Clay Research Articles

METHODS FOR DESIGNING PARTIALLY INFLATED GEOTUBES

A widely used technique in constructing dikes for land reclamation is to use tubes made of sewn geosynthetic sheets. These tubes are usually filled with slurry comprising soils, such as sand, silt, and clay. The tension stress that develops in geosynthetic tubes during tube filling is the dominant factor considered in constructing safe dikes. Existing design methods are effective for sausage-shaped tube designs; however, they cannot be directly applied in flat tubes, which are commonly used in dike construction. This paper presents a procedure that can determine the relationships among tube size, pumping pressure, unit weight of the slurry, and tension stress in geosynthetic tubes. All these approaches are programmed to enable dike designers to select a suitable geosynthetic design for dike profiles.

ASSESSING SOIL ERODABILITY FACTOR FOR RUSLE2 IN BAHLUIEȚ CATCHMENT, EASTERN ROMANIA

In Romania, there is a lack of methodology for soil erosion estimation, in the sense that although a soil loss estimation equation similar with USLE is used, the factor estimation is not comprehensively covered. That is why we have turned to RUSLE2 methodology to compute soil erodability factor (K) for Bahluieț catchment (Eastern Romania). We have used a soil profile and soil unit legacy database for estimating K values from granulometry sand, silt and clay values. We tested the two equations proposed by the RUSLE2 methodology, but we have chosen to use the values from only one of them, because for the other the estimated value were incomprehensibly high. For comparison, we have used also an estimation made by the EUROSOIL JRC and based on the same equation for which the estimation failed. The majority of the soils from the study area are from the clay loam, sandy clay loam, sandy loam and loamy texture classes. The mean K factor value is 0.0181, corresponding to soils with low erodability. The K values stretch from 0.01 to 0.03, the majority of the soils in the study area having K values in the range between 0.01 and 0.022. We observed a spatial pattern in K values distribution which is explained by the lithology of the study area, the central, southern and eastern areas having bigger soil erodability, because of the loamy texture, while western areas have a sandy loam texture, which give lower soil erodability values. Our result is lower than the estimation of EUROSOIL JRC modelling, which for our study area has a mean of 0.043, and the majority of values falling in the 0.026-0.054 range. Our opinion is that these values are too big, since the texture of the soils is clayey to sandy loam. This conclusion seems to be sustained also by the soil erosion values and sediment yields obtained using our estimated K values, which are consistent with the soil losses and sediment yields reported in the study area, conclusion which cannot be drawn for the estimation of EUROSOIL JRC data (which will give overestimated soil erosion and sediment yield values).

PARTICULARITIES OF SOIL FORMING PROCESSES IN STEMNIC (BUDA) BASIN

The paper proposes the study of pedogenetic processes in Stemnic (Buda) basin in close connection with natural factors (rocks, relief, water, vegetation) to which is added human activity. In order to understand the distribution of the soil types in the study area is analysed the distribution and intensity of the pedogenetic processes. Representative pedogenetic factors have acted at the same time, resulting processes such as bioaccumulation, cambization, salinization and alkalization, gleyzation and stagnogleyzation, carbonation and last but not least shrinking-swelling. Bioaccumulation is omnipresent in the basin, being represented by an Am horizon with humus accumulation in the first 25 cm, on 44% of the carted surface, and an Ao horizon with a reduced content of organic matter. Clay illuviation is specific for luvisols, appearing on 31.8% of the mapped surface, then cambization on 12%, following in decreasing order of the surfaces by alkalization and salinization, gleyzation and stagnogleyzation and with only 2% vertisoils.

Multi-scale analysis of porosity in diagenetically altered reservoir sandstone from the Permian Rotliegend (Germany)

Abstract We present a multi-scale 3D analysis of the pore network in a Rotliegend reservoir sandstone, both at the scale of the sand grains and the scale of the diagenetic clay cements that grow in the intragranular volume (IGV). For this we combine optical microscopy, micro-CT, Broad Ion Beam polishing, Scanning Electron Microscopy, Woods Metal Porosimetry and Focussed Ion Beam–SEM tomography. In cm-scale layers the samples show differences in IGV and sand fabric. In the layers where IGV is higher, there is less diagenetic cement and the IGV forms a connected network; in the layers where the sand fabric is more compacted, larger pores are connected via the pore network in the diagenetic clay cements with pore throat size down to 20 nm in diameter. We show that the pore network in all types of diagenetic clay is connected and conclude that the total gas volume that can be produced from such a reservoir sandstone includes the pore volume in the diagenetic clay cements. We predict a major change in transport properties when the diagenetic clay fill renders the IGV disconnected.

The Effect of Avocado Tree (Persea americana Mill.) on Selected Soil Properties and Under storey Plants in Southern Ethiopia

Avocado tree plays an important role in influencing soil properties and under storey plants. Thus, evaluating its influence becomes valuable for identifying sustainable land management practices. With the objectives of assessing the effect of avocado tree on selected soil properties and understorey plants, thirty (30) model farmers were selected from three Woredas using simple random sampling technique for semi-structured interview. In addition, a total of 72 composite and undisturbed soil samples were collected using RCBD design to analyze chemical, physical and biological properties of the soil. Understorey plants were counted within 2m2 at each treatment for determination of richness (S) and Shannon diversity index (H'). Root distribution was counted within 0.2m2 area. The result of the study indicated that all farmers in the study area have witnessed the negative impacts of avocado tree on soil and understorey plants. However, the soil analysis didn't support the farmer's apprehension. SOC, TN, Pt and sand decreased while bulk density, silt and clay fractions increased along treatments and soil depths. Species richness and diversity of plants increased along the treatments. Higher root density was observed at the top soil surface and becomes less in number along treatments. SOC played a vital role in influencing soil properties in the area. Management differences (land use, shading and spacing), micro-climate variability and hydrology might be the contributing factors for the influence of avocado tree on the soil and understorey plant. Thus, adjusting the spacing between avocado trees, land use and implementing site-specific management practices may reduce the problem. Key Words: Model Farmers; Persea Americana; Soil Properties; Under storey Plant.

Crop water productivity for sunflower under different irrigation regimes and plant spacing in Gezira Scheme, Sudan

Two field experiments with Sunflower on deep cracking soil with heavy clay (vertisol) were conducted at Gezira Research Station Farm during two executive winter seasons, in WadMedani, Sudan. The crop was sown in the third week of November and in the first week of December for seasons 2012 and 2013 respectively. The experimental design was split plot design with three replicates. The Sunflower hybrid tested in the study was Hysun 33. The objective of this study was to determine the effect of three different irrigation intervals of 10, 15 and 20 days and two intra-row plant spacings of 30 cm and 40 cm on yield and yield components of Sunflower. The seed yields obtained from the different treatments were in the ranges of 1890-3300 kg/ha and 1590-3290 kg/ha for the first and second season respectively. The corresponding computed on average crop water productivity was in the range of 0.31-0.43 kg/m3. The study clearly indicated that the highest seed yield was obtained when the crop was sown at 40 cm plant spacing and irrigated every 10 days. The highest crop water productivity was achieved from irrigation every15 days in both planting spacings

The effect of principal stress ratio on creep behaviour of over-consolidated clay under plane strain conditions

The effect of principal stress ratio on creep behaviour of over-consolidated clay under plane strain conditions

Kinetics of Cu (II) Adsorption on Organo-Montmorillonite

Commercially available montmorillonite (Mt) was converted to organo-montmorillonite by grafting with tetramethylammonium (TMA) and tetrapropylammonium (TPA) cations to obtain potential adsorbents for metal cations. TMA-Mt and TPA-Mt showed IR bands at 1489 cm -1 and 1389 cm -1 attributed to C-N vibrations in tertiary amines and ơ as (C-H) bending vibrations due to CH 3 groups of the (CH 3 ) 4 N + cation, indicating intercalation of Mt with TMA and TPA. The basal spacings obtained from the XRD data showed marginal increase due to introduction of the quarternary ammonium ions. The CEC of Mt, TMA-Mt and TPA-Mt were 220, 294 and 257 cmol/g respectively showing an increasing order with modification of the clay. Cu(II) adsorption on the adsorbents showed that the interactions conformed to second order kinetics with the second order rate coefficient of 1.06 × 10 -2 , 9.00 × 10 -3 and 1.31 × 10 -2 L mg -1 min- 1 respectively for Mt, TMA-Mt and TPA-Mt.

Effects of Banana Compost on Growth, Development and Productivity of Sorghum bicolor Cultivar (Tabat)

The research was targeted to determine the effect of organic fertilizer prepared from the composting of banana waste on growth, development, morphologically and productivity of Sorghum bicolor ‘cv (Tabat)’. In order to convert huge of banana residues parts wastes and to reduce the chemicals fertilizers pollution, the banana compost was used on Sorghum bicolor in this study. This type of organic fertilizer detected magnitude of morphological changes on different parts of the plant used in this experiments. The other uses of the banana compost were the improvement of texture, structure, water holding capacity, permeability and productivity of the soil. The experiments were conducted at the green house of the Department of Biological and Biotechnology and Environmental Science, Al Neelain University, Khartoum, Sudan. In these experiments banana compost was used at different levels (10g , 20g and 30g) for each 500g of clay soil, which were equivalents to 1 ton, 2 tons and 3 tons per fedan respectively. Two controls, control virgin soil and control with recommended nitrogen level were used. The results showed that the treatments with 3 tons banana compost level had its significant ( P < 0.05) over the both controls with a maximum growth rate in the plants morphology as well as length of the plants of 11.9cm. and the mass productivity of one gram.

Secondary mineral assemblage as indicator of multistage alteration processes in basaltic lava flows: evidence from the Lessini Mountains, Veneto Volcanic Province, Northern Italy

The secondary mineral assemblages in the Tertiary basalts from the Lessini Mountains are mainly clay minerals and zeolites, and result from multistage alteration processes. In the earliest Stage I, clay and silica minerals precipitate along the inner walls of the vesicles, followed by the deposition of the fine-grained zeolites of the Stage II (erionite, offretite, analcime, natrolite, heulandite and stilbite). The final Stage III is marked by a new generation of large, well-shaped zeolites (phillipstite-harmotomo, gmelinite, chabazite, willhendersonite and yugawaralite), followed by extensive crystallization of calcite. New morphological and chemical data are presented herein in order to reveal the chemical compositions of Lessini zeolite species, which have never been analyzed before. Textural and chemical observations indicate that the chemical elements for Stage I and II alteration minerals derived from the alteration of the basaltic glass and the primary phases in the volcanic host rocks. The final mineral assemblages of the Stage III suggest a variation in the crystallization conditions, probably related to the presence of new, late-stage fluids enriched in Ca and (CO 3 ) 2- , leached from the surrounding calcareous rocks.

Grounding Resistance Characteristics of Gravity Foundations of Offshore Wind Turbines in the Intertidal Zone

Compared with onshore wind turbines, offshore wind turbine develops very quickly in recent years due to less land cover, higher wind speed and steady wind direction. At present, gravity foundations of offshore wind turbines are widely applied in Rudong intertidal wind farm in China. However, up to now, few attentionsare paid to grounding of gravity foundations. In this paper, grounding resistance characteristics of gravity foundations of intertidal wind turbines were calculated and analyzed systematically. Various impact factors, including depth of seawater, resistivity and thickness of clay and gravel layers, and size and depth of pile pumped into ground, were considered. Analytical results show that grounding resistance is affected significantly by depth of seawater. If seawater depth is less than 0.3 m, power-frequency and impulse grounding resistances in intertidal zone of gravity foundation offshore turbine will, in some conditions, exceed limited value specified in standards. As seawater depth increases, both power-frequency and impulse grounding resistances decrease rapidly. Moreover, the two types of grounding resistances increase with increase of soil resistivity of clay and gravel layers, and decrease with increase of clay layerthickness, although these effects become weaker as depth of seawater increases. Structure size of gravity foundation, including its diameter and driven depth, has limited effect on resistances. These results are of great significancefor grounding design of gravity foundations of offshore wind turbines.

Improvement of silty clay by vacuum preloading incorporated with electroosmotic method

A laboratory test was performed to assess the effectiveness of vacuum preloading incorporated with electroosmotic (EOM) treatment on silty clay (combined method) for reclamation projects like new disposal ponds, where the horizontal electrode configurations beneath the soil layer were possible and the drainage pipes and the prefabricated vertical drains (PVDs) system could be easily installed in advance before the sludge dragged from sea bed or river bed was filled into the site. Three groups of tests were conducted on the silty clay from Qinhuai River in Nanjing, China. The model is able to apply vacuum pressure at the bottom of the soil layer and a direct current electric field simultaneously. It is also possible to measure the pore pressures at different depths of soil column, and the changes in settlement and volume with the elapsed time. In this study, the vacuum preloading method, vacuum preloading applied at the bottom (VAB method), was applied and the cathodes were installed beneath the soil layer. The results obtained indicate substantial reduction in water content, and increases in dry density and undrained shear strength in comparison with those obtained by the vacuum preloading only, particularly at the positions close to the anode. The combined method utilizes the vertical drainage flow created by the electroosmosis integrating the horizontal drainage flow created mostly by the vacuum pressure. The total drainage flow can be calculated as a result of the vertical drainage flow by electroosmosis only and the horizontal drainage flow by the vacuum preloading only. The way of placement of the cathode and the anode in the combined method also overcomes the disadvantage of EOM method itself, i.e. the appearance of cracks between the anode and the surrounding soil. Moreover, it is observed that the vacuum preloading plays a primary role in earlier stage in deduction of free pore water; meanwhile, the electroosmotic method is more efficient in later stage for absorbing water in the diffused double layers of soil.

Poly (Lactic Acid)/MMT Nanoclay Hybrid Nanocomposites : Mechanical and Thermal Properties

Poly (lactic acid)/clay nanocomposites were prepared by solution-casting and melt-blending techniques, and their morphologies and mechanical properties were studied. In morphology studies revealed an intercalated–exfoliated mixed structure for the nanocomposites obtained by both techniques. SEM images show a good clay dispersion degree. Sodium lauryl sulphate (SLS here after called) is used to modify the MMT Clay to improve the surface characteristic of the clay. The mechanical properties of nanocomposites from the melt-blending technique were superior to those obtained by solution-casting method. In both cases, the highest elongation at break and Young’s modulus were achieved at 5wt% SLS-montmorillonite SLS-MMT content.

Characterization of Two Natural Clays and Their Application as Adsorbents for Treatment Process of Dye Effluents

The aim of the present work is to explore and compare the adsorption capacity of two different clays for removal of textile dye from aqueous solutions. For this purpose, the adsorption of Green Remazole 6B; a reactive dye used in textile industry, was studied in batch mode. The clays used were provided from two different deposits in west of Algeria, one located in Ain-Temouchent (C46) and the other in the region of El Bayadh (C32). Before investigating the adsorption of textile dye, the clays were characterized by various techniques of analysis in order to study all the relevant features. The techniques used are: X-ray diffraction, infrared spectroscopy (IR) and Chemical analysis. Chemical analysis and infrared spectroscopy (IR) show that clays are mainly constituted of alumina and silica in major quantities and other elements in minor quantities. XRD analysis shows that C46 is illite clay, contaning kaolinite, smectite and quartz. On the other hand, C32 is kaolinite clay with presence of illite, smectite, chlorite and quartz. To investigate the adsorption of the textile dye, clays have been previously modified by acid treatment with H2SO4 and they were tested in their natural state and in their acid-activated form. Different adsorption tests concerning the contact time, the initial dye concentration and the pH were investigated by conducting a series of batch adsorption experiments at room temperature. The adsorption equilibrium data were analyzed by using Langmuir and Freundlich adsorption isotherms models. The results show that Acidic pH was favorable for adsorption of the dye and the Freundlich model agrees very well with experimental data. (C32) clay has the best removal power.

Mechanism of fluorine releasing in coal and clay and its effects on environment in Zhaotong, Yunnan Province.

Objective To study the real releasing of fluorine (F) and its effects on environmen in coalburning-borne fluorosis areas. Methods The coal, clay, briquette, cinder, fresh corn and roasted corn samples from 24 households were collected systematically in Zhaotong of City, Yunnan Province, and the F concentration in all samples was measured using the combustion hydrolysis/fluoride- ion selective electrode method, and the released amount and rate of F in briquette was calculated, and the relation between the released amount of F from briquette and the increase of F in roasted corn was analyzed. Results The F concentration of clay ranged from 266.4 to 2 536.7 mg/kg with a median of 1 087.1 mg/kg; the F concentration of briquette ranged from 115.9 to 635.0 mg/kg with a median of 308.8 mg/kg. The released amount of F in briquette ranged from 63.5 to 432.2 mg/kg with a median of 248.2 mg/kg. The releasing rate of F in briquette ranged from 30.3% to 91.5% with a average of 73.8%. The F concentration in fresh corn ranged from 0.43 to 2.00 mg/kg with a median of 1.31 mg/kg; the F concentration in roasted corn ranged from 2.21 to 44.88 mg/kg with a median of 10.49 mg/kg. The increased amount of roasted corn ranged 0.90 to 44.46 mg/kg. There was a significant correlation between the emission amounts of F from briquette and the F concentration in binder clay (r = 0.714, P 0.05). Conclusion The clay is an important source of F pollution, and the F increase in roasted corn is not only determined by the released amount of F in briquette, but also by several factors. Key words: Coal; Fluorine; Fluorosis, dental

Organic Additives of the Clay Layers: Hair Identification

Organic Additives of the Clay Layers: Hair Identification

Implementation Web Decision Support Model for Predicting Performance of Field Machinery Operation (DWDSS)

Farm machinery planning, design and operation are complicated undertaking due to time and cost constraint and due to prevalence of complicated interacting and overlapping field operations involving capacity constraints and cooperating units. The classical DSS models that applied in the past to machinery planning and policy analysis as well as to performance assessment and simulation of machinery demand, and supplies are criticized by limitations in programming and the difficulty in manipulation and storing the bulky data usually encountered in machinery records. In contrast by application of a web-based decision support system (DWDSS) the user can enjoy the facility to store the data in the server. (DWDSS), is a user-friendly interactive program which permits the user to interact by entering the required input records. The model estimates machinery performance of various farm machines. It consists of one model, which helps the farm manager to take the correct optimum selection of his agricultural machinery. DWDSS predicts field efficiency, field capacity, draft power required to operate machines and PTO power. The DWDSS was successfully validated statistically in comparison to the published data from the ASAE (2009). The comparison indicated that there were no significant differences (probability = 0.05) between them in the calculations that were executed. The DWDSS model was applied to real case conditions in Wad Salma and Rahad irrigated schemes in the central clay plains under similar treatments. The DWDSS results of field efficiency, theoretical field capacity, working rate and draw bar power was found fairly identical to the actual Wad Salma and Rahad data. The results indicated that, generally, the actual field efficiencies of the studied machines were found to be lower by 7% than ASAE published data and t-test comparison between Wad Salma and Rahad schemes in working rate of the three tillage implement, indicated no significant difference between the two means at probability level =0.05. In general, the results indicated that the DWDSS could be applied to any real-life case successfully and with confidence. This is reached by helping the decision maker in planning and operation of a farm fleet by deciding size of farm power.

Where Did the Wood Go? Rethinking the Problematic Role of Wood in Wood-Like Mimicry

This paper explores fangmugou (“imitating the mode of building with wood”), a comprehensive and longstanding architectural leitmotif reflective of the socio-cultural environment of China. Whether carved in stone, molded in clay, or cast in metal fangmugou continuously serves to visually confirm and ratify the significance of wood as the primary building material in Chinese architectural history. By peeling off the successive layers of distortion between model and replica, this paper uncovers the traces of wood embedded in fangmugou, and deciphers the visual and symbolic language that evolved out of the physical properties of wood, even as the final product transcends materiality by adapting to new media.

Narrow Grass Hedge Effects on Nutrient Transport Following Swine Slurry Application

Abstract. The effectiveness of a narrow grass hedge in reducing runoff nutrient loads following swine slurry application was examined. Slurry was applied to 0.75 m wide by 4.0 m long plots established on an Aksarben silty clay loam soil located in southeast Nebraska. Manure treatments consisted of no manure application and manure application to meet the 1, 2, or 3 year nitrogen (N) requirements for corn. Runoff water quality was measured during three 30 min simulated rainfall events. The grass hedge did not significantly reduce runoff nutrient transport after the swine slurry, which contained relatively small amounts of manure, was applied. Increasing the N application rate from a 1 year to a 3 year corn N requirement also did not result in a significant increase in N or phosphorus (P) loads in runoff. The grass hedge significantly reduced electrical conductivity (EC) measurements from 0.78 to 0.73 dS m -1 and pH values from 8.16 to 7.85. The rates of transport of dissolved P, particulate P, and total P were each influenced by runoff rate and increased in a linear fashion from 7 to 25, 65 to 357, and 72 to 382 g ha -1 min -1 , respectively. Runoff rate significantly affected rates of transport of NO 3 -N, NH 4 -N, and total nitrogen, which increased in a linear fashion from 273 to 1204, 30 to 47, and 323 to 1490 g ha -1 min -1 , respectively. Runoff rate is an important variable that should be considered when estimating nutrient transport following application of swine slurry containing relatively small amounts of nutrients.

The bitumen extraction from Nigerian tar sand using dense carbon dioxide

The need for alternative sources of energy has become even more acute in light of the recognition of the dwindling conventional world oil reserves. The interest in exploring other avenues of complimenting and/or eventually replacing this resource is growing quite rapidly. A ready alternative to conventional crude oil is oil sands which are abundant and vastly unexplored. The huge deposits of tar sand found in SouthWestern Nigeria remain untapped due to concerns about the environmental impact. The consequences of the methods in processing tar sand, ranging from water pollution to emission of greenhouse gases, especially in Canada bring in to sharp focus the urgent need for an alternative means of extracting oil from tar sand. A more effective and less environmentally damaging procedure could be the break through needed to open a new chapter in the exploitation of oil sands. The alternative recovery procedure is supercritical carbon dioxide extraction. Recent supercritical extractions use high temperatures and pressures. The upgrade in this research involves using high pressures and lower temperatures which saves energy and improves the process. The experimental study of the bitumen extraction from Nigerian tar sand by dense CO2 was carried out by high pressure extractor. The samples of tar sand were first heated in an oven at 120 °C to melt. A 50 g sample of melted tar sand with addition of 3 g of ethanol was placed into an extractor and heated to 80 °C to initiate the experiment. Carbon dioxide was injected in to the extractor to create 50 MPa of pressure in static mode for 20 min after which the extract was collected. In the presence of ethanol, the extract had a lighter colour than the usual black. Nigerian tar sand is known to be composed of 84 % sand, 17 % bitumen, 4 % water and 2 % mineral clay. Using this data, an extract of 19.47 % was calculated which makes the recovery achieved very encouraging. The experiment shows that recovery of bitumen from tar sand is possible under relatively low temperatures and can be possibly economically profitable.