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1
Liang, Chen, Cai Guo-dong, Gu Jia-hui, Tan Ye-fei, Chen Cheng und Yin Zi-xue. „Effect of Clay on Internal Erosion of Clay-Sand-Gravel Mixture“. Advances in Civil Engineering 2020 (26.08.2020): 1–18. http://dx.doi.org/10.1155/2020/8869289.
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In this study, a one-dimensional seepage test apparatus was used to investigate the effect of clay on the critical hydraulic gradient, hydraulic conductivity, migration of fine particles in soil, and percentage of fine particle loss during the internal erosion of clay-sand-gravel mixture, compared with clean gravel. The critical hydraulic gradient and fine sand loss percentage of the clay-sand-gravel mixture decreased, and critical flow velocity and the hydraulic conductivity increased. Six clay-sand-gravel mixture samples with different clay contents were used to evaluate the effect of different clay contents on internal erosion. As the percentage of clay mass to fine particle mass increases from 0% to 25%, the critical hydraulic gradient of soil samples decreases by nearly half and the fine sand loss percentage decreases from 13.73% to 3.48%. Overall, clay has a significant effect on the development of internal erosion of clay-sand-gravel mixture. And attention should be paid in engineering project; clay-sand-gravel mixture with a small amount of clay is more likely to be damaged than clean gravel.
2
Chu, Chengfu, Zilong Wu, Yongfeng Deng, Yonggui Chen und Qiong Wang. „Intrinsic compression behavior of remolded sand–clay mixture“. Canadian Geotechnical Journal 54, Nr. 7 (Juli 2017): 926–32. http://dx.doi.org/10.1139/cgj-2016-0453.
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A series of incremental loading oedometer tests was conducted on pure clays and sand–clay mixtures with various sand/clay ratios and clay mineral compositions. The void indexes Iv and IvH were introduced to evaluate their intrinsic compressibility. Test results revealed that Iv was more suitable for depicting the compression behavior of pure clays than IvH; whereas, for the compressibility of sand–clay mixtures, the normalized compression line by using Iv was obviously different from that of pure clays and traditional soils due to the presence of sand particles. Therefore, a four-phase analysis framework of sand–clay mixtures was introduced to unify the intrinsic compression behavior of soils with and without sands. It was found that the updated clay void index Ivc parameter was effective to unify the soil’s compression behavior by excluding the influence of sand particles in clays before the sand skeleton formation. After the formation of the sand skeleton, the cluster particles change the stress distribution of mixtures, leading to less stress being applied on the clay matrix and thus the bifurcation of the intrinsic compression behavior.
3
Subramanian, Sathya, und Taeseo Ku. „Yielding behaviour of cemented binary mixture“. E3S Web of Conferences 92 (2019): 11007. http://dx.doi.org/10.1051/e3sconf/20199211007.
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Cement stabilization is commonly used for improving soft soils and the mechanical behaviour of cemented pure clay has been well documented. However, limited studies have investigated the effect of sand in a cement-clay matrix because the conventional water to solid (solid includes soil and cement) ratio cannot be simply used to characterize the behaviour of cemented binary mixture. The water holding capacity of the mixture reduces with increase in sand content, when the water to solid ratio is kept constant. In this study, the ratio of water to clay and cement is kept constant, so that the effect of sand content could be studied. The materials used in this study are kaolin clay, sand with D50 of 0.71 mm and Ordinary Portland cement type 1. Sand content varies from 0% to 50% and curing time is kept constant at 7 days. We used three ratios of water to clay and cement which correspond to 139%, 104% and 78%. The isotropic yield point increases with increase in sand content and cement content, while it reduces with increase in water content. A power function captures the variation of yield point with the ratio of water to cement and clay.
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Yin, Kexin, Jiangxin Liu, Andreea-Roxana Vasilescu, Eugenia Di Filippo und Khaoula Othmani. „A Procedure to Prepare Sand–Clay Mixture Samples for Soil–Structure Interface Direct Shear Tests“. Applied Sciences 11, Nr. 12 (08.06.2021): 5337. http://dx.doi.org/10.3390/app11125337.
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A large number of experimental studies on sand–clay mixtures are well documented in the literature; however, the preparation protocol is rarely clearly detailed or varies a lot according to the authors. Variations in the preparation technique obviously increases the challenge of comparing different test results. As a consequence, sample preparation for sand–clay mixtures should be kept as constant as possible to ensure homogeneity and uniformity of samples and limit result variability. This paper develops a detailed procedure on how to prepare sand–clay samples for interface direct shear tests. Sand–clay mixtures are prepared with Fontainebleau sand, kaolinite clay and distilled water by the S1 (sand–water–clay) protocol. The uniformity of the reconstituted specimens is assessed by measuring the water content and density on three slices from the top to the bottom across the specimens. The repeatability of the samples is checked with oedometer and interface direct shear tests. This sample preparation procedure can be used for preparing sand–clay mixture for interface direct shear tests to investigate the influence of clay content or other effects (e.g., temperature) on the mechanical behavior of soil–structure interface. It has demonstrated great performance in preparing samples with good homogeneity and shape, compared to other traditional reconstitution techniques. With the sample preparation procedure, we can obtain repeatable test results as well.
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Eze, E. O., und L. E. Ileli. „Use of "Shikoko” Clay for Synthetic Sand Moulding“. Advanced Materials Research 367 (Oktober 2011): 353–58. http://dx.doi.org/10.4028/www.scientific.net/amr.367.353.
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“Shikoko” clay and dredged river sand from Warri, Nigeria were investigated for their use in synthetic sand moulding. Shikoko is a local name for organic clay that dries appreciably to a brownish gray, leather-like consistency. The clay was initially tested for organic matter content, natural water content, particle size distribution, consistency limits and linear shrinkage. The base sand dredged river sand from the same town - was tested for specific gravity, and grain size characteristics. Tests showed that the best mix with the clay was at the binder contents of 13, 17, 33 and 50% of the dry weight of the sand. The synthetic sand mixture was tested for the dry and green compressive strengths, and green permeability. At clay contents of 13 and 17 %, the green and dry compressive strengths of the synthetic mixtures at 5, 10, 15 and 20% moisture contents compared well and were at times higher than the corresponding values for synthetic moulds used in founding. Test results indicated that the synthetic mixture can be used for light casting and in non-ferrous production.
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Dafalla, Muawia A. „Effects of Clay and Moisture Content on Direct Shear Tests for Clay-Sand Mixtures“. Advances in Materials Science and Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/562726.
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The direct shear test using shear box is commonly recommended by practicing geotechnical engineers to obtain the cohesion and angle of internal friction for granular soils. The clay liners involve sand as a main constituent with added clay of variable proportions. This research aims at investigating the reliability of using the direct shear test for different clay contents and different moisture contents using an adequate shearing strain. These factors were found to affect the bilinear trends of shear force versus horizontal displacement profile as well as vertical displacement versus horizontal displacement curves. The cohesion of the mixture was found to increase consistently with the increase of clay content. Increase in moisture content was found to cause a drop in both cohesion and angle of internal friction. These changes are not independent of the density state of clay-sand mixtures. Standard compaction properties for a range of clay-sand mixtures were investigated. This work provides the general trends expected in direct shear tests for clay-sand mixtures of variable clay and moisture contents.
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Zlateva, Penka, Krastin Yordanov und Rositsa Petkova-Slipets. „A study of the thermal properties of an alternative straw-containing building material“. E3S Web of Conferences 207 (2020): 01004. http://dx.doi.org/10.1051/e3sconf/202020701004.
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Thermal comfort in buildings is usually achieved through sustainable materials obtained from natural sources, which justifies their use for developing building mixtures. Many natural materials were used as early as in ancient times to build homes that are warm in winter and cool in summer: a mixture of straw, clay and sand is an example of such a material. The objective of this article is to evaluate the effect of a mixture of clay, sand and straw on thermal comfort. For the purposes of this study, several types of sample plates were made from clay and sand mixture by adding different amounts of straw. The experiments were carried out and the thermal conductivity coefficient was determined using the method of infinite flat layer. The results indicate that the combination of different amounts of straw can be considered as good reinforcement of the sand and clay matrix and is characterized by a low thermal conductivity. Furthermore, 3D modelling was performed using Finite Element Analysis (FEA) software and a predictive model of the thermal behaviour of the samples from the different mixtures was developed. The thermal field distribution and the thermal conductivity coefficient thus determined were compared with the experimental data and showed consistency.
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Kacprzak, G., C. Boutin und T. Doanh. „Permeability of Sand-Clay Mixtures“. Archives of Civil Engineering 56, Nr. 4 (01.12.2010): 299–320. http://dx.doi.org/10.2478/v.10169-010-0017-6.
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Abstract This study deals with the behavior of composite blends constituted of rigid and impervious grains included in saturated clay paste of kaolin, considered as permeable and deformable. Permeability tests performed during standard oedometr tests (before each load step) highlight the key role of the original and actual state of the clay paste, and show the existence of a threshold of sand grain concentration above which a structuring effect influences its permeability. In the light of these experiments some usual homogenization methods (with simplifying assumptions to make the problem manageable) are considered in order to model the mixture permeability. Qualitative and quantitative comparisons with experimental data point out their respective domain of interest and limitations of such approaches
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Al-Mahbashi, Ahmed M., Muawia Dafalla, Abdullah Shaker und Mosleh A. Al-Shamrani. „Sustainable and Stable Clay Sand Liners over Time“. Sustainability 13, Nr. 14 (13.07.2021): 7840. http://dx.doi.org/10.3390/su13147840.
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The washout of fine materials from liners consisting of clay–sand mixtures is expected to influence the hydraulic conductivity. Clay sand liners must be assessed for efficiency when initially subjected to flood or standing water as the wetting under a hydraulic gradient can cause fine material to move and migrate away from the mixture. During wetting and drying complex expansion and shrinkage, changes take place. These changes affect the hydraulic conductivity and are likely to go out of the design range set out for the facility. The research covers the behavior of two clay sand liners tested over an extended time. The hydraulic conductivity measured under a specific hydraulic gradient was measured continuously following the establishment of the test set-up. Self-recording sensors were used to measure the temperature during the tests. The results indicated that the hydraulic conductivity reduces after an initial period of increase and fluctuation caused by the loss of mass because of fine material migration and swelling initiated due to the high content of smectite minerals. The testing and monitoring continued for more than 400 days. The permanent reduction in the hydraulic conductivity occurs after the initial period of repeated rise and fall. The extent of the initial period for the two tested mixtures is subject to the fine content mass and the clay mineralogy. The continuous reduction in the hydraulic conductivity after the initial period is due to the rearrangement of particles and compression in the sand–clay mixture.
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Deng, Yongfeng, Zilong Wu, Yujun Cui, Songyu Liu und Qiong Wang. „Sand fraction effect on hydro-mechanical behavior of sand-clay mixture“. Applied Clay Science 135 (Januar 2017): 355–61. http://dx.doi.org/10.1016/j.clay.2016.10.017.
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Dafalla, Muawia A. „The Compressibility and Swell of Mixtures for Sand-Clay Liners“. Advances in Materials Science and Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/3181794.
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Sand-clay liners utilize expansive clay to act as a filler to occupy the voids in the sand and thus reduce the hydraulic conductivity of the mixture. The hydraulic conductivity and transfer of water and other substances through sand-clay mixtures are of prime concern in the design of liners and hydraulic barriers. Many successful research studies have been undertaken to achieve appropriate mixtures that satisfy hydraulic conductivity requirements. This study investigates compressibility and swelling properties of mixtures to ensure that they were acceptable for light structures, roads, and slabs on grade. A range of sand-expansive clay mixtures were investigated for swell and compression properties. The swelling and compressibility indices were found to increase with increasing clay content. The use of highly expansive material can result in large volume changes due to swell and shrinkage. The inclusion of less expansive soil material as partial replacement of bentonite by one-third to two-thirds is found to reduce the compressibility by 60% to 70% for 10% and 15% clay content, respectively. The swelling pressure and swell percent were also found significantly reduced. Adding less expansive natural clay to bentonite can produce liners that are still sufficiently impervious and at the same time less problematic.
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Putri, Aulina Reza, Wiwik Rahayu und Puspita Lisdiyanti. „Effect of urease enzyme and clay mixture in shear strength properties of sand“. MATEC Web of Conferences 280 (2019): 04014. http://dx.doi.org/10.1051/matecconf/201928004014.
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The utilization of environmentally friendly materials in soil stabilization has grown in the last decade. Recent studies have shown that adding urease enzyme in calcium chloride and urea solution will improve the shear strength properties of sand. The purpose of this paper is to introduce the usage of clay to improve the performance of calcite produced in the mixture of urease enzyme and calcium chloride-urea solution. This mixture is then mixed manually with the clay-sand mixture and its effect is further tested using a direct shear test conducted at every two weeks of curing. The test is carried out to determine the development of the shear strength properties of the stabilized sand. The results from the test show that there is a rise in the cohesion value of the sand due to the addition of the clay mixture.
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Brown, Philip J., Lambert B. McCarty, Virgil L. Quisenberry, L. Ray Hubbard und M. Brad Addy. „Influence of Increasing Fines on Soil Physical Properties of U.S. Golf Association Sand“. HortScience 54, Nr. 11 (November 2019): 2063–66. http://dx.doi.org/10.21273/hortsci14110-19.
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Drainage is important to golf and athletic facilities trying to avoid lost play time. Native soil containing clay is sometimes incorporated into sand profiles with the intent to increase water and nutrient holding capacities. However, mixes high in silt and/or clay often have drainage problems. Research was conducted on soil physical properties from incremental 10% v/v additions of silt and clay (fines) to a U.S. Golf Association (USGA)-specification sand. Soils were evaluated based on volumetric water retention from 0 to 50 cm matric potential, saturated hydraulic conductivity (Ksat), porosity, and bulk density. The soil water characteristic (SWC) for 100:0 (sand:fines) had lower volumetric water content (θv) throughout the profile than any other mixture. Addition of 10% fines increased θv to more than 0.17 cm3·cm–3 throughout the 0- to 50-cm matric potential range, whereas 20% fines increased θv to more than 0.26 cm3·cm–3. The 70:30 mixture had greater θv throughout the profile than mixtures containing more than 70% sand. Mixtures with less than 70% sand produced similar SWCs. Increasing sand content increased bulk density, which altered saturated volumetric water content. Ksat was reduced from more than 265 cm·h–1 in 100:0 mixtures to 43 cm·h–1 for 90:10 mixtures, and to less than 5 cm·h–1 with ≥20% fines. The addition of ≥20% by volume of fines to a USGA sand increased water content in the soil to the point it was rendered unacceptable for trafficked turf sites. This research illustrates the influence fine particles, even in small amounts, can have on a USGA sand, and why they should not be added without prior evaluation.
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Sun, Qing Zhou, Jian Jing, Pu Qing Zhang, Yu Shuang Huo, Zhong Kui Zhao und Jian Wang. „Research on Changing Regularity of Green Sand Properties“. Advanced Materials Research 328-330 (September 2011): 1224–27. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1224.
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The research represents the actual effect of clay and core sand content on the permeability, compressive strength and hot wet tensile strength of green sand by adding clay and core sand into green sand mixture in order to simulate the actual situation of clay and core sand continuously increasing in the used sand during the foundry production. It was found that the content of clay and core sand affect the permeability, compressive strength and hot wet tensile strength of molding sand. With the content of clau and core sand increasing, the permeability of molding sand reduces and has a peak when core sand reaches certain content; the strength of molding sand is high and stable when the content of clay and core sand is below certain amount, and then decreases with the content of clay and core sand increasing. For green sand with resin bonded sand, the effect of clay on hot wet tensile strength appears a curve of “Peak shape”, while for green sand with sodium silicate bonded sand, the effect of clay and core sand on hot wet tensile strength appears “Annual Ring shape” as whose center is the coordinate’s dot.
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Mollins, L. H., D. I. Stewart und T. W. Cousens. „Predicting the properties of bentonite-sand mixtures“. Clay Minerals 31, Nr. 2 (Juni 1996): 243–52. http://dx.doi.org/10.1180/claymin.1996.031.2.10.
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AbstractOne-dimensional swelling tests and hydraulic conductivity tests have been performed at vertical effective stresses up to 450 kPa on Na-bentonite powder and compacted sand/Na-bentonite mixtures (5, 10 and 20% bentonite by weight) to investigate the use of bentonite-improved soils for waste containment. It was found that bentonite powder swells to reach a final state described by a single straight line on a plot of void ratio against the logarithm of vertical effective stress, regardless of preparation technique. Swelling of sand/bentonite mixtures expressed in terms of the clay void ratio show a deviation from bentonite behaviour above a stress which depends on the bentonite content. Hydraulic conductivity data for bentonite and sand/bentonite mixtures indicate an approximately linear relationship between logarithm of hydraulic conductivity and logarithm of void ratio. A design model based on the clay void ratio, and the sand porosity and tortuosity is presented enabling the hydraulic conductivity of a mixture to be estimated.
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Mužíková, Barbora, Tereza Plaček Otcovská und Pavel Padevět. „FRACTURE ENERGY OF ILLITIC RAMMED EARTH WITH HIGH WATER-CLAY RATIO“. Acta Polytechnica CTU Proceedings 30 (22.04.2021): 53–57. http://dx.doi.org/10.14311/app.2021.30.0053.
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The article is focused on design of mixture of rammed earth, producing, testing and determination of fracture energy of unfired rammed earth and its stress-strain curve in tensile bending test. Three different mixtures of rammed earth were designed and tested. The amount of water and binder is one of the key properties of the rammed earth, the amount of the water is expressed by the water-clay ratio. Mechanical properties of the earth material highly depend on the composition of sand, clay and water. The prescription AGL III with 80 % of sand, 20 % of clay and 0.400 water-clay ratio reached the maximum value of fracture energy 4.858±0.002 J/m2 and set AGL V had the minimum value 1.934±0.310 J/m2.
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Blatz, James, David E. S. Anderson und Greg Siemens. „Evaluation of the transitional inelastic behaviour of unsaturated clay–sand mixtures“. Canadian Geotechnical Journal 44, Nr. 4 (01.04.2007): 436–46. http://dx.doi.org/10.1139/t06-128.
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This paper examines and compares the mechanical behaviour of two different unsaturated clay mixtures comprised of bentonite clay (Saskatchewan or Wyoming) and quartz sand. The two mixtures have been proposed as compacted barrier materials for reducing groundwater flow in the vicinity of waste disposal repositories. Triaxial specimens were compacted to consistent properties, and then specified suction conditions were applied to the specimens using the vapour equilibrium technique. Following equilibrium at the specified initial suction, specimens were subjected to isotropic and shear loading in a conventional triaxial cell to measure the mechanical response under selected stress paths. The results are interpreted in terms of the yield, strength, and stiffness behaviour at the various suction levels. Results suggest that the clay component of the mixture dominates the behaviour at suctions less than approximately 30 MPa, and the sand component dominates the behaviour above approximately 30 MPa. The transition from clay- to sand-dominated behaviour is attributed to volume strain during application of the initial suction bringing the sand particles into contact. The discussion highlights how the results can be used to modify constitutive models to incorporate the transitional behaviour in numerical modeling.Key words: inelastic, yielding, unsaturated, stress–strain, triaxial testing.
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Nutt, Nele, und Ardo Kubjas. „Moisture Buffer Value of Composite Material Made of Clay- Sand Plaster and Wastepaper“. Journal of Sustainable Architecture and Civil Engineering 27, Nr. 2 (05.11.2020): 108–15. http://dx.doi.org/10.5755/j01.sace.27.2.25391.
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The scope of the Nordtest method is to evaluate the moisture buffer value (MBV) for materials exposed to indoor air. The test is intended to simulate daily variations with relative humidity (RH) of 75% during 8 hours and 33% during 16 hours.Many authors have noted that clay plaster has a very good MBV (Altmäe et al. 2019). Our previous tests have shown that the MBV of clay plaster can be increased by adding paper plaster mixture (Nutt et al. 2020a). The specimen made according to a recipe contains the following: waste paper, glue, clay plaster mixture and water. Eleven paper plaster mixtures with different percentages were used.Test results showed that a large percentage of paper in the plaster increases the MBV. An impressive result, which needs to be studied further, was that the MBV was the highest in the mixture that consisted of 80% paper.
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El-Husseiny, Ammar. „Improved Packing Model for Functionally Graded Sand-Fines Mixtures—Incorporation of Fines Cohesive Packing Behavior“. Applied Sciences 10, Nr. 2 (13.01.2020): 562. http://dx.doi.org/10.3390/app10020562.
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Binary soil mixture, containing large silica particles (sand) mixed with variable content of very fine silt or clay, is an example of a functionally graded material that is important for several science and engineering applications. Predicting the porosity (or void ratio), which is a fundamental quantity that affects other physical properties, of such material as function of fines (clay or silt) fraction can be significant for sediment research and material design optimization. Existing analytical models for porosity prediction work well for binary mixed soils containing multi-sized non-cohesive particles with no clay, while such models frequently underestimate the porosity of sand-clay mixtures. This study aims to present an analytical model that accurately predicts the porosity of mixed granular materials or soils containing sand and very fine silt or clay (cohesive particles). It is demonstrated that accounting for the cohesive nature of very fine particles, which exists due to the effect of inter-particle forces, is a major missing aspect in existing packing models for mixed soils. Consequently, a previously developed linear packing model is modified so that it accounts for fines cohesive packing in sand-fines mixtures. The model prediction is validated using various experimental published data sets for the porosity of sand-fines mixtures. Improvement in the prediction of permeability and maximum packing dry density when incorporating cohesive packing behavior is discussed. The current model also provides important insights on the conditions under which, the lowest permeability and maximum packing state are expected.
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Trask, Parker D., und James E. H. Close. „EFFECT OF CLAY CONTENT ON STRENGTH OF SOILS“. Coastal Engineering Proceedings 1, Nr. 6 (29.01.2011): 50. http://dx.doi.org/10.9753/icce.v6.50.
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Engineers have worked greatly on measuring the strength of soils but relatively little on the fundamental geologic causes of strength. Strength depends principally upon the content of (1) water, (2) clastic materials and (3) plastic materials. Soils are primarily of two types (1) cohesionless soils in which the strength is produced mainly by the friction of clastic particles against one another, and (2) cohesive soils in which the strength, among other things, is influenced by forces between clay particles. The present investigation is a study of the effect of clay content upon the strength of cohesive soils. The strength was measured by a shear vane device working upon synthetic mixtures of clays of known composition. In each mixture strength varies inversely with water content in a straight line relationship when strength is plotted logarithmically and water arithmetically. Mixtures of glycerine with vol-clay (a montmorillonite) give a curvilinear relationship. For given water content the strength increases with respect to type of clay from kaolin through illite, ball clay to montmorillonite. Strength also increases progressively with increasing clay-sand ratio for all types of clay. In clay-sand mixtures of given clay composition strength increases with increasing fineness of grain of the sand mixed with clay. The liquid limit likewise increases regularly with increasing clay concentration and varies with clay type fci the same way as does strength. Strength varies inversely with temperature to a slight extent, changingjess than one percent per degree Centrigrade. Hydrogen kaolin clay, for given water content is several times stronger than sodium clay.
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Abdullah, A., Shamsuddin Sulaiman, B. T. Hang Tuah Baharudin, Mohd Khairol A. Arifin und T. R. Vijayaram. „The Effect of Bentonite Clay on Green Compression Strength for Tailing Sands from Old Tin Mines in Perak State, Malaysia for Making Green Sand Casting Mould“. Key Engineering Materials 471-472 (Februar 2011): 769–74. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.769.
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Clay has an important role in making green sand casting mould beside water. Clay acts as binders, holding the sand grains together. Water is needed to activate the clay bond. Without the addition of water on clay, no strength would be achieved on sand mould, as the sand and clay would be just two dry materials. Bentonite clay was used in this study. Adequate clay content with suitable moisture in moulding sand is important for optimum strength and casting quality. Too little or too much clay will not give proper strength. Green compression strength is one of the mechanical properties to be considered for making green sand casting mould. The green compression strength of foundry sand is the maximum compressive strength that a mixture is capable of sustaining when prepared, rammed and tested according to standard procedure. For this study, test is conducted according to Foundry Sand Testing Equipment Operating Instructions from Ridsdale and Dietert. Result from this study indicates that tailing sand has potential for making green sand casting mould in term of green compression strength. Other factors that must be considered are permeability and shatter index.
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Kidalov, Nikolay A., Anna S. Adamova und Viktoria V. Smirnova. „Effect of Temperature Calcinations of Clay on Strength of Moulding Mixture“. Materials Science Forum 973 (November 2019): 26–29. http://dx.doi.org/10.4028/www.scientific.net/msf.973.26.
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Keren, Rami, und Meni Ben-Hur. „Interaction effects of clay swelling and dispersion and CaCO3 content on saturated hydraulic conductivity“. Soil Research 41, Nr. 5 (2003): 979. http://dx.doi.org/10.1071/sr02102.
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Typic Chromoxeret-sand and Lithic Ruptic Xerochrept-sand mixtures, of high sodicity, and containing 8 and ~0% CaCO3, respectively, were packed in columns and leached with electrolyte solutions. When a reference solution of 500 mmol/L was replaced successively with solutions containing 100, 50, 10, 5, and 1 mmol/L and then with deionised water (gradual leaching), the saturated hydraulic conductivity (Ks) decreased gradually to steady-state values, and no clay was observed in the leachate. Under deionised leaching, the relative Ks (Ks/Ks0) (the ratio between the observed Ks and that under leaching with the reference solution) in the Chromoxeret mixture at exchangeable sodium percentages (ESPs) of 30, 38, and 63 was 0.83, 0.47, and 0.41, respectively, and that in the Xerochrept mixture at ESPs of 23, 28, and 36 were 0.82, 0.71, and 0.39 respectively. When a solution of 50 mmol/L was replaced directly with deionised water (abrupt leaching), the Ks/Ks0 of the Chromoxeret mixture at the above ESPs dropped sharply to minimum values of 0.25, 0.18, and 0.11, respectively, and that of the Xerochrept mixture to 0.42, 0.04, and 0.13, respectively, and dispersed clay was observed in the leachate. It is hypothesised that the abrupt leaching with deionised water generated a steep concentration gradient between the solutions within and around the aggregates, leading to clay dispersion and rapid Ks/Ks0 reduction; under gradual leaching, no steep concentration gradient developed, there was no clay dispersion, and clay swelling caused gradual Ks/Ks0 reduction. In the Chromoxeret, the CaCO3 decreased the clay swelling and dispersion, and probably acted as a cementing agent that stabilised the soil aggregates against slaking during the initial wetting of the mixture.
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Graham, J., J. M. Oswell und M. N. Gray. „The effective stress concept in saturated sand–clay buffer“. Canadian Geotechnical Journal 29, Nr. 6 (01.12.1992): 1033–43. http://dx.doi.org/10.1139/t92-121.
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Uncertainty has existed about the applicability of the effective stress concept to dense, compacted, plastic clays. To examine this, a series of tests has been performed on mixtures of sand and bentonite. Specimens were made by combining equal weights of the dry components with water and compacting the mixture to 85 or 95% ASTM Modified maximum dry density. The tests investigated the proposition that the behaviour of the mixture can be expressed in terms of effective stresses defined as the tensor difference between externally applied total stresses and pore-water pressures measured outside the cell. The proposition cannot be examined directly, but must be studied through a series of corollaries, that is, statements of behaviour that would be expected if the proposition were true. The testing considered the behaviour of specimens in consolidation and shear. Effective consolidation pressures were from 0.3 to 3.0 MPa, with back pressures from 0.2 to 7.0 MPa. Within acceptable bounds of experimental error, the tests show that effective stresss can be used to describe consolidation and shear behaviour. However, because part of the effective stress in the clay is derived from net interparticle repulsive (unit) forces seated in diffuse double layers around aggregations of bentonite particles, the applicability of the concept has at this stage been restricted to conditions of constant volume (or possibly constant straining rate), constant chemistry, and constant temperature. Key words : clay, plastic clay, expansive clay, bentonite, effective stress, triaxial, swelling pressure, swelling equilibrium.
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Slater, Lee, Dimitrios Ntarlagiannis und DeBonne Wishart. „On the relationship between induced polarization and surface area in metal-sand and clay-sand mixtures“. GEOPHYSICS 71, Nr. 2 (März 2006): A1—A5. http://dx.doi.org/10.1190/1.2187707.
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Induced polarization (IP) measurements were conducted on saturated kaolinite-, iron-, and magnetite-sand mixtures as a function of varying percentage weight of a mineral constituent: 0%–100% for iron and magnetite and 0%–32% for kaolinite. We determined the specific surface area for each mineral using nitrogen gas adsorption, where the porosity of each mixture was calculated from weight loss after drying. We fit a Cole-Cole model (Cole and Cole, 1941) to the electrical data obtained for the magnetite and iron mixtures. In contrast, the kaolinite mixtures showed a power-law dependence of phase-on frequency. The global polarization magnitude we obtained from the Cole-Cole modeling of the iron and magnetite mixtures displays a single, near-linear dependence on the ratio of surface area to pore volume ([Formula: see text]) calculated for the mixtures. A similar relationship is found using a local measure of polarization (imaginary conductivity at 1 Hz) for the clay-sand mixtures. The [Formula: see text] appears to be a critical parameter for determining IP in both metallic- and clay-containing soils. This result is not easily reconciled with traditional models of induced polarization.
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Abdullah, Azhar, S. Sulaiman, B. T. H. T. Baharudin, M. K. A. Ariffin und N. Haliza. „Mechanical Properties of Tin Tailing Sand-Clay Mixture from Batu Gajah, Perak, Malaysia for Making Greensand Casting Mould“. Materials Science Forum 773-774 (November 2013): 211–17. http://dx.doi.org/10.4028/www.scientific.net/msf.773-774.211.
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Tailing sand from ex-tin mine in Batu Gajah containing between 95.9 to 98.9% silica. In this research involved the process of, conducting the mechanical sieve grading to identify the size spread, plotting the grain size distribution and calculating the average grain size. Further on with the effects of controlled additions of clay (bentonite) and water and determining the working range on the mechanical properties. The investigation involved comparing the mechanical properties of the tailing sand to the requirement for foundry sand applications listed by Foseco Ferrous Foundrymans Handbook (Foseco). Permeability and green compression strength are the important mechanical properties and considered much in the sand casting mould preparation. These mechanical properties play a vital role in determining the allowable clay and moisture content for working range of tailing sand for making green sand casting mould. Experiments for this investigation were conducted according to American Foundrymen Society (AFS) standard of procedures. Cylindrical test pieces dimensioning of Ø50 mm×50 mm in height from various sandwater ratios bonded with 3.8%wt clay and then 7.4%wt clay, were compacted by applying three ramming blows of 6666 g each using Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using Ridsdale-Dietert universal sand strength machine and permeability number with Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured using moisture analyser. Tailing sand with allowable moisture content ranging from 3 to 3.5% (bonded with 3.8%wt clay) and 5.5 to 6% (bonded with 7.4%wt clay) were found to have optimum working range with effective green compression strength and permeability.
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Kingsley Okechukwu Ikebudu, Swift Kenneth Onyegirim und Philip Ifchukwu Udeorah. „Effect of green sand mixture with dextrin additives on mechanical properties of aluminum 6351“. Global Journal of Engineering and Technology Advances 6, Nr. 2 (28.02.2021): 131–41. http://dx.doi.org/10.30574/gjeta.2021.6.2.0013.
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Quality of cast produced from green sand mold is been influenced by mold properties which includes green compression strength, permeability, etc. In this work the green sand used for casting of aluminum 6351 alloy specimens were made by mixing in varied percentage proportions; bentonite clay, dextrin additive and moisture content with local silica sand considering the need for most effective proportions of these mixtures to enhance green sand production of aluminum 6351 alloy products. A 3 factor, 3 level (33) design of experiment (DOE) was made for this research work using Optimal (custom) design of Design-Expert 10 software which gave 20 runs. Cylindrical specimens for green sand test were prepared according to standard per run. This was in order to study effects of bentonite clay, dextrin additive and moisture content of the green molding sand used for casting per mold this aluminum 6351 alloy. Prepared sand specimens were individually subjected to basic sand test like green sand strength and permeability test and also cast specimens per mold achieved were subjected to mechanical property test to achieve results which become the Response output of the study. These experimental results were optimized for the purpose of achieving most effective proportions of the mixtures to give effective results and from the optimal validation values, 5% water content, 12% bentonite and 8.85182% dextrin organic additive was found to be the optimized solution that gave the most effective hardness at (40.4GSS and 112PN) while 3% water, 12% bentonite clay and 9% dextrin additive gave most effective toughness at (41.9GSS and 96.10PN).
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Liu, Jiang-Feng, Yang Song, Frédéric Skoczylas und Jian Liu. „Gas migration through water-saturated bentonite–sand mixtures, COx argillite, and their interfaces“. Canadian Geotechnical Journal 53, Nr. 1 (Januar 2016): 60–71. http://dx.doi.org/10.1139/cgj-2014-0412.
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France’s deep-seated nuclear waste repository consists of a natural barrier located at a depth of 500 m in a Callovo-Oxfordian clayey formation. This repository has artificial barriers that include plugs of swelling clay (MX80 bentonite – sand mixtures) for sealing purposes. This paper focuses on the gas migration properties of water-saturated bentonite–sand mixtures and their interfaces with COx argillite. The main contribution of our study is the identification of a preferential gas migration pathway by measuring the downstream gas breakthrough pressures and gas flow rates. The water permeabilities of the bentonite–sand mixtures and their interfaces with COx argillite or COx argillite itself are the same order of magnitude (10−20–10−21 m2). Thus, water tightness can be obtained for these materials when they become completely saturated. The results obtained from the gas breakthrough tests suggest that both the COx argillite and its interface with the bentonite–sand mixture can act as preferential pathways for gas migration. The transport of the gas through the COx argillite or through its interface with the bentonite–sand mixture depends on the initial state of the COx argillite.
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Shawabkeh, Reyad A. „Solidification and stabilization of cadmium ions in sand–cement–clay mixture“. Journal of Hazardous Materials 125, Nr. 1-3 (Oktober 2005): 237–43. http://dx.doi.org/10.1016/j.jhazmat.2005.05.037.
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Ghorbani, Ali, und Meysam Salimzadehshooiili. „Evaluation of Strength behaviour of Cement-RHA Stabilized and Polypropylene Fiber Reinforced Clay-Sand Mixtures“. Civil Engineering Journal 4, Nr. 11 (30.11.2018): 2628. http://dx.doi.org/10.28991/cej-03091187.
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In this paper, regarding the high availability of rice husk ash (RHA) in Guilan province, also, to decrease the geo-environmental issues caused by dumping RHA in the environment, different clay-sand mixtures are stabilized using the combination of cement and RHA. Polypropylene (PP) fibers are also used to decrease the growth of tensile cracks and increase the overall strength of samples. As the main scope, effect of sand content (in different conditions: with and without presence of RHA) on the compressive strength of stabilized and reinforced samples is investigated. In this regard, 28 day cured clay-sand samples are prepared and unconfined compressive strength (UCS) tests are conducted and the results are compared. It is obtained that with addition of 20% sand to the clay samples, their UCS increases in both cases of non-RHA and RHA-stabilized samples. Moreover, such behavior has been observed with the length of studied PP fibers. As the second scope, based on the conducted UCS tests on the 7-, 28- and 90- day cured clay samples, compressive strength of non-RHA samples are almost completely achieved in a 28-day curing period, while samples containing RHA continue to strengthening after such a period toward a 90-day curing period. Next, a simple relationship for the prediction of UCS of cement-RHA stabilized and PP reinforced clay is presented based on the evolutionary polynomial regression (EPR) technique. This relationship can be efficiently applied by construction engineers to obtain the appropriate mixture design for the stabilization of clay with cement, RHA and PP fibers.
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Alkroosh, Iyad, Ali Al-Robay, Prabir Sarker und Saif Alzabeebee. „Effect of Sand Percentage on the Compaction Properties and Undrained Shear Strength of Low Plasticity Clay“. ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY 9, Nr. 1 (01.03.2021): 16–20. http://dx.doi.org/10.14500/aro.10748.
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This paper investigates the influence of sand content on the mechanical behavior of a low plasticity clay that collected from south of Iraq (Sumer town). Samples have been prepared with sand contents of 0%, 10%, 20%, 30%, and 40% of the clay weight. Standard Proctor and unconfined compression tests have been carried out and the optimum moisture content, maximum dry density, and undrained shear strength have been determined. The results show a gradual increasing trend of the maximum dry density with the increase of the sand content up to 30%. The highest dry density reaches 1.90 g/cm3 corresponding to an optimum moisture content of 12%. In addition, this paper shows that the undrained shear strength is inversely proportional to the increase of the percentage of sand. The results of this work provide a useful addition to the literature regarding the behaviour or low plasticity clay-sand mixture.
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Pullen, Quinn M., und Todd V. Scholz. „Index and Engineering Properties of Oregon Cob“. Journal of Green Building 6, Nr. 2 (01.05.2011): 88–106. http://dx.doi.org/10.3992/jgb.6.2.88.
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Cob is an earthen building material comprised of sand, clay, straw, and water used for millennia to construct dwellings. Although cob construction largely died out during the nineteenth century, it is experiencing a revival in England and the Pacific Northwest of the United States. Little scientific research has investigated the engineering properties of cob, knowledge of which is important for modern-day design practices and code requirements. Researchers at Oregon State University investigated six different Oregon cob mixtures using a series of standard soils and concrete tests adapted for this material. The objectives were to characterize the constituents, to establish estimates for the magnitude of, and degree of variability in, the mixture properties, and to develop correlations between the engineering properties and mixture composition. Results indicated low to moderate variation in basic mixture properties (i.e., unit weight, moisture content, and sand equivalent), moderate variation in strength properties, and high variation in the elastic modulus. Several reasonable correlations were found between shrinkage, compressive strength, elastic modulus, and sand equivalent and between flexural strength and fiber tensile strength.
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Boldt-Leppin, Brigitte EJ, Moir D. Haug und John V. Headley. „Use of organophilic clay in sand-bentonite as a barrier to diesel fuel“. Canadian Geotechnical Journal 33, Nr. 5 (06.11.1996): 705–19. http://dx.doi.org/10.1139/t96-097-318.
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A laboratory research program was conducted to evaluate the long-term hydraulic performance of sandbentonite liners augmented with organophilic clay and permeated with diesel fuel. This program was also designed to establish guidelines for the incorporation of organophilic clay in sandbentonite liners. The study involved three areas of testing. The first was to characterize the materials. The second was to evaluate various combinations of materials and preparation techniques through hydraulic conductivity tests. The third area involved unconfined infiltration tests. The primary hydraulic conductivity testing was broken into three phases. These investigated the hydraulic conductivity of organophilic sandbentonite liners using various percentages of organophilic clay and evaluated the hydraulic performance of these specimens when permeated with distilled water and diesel fuel. Hydraulic conductivity was measured in specially designed low gradient, low effective stress stainless-steel triaxial permeameters. The results of this test program indicated that small percentages (3%) of organophilic clay in a sandbentonite liner material could effectively be used to avoid desiccation cracking in a liner permeated with petroleum products. High percentages (7.5%) of organophilic clay in a sandbentonite mixture resulted in a liner permeable to water, but reduced permeability to diesel fuel. Key words: organophilic clay, diesel fuel, bentonite, liners, hydraulic conductivity, triaxial permeability testing.
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Okay, Gonca, Phillipe Leroy, Ahmad Ghorbani, Phillipe Cosenza, Christian Camerlynck, Justo Cabrera, Nicolas Florsch und André Revil. „Spectral induced polarization of clay-sand mixtures: Experiments and modeling“. GEOPHYSICS 79, Nr. 6 (01.11.2014): E353—E375. http://dx.doi.org/10.1190/geo2013-0347.1.
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Spectral induced polarization or complex conductivity is a promising electric method in hydrogeophysics because of its sensitivity to water saturation, permeability, and particle size distribution (PSD). However, the physical and chemical mechanisms that generate the low-frequency complex conductivity of clays are still debated. To explain these mechanisms, the complex conductivity of kaolinite, smectite, and clay-sand mixtures was measured in the frequency range 1.4 mHz–12 kHz with various clay contents (100%, 20%, 5%, and 1% in volume of the clay-sand mixture) and salinities (distilled water, [Formula: see text], [Formula: see text], and [Formula: see text] of NaCl in solution). The results indicated the strong impact of the cation exchange capacity of smectite upon the complex conductivity of the material. The quadrature conductivity increased steadily with the clay content and was fairly independent of the pore fluid salinity. A mechanistic induced polarization model was also developed. It combined a Donnan equilibrium model of the surface electrochemical properties of clays and sand, a conduction model of the Stern and diffuse layers, a polarization model of the Stern layer, and a macroscopic conductivity model based on the differential effective medium theory. It also included the effect of the PSD. Our complex conductivity model predicted very well the experimental data, except for very low frequencies ([Formula: see text]) at which membrane polarization may dominate the observed response.
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Wareham, David G., Arman Farajollahi und Mark W. Milke. „Influence of alkalinity on the hydraulic conductivity of bentonite-sand liners“. Water Science and Technology 38, Nr. 2 (01.07.1998): 151–57. http://dx.doi.org/10.2166/wst.1998.0127.
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The aim of this research is to record the impact of specific changes in the molding water alkalinity on the hydraulic conductivity of a compacted bentonite-sand mixture. Adding alkalinity to the molding water influences the charge density existing on the clay particles. This can increase the amount of separation of the bentonite particles which causes a decrease in the hydraulic conductivity of the compacted mixture. At the optimum alkalinity the mixture possesses the smallest hydraulic conductivity. In this research an optimum alkalinity (pH=10.1) for a compacted bentonite-sand mixture (7.5% bentonite) was derived from the liquid limit test and the falling-head permeability test.
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Boutin, Claude, Gregory Kacprzak und Thiep Doanh. „Interpretation of the stiffness and permeability of Sand-Kaolin mixtures in the framework of homogenization“. Anais da Academia Brasileira de Ciências 82, Nr. 1 (März 2010): 243–60. http://dx.doi.org/10.1590/s0001-37652010000100017.
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This study deals with the behaviour of mixtures of sand and saturated kaolin paste considered as composite materials made of permeable and deformable (with non-linear behaviour) matrix (the kaolin paste) with rigid and impervious inclusions (the sand grains). Oedometric and permeability tests conducted on such mixtures highlight the key role of the state of the clay paste, and show the existence of a threshold of sand grain concentration above which a structuring effect influences both modulus and permeability. At the light of these experiments, the usual and tangent homogenization process (with simplifying assumptions to make the problem manageable) has been applied to estimate the mixture permeability and tangent compressibility. Qualitative and quantitative comparisons with experimental data point out the domain of interest and the limitations of such approaches.
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Belmahi, Samir, Mohammed Zidour und Tayeb Bensatllah. „Mechanical behavior of mortars composed of a mixture of cement and lime stone filler“. Lebanese Science Journal 19, Nr. 1 (27.04.2018): 95–104. http://dx.doi.org/10.22453/lsj-019.1.095-104.
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This work consists in studying the mechanical behavior of mortars composed of a mixture of cement and fire-clay. The limestone filler is used as an additive in this mixture. The main idea wasto compare this mortar with an ordinary mortar,made with a normal sand, thus,to know the limit of their use in construction.The results showed and confirmed that fire-clay mortar, cannot give better resistances than a normal sand mortar. The second idea wasto introduce the limestone filler manufactured by ENG Tlemcen (Algeria) as an addition. Theproposed percentages varied from 5% to 30% of the cement mass. The resultsobtained showed that the substitution of a part of cement by the limestone filler helps to improve the mechanicals resistances of mortars and that the best fraction of limestone filler wasfixed at 10%.
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Pan, Dong-Bin, Xiu-Ping Zhong, Bing Li, Xi-Tong Li und Chen Chen. „Experimental investigation into methane production from hydrate-bearing clayey sediment by CO2/N2 replacement“. Energy Exploration & Exploitation 38, Nr. 6 (27.07.2020): 2601–17. http://dx.doi.org/10.1177/0144598720941182.
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The replacement of gas hydrate in clayey sediment by a CO2/N2 (20:80) gas mixture injection was experimentally studied to explore the influence of clay on the gas exchange behaviours in the gas hydrate. Clay (montmorillonite) and silica sand were mixed in three different proportions (clay mass ratios of 10%, 30% and 50%) to simulate the host sediments of natural gas hydrate while pure silica sand sediment was selected for comparison. Experimental results showed that clay hindered gas diffusion during the initial replacement stage and thus reduced the methane recovery rate. In the later stage, the gas exchange between CO2/N2 and methane in the hydrate structure might be subject to thermodynamic inhibition and geometric constraints of the clay interlayer. Moreover, the CO2 sequestration ratio was lowered significantly in the sediment with a 50% clay mass ratio. Therefore, it was determined that clay has an inhibitory effect on gas hydrate replacement by CO2/N2.
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Keren, R., und M. J. Singer. „Effect of pH on Permeability of Clay-Sand Mixture Containing Hydroxy Polymers“. Soil Science Society of America Journal 54, Nr. 5 (September 1990): 1310–15. http://dx.doi.org/10.2136/sssaj1990.03615995005400050018x.
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Hasan, Md Farhad, Hossam Abuel-Naga und E. C. Leong. „A modified series-parallel electrical resistivity model of saturated sand/clay mixture“. Engineering Geology 290 (September 2021): 106193. http://dx.doi.org/10.1016/j.enggeo.2021.106193.
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Oke, A. O., und B. V. Omidiji. „Investigation of Some Moulding Properties of a Nigerian Clay-Bonded Sand“. Archives of Foundry Engineering 16, Nr. 3 (01.09.2016): 71–76. http://dx.doi.org/10.1515/afe-2016-0053.
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Abstract Moulding properties of Isasa River Sand bonded with Ipetumodu clay (Ife-North Local Government Area, Osun State, Nigeria) were investigated. American Foundry men Society (AFS) standard cylindrical specimens 50mm diameter and 50mm in height were prepared from various sand and clay ratios (between 18% and 32%) with 15% water content. The stress-strain curves were generated from a universal strength testing machine. A flow factor was calculated from the inclination of the falling slope beyond the maximum compressive strength. The result shows that the flowability of the samples increases from 18% to 26% clay content, its maximum value was attained at 26% and then it decreases from 30% to 32% clay content. The green compressive strength, dry compressive strength and air permeability values obtained from the mould samples were in accordance with standard values used in foundry practice. The x-ray diffraction test shows that the sand contains silicon oxide (SiO2), Aluminium oxide (Al2O3), and Aluminium silicate (Al6Si2O13). The mould samples were heated to a temperature of 1200 °C to determine the sintering temperature; fussion did not take place at this temperature. The results showed that the sand and clay mixture can be used to cast ferrous and non-ferrous alloys.
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Omarov, A. O., und K. A. Otsokov. „REDUCTION OF EMPLOYMENT OF FORMULA WORKING BY USING LOCAL FILL-ERS AND WASTE OF PRODUCTION“. Herald of Dagestan State Technical University. Technical Sciences 45, Nr. 3 (12.05.2019): 221–30. http://dx.doi.org/10.21822/2073-6185-2018-45-3-221-230.
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Objectives.The purpose of this study is to study the increase in turnover of formwork and reduce the complexity of formwork for monolithic foam concrete by regulating its properties through the optimal use of local aggregates of the Republic of Daghestan and industrial waste. In particular, the experimental work used cement grade M500, silica filler - deposits of quartz sand in Kumtorkala district of the Republic of Daghestan with a low module of size, various synthetic foaming agents, perlite sand, ground expanded clay sand (Kizilyurt, Republic of Daghestan),stone crushing roar (Kizilyurt).Method.In the production of foam concrete, a method was used in which foam was prepared in the foam generator, then a solution of cement, filler and water was prepared. Then the foam is mixed with a solution in a foam mixer until a set of appropriate multiplicity. (Multiplicity in this case was defined as the ratio of the volume of the foam concrete mixing solution after mixing to the volume of the solution before mixing). During the study, the water-cement ratio was determined using three types of aggregates (expanded clay sand, quartz sand deposits Kumtorkala district and perlite sand). The turn-over rate of the concrete mixture was determined using the Attard viscometer.Result.The results of studies have shown that with an increase in the water-cement ratio using three types of aggregates (expanded clay sand, quartz sand deposits Kumtorkala district and perlite sand ) will increase the flow rate of the foam concrete mixture.Conclusion.At the same values of the water-cement ratio, the mixture with a filler of perlite sand has the lowest fluidity, which in turn affects the further structure formation of foam concrete and allows you to choose the optimal composition with the desired properties. The possibility of increasing the turnover of artwork and reducing the complexity of artwork work for monolithic foam concrete by regulating its properties due to the optimal use of local aggregates of the Republic of Daghestan and industrial waste.
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Kolokol’tsev, V. M., A. S. Savinov, N. A. Feoktistov und A. S. Postnikova. „Impact of transportation on foundry coke quality“. Izvestiya. Ferrous Metallurgy 63, Nr. 10 (10.12.2020): 829–35. http://dx.doi.org/10.17073/0368-0797-2020-10-829-835.
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One of the ways to increase economic efficiency of the foundry is to reduce the product cost by reducing scrap, a significant proportion of which is formed due to formation of hot and cold cracks during solidification and cooling in the casting-mold system. The formation of cracks occurs due to the force interaction of casting with mold. Currently, a number of approaches are used to determine the value of stress state in the casting material and, accordingly, to determine the value of force interaction. The paper considers the developed estimation of stress-strain state of the casting-mold system, which is determined by deformation resistance of the molding mixture. Change in deformation resistance of the molding mixture is complex due to the multi-factor nature of resulting stresses interaction with thermal and component composition of the sand-clay layer. We have studied the influence of geometric parameters and thermophysical properties of the casting on deformation resistance of the molding mixture. A mathematical model was developed that takes into account the heat transfer between casting and mold, increase in mold dry layer, and the migration of moisture in layer of the sand-clay mixture. On the basis of mathematical modeling, we have made a quantitative analysis of the influence of thermophysical properties of casting (thermal conductivity, volumetric heat capacity, heat of crystallization, geometric parameters) on ductility of raw sand-clay mold with humidity of 5 % expressed in terms of the average resistance to deformation under an obstruction element 100 mm long. It was established that increase in the above-mentioned factors, at a fixed time, increases the average value of deformation resistance. The quantitative relationship of the released heat with growth of the dry layer of the molding mixture is described. It was noted that dynamics of changes in the average temperature does not always coincide with increase in deformation resistance of the molding mixture.
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Fan, Ridong, Yuling Yang und Songyu Liu. „Impact of In Situ Soil in Soil-Bentonite Cutoff Wall Backfill on Compressibility and Hydraulic Conductivity“. Advances in Civil Engineering 2021 (19.01.2021): 1–12. http://dx.doi.org/10.1155/2021/9350604.
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Soil-bentonite cutoff walls, consisting of excavated in situ soil and bentonite as backfills, are used extensively as vertical barriers for groundwater pollution control. Sand mixed with high-quality natural sodium bentonite (NaB) is commonly used as a research object to investigate the hydraulic and compression properties of soil-bentonite backfills. However, pure sand could rarely be found in real conditions, and natural NaB may not be available readily in some countries such as China, India, and Turkey. This paper presents a comprehensive laboratory investigation on the compressibility and hydraulic conductivity (k) of soil-bentonite backfills created by simulated in situ soil and low-quality sodium activated calcium bentonite (SACaB). The simulated in situ soils are prepared using sand-natural clay mixtures with sand to natural clay mass ratios ranging from 0.5 to 6.0, and the bentonite content (BC) in the base mixture ranges from 0 to 15%. The result indicates that BC dominates the compression index (Cc) of the backfill, and a unique relationship between void ratio at effective vertical compression stress of 1 kPa and compression index is proposed for various types of soil-bentonite backfills. An increase in either BC or clay size fraction (CF) in simulated in situ contributes to reducing k, but the impact of CF in simulated in situ soil on k tends to be insignificant for backfill with BC higher than 6%. A new characteristic parameter based on the concept of void ratio of bentonite (eb), named apparent void ratio of clay size fraction (eC), is developed for predicting soil-bentonite backfills created by in situ soils and bentonites with various contents.
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Fay, Emily L., und Rosemary J. Knight. „Detecting and quantifying organic contaminants in sediments with nuclear magnetic resonance“. GEOPHYSICS 81, Nr. 6 (November 2016): EN87—EN97. http://dx.doi.org/10.1190/geo2015-0647.1.
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We have conducted proton nuclear magnetic resonance (NMR) measurements of relaxation times [Formula: see text] and [Formula: see text] as well as the diffusion coefficient [Formula: see text] to detect and quantify gasoline, diesel, crude oil, and trichloroethylene (TCE) in sediment samples containing water. The sediment samples were coarse sand, fine sand, and a sand-clay mixture. We found that water, gasoline, diesel, and crude oil all exhibited similar signal amplitudes per unit volume, whereas TCE exhibited one-tenth the signal. The ability to use [Formula: see text] measurements to distinguish the contaminant signal from the water signal depended on the bulk-fluid properties as well as the sediment texture and grain size. In the [Formula: see text] distributions for samples containing equal volumes of contaminant and water, the contaminant signal could be resolved for crude oil in sand and for gasoline and TCE in the sand-clay mixture. Adding the diffusion measurement, using either pulsed or static gradients, made it possible to distinguish diesel and crude oil in all of the samples due to the large differences between the [Formula: see text] of the contaminants and water. From the diffusion measurements, we were able to accurately quantify diesel and crude oil volumes ranging from 1% to 17% of the total sample volume. These methods could be applied in the field using NMR logging tools to quantify and monitor subsurface contamination.
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Abdullah, A., Shamsuddin Sulaiman, B. T. Hang Tuah Baharudin, M. K. A. M. Arifin und T. R. Vijayaram. „Effect of Moisture Content on the Permeability of Tailing Sand Samples Gathered from Ex Tin Mines in Perak State Malaysia“. Applied Mechanics and Materials 66-68 (Juli 2011): 1384–89. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.1384.
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Tailing sand is one of the residue minerals obtained after tin extraction. It contains silica in between 94% and 99.5% and available in abundance at the Kinta Valley, Perak State, Malaysia. Permeability is one of the important molding sand properties and considered much in the sand casting mold preparation. This molding sand property plays a vital role in the sand casting process and helps to remove the gases during the casting processing. In this research work, samples of tailing sands were gathered from four identified ex tin mines located at the Perak State, Malaysia. They were investigated by the standard sand testing procedures prescribed by the American Foundrymen Society (AFS). Sand specimens of size Ø50 mm×50 mm in height from various sand–water ratios bonded with 4% and 8% clay were compacted on applying three ramming blows of 6666 g each by using a Ridsdale-Dietert metric standard rammer. The specimens were tested for permeability number with the aid of a Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured by using a moisture analyzer. The results were compared with the properties of the molding sand samples collected from RCS Manufacturing Sdn. Bhd., the company supplying sand to the Proton Casting unit car manufacturing company. The molding sand sample sample bonded with 8% clay was found to have maximum permeability with an optimum allowable moisture content range of 3.5-6.0% and for the sand mixture bonded with 4% clay at 3.0-3.5% moisture.
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Zhang, Z. D., X. M. Yang, C. F. Drury, W. D. Reynolds und L. P. Zhao. „Mineralization of active soil organic carbon in particle size fractions of a Brookston clay soil under no-tillage and mouldboard plough tillage“. Canadian Journal of Soil Science 90, Nr. 4 (01.12.2010): 551–57. http://dx.doi.org/10.4141/cjss09081.
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Soil organic matter is a heterogeneous mixture of organic substances with different compositions and stabilities. To enhance soil organic carbon (SOC) sequestration, it is helpful to understand the distribution of SOC among the soil particle size fractions, the stabilities of the SOC within each fraction, and the influence of management practices, such as tillage, on SOC mineralization. Hence, the objectives of this study were to determine the distribution and mineralization rate of active SOC in the sand (53-2000 µm), silt (2-53 µm) and clay (<2 µm) size fractions of a Brookston clay soil under a corn-soybean rotation and three tillage scenarios. The tillages included long-term (24 yr) mouldboard plough (MP83), long-term (24 yr) no-till (NT83) and short-term (10 yr) no-till (NT97). Bulk soil from the top 10 cm was dispersed into sand, silt and clay size fractions by applying ultrasound energy (750 J mL-1) to a 1:4 soil:water suspension. The sand, silt and clay fractions of the three tillages were aerobically incubated at 20°C and 30% moisture (wt/wt), and the CO2-C emissions were measured over 103 d. The SOC contents followed the order clay > silt > sand for all three tillages. On a whole-soil basis and averaged over the tillage treatments, 55.8% of the SOC was in the clay size fraction, 37.2% was in the silt fraction and 7.0% was in the sand fraction. Carbon mineralization rate in the incubated samples decreased over time, and was related to both particle size fraction and tillage practice. There was very good agreement between a first-order decay model (Ct= C1 + C0 (1-e-kt)) and measured SOC mineralization rates for all size fractions and tillages. The C mineralization data indicated that: (1) the SOC in the clay and sand fractions was more decomposable than the SOC in the silt fraction; and (2) the SOC associated with the clay and silt fractions was more readily decomposable under no-till than under mouldboard plough.
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Маркина, Zoya Markina, Вечеров und Vladislav Vecherov. „Particle size distributions of radioactive pollution soils and its influence on consistence of the shelterbelt forest ranges“. Forestry Engineering Journal 5, Nr. 2 (24.09.2015): 93–103. http://dx.doi.org/10.12737/11983.
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Presents characteristic of the soil texture that formed at mixture of moraine and fluvial-glacial deposits, moraine that overlaid clay loam mantle, clay loam mantle in shelterbelt forest ranges at south-west areas of the Bryansk region that contaminate radioactive fallouts in conse-quence of the Chernobyl accident. Dominant soil fractions determined in soil horizonts, its formed at different parent rock materials. There is a growing number of fine-grained sand and silt soil fractions in the moraine overlaid clay loam mantle compared to fluvio-glacial deposits in the relief of parent materials.
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Samstag, F. J., und F. D. Morgan. „Induced polarization of shaly sands: Salinity domain modeling by double embedding of the effective medium theory“. GEOPHYSICS 56, Nr. 11 (November 1991): 1749–56. http://dx.doi.org/10.1190/1.1442987.
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A modeling technique is proposed that assumes a typical shaly sand to be a three‐phase porous mixture: water, quartz, and clay. The complex conductivity of such a mixture can be modeled with an equation containing only the complex conductivity of each constituent and the geometry of the pore structure. The effective medium theory provides the basis for such a model. The model typically handles two phases at a time, but one of the phases can be considered as a submixture and then the model is simply applied again after the first inversion to determine the properties of the submixture. In the first inversion, the two phases are water and matrix. For the second inversion, the matrix conductivities are modeled by a mixture of quartz and clay. The present work relies on a published data set of 19 samples, with measurements as a function of salinity taken at constant frequency (Vinegar and Waxman, 1984). The proposed technique fit this data better than the Vinegar‐Waxman model which requires more variables. Moreover, this “double embedding” procedure yields realistic values for clay conductivity, clay dielectric constant, and fractional volume of clay.
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Issagulov, A. Z., V. Yu Kulikov, D. A. Issagulova und T. V. Kovalyova. „IMPROVEMENT OF TECHNICAL CHARACTERISTICS ON SAND-CLAY FORMS AT CONSOLIDATION BY THE AIR STREAM“. Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), Nr. 1 (06.04.2018): 75–77. http://dx.doi.org/10.21122/1683-6065-2018-1-75-77.
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One way to compact large-sized sandy-clay mixtures is air-pulse molding. Spreaders used in practice in pulsed molding do not ensure homogeneity of the density at the surface and in the volume of the mold. The design of a gas flow divider is proposed that allows changing the area of the apertures due to the shaped plate and, accordingly, increasing or decreasing the speed and volume of the transmitted air fl w acting on the mixture. This ultimately guarantees uniformity of density throughout the volume of the mold.Also results of researches of voltages and the density appearing in a coma of a mix on height at sealing of sandy-clay forms by an air stream are resulted. The use of air molding with a dissector and a plate for making large-sized molds made it possible to obtain a batch of castings with high geometric accuracy and surface roughness.