increasing the negative-charge density of filter-cakes and decreasing pore size. Anionic species cause further clay dispersion, but nonionic species do not, and both of them are beneficial to colloid stability [1890]. 

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