the main role ofcore in earth dams is to reduce and control the seepage flow through the dam. in order to achieve this purpose, the core material is usually selected from pure or mixed clays.due to very small coefficient of permeability, the clay cores can prevent water leakageeasily. however, pore water pressures developed inside the core during construction, can not be dissipated quickly. as ...

Clay, as a rock term, describes a soft, loose, earthy material containing particles with an average grain size of less than than 0.004 mm (4 mm) in the Wentworth grain size scale and less than 0.002 mm (2 mm) in most soil investigations. Clay is composed mostly of clay minerals, but may also contain quartz, feldspar, carbonates, ferruginous material, and other non-clay materials. All clays, apa...

The work described in this paper is focused on evaluating the effect of the processing method and nanoclay (montmorillonite) content on the tensile, compressive, and impact properties of clay-epoxy nanocomposites. Nanocomposites are synthesized by two methods: mechanical mixing and shear mixing. Both these methods are capable of producing bulk quantities of clay-epoxy nanocomposites. X-ray diff...

We studied the temporal patterns of tracer throughput in the out ̄ow of large (30 cm diameter by 38 cm long) undisturbed cores from the Panola Mountain Research Watershed, Georgia. Tracer breakthrough was a€ected by soil structure and rainfall intensity. Two rainfall intensities (20 and 40 mm hr71) for separate Cl7 and Br7 amended solutions were applied to two cores (one extracted from a hillslo...

The vertical migration of M. incognita juveniles introduced at 20 cm from the roots was studied in five natural soils, 100% silica sand, 95% silica sand with 5% clay, 90% silica sand with 10% clay, and 95% silica sand with 5% clay as a concentrated layer. In natural soils the percentage of juveniles capable of migrating 20 cm and penetrating the roots decreased when the percentage of clay and s...

Identification of clay minerals based on chemometric analysis of measured infrared (IR) spectra was suggested. IR spectra were collected using the diffuse reflection technique. Discriminant analysis and principal component analysis were used as chemometric methods. Four statistical models were created for separation and identification of clay minerals. More than 50 samples of various clay miner...

Shale formations are composed of clays, feldspars, carbonates, and quartz as major ingredients. Among all the constituents, clays are the most important parameter from an application point of view because of their possibly sensitive nature; they are further categorised as migrating (illite, kaolinite, and chlorite) and reactive (smectite and mixed layers) clays. Smectite is always considered as...

X-ray phase analysis of clays is difficult because these materials generally consist of a mixture of different phases, i.e., mixed-layer minerals, individual clay minerals (non mixed-layer), and associated minerals, such as calcite and quartz. The analysis requires knowledge that presently is incorporated in a computer-based expert system. This expert system is capable of a) identification of a...

this paper presents the results of a series of monotonic and post-cyclic triaxial tests carried out on a clay specimen and three types of clay-sand mixed specimens. the focus of the paper is on the post-cyclic mechanical behavior of the mixed specimens, as compared to their monotonic behavior. analyses of the tests results show that cyclic loading degrade undrained shear strength and deformatio...

This work identifies the main phenomena that control the peptisation and transport of clay particles in a sand core. Clay can be dispersed into small particles in an aqueous solution of low ionic strength. This property is used to generate clay particles with NaCl concentration varying from 0.5 M to 0.015 M. For this purpose, a chromatographic column is initially packed with a 5 % clay-sand mix...