Natural Earth Materials Research Articles

Geosynthetic Encased Concrete Debris Stone Columns

Rapid urbanization has compelled the building industry to improve the soft soil grounds which otherwise are unsuitable for construction activities. Ground improvement helps achieve better performance by avoiding several problems like excessive settlements, large lateral flow of soft soil beneath the structures, and loss of global or local stability under operational loading conditions by modification of foundation soils. The growing quantities and types of waste materials, shortage of landfill spaces, and lack of natural earth materials highlight the urgency of finding innovative ways of recycling and reusing waste material additionally can reduce the demand for natural resources creating sustainable ecosystem. The aim of this experiment is to use crushed concrete debris (CCD) in soil stabilization. A series of experiments are to be carried out to develop an understanding on the performance of soft clay foundation beds reinforced using geosynthetic encased stone-concrete debris column. Model tests was conducted on clay reinforced with encased vertical columns filled with both CCD and aggregates. A comparative study is to be done and an assessment of ultimate bearing capacity of the composite ground is to be done. The column failure mechanism in the both the cases are to be carefully studied. Modal tests and later numerical analysis is done in PLAXIS 2D for analyzing the behavior of geosynthetic encased stone column stabilized clay bed numerically. Analyses were carried out using Mohr-Coulomb’s criterion. Lab conditions were simulated in PLAXIS for accurate comparison for same model tests.

Method to characterize inorganic particulates in lung tissue biopsies using field emission scanning electron microscopy

Humans accumulate large numbers of inorganic particles in their lungs over a lifetime. Whether this causes or contributes to debilitating disease over a normal lifespan depends on the type and concentration of the particles. We developed and tested a protocol for in situ characterization of the types and distribution of inorganic particles in biopsied lung tissue from three human groups using field emission scanning electron microscopy (FE-SEM) combined with energy dispersive spectroscopy (EDS). Many distinct particle types were recognized among the 13 000 particles analyzed. Silica, feldspars, clays, titanium dioxides, iron oxides and phosphates were the most common constituents in all samples. Particles were classified into three general groups: endogenous, which form naturally in the body; exogenic particles, natural earth materials; and anthropogenic particles, attributed to industrial sources. These in situ results were compared with those using conventional sodium hypochlorite tissue digestion and particle filtration. With the exception of clays and phosphates, the relative abundances of most common particle types were similar in both approaches. Nonetheless, the digestion/filtration method was determined to alter the texture and relative abundances of some particle types. SEM/EDS analysis of digestion filters could be automated in contrast to the more time intensive in situ analyses.

Temporal and spatial variations in the engineering properties of the sediments in Ramganga River, Ganga Basin, India

Development of infrastructure needs enormous natural Earth materials in the form of coarse and fine river aggregate materials. In India, flood plains of the Himalayan Rivers serve as an important source of river sand, leading to extensive sand mining. River Ramganga, the first major tributary of River Ganga, is one such river. In this study, 28 samples of river sediments across the stretch of the river were collected over two seasons: pre-monsoon and monsoon. The engineering properties of these sediments were studied with respect to the specifications of the Bureau of Indian Standards (BIS) and the American Society for Testing and Materials (ASTM) to understand the suitability of their use as fine aggregates in construction. An attempt has also been made in this study to correlate the variability of these properties with respect to the location and time of collection to the Ramganga River Dam at Kalagarh, the contribution of major tributaries, and the effect of monsoon. A pattern emerges from the variation of the physical properties that is explicable by these factors, whereas in general, the variation of the chemical properties does not follow a regular pattern.

Simulation and prediction for energy dissipaters and stilling basins design using artificial intelligence technique

AbstractWater with large velocities can cause considerable damage to channels whose beds are composed of natural earth materials. Several stilling basins and energy dissipating devices have been designed in conjunction with spillways and outlet works to avoid damages in canals’ structures. In addition, lots of experimental and traditional mathematical numerical works have been performed to profoundly investigate the accurate design of these stilling basins and energy dissipaters. The current study is aimed toward introducing the artificial intelligence technique as new modeling tool in the prediction of the accurate design of stilling basins. Specifically, artificial neural networks (ANNs) are utilized in the current study in conjunction with experimental data to predict the length of the hydraulic jumps occurred in spillways and consequently the stilling basin dimensions can be designed for adequate energy dissipation. The current study showed, in a detailed fashion, the development process of different ...

Analysis of the Tropism and Anti-Bacterial Potential of a Type of Clay

Natural clays have been used by man in infections of bacterial etiology, since the first historical registers. Our attention turned to a red-colored clay, known in the northeast of Brazil as “barro de lou&#231a” (dish clay). These clays and other natural earth materials seem interesting to us, as the blockage of the liberation of toxins or inactivation, may be related to the interruption of infection cycles in the skin and mucous membranes. The adsorptive and absorptive properties of the mineral clays are well documented in the cure process of skin and gastrointestinal diseases. Susceptibility and bacterial tropism tests were carried out. The results were analyzed and interpreted according to the conventional microbiological protocol. The bacterial strains, Staphylococcus aureus, Escherichia coli e Pseudomonas aeruginosa, did not present a susceptibility profile to an isotonic solution of clay, but there was an increase of the bacterial tropism as the concentration of the isotonic solution was increased, being the minimal observed concentration of 100 mg/mL. Our aim is to document a type of red clay from the northeast of Brazil with possible attraction properties (Tropism) to bacteria and their toxins.

Strength characteristics of compacted pond ash

Strength properties of compacted ash layers depend to a great extent on the moulding conditions. This paper focuses on the effects of compaction energy and degree of saturation on strength characteristics of compacted pond ash. The pond ash sample, collected from the ash pond of Rourkela Steel Plant (RSP), was subjected to compactive energies varying from 357 kJ/m3 to 3488 kJ/m3. The optimum moisture content and maximum dry densities corresponding to different compactive energies were determined by conventional compaction tests. The shear strength parameters, unconfined compressive strengths (UCS) and California bearing ratio (CBR) values of specimens compacted to different dry densities and moisture content were assessed and reported. The effects of compaction energy and degree of saturation on shear strength parameters i.e. unit cohesion (cu) and angle of internal friction (Ф) values and also the UCS values are evaluated and presented herein. The results indicate that the dry density and strength of the compacted pond ash can be suitably modified by controlling the compactive energy and moulding moisture content. The strength achieved in the present study is comparable to the good quality, similar graded conventional earth materials. Hence, it may be safely concluded that pond ash can replace the natural earth materials in geotechnical constructions.

The Effect of pH on the Uptake of Radioactive Isotopes from Solution by a Soil

AbstractThe reactions with natural earth materials of fission products and plutonium are of current interest in the field of atomic energy waste disposal and soil chemistry.Solutions containing less than 1 × 10‐9 moles per liter of selected radioisotopes were equilibrated with samples of a calcareous subsoil. The uptake of these radioactive isotopes by the soil was measured as a function of pH. The uptake of Cs137 was not affected appreciably by varying the pH between 4 and 10. The maximum uptake of Sr90 occurred at about pH 10 and decreased rapidly as the pH was lowered. The radioisotopes Pu239, Ce144, Zr95, ‐Nb95, Y91, and Ru106 exhibited a maximum uptake between approximately pH 4 and pH 8. Above pH 8 a region of reduced uptake occurred and persisted up to at least pH 11 for most of the polyvalent radioisotopes.The addition of high concentrations of sodium salts to the solution inhibited the uptake of both Cs137 and Sr90 by soil. A relatively small concentration of phosphate (0.01 M) added to the system was found, in effect, to nullify the interference of sodium ion with the uptake of Sr90, but the phosphate ions had no apparent influence on the uptake of Cs137.