B. B. Basak, Sharmistha Pal and S. C. Datta* Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi 110 012, India Present address: Directorate of Medicinal and Aromatic Plant Research, Boriavi, Anand 387 310, India Present address: Central Soil and Water Conservation Research and Training Institute, Research Centre, Madhya Marg, Chandigarh 160 01...

The Soil Series It is frequently possible to encounter, in a very limited area, almost the whole range of every soil property: from soil reaction values of pH 3.5 to pH 9.0, from structureless to very strongly structured, from sands to clays, from impermeable to excessively permeable materials etc. It has been one of the main objectives of the pedologist to classify this seemingly incomprehensi...

Clays have been used in southern Africa as photoprotectants by the indigenous people. Typically, two types of clay are used: one white in colour and the other red. In this work, the two clays were identified and characterized, and their in vitro SPF values measured. The clays afford a low SPF but offer broad-spectrum protection. No cutaneous side effects from the use of these clays are known. F...

Scaling relationships are identified between NMR longitudinal relaxation times and clay dispersion quality in polymer-paramagnetic clay nanocomposites. Derived from a previously published analytical relationship developed from a lamella-based model, the scaling relationships are based on the enhancement of NMR relaxation rates with increasing exfoliation and dispersion homogeneity. The paramagn...

To address the high salinity of flow-back water during hydraulic fracturing, we have studied the equilibrium partitioning of NaCl and water between the bulk phase and clay pores. In shale rocks, such a partitioning can occur between fractures with a bulk-like phase and clay pores. We use an advanced Grand Canonical Monte Carlo (GCMC) technique based on fractional exchanges of dissolved ions and...

-A method of clay mineral sample preparation for electron microprobe analysis has been developed in which a film of clay plus 10-12 wt. % colloidal graphite is deposited on a porous ceramic disc using a specially designed suction device. Correction procedures are used to obtain quantitative elemental analyses representing the average chemical composition of the prepared sample. A statistical te...

Consolidation properties of soil are essential for prediction of the deformation characteristics, determination of which involves considerable time, cost, and rigorous testing process. Further, natural state of saturation is not simulated and thus for partially saturated soils the standard odometer test gives misleading results of the evaluated consolidation parameters particularly the overcons...

Using experiments, theory and simulations, we show that the arrested state observed in a colloidal clay at high concentrations is stabilized by screened Coulomb repulsion (Wigner glass). Dilution experiments allow us to distinguish this disconnected state, which melts upon addition of water, from a low-concentration gel state, which does not melt. Theoretical modeling and simulations at high co...

This study deals with a methodical identification and evaluation of physical-mechanical properties of one genetic type of geological structure. This is represented by an engineering-geological zone of eolian sediments, which is regionally rather abundant. The paper contributes to a need to identify typical soil properties for widespread geological environments in a particular region and thus ad...

The theological parameters of a clay suspension can be used to evaluate particle-particle interactions. Although there have been many studies of the rheological behavior of suspensions of reference clays, only few studies were performed with suspensions of mixed clays, and the rheological properties of these suspensions are not yet fully understood. The length-to-width ratio of some soil clays ...