Physical Properties Of Clays Research Articles

Preliminary study on the mechanical behavior of clay in one-dimensional compression with DEM simulations

The mechanical behavior and physical properties of clay are closely associated with its microstructure. Current research on the macroscopic mechanics and physical properties of clay is comprehensive and systematic. However, the microstructural variations underlying these characteristics have been predominantly examined under mercury intrusion porosimetry and scanning electron microscopy, while quantitative and systematic studies are notably limited. This research employs the discrete element method (DEM) simulation to investigate the microscopic responses of clay, simulating one-dimensional compression tests on two clay types: card-house and book-house structures. The analysis of pore size and morphology was conducted using virtual mercury intrusion porosimetry and the pore segmentation method. The clay microstructure was quantitatively characterized by parameters such as pore aspect ratio, orientation distribution, and cumulative pore volume curve. The findings demonstrate that DEM effectively replicates the fundamental mechanical behavior of clay, revealing and explaining the evolution pattern of clay pore structure during one-dimensional compression in terms of platelet alignment adjustment. This macroscopic compression is characterized by variations in pore size distribution, orientation, and aspect ratio.

The influence of art material and instruction during art making on brain activity: A quantitative electroencephalogram study

In art therapy, it is assumed that art materials and the given instructions during art making evoke different experiences that contribute to mental health. It is theorized that cognitive, affective and sensory experiences during art therapy engage several brain networks. Electroencephalogram (EEG) measurements appears to be a promising way to measure brain activity during art making. The aim of this study was to investigate whether brain activity patterns will differ during the use of specific art material properties and instructions during art making. In this study, a quantitative EEG experiment (n = 50) using a within subject design with three conditions was conducted; art making with pencil without instruction, art making with pencil with instruction and art making with clay without instruction. Results showed that working with clay resulted in more delta activity compared to working with pencil. The different physical properties of clay and pencil seem to activate different brain activity with clay leading to more delta activity than working with pencil, which may be explained by a more relaxed state. In addition, results show that art making with instruction leads to more relaxation than working without instruction. During the condition with a specific instruction, there was less alpha and beta1 activity, compared to the pencil condition without a specific instruction. All art making conditions led to more activity in the parietal lobe compared to the frontal lobe. We discuss these findings and their implications for future research and clinical art therapy practice.

SOME PHYSICOCHEMICAL PROPERTIES OF GEORGIAN BENTONITE CLAY

Clay minerals are known as biocompatible materials and have been utilized for medicinal aims from long ago. Currently, bentonite clays have also been widely investigated for broad spectrum of new applications in many biomedical spheres due to their unique properties - expansion and adsorption abilities - which are very useful in pharmaceutics, cosmetics, drug delivery systems and tissue engineering. Swelling has a significant impact on the rheological and physical properties of clay. It depends on many factors including temperature, pH, and polarity. In addition, since bentonites have negative surface charge they possess high adsorption ability for cationic elements. The priority task at the I. Kutateladze Institute of Pharmacochemistry TSMU is to extend the biopharmaceutical application of Georgian bentonite clay. Several semisolid formulations were proposed on the bases of the preparation - Tikha Ascane (TA), received from the clay of Askana Deposit (Ozurgeti region of Georgia). In this study we investigated the swelling capability of TA in the presence of different temperatures, polarities and pH; the interaction behaviour of bentonite with cationic compounds was also evaluated. As many researches are focused on the combination clay minerals with cationic polymers for the preparation of effective therapeutic systems, we examined the suitability of TA as a substrate for the obtaining hybrid composites with biopolymer Chitosan (CS). The samples were characterized by examining FTIR spectra and morphology. The obtained data indicate that swelling capability of TA is affected by temperature, pH, and polarity of solutions.  FTIR analysis showed that cationic drug and polymer (CS) can be successfully incorporated in TA through adsorption and formation chemical bonds. Microscopic analyses demonstrated homogeneity of TA-CS composites. These results will be used in future for preparing drug - clay or drug - polymer composites based on TA for biomedical application.

Effect of Sand Faction Percentage in Soil Mixture towards Soil Support Power for Dam Construction

Knowledge of soil, which is an essential construction material, has great importance for dam construction. The level of density and carrying capacity of the soil is very important and should be taken into consideration in the planning and designing stages of civil construction, considering the soil functions as a means to withstand the load or structure built on it. Stabilization using sand soil material is one of the ways to meet the strength requirements of soil carrying capacity when there is no suitable soil material found in the nearby area. This paper aims to elucidate the physical properties of clay using a mixture of fine sand to reduce the risk of shrinkage when used for dam construction. Several analyses were carried out to find out the effect of the fine sand percentage in the clay mixture to decrease the swelling test value and permeability test of the soil carrying capacity for dam construction. The types of soil tested were silt clays taken from Tritisan subdistrict of East Lampung which were then stabilized using fine sand material from Central Lampung, Indonesia. This research was conducted using a mixture of sand, with percentages of 10%, 20%, 30%, and 40%. Subgrade tests such as CBR and permeability tests were also undertaken to investigate other soil properties from each sample. The results indicate that a higher percentage of sand causes decreasing water content. Thus, the value of the carrying capacity of the soil is increasing. The findings can be used to facilitate the increasing use of clay mixtures with the percentage of fine sand in case suitable clay material cannot be found around dam construction sites. The implications with suggestions for future research are also discussed.

Ion exchange in atomically thin clays and micas.

The physical properties of clays and micas can be controlled by exchanging ions in the crystal lattice. Atomically thin materials can have superior properties in a range of membrane applications, yet the ion-exchange process itself remains largely unexplored in few-layer crystals. Here we use atomic-resolution scanning transmission electron microscopy to study the dynamics of ion exchange and reveal individual ion binding sites in atomically thin and artificially restacked clays and micas. We find that the ion diffusion coefficient for the interlayer space of atomically thin samples is up to 104 times larger than in bulk crystals and approaches its value in free water. Samples where no bulk exchange is expected display fast exchange at restacked interfaces, where the exchanged ions arrange in islands with dimensions controlled by the moiré superlattice dimensions. We attribute the fast ion diffusion to enhanced interlayer expandability resulting from weaker interlayer binding forces in both atomically thin and restacked materials. This work provides atomic scale insights into ion diffusion in highly confined spaces and suggests strategies to design exfoliated clay membranes with enhanced performance.

DETERMINING QUASI-SINGLE-PHASE SOIL SYSTEM SETTLEMENTS TAKING INTO ACCOUNT THEIR CREEP

This article discusses determining foundation settlements taking into account the creep of quasi-single-phase and two-phase soil systems of the bases. There is presented distribution of clay soils in depth in the territory of Central Kazakhstan. The analysis of the stratification results shows that physical properties of clays are heterogeneous and have sufficiently large scattering of values in depth. It has been experimentally established that clay soils selected at different depths are characterized by shear decaying creep. Methods of determining the coefficients of consolidation and creep, the deformation modulus from experimental curves are described. The calculationformulas are given for determining quasi-single-phase and two-phase soil systems taking into account their creep. The calculation formulas obtained on the basis of the results of experimental data indicate the novelty of the method.

Potential Recovery of a Textile Wastewater Treatment Plant Sludge Into Clay Bricks

As the country started to become an export oriented country since the early 1970s, the growth of Malaysia’s textile industry has increased greatly. In 2011 alone, the country has provided a total of RM10.8 billion of exports of textile products and RM 6.6 billion of imports. This valuable improvement has lead to several environmental impacts involving land and water pollution. The current trend in waste management is to examine the feasibility of using textile sludge generated in wastewater treatment plants of textile industry as a partial replacement for clay as building materials. The chemical and physical properties of clay and textile have been analyzed. The effects of sludge proportion (0%-10%), and firing temperature (950oC and 1180oC) on the quality of the clay bricks were examined. The tests were conducted as per British Standard (BS) codes to investigate the potential of the textile sludge to be incorporate into clay for use as engineering blocks and load bearing bricks. According to the results, sludge addition and firing temperature are the important factors to determine the quality of clay bricks. All clay samples satisfied the requirement of British Standard norms in term of compressive strength and water absorption. It is seen that all bulk density of clay samples did not comply with good quality of clay brick but they can be categorized as lightweight building materials. Textile sludge was also tested for substitution into cement bricks. Cement samples with 10% textile sludge substitution comply with the requirement of British Standard norm for load bearing class 3. In summary, this study provides a preliminary research output that will contribute to expand a new area of research in recycling of textile sludge.

Some generic trends on the basic engineering properties of fine-grained soils

The factors influencing the engineering properties of fine-grained soils are the consistency limits, defined as primary properties, and water content, density and soil structure defined as secondary properties. This paper considers over 1000 data from the literature and laboratory tests where the plasticity ratio of clays (Rp), defined as the ratio of plastic limit to liquid limit, was tentatively correlated to the specific surface area (SSA), clay fraction of clays, and the liquidity index (LI). Rp was also used to interpret the Casagrande plasticity chart. Rp decreases for increasing “modified” SSA, whereas the correlation with the clay fraction is less pronounced. Rp is linked with the LI within a range of 0.2–0.8. Results show, therefore, that physical properties of clays are extremely variable and a unique relation among the properties is extremely difficult to obtain. The goal of this paper is to provide a general overview about the intercorrelation among the engineering properties of clays.

Psyllium Seeds Used as Pore Forming Agent in Clay Bricks

Abstract Psyllium seeds were used as a pore forming agent in clay mixtures due to their properties to swell in the presence of water in a similar way with clays. The purpose of the study it was to establish the optimal quantity of psyllium seeds that can be added as pore forming agent in clay bricks to maintain the mechanical properties required. The physical properties of clays and of the psyllium seeds were analyzed, and then psyllium seeds were added in clay matrix in percentages of 5, 10, 15 of volume. The compressive strength and water absorption were determined for each sample. The pore size distributions were measured by using image J software and analyzed microscopically. The texture, the porosity and the fissure/cracks size are directly influenced by the amount of psyllium seeds contained in the clay mixtures. Reducing the pore forming agent to 5%, the tendency of cracking decreases and suggests that the mixture can be used in clay bricks manufacturing.

Mechanical properties of clayey soil relevant for clogging potential

Due to its advantages, including reduced operation time and cost, tunnelling with boring machines in urban areas has become a popular technique over hand-tunnelling or open-trench excavations. However, tunnelling in clayey soil poses a great challenge since the mechanical and physical properties of clays cause different issues, one of which is clogging. To solve this problem, engineers have treated the soils with different soil conditioners in order to change their rheological properties, improve their manageability and eliminate undesirable characteristics. However, the root of this problem is the lack of understanding the phenomenon and characterising it on the framework of soil mechanics. By considering the use of polymers, this paper aims to provide information regarding the theory involved in this mechanism and the factors influencing clogging potential. The authors present a systematic study of the physical and mechanical properties of plain soil and conditioned soil, which includes a direct shear test, vane shear test and Atterberg limits test. Results show that the initial water content, roughness of shear plate and percentage of additive have a significant effect on the clogging potential. Additionally, the results are plotted on an empirical diagram to understand the clogging potential by relating the clogging potential to soil properties.

Исследование неолитической керамики КНР методами естественных наук

Neolithic Age is characterized by great changes in social, demographic and economic life of prehistoric tribes of China. It was the time of development of different spheres of material production including the production of ceramics. During this period, all the basic methods of vessel construction were formed, a primitive potter’s wheel appeared, firing technology and the principles of ornamentation were improved and became more complex. At the Neolithic Age the ancient ceramists developed a basic set of categories and forms of pottery. Currently over 30 Neolithic cultures of China were allocated, they are being combined in some local traditions, depending on the geographic area. The article provides an overview of the publications of Chinese archaeologists dedicated to the analysis of the most representative pottery cultures of China by methods of natural sciences. These are the results of radiocarbon analysis to justify the absolute chronology of the sites, as well as petrographic and chemical analyzes which determine the composition and physical properties of clays. The article represents not only the Huanghe River basin cultures (Peiligang, Yangshao, Longshan), but also the cultures of lower and middle reaches of the Yangtze river (Hemudu, Daxi, Qujialing) of various Neolithic periods that helps to provide a holistic view on the development of pottery techniques during this period and highlight the characteristics of the various regional traditions.

Experimental study on physical properties of clays with organic matter soluble and insoluble in water

Six natural clays with a predominant clay mineral of illite and two pure clay minerals (kaolinite and smectite) were mixed with organic matter to prepare 64 samples of organic clays containing different organic compounds at different contents. The organic compounds are classified into two categories (insoluble and soluble in water) for studying their effects on physical properties of organic clays investigated. When original clays are mixed with organic material insoluble in water, the particle size distributions and the particle densities of organic clays can be approximately determined pro ratio of each component. Adding humic acid into original clays causes little aggregate or disperse action on solid particles. The Atterberg limits of organic clays containing organic matter insoluble in water vary with organic content in a nonlinear fashion, and its changing rate depends on the liquid limits of original clays. On the other hand, when original clays are mixed with organic compounds soluble in water, dissolved organic matter in pore water should be taken into account for measuring their Atterberg's limits. Atterberg's limits of organic clays containing organic matter soluble in water are greatly affected by the predominant clay mineral of original clays. For the original clays with a predominant clay mineral of illite and kaolinite, liquid limit increases with the increase in organic content, but contrary changing fashion is found for smectite.

Physical Properties of Clay and Bricks in Nyagatare, Rwanda

The proportion of Rwanda population that will be living in urban centres will be 35% by the year 2017. The extra buildings will definitely be made of bricks because of its abundance in the country. The objectives of the study were: firstly, to determine brick production at the site, secondly, was to determine depth of borrow pits for clays. Thirdly to determine Atterberg limits for clay at 300mm and 500 mm depths. Lastly, was to determine percentage losses in bricks. Methodology involved use of questionnaires to determine brick production and losses, measurements of depths of clay borrow pits and laboratory work for Atterberg limits of clay. The results showed that the cumulative brick production at the site was 58.12 million bricks during 2000 to 2013 period with average production of 4.15± 0.55 bricks per year. The depth of borrow pits varied from 29 cm to 43 cm with an average depth of 34 cm. The values of Liquid Limit, Plastic Limit and Plastic index were 49.15%, 19.78% and 29.37%, respectively at 500mm depth. There were more bricks that were broken during burning than drying. The average losses for the study site were 27.13 ± 3.67% during the brick manufacturing process.

222Rn and CO2 soil–gas geochemical characterization of thermally altered clays at Orciatico (Tuscany, Central Italy)

Abstract The physical properties of clay allow argillaceous formations to be considered geological barriers to radionuclide migration in high-level radioactive-waste isolation systems. As laboratory simulations are short term and numerical models always involve assumptions and simplifications of the natural system, natural analogues are extremely attractive surrogates for the study of long-term isolation. The clays of the Orciatico area (Tuscany, Central Italy), which were thermally altered via the intrusion of an alkali-trachyte laccolith, represent an interesting natural model of a heat source which acted on argillaceous materials. The study of this natural analogue was performed through detailed geoelectrical and soil–gas surveys to define both the geometry of the intrusive body and the gas permeability of a clay unit characterized by different degrees of thermal alteration. The results of this study show that gas permeability is increased in the clay sequences subjected to greater heat input from the emplacement of the Orciatico intrusion, despite the lack of apparent mineral and geotechnical variations. These results, which take into consideration long time periods in a natural, large-scale geological system, may have important implications for the long-term safety of underground storage of nuclear waste in clay formations.

Developing Preschoolers' Science Vocabulary through Clay Explorations

The purpose of this study was to determine the improvement in descriptive vocabulary of preschool children as a result of lessons that focused on the physical properties of clay. During a six-lesson art-science unit, four and five year old children used familiar artificial clay, unfamiliar modeling clay, mud, and natural potter's clay to experiment with different techniques and to make a pinch pot, which they subsequently glazed and had fired. Throughout the lessons, descriptive vocabulary was repeatedly modeled and reinforced. Two pretest-posttest instruments were administered. Students improved in demonstrating targeted vocabulary words (e.g. pinch, bend, coil, flat) with a mean of 50% of the students demonstrating each of the sixteen words correctly on the pretest compared to 81% on the posttest. Students were also assessed on vocabulary used as they verbally described wet and dry natural clay samples and unglazed and glazed ceramic pieces. Again, students showed a significant increase in speaking vocabulary. However, passive and observational tasks, requiring little or no use of language and vocabulary, revealed minimal acquisition of targeted vocabulary.

Physical Characterization of Ukpor and Ahoko Clay Deposits for use as Industrial Raw Material

The physical properties of some Nigerian clays were studied in order to determine their suitability for a variety of industrial applications. From the analysis, the specific gravity of Ukpor and Ahoko clays were 1.89 and 2.26 respectively and the Plasticity Index 26.05% and 22.45%, drying shrinkage was 18.90% and 8.2% and particle size distribution showed that the samples are clays. The results show that the physical properties of the clays are within the specifications for kaolin clays and are suitable for industrial uses.

Diffusion through Pulverized Stone Compared to Other Mineral Barrier Materials

Construction of a waste disposal site requires an effective barrierthat separates waste from a sub-base and minimizes the migrationof contaminants from the site to an aquifer. Barrier layers mostoften used are natural clayey deposits or compacted clay liners andPEHD geomembranes. However, some regions, the Croatian karstfor example, are mostly short of clay. For this reason, the use ofpulverized stone, the by-product in the building-stone industry – as apotential liner material was investigated. Considering diffusion is animportant mechanism of contaminant transport through barriers, thispaper describes the method and apparatus for determining the diffusioncoefficient of pulverized stone. Measured diffusion values wererelated to sample compaction and compared with the physical propertiesof clay, geosynthetic clay liners and PEHD geomembranes. Otherphysical properties of pulverized stone such as the filtration coefficient,density and particle size distribution are also presented. Finally,the suitability of pulverized stone for barrier construction is discussedbased on the results obtained.

Impact of microstructure on the hydraulic conductivity of undisturbed and artificially prepared smectitic clay

The microstructure controls most physical properties of clays. This is obvious when comparing natural smectitic clay and clay prepared by drying, grinding and compression of air-dry powder. The hydraulic conductivity of the artificially prepared clay is higher than that of the undisturbed, natural clay. If the latter clay is percolated with distilled water and Ca-rich water, the difference in conductivity is obvious, while percolation of the natural clay with these solutions does not yield a very dramatic change. This is because the microstructure of the natural clay is very homogeneous, while the artificially prepared clay preserves the high density of the powder grains while the gels in the voids between the grains are soft.

The application of clay minerals in ceramics

Deriving in ancient Greece as keramikos, the term potters clay was only reconfirming the recognition of clay as man's earliest utilitarian raw material. Clay is no doubt man's first manufacturing and construction raw material and fortunately, through the miracle of fire, the first lasting chronicler of his own origin and early history. Oddly enough, millennia later, the material still occupies leading positions in the construction and manufacturing areas with each generic end-use accounting annually for about one billion dollars of salable product in the U.S. alone. Needless to say, clay ceramics are proven products. The longevity of clay in the ceramics industry stems in part from its variable and some times unique physical and chemical properties and in part to its ubiquitous occurrence and relatively inexpensive produced value. Clay properties of interest to the ceramics industry are plasticity and moldability, of course, but also chemistry, color, refractoriness, solubility and corrosion resistance, electrical properties and the many possible variations on these and other properties afforded by the essentially two-dimensional morphology of the individual clay platelets. In addition to construction (brick, tile, sewer pipe, cement, fiberglass, roof granules, paint, etc.) and manufacturing (refractories, kiln furniture, sanitary ware pottery and dinnerware) clays are used in the calcined form as fillers, carriers, extenders and grogs. Chemistry, because of its basic relationship to both the chemical and physical properties of clay, has been the subject of continuous studies over the past few decades and is responsible for most of advances in processing which have taken place. Color body removal and the elutriation of objectionable salts have led to more or less sophisticated slurrying and the beneficiation which this medium affords. In particular, the water washing, first initiated by the kaolin industry and now extended to ball clays, and high-energy magnetic filtration have noticeably improved the quality of clay and broadly expanded its market in the ceramics industry. At the present time, ceramics markets are under pressure in several areas. Refractories have followed the downturn in American steel production. Although stabilizing, this industry continues at reduced levels which threatens to become the new norm. Likewise, dinnerware and tile production in the U.S. have declined because of foreign competition.

Importance of Physical Properties of Clays in Oil Formation and Migration: ABSTRACT

Many source rocks have argillaceous matrixes. Until recently, only chemical interactions between clay minerals and organic matter (catalytic effect) have been given serious consideration. It appears now that the physical or physico-chemical properties of clays also play a key role in the processes of primary migration of oil. Among these properties are (1) microstructure of clays which influences the porosity and permeability in both the water and oil phase, (2) mechanical behavior of clays which may contribute to the microfracturing processes thus allowing the expulsion of oil from source rocks, and (3) physico-chemical properties of adsorption and wettability of clays which act strongly because of the high specific area of clay minerals. This property may influence the ermeability of clay shales. In addition, adsorption is selective toward various components generated by organic matter, thus explaining major differences observed between the composition of source rock extracts and reservoir oils. On a larger scale, such as anticlinal structures, clays are commonly the origin of fluid pressure anomalies. High pressures modify the flow system, since fluids are drained preferably by the tops of structures. The flow of water due to natural convection eventually may cause the alteration of clay minerals and enhance the permeability of the overpressured sections beneath the pressure seal. This process contributes to the modification of geothermal conditions in undercompleted rocks where poor thermal conductivity conditions exist. These combined effects influence both the nature and spatial distribution of hydrocarbons trapped in reservoirs. Therefore, a better knowledge of the physical properties of clays should lead to a better understanding of the role of clays in the formation and migration of oil and gas and thus lead to better exploration practices. End_of_Article - Last_Page 1447------------