Journal articles on the topic 'Clay soils Drying'
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1
Carter, Michael, and Stephen P. Bentley. "Practical guidelines for microwave drying of soils." Canadian Geotechnical Journal 23, no. 4 (November 1, 1986): 598–601. http://dx.doi.org/10.1139/t86-088.
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This note provides practical guidelines for the use of microwave drying in the determination of soil water contents. The results are based on over 250 individual tests performed on sand, sandy clay, estuarine clay, marl, lateritic clay, kaolin, and bentonite (sodium). All soils tested fell into one of three distinct categories and drying times for each are presented as a function of initial sample mass. The recommended drying times give results within 0.5 wt% of those obtained by standard oven drying. No limitations were observed in the performance of a 600-W domestic microwave oven. Key words: water contents, microwave, drying, sand, silt, clay, procedures.
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Vishweshwaran, Muralidaran, and Evangelin Ramani Sujatha. "Geotechnical Investigation of Gelatin Biopolymer on Cohesive Soils." Sustainability 15, no. 3 (January 20, 2023): 2041. http://dx.doi.org/10.3390/su15032041.
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Gelatin, a biopolymer derived from animal proteins, has been selected to stabilize three fine-grained soils by determining select index and engineering properties. Specimens for California Bearing Ratio (CBR) were tested using three different curing methods, i.e., thermally cured at 60 °C, unsoaked, and 7 days air-cured submerged specimens. The amount of gelatin added to the soil ranged from 0.5% to 2% by soil weight. The sequence of the interaction between gelatin and the clays is as follows: (A) The biopolymer solution is adsorbed and agglomerated onto the surface of the clay. (B) The presence of Al3+, Si4+, and K+ ions on the clay promotes the blending of connective linkages with negatively charged gelatin. (C) The connection reinforcements harden with the curing period and subsequent drying of the stabilized soils. (D) Drying of the gelatin–clay complex also establishes alternative bonding modes such as van der Waals interactions and ligand exchange. The biopolymer formed dry, rigid films after 72 h which were responsible for coating and reinforcing the soil particles. Thermal curing by 1% addition of gelatin yielded the maximum CBR of 91.42%, 141.1%, and 122.3% for high compressible clay, low compressible clay, and low compressible silt, respectively, and a maximum Unconfined Compressive Strength (UCS) of 3968 kN/m2 for the low compressible clay. The UCS results revealed that brittle failure was predominant for the gelatin-amended soils after 28 days of curing while shear failure was observed for the treated soils tested 2 h after sample preparation. Tests on pH revealed that the gelatin-stabilized soils displayed marginal variations after 28 days. Spectroscopic analysis revealed the various types of bonds between gelatin and the clays. A reduction in mass of 9% was observed for the alternate wetting and drying of the high compressible clay after a period of 12 cycles. The adsorption of the clay–gelatin complex was indicated by variation in average particle diameter and specific surface. Savings in 450 m3 and 93.75 m3 of coarse aggregates and dense bituminous macadam, respectively, were observed for a 1 km pavement for the stabilized low compressible clay.
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Morris, Peter H., J. Graham, and David J. Williams. "Cracking in drying soils." Canadian Geotechnical Journal 29, no. 2 (April 1, 1992): 263–77. http://dx.doi.org/10.1139/t92-030.
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Cracking in soils that are undergoing drying is controlled by soil suctions and by soil properties such as compression modulus, Poisson's ratio, shear strength, tensile strength, and specific surface energy. The paper reviews the occurrence and morphology of cracks in dry-climate regions of Australia and Canada. After reviewing the behaviour of unsaturated soils and the mechanics of cracking, solutions are developed based on (i) elasticity theory, (ii) the transition between tensile and shear failure, and (iii) linear elastic fracture mechanics. The solutions are compared and related to crack depths observed in the field. Key words : clay, cracks, crust, shear strength, soil suction, tensile strength, unsaturated soil, weathering.
4
Rayhani, M. HT, E. K. Yanful, and A. Fakher. "Desiccation-induced cracking and its effect on the hydraulic conductivity of clayey soils from Iran." Canadian Geotechnical Journal 44, no. 3 (March 1, 2007): 276–83. http://dx.doi.org/10.1139/t06-125.
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Clay materials have many environmental applications, especially in situations where a hydraulic barrier is desired. However, as the plasticity of clay increases, cracks tend to develop during cycles of long dry spells. This is particularly a concern in the construction of covers or installation of landfill liners prior to waste filling. In the present study, specimens prepared from three natural clayey soils from Iran used for clay barrier construction, and one artificial clayey soil, were subjected to cycles of wetting and drying. Surface cracks of different dimensions formed as a result of drying. Specimens with the largest volumetric shrinkage strains typically contained the highest number of cracks. Specimens that developed cracks were subjected to hydraulic conductivity testing. The results showed that the dimension of cracks increased with increasing plasticity index and clay content and, so, the initial hydraulic conductivity increased with increasing plasticity index and cycles of drying and wetting. Cracking increased the hydraulic conductivity by 12–34 times, depending on the plasticity of the soil. After a long saturation time, the hydraulic conductivity of the soils decreased with an increase in saturation time, which could be associated with a self-healing process that affects the soils by different degrees.Key words: desiccation, cracking, plasticity, hydraulic conductivity, clay barriers, self-healing, volumetric shrinkage.
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Wang, Dong Lin. "Experimental Study on Relationship between Saturation Degree and Void Ratio of Remolded Soils on Drying Path." Advanced Materials Research 194-196 (February 2011): 1045–48. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1045.
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By using of shrinkage curve, the empirical relationship between the degree of saturation and the void ratio on drying path was established for four types of soils including sand, silt, clay and soft clay. It was indicated that during the process of drying, the soil samples continuously shrunk with the decrease of saturation degree. For test samples of sand and silt, the curve of saturation degree and void ratio is flat; For test samples of clay and silt clay, however, the shrinkage of the soil samples was almost fulfilled when the degree of the saturation of soil samples decreased to 90% and the void ratio of the soil samples almost kept unchanged while the degree saturation of soil was reduced to 70%.
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Niskanen, Raina, and Väinö Mäntylahti. "Determination of soil specific surface area by water vapor adsorption: I Drying of soil samples." Agricultural and Food Science 59, no. 2 (April 1, 1987): 63–65. http://dx.doi.org/10.23986/afsci.72248.
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Drying of three mineral soil samples (clay content 4—58 %, organic carbon content 1—5 %) equilibrated at 75.5 % relative humidity was studied. The soils were dried in an oven at +50°C, +70°C and + 105°C for 4 and 8 hours and in a desiccator over pure concentrated H2SO4 and P2O5. Drying over desiccants for 8 hours removed less water than drying at + 50°C. Drying over desiccants for 3—7 days was as efficient as drying at +70°C, for 14—24 days as efficient as 4 hours of drying at + 105°C. Eight hours of drying at + 105°C seemed to be too drastic, because it caused a greater weight loss in the clay sample of 5 % organic carbon content than did prolonged desiccant-drying. Drying at + 70°Cremoved as much water from fine sand which contained 4 % clay as prolonged desiccant-drying.
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Kaczmarek, Łukasz, Małgorzata Jastrzębska, and Tomasz Wejrzanowski. "The Impact of Microwave Drying on the Structure of Exemplary Soils—Insights Using X-ray Microtomography." Materials 15, no. 17 (August 26, 2022): 5891. http://dx.doi.org/10.3390/ma15175891.
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In the field of soil drying methods, rapid microwave heating is progressively replacing conventional techniques. Due to the specific heat transport caused by microwaves, the drying process can significantly modify soil structure, which, in turn, can influence mechanical and filtration characteristics. In this study, we compared structural changes of exemplary non-cohesive (medium quartz sand (MSa)) and cohesive soil (silty clay mainly composed of kaolinite (siCl)). The sample materials were subjected to three different drying methods: air-drying, conventional oven (CO) drying, and microwave oven (MO) drying (MO). Soil structure was studied using X-ray microtomography (XµCT) and described in detail by image analysis methods. The study showed that the analyzed types of heating had a negligible effect on the structure of the sands, but a significant impact in the case of silty clay. Such a phenomenon is discussed and explained in this paper. The study advances the testing of soils microwave drying in a geotechnical laboratory.
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Bronswijk, J. J. B., and J. J. Evers-Vermeer. "Shrinkage of Dutch clay soil aggregates." Netherlands Journal of Agricultural Science 38, no. 2 (June 1, 1990): 175–94. http://dx.doi.org/10.18174/njas.v38i2.16603.
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Shrinkage characteristics and COLE and PLE values of undisturbed natural aggregates of clay soils from the Netherlands were measured. The course of the shrinkage process upon drying varied strongly between soils, and very often the measured characteristics diverged from the theoretical curve. Some Dutch clay soils are amongst the strongest swelling and shrinking soils in the world, with volume decreases of aggregates up to 49% between saturation and oven-dryness, and 42% between saturation and a pressure head of -16 000 cm. Potential subsidence of a Dutch field soil due to shrinkage is up to 15 cm. In some Netherlands clay soil, as a result of normal shrinkage, the aggregates remain saturated throughout the whole year; only inter-aggregate pores such as shrinkage cracks, contain air. (Abstract retrieved from CAB Abstracts by CABI’s permission)
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Poncelet, Nicolas, and Bertrand François. "Desiccation crack in lime-treated silty clay: Experimental evaluation and constitutive interpretation." E3S Web of Conferences 92 (2019): 11002. http://dx.doi.org/10.1051/e3sconf/20199211002.
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The present work investigates the desiccation effects on a lime-treated clayey silt. Original experimental techniques have been developed to control suction conditions (with osmotic technique) and to track volume variations and cracks occurrence upon drying. Free and constrained dryings are performed to evaluate the shrinkage potential (for free drying) and the conditions of desiccation crack triggering (upon constrained drying). Also, indirect tensile tests and uniaxial compression tests are carried out to evaluate the strength at various suctions. Those investigations have been performed on natural and lime-treated clayey silt in order to emphasis the role of the lime treatment in the triggering and/or mitigation of the cracking process. At the end, generalized effective stress framework with an effective stress parameter χ calibrated according to a power law is used to provide a constitutive interpretation of the occurrence of desiccation cracks in relation with the water retention properties, the soil stiffness, the tensile strength and the geometrical constraints of the soil samples. For the used compacted materials, it is demonstrated that the lime treatment postpones the occurrence of desiccation cracks and so, plays a favourable role in the stabilization of soft soils subject to drying.
10
Ohtsubo, Masami, Kazuhiko Egashira, and Masateru Takayama. "Properties of a low-swelling smectitic marine clay of interest in soil engineering." Canadian Geotechnical Journal 22, no. 2 (May 1, 1985): 241–45. http://dx.doi.org/10.1139/t85-033.
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Smectite is generally a high-swelling clay. However, the smectite found in marine quick clays in the Ariake Bay area of Japan is a low-swelling clay like illite and kaolinite. The low swelling properties of an Ariake marine clay are investigated here in terms of consolidation, swelling, and shrinkage characteristics. The void ratios in compression curves of soils containing sodium are lower at 0.01 N than at 1.0 N NaCl concentration, and the slopes of swelling curves are independent of salt concentration in the pore water and cation valency. These tendencies are contrary to those observed for montmorillonite and a paddy soil containing high-swelling smectite. Measurements of swelling pressure suggest that the smectite in the Ariake marine clay exhibits little intracrystalline swelling even after saturation with Na. The volume shrinkage of the Ariake marine clay by air-drying is smaller than that of the paddy soil. Key words: compressibility, marine clays, smectite, swelling.
11
Grant, CD, and AV Blackmore. "Self mulching behavior in clay soils - Its definition and measurement." Soil Research 29, no. 2 (1991): 155. http://dx.doi.org/10.1071/sr9910155.
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The history of the self-mulching concept is reviewed and from this a definition is proposed. Observation of the phenomenon to date has been quite subjective and qualitative, and the causes and mechanisms are little understood. A numerical index is developed to help redress these deficiencies. The self-mulching property embodies the ability of a soil to re-aggregate its clay in the course of wetting and air drying after the natural structure has been disrupted by puddling. A comparison of the clay released by such puddling with the clay released by shaking after drying and slaking of the puddle, forms the basis of the components for the numerical index. Suitable parameters for these components were extracted from experiments using typical Australian self-mulching soils. These soils also displayed a degree of subplasticity in at least part of their aggregated clay fraction. The numerical index values were compared with field structure ratings, made by pedologists, for 47 (mostly surface) soils from Australia and other parts of the world, and good agreement was found. The index is relevant to further work on mechanisms and modifications in self-mulching or potentially self-mulching soils.
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Kozlovsky Dufková, Jana. "Influence of low temperatures on aggregate disruption of heavy clay soils." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 58, no. 2 (2010): 161–68. http://dx.doi.org/10.11118/actaun201058020161.
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Heavy clay soils that are normally resistant to wind erosion, from study site Ostrožská Nová Ves situated in the foothills of the Bílé Karpaty Mountains, Czech Republic, were a subject of laboratory analyses. The analyses should found out the influence of overwinter processes on disruption of soil aggregates and thus reason of vulnerability to soil loss by wind. Two overwinter processes were observed – freezing and thawing, and freeze-drying of the soil. Both processes have indicated the increasing of erodible fraction in dependence of water content of analysed soils. Exposed frozen clay soils that freeze-dries during the winter in the foothills of Bílé Karpaty, leaves soils highly erodible in late winter and early spring.
13
KIMPE, C. R. DE. "EFFETS DE LA PRÉPARATION DU SOL POUR ESSAIS DE CULTURE SOUS CONDITIONS CONTRÔLÉES." Canadian Journal of Plant Science 65, no. 3 (July 1, 1985): 761–69. http://dx.doi.org/10.4141/cjps85-096.
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The effect of soil preparation on oat yield was investigated in two pot experiments involving several Quebec soils. The soils were used either untreated or were sieved after air-drying or at field moisture. Bulk density was higher for the soils sieved after air-drying, which generally gave the highest yields. When the soils were grouped as function of yield, it appeared that clay-rich soils low in organic matter were most susceptible to loss of structure and subsequently produced the lowest yield. A statistical analysis of the yields was conducted as a function of soil preparation and bulk density. The results suggest that in the case of experiments involving several soils, the method of soil preparation can induce or suppress differences that would be attributed to treatments.Key words: Soil preparation, bulk density and yield, soil disaggregation
14
Kong, Lingwei, Hossain Md Sayem, and Huihui Tian. "Influence of drying–wetting cycles on soil-water characteristic curve of undisturbed granite residual soils and microstructure mechanism by nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) relaxometry." Canadian Geotechnical Journal 55, no. 2 (February 2018): 208–16. http://dx.doi.org/10.1139/cgj-2016-0614.
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Due to the formational environment and climatic variability, granite residual soils with grain-size distribution ranging from gravel to clay undergo multiple drying–wetting cycles. The influences of multiple drying–wetting cycles on the soil-water characteristic curve (SWCC) and pore-size distribution (POSD) of undisturbed granite residual soils are investigated using the pressure plate test and nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) distribution measurement, respectively. Results show that the water-retention capacity and air-entry value decrease and pores become more uniform with increasing drying–wetting cycles. After four drying–wetting cycles, the soil reaches a nearly constant state. The POSD change of multiple drying–wetting cycle samples is consistent with the SWCC of the soils. Furthermore, a modified van Genuchten model in terms of cumulative pore volume is used to obtain the best-fit POSD of the drying–wetting cycle samples. The shape and changing tendency of both curves of SWCC and POSD are quite similar and achieved a better correlation. It can be concluded that the SWCC is strongly dependent on the POSD of the soil and NMR T2 relaxometry can be used as an alternative to the assessment of microstructural variation of residual soils subjected to the periodic drying and wetting process.
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Bi, Yu-Zhang, Jia-Ming Wen, Hao-Liang Wu, and Yan-Jun Du. "Evaluation of Performance of Polyacrylamide-Modified Compacted Clay as a Gas Barrier: Water Retention and Gas Permeability and Diffusion Characteristics." Applied Sciences 12, no. 16 (August 22, 2022): 8379. http://dx.doi.org/10.3390/app12168379.
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In this paper, the performance of a gas barrier that consisted of polyacrylamide (PAM)-modified compacted clayey soil was experimentally explored. The moisture content and water loss characteristics of the tested soils were adopted as indicative indices of water retention capacity (WRC). The gas permeability (Kp) and gas diffusion coefficient (Dp) of the modified compacted clays were evaluated via gas permeability and gas diffusion tests. The test results showed that the moisture content of the modified compacted clay samples subjected to drying tests increased with increasing polyacrylamide content. Kp and Dp decreased with increasing PAM content. Compared with 0.2% PAM content, the Kp of the sample with 1.0% PAM was reduced by ten times, and the Dp was reduced to ~35%. Compared to the unmodified clay, the liquid limit of the PAM-modified clay increased by 45~55%. Comparison of the liquid limit tests between this study and previous studies revealed that the liquid limit ratio of the zwitterionic polyacrylamide (ZP)-modified soil was much higher than the other material-modified soils. The results of this study are useful to facilitate the application of modified compacted clays as gas barrier materials at industrial contaminated sites.
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Bristow, KL, and DG Abrecht. "The physical environment of two semi-arid tropical soils with partial surface mulch cover." Soil Research 27, no. 3 (1989): 577. http://dx.doi.org/10.1071/sr9890577.
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The seedbed microenvironment in soils with partial surface mulch cover will be affected by the width of the bare row zones. In this paper we compare seedbed conditions under four bare row widths [0 cm (completely mulched), 5 cm, 15 cm and completely bare] during a drying cycle in a loamy sand and clay loam soil in a semi-arid, tropical environment. It is shown that for both soils the rates of drying were greatest in the bare soil and least in the mulched soil, with the 5 and 15 cm bare row width treatments showing trends which were intermediate between the two extremes. Although soil surface temperatures were not noticeably different between the two soils, differences at depth became substantial as the soils dried, with the maximum temperature at 5 cm depth in the loamy sand exceeding that in the clay loam. There was also a steepening in the temperature gradient with depth as the soils dried. Under both wet and dry conditions, maximum temperature at 5 cm depth increased significantly with bare row width up to a width of about 25 cm which, for mulch of negligible height, approximates a bare soil. Results of this work demonstrate the benefits of maximizing surface mulch cover in the semi-arid tropics.
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Alhaj, K. M. A., G. Biscontin, M. Z. E. B. Elshafie, and A. S. Osman. "Water retention and characteristic curves representing tropical clay soils from Africa." E3S Web of Conferences 195 (2020): 01019. http://dx.doi.org/10.1051/e3sconf/202019501019.
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Soil water retention curves (SWRCs) form an essential component of frameworks coupling the hydromechanical behaviour of unsaturated soils. The curves describe how suction changes with variables such as degree of saturation, void ratio and volumetric/gravimetric water content. SWRCs can be determined from incrementally drying initially saturated reconstituted samples to a final residual state, thus developing the primary drying curve (PDC). The primary wetting curve (PWC) is established from subsequent incremental wetting from residual state and is hysteretic compared with the PDC. SWRCs for reconstituted, high-plasticity, tropical clays from Africa (Sudan, Tanzania and South Africa) will be produced using suction measuring instruments, a tensiometer, filter paper and a dew point potentiometer. The development of SWRCs under various subsequent cycles of drying will be presented and discussed along with details concerning volumetric changes and cracking during drying. In order to investigate the uniqueness of the PDC and PWC and the effect of initial void ratio, SWRCs will be determined for samples formed by reconstituted from slurry under different applied energy levels.
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Charkley, Frederick Nai, Kunyong Zhang, and Guoxiong Mei. "Shear Strength of Compacted Clays as Affected by Mineral Content and Wet-Dry Cycles." Advances in Civil Engineering 2019 (October 24, 2019): 1–8. http://dx.doi.org/10.1155/2019/8217029.
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The behaviors of high-plasticity clays depend largely on the clay mineral content. Recently, it has been observed that sudden slope failures of most clay slopes occur in regions pronounced with repeated rainfall and sunny climate. The reason for this is still unclear. Examining the effect of clay minerals and drastic weather changes on shear strength will be useful in predicting the performance of structures built in such soils and to take precautionary measures to improve the properties before failure. Therefore, a series of quick direct shearing tests were conducted on 11 artificial clay mixtures. The cohesion and frictional strength properties were determined and linked to the proportion of clay minerals and the number of wetting and drying cycles. The results show a significant reduction in shear strength after exposure to wetting and drying. Generally, montmorillonite-dominated mixtures were less susceptible to the changes in cohesion strength than kaolin-dominated mixtures, and the reduction in frictional strength was relatively insignificant.
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Girkontas, Romas, Tadas Tamošiūnas, and Andrius Savickas. "RESEARCH OF DEFORMATION OF CLAY SOIL MIXTURES MIXTURES / MOLINIŲ GRUNTŲ MIŠINIŲ DEFORMACIJŲ TYRIMAS." Mokslas – Lietuvos ateitis 6, no. 5 (December 19, 2014): 488–92. http://dx.doi.org/10.3846/mla.2014.690.
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The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bearing capacity and failure mode were determined. For investigations Vilnius Gediminas Technical University Civil Engineering Scientific Research Center infrastructure was used. Tyrimo tikslas – nustatyti molinio grunto mišinių džiūvant atsirandančias deformacijas. Eksperimentams buvo naudojama: a) moliniai ir molio mišinių tiltai (aukštis ~0,30 m, tarpatramis ~1,00 m, plotis 0,07–0,1 m); b) plytelės iš molio; molio, smėlio ir šiaudų (l; b; h); c) cilindrai iš molio; molio ir šiaudų; molio, šiaudų, smėlio (d; h). Pagal gautus bandymo rezultatus pateiktos rekomendacijos molinių gruntų mišinių džiovinimo technologijai taikyti. Nustatyta molinių tiltų laikomoji galia ir suirimo pobūdis. Atliekant tyrimus buvo pasinaudota Vilniaus Gedimino technikos universiteto Civilinės inžinerijos mokslo centro MTEP infrastruktūra.
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Al Zubaydi, Abdulrahman H. T. "Effect of Wetting and Drying Cycles on Swell/Collapse Behavior and Cracks of Fine – Grained Soils." Tikrit Journal of Engineering Sciences 18, no. 4 (December 31, 2011): 71–79. http://dx.doi.org/10.25130/tjes.18.4.08.
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Many of the soils undergo volumetric changes due to the change in the water content. Swell-shrink and collapse behavior of those soils affects the stress state in soil and the interacted structures. Shrinkage in the soil produce cracks of different patterns, and affects the swelling potential in next wetting cycle.This study covers swelling and collapsing properties of four different soils from Mosul city. The changes in swelling and collapsing properties with respect to number of wetting and drying cycles have been investigated. Also, A shrinkage cracks have been studied with aid of digital image after each drying cycle. Number of segments and area of cracks calculated with aid of AutoCAD package.Results indicated that, the collapse potential is influenced by soil type (soil composition) and applied loads. As the applied loads increase the collapse potential increases. For sandy soil the collapse potential decreased with increasing wetting and drying cycles, and for the clayey soils, swell potential decreased while collapse potential increased with these cycles. It has been shown that the cracks increase with wetting-drying cycles. Larger values of percent crack area to the initial sample area has been observed in the soil that contain more clay content than other types of soils.
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Jiao, Yu-Yong, Liang Song, Hui-Ming Tang, and Yun-An Li. "Material Weakening of Slip Zone Soils Induced by Water Level Fluctuation in the Ancient Landslides of Three Gorges Reservoir." Advances in Materials Science and Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/202340.
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This experimental study investigated the effect of repeated wetting and drying on the reduction of slip zone soils taken from the Huangtupo landslide in the Three Gorges Reservoir, China. The variation process of the physical property and substance composition of the slip zone soils under the wetting-drying cycles was studied through liquid and plastic limit test and X-ray diffraction test. The results indicate that (1) the shearing strength of the slip zone soil dramatically decreased after one wetting-drying cycle and then gradually decreased until reaching a relatively stable state at the fourth cycle; (2) the plasticity index of the slip zone soil varied with increasing number of cycles and a variation process opposite to that of the strength value was observed; and (3) the clay mineral content in the slip zone soil increased and the calcite and quartz contents relatively decreased with increasing number of cycles. The variations in the plasticity index of the slip zone soil, as well as the increase in its clay mineral content, play important roles in the strength reduction. The results of this study provide a foundation for revealing the deformation and damage mechanism of landslides in reservoir banks.
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Farahani, Elham, Hojat Emami, and Thomas Keller. "Impact of monovalent cations on soil structure. Part II. Results of two Swiss soils." International Agrophysics 32, no. 1 (January 1, 2018): 69–80. http://dx.doi.org/10.1515/intag-2016-0092.
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AbstractIn this study, we investigated the impact of adding solutions with different potassium and sodium concentrations on dispersible clay, water retention characteristics, air permeability, and soil shrinkage behaviour using two agricultural soils from Switzerland with different clay content but similar organic carbon to clay ratio. Three different solutions (including only Na, only K, and the combination of both) were added to soil samples at three different cation ratio of soil structural stability levels, and the soil samples were incubated for one month. Our findings showed that the amount of readily dispersible clay increased with increasing Na concentrations and with increasing cation ratio of soil structural stability. The treatment with the maximum Na concentration resulted in the highest water retention and in the lowest shrinkage capacity. This was was associated with high amounts of readily dispersible clay. Air permeability generally increased during incubation due to moderate wetting and drying cycles, but the increase was negatively correlated with readily dispersible clay. Readily dispersible clay decreased with increasing K, while readily dispersible clay increased with increasing K in Iranian soil (Part I of our study). This can be attributed to the different clay mineralogy of the studied soils (muscovite in Part I and illite in Part II).
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Nelson, P. N., J. A. Baldock, and J. M. Oades. "Changes in dispersible clay content, organic carbon content, and electrolyte composition following incubation of sodic soil." Soil Research 36, no. 6 (1998): 883. http://dx.doi.org/10.1071/s98024.
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Measurement of dispersible clay is important for the diagnosis of structural stability problems in soil. However, clay dispersibility is known to change with water content and time. The purpose of the present study was to determine how incubation of sodic soil under different water content regimes influences clay dispersibility. Two topsoils (depth 0-0·1 m), one sodic [exchangeable sodium percentage (ESP) 9 · 7] and the other non-sodic (ESP 3·8), were collected from an experimental pasture at Kyabram, Victoria, and 2 soils, a sodic topsoil (depth 0-0·1 m, ESP 6·9) and the corresponding subsoil (depth 0·2-0 m, ESP 25·7), were collected from a cropped field at Two Wells, South Australia. The soils were incubated for 264 days in a split-plot design. The main treatments were soil type and incubation water content: continuously air-dry, continuously wet (-50 kPa), or with wet/dry cycles. The subtreatment was water content at analysis: air dry or wet (-50 kPa). Clay dispersion was greater when measured on wet soils than dry soils, irrespective of water contents during the prior incubation. Electrical conductivity increased, and sodium adsorption ratio (SAR), pH, and organic carbon content decreased as a function of the time for which the soils were wet. In the Kyabram soils that were wet when analysed, easily dispersible clay content increased with SAR. Decreases in moderately dispersible clay under the wetting/drying regime were not related to electrolyte composition, and were attributed to particle rearrangement and cementation. The decreases in clay dispersibility with time occurred despite net losses of carbohydrate and aliphatic materials. An implication of the work is that the decomposition of soil organic matter, even in the absence of fresh additions, may reduce clay dispersion in sodic soils by altering electrolyte concentration and composition.
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Singer, A., WFA Kirsten, and C. Buhmann. "Clay dispersivity and crusting of soils determined by Buchner funnel extractions." Soil Research 32, no. 3 (1994): 465. http://dx.doi.org/10.1071/sr9940465.
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Soil dispersivity tests strongly disturb soils and therefore only remotely reproduce conditions in the field. A quick and inexpensive laboratory method for the assessment of clay dispersivity of soils is proposed that involves a much milder soil treatment. The method is based on the observation that, during the separation of the soil solution from soil pastes, the separated soil solution in some soils contains suspended fine matter. The method involves the consecutive extraction of wetted and only mildly disturbed soil packed in a Buchner funnel, under standardized conditions. The time needed for the completion of the extraction of 20 mL of solution, and the extracted mineral load, are monitored. After drying, the micromorphology of the soil cake can be observed by scanning electron microscopy. By this method, the results obtained from six South African soils compared well with spontaneous dispersion test data (after Rengasamy et al., Aust. J. Soil Res., 1984, 22, 413-31) obtained independently.
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Pillai-McGarry, UPP, and N. Collis-George. "Laboratory simulation of the surface morphology of self-mulching and non-self-mulching vertisols .1. Materials, methods and preliminary results." Soil Research 28, no. 2 (1990): 129. http://dx.doi.org/10.1071/sr9900129.
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To date, the definitions of 'self-mulching' in Vertisols describe the phenomenon only in the air-dry state with no details of the dynamics of the system. A laboratory study was carried out to simulate the field morphological features of the soil surface of three Vertisols, one self-mulching and two non self-mulching. The soils differed in shear strength in the field, clay type, ESP and exchangeable Ca/Mg ratio. The laboratory simulation involved both repeated wetting/drying cycles with 6 mm of water every 48 h, and a continuous drying phase. These were imposed on ponded and puddled samples of the soils. With repeated wetting and drying the self-mulching soil developed a surface with a more complex organization of structural features than either of the non self-mulching soils. The self-mulching soil generated a granular structure and developed the widest cracks. Most elements of the surface morphology observed in the field were achieved in the laboratory simulation.
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Strong, D. T., P. W. G. Sale, and K. R. Helyar. "The influence of the soil matrix on nitrogen mineralisation and nitrification. IV.Texture." Soil Research 37, no. 2 (1999): 329. http://dx.doi.org/10.1071/s98043.
Full textAbstract:
Small undisturbed soil volumes (c. 1·7 cm3) were collected from the surface of a small field plot. Soil volumes were treated with clover-derived substrate, dried and rewetted, or retained continuously moist from the field. These soil volumes were then incubated for 20 days at a matric water potential of either –10 or –30 kPa. At the end of the incubation the soil was analysed for volumetric water content (θv), NO-3 -N, NH+4 -N, total N (%N), and percentages of sand, silt, and clay. The texture terms were included in linear regression models, together with %N and θv as predictors of N mineralisation and nitrification. Clay and sand were often observed to have a significant influence on N mineralisation and nitrification, but silt rarely appeared to influence these processes. In soils retained continuously moist, %clay had a negative relationship with N mineralisation and nitrification, but this relationship was positive in soils that had been dried and rewetted. The results suggest that during periods of relatively high moisture content, soils that are higher in clay are able to protect organic N more effectively from microbial attack. However, on drying and rewetting, the protective mechanisms of clay are undermined, the relatively large protected reservoirs of organic N in high clay soils become more vulnerable to microbial attack, and these soils therefore experience a greater flush of N mineralisation than soils with lower clay levels. The negative influence of clay in the continuously moist soils was not as clearly observed in the soils incubated at –10 kPa as in soils incubated at –30 kPa, suggesting that the decomposition of organic N resident in larger pores (10–30 µm neck diameter) may not be as strongly regulated by clay as that resident in smaller pores. When soils were treated with clover-derived substrate, clay had a positive relationship with N mineralisation and nitrification rates. This may have been because clay limited the diffusion of partially decomposed organics away from the decomposing microbial population, thereby helping to facilitate more complete decomposition of the organic material. Texture had very little influence on the nitrification of urea-derived ammonium.
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Tollenaar, Roderick N., Leon A. van Paassen, and Cristina Jommi. "Small-scale evaporation tests on clay: influence of drying rate on clayey soil layer." Canadian Geotechnical Journal 55, no. 3 (March 2018): 437–45. http://dx.doi.org/10.1139/cgj-2017-0061.
Full textAbstract:
Cracks in drying soils have detrimental effects on the integrity of geotechnical structures. The evaporation rate is recognized to play an important role in fracture generation, having a direct impact on the amount of cracks produced. This investigation examined the drying behaviour of a clay with different initial water contents and under different evaporative conditions. Small-scale evaporation experiments were carried out using a river clay and commercially available suction-measuring equipment. The results showed that the initial conditions have great influence on the drying performance of a soil, which can be partly attributed to the influence of the surface texture and the pore structure. It was observed that under certain circumstances, the evaporation of a soil surface can be higher than that of open water. The different evaporation rates had a marked effect on the water distributions with depth within the soil. The evaporation rate also produced a dynamic response of the soil-water retention curve.
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Levy, GJ, and M. Agassi. "Polymer molecular-weight and degree of drying effects on infiltration and erosion of three different soils." Soil Research 33, no. 6 (1995): 1007. http://dx.doi.org/10.1071/sr9951007.
Full textAbstract:
Low infiltration rate and high levels of soil erosion are critical problems in many soils worldwide. Amendment of soils with organic polymers could alleviate these problems. The objective of the present study is to investigate the effects of polymer molecular weight and the degree of drying on the infiltration rate of, and erosion from, three different soil types from Israel. A solution of high-molecular-weight (2x107 Da) or low-molecular-weight (2x105 Da) negatively charged polyacrylamide (PAMH and PAML, respectively) was added to the surface of soil samples packed in trays, at a rate of 20 kg ha-1. The soil samples were allowed to dry to varying degrees and were then exposed to 60 mm of simulated rain during which infiltration rate and soil loss were determined. The ability of the polymer to maintain high final infiltration rates (FIR) depended on its molecular weight and the clay content of the soils. In the coarse- and medium-textured soils, the PAMH was more effective than the PAML in maintaining high FIR. In the fine-textured soil, the effects of both polymers on Fm. were comparable; the use of the PAML is therefore preferable since it is easier to handle. Both polymers had reduced soil loss comparably. The effects of drying were similar for both polymers: the FIR and soil loss values with the intermediate degrees of drying were higher and lower, respectively, than they were with the no-drying or complete-drying treatments.
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Kowalenko, C. G., and S. Yu. "Solution, exchangeable and clay-fixed ammonium in south coast British Columbia soils." Canadian Journal of Soil Science 76, no. 4 (November 1, 1996): 473–83. http://dx.doi.org/10.4141/cjss96-059.
Full textAbstract:
Solution, exchangeable and clay-fixed ammonium were measured in a variety of south coast British Columbia soils in the laboratory using extraction, equilibration and leaching procedures, and with and without ammonium amendments in order to evaluate the relative significance of adsorption and fixation processes on nitrogen behavior. Non-amended soils contained from 59 to 224 g N g−1 of fixed ammonium and these amounts were correlated with clay (positive) and sand (negative) contents. The amount of native fixed ammonium in the soils was influenced by management history. Recovery of ammonium added to eight selected samples by a small volume of solution followed by air drying was the same with 1 and 2 M KCl extractions, but less was extracted by 0.1 M KCl and even less by water. This showed that both 1 and 2 M KCl had sufficient K+ to displace the NH4+ present (inherent and added) on the exchange sites without an apparent effect on fixed ammonium. Up to 68% of the ammonium added was not extracted by 2 M KCl and assumed to have been fixed in the clay lattice. The proportion of the added ammonium that was adsorbed onto the exchange sites was linear up to 200 μg N g−1 application, but the amount fixed by the clays was linear to only about 100 μg N g−1 application rate. Data from studies where soil columns were leached with NH4NO3 provided only limited information on the relative importance of exchange versus fixation processes to the adsorption of ammonium. Leaching columns with a limited number of batches of NH4NO3 followed by water (short cycle) were useful for comparing the ability of different soils to adsorb and retain ammonium, but the relative importance of exchange versus fixation could not be determined. In the 18 samples of this study, the amount of NH4+ adsorbed ranged from 84 to 25% during short cycle column leachings. Different patterns of adsorption occurred among the four soil samples that were leached with a large number of batches of ammonium (long cycle), but it could not be determined whether or not these patterns were related to differences in proportions of fixation relative to exchange. Measurements showed that ammonium was fixed in the soils during the long cycle leachings but that the amounts of fixed ammonium measured were influenced by air drying the sample before analysis. Several studies with and without toluene additions showed that microbial activity must be controlled during these measurements. It was concluded that south coastal soils contained significant amounts of fixed ammonium and can fix additional ammonium. The amount of ammonium in the clay fixed pool and the potential to fix added ammonium was different in relation to the soil type, their previous management, and wetting and drying cycles. The biological significance of fixed ammonium and the fixation process must not be discounted in any nitrogen studies of these soils for proper interpretation of data. Key words: Ammonium fixation, equilibration, column leaching, microbial/enzyme inhibition, extractant concentration
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Araujo, Arthur Gomes Dantas de, Nayara Torres Belfort, Felipe Araujo Silva Barbosa, Thalita Cristiana Rodrigues Silva, Silvio Romero de Melo Ferreira, Leonardo José do Nascimento Guimarães, and Izabela Medeiros de Lima Bezerra. "Expansive Clay Cracking Behavior through Digital Image Correlation." E3S Web of Conferences 195 (2020): 03006. http://dx.doi.org/10.1051/e3sconf/202019503006.
Full textAbstract:
Expansive soils may present cracks arising from the drying process and their evolution can cause irreparable damages to engineering projects. Investigating this phenomenon is vital to understanding its geomechanics. The objective of this article is to present numerical modelling of the formation and propagation of cracks in expansive soil. A desiccation experiment was therefore carried out using an expansive silty clay from Paulista, in northeastern Brazil. The drying process was monitored by measuring the temperature and relative humidity of the air, as well as by capturing images with a camera. The digital images were correlated using the Ncorr numerical tool in MATLAB. As a result, this study made it possible to conclude that the soil cracking dynamics presented a non-orthogonal pattern during the dryness test, while the image treatment made it possible to observe the tendency of cracks to appear and propagate on the soil surface, allowing for the detection of crack growth and propagation trends.
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Chinh, Ngo Duc, and Nguyen Ngoc Tan. "Design of a new soil concrete as an eco-material: Effect of clay and hemp fibers proportions." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 14, no. 1 (January 22, 2020): 77–88. http://dx.doi.org/10.31814/stce.nuce2020-14(1)-07.
Full textAbstract:
This study presents a series of soil concrete mix that is made of excavated soils, cement, lime and hemp fibers. An experimental program was carried out on the testing samples of soil concrete with different proportions of clayey soil and hemp fibers. This program focus on several properties of soil concrete, such as compressive strength, autogenous shrinkage, drying shrinkage and water mass loss with time. The obtained results show that the compressive strength of soil concrete increases even after 28 days, and can be reduced significantly with increasing the proportion of clayey soil. The effect of clayey soil on the properties tested of soil concrete is more than that of hemp fibers. In addition, drying shrinkage associated with water mass loss allows to describe the drying process of soil concrete.
Keywords:
soil concrete; hemp fibers; compressive strength; autogenous shrinkage; drying shrinkage; water mass loss.
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Veena, V., Sobha Cyrus, Benny Mathews Abraham, and Babu T. Jose. "Soil Water Characteristic Curves of Compacted Marine Clay." Journal of Solid Waste Technology and Management 47, no. 4 (November 1, 2021): 717–25. http://dx.doi.org/10.5276/jswtm/2021.717.
Full textAbstract:
The soil water characteristics play an important role in predicting the engineering behaviour of unsaturated soils. An experimental programme was performed using pressure plate apparatus to investigate the effect of moulding water content, compactive effort and cycles of wetting and drying on Soil Water Characteristic Curves (SWCC) of compacted marine clay. The specimens were prepared with moulding water contents (optimum, dry of optimum and wet of optimum) for both Standard Proctor and Modified Proctor compactive efforts. The results obtained were fitted to Brooks and Corey (BC) and Van Genuchten (VG) models. The study indicated that SWCC for specimens with higher compactive efforts plotted above those with lower compactive efforts. It was observed that the variation in moulding water content had no significant effect in the resulting SWCC. With the increase in the number of cycles of wetting and drying, a decrease in the water retention capacity was observed.
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Widomski, Marcin K., Anna Musz-Pomorska, and Wojciech Franus. "Hydraulic and Swell–Shrink Characteristics of Clay and Recycled Zeolite Mixtures for Liner Construction in Sustainable Waste Landfill." Sustainability 13, no. 13 (June 29, 2021): 7301. http://dx.doi.org/10.3390/su13137301.
Full textAbstract:
This paper presents research considering hydraulic as well as swelling and shrinkage characteristics of potential recycled fine particle materials for compacted clay liner for sustainable landfills. Five locally available clay soils mixed with 10% (by mass) of NaP1 recycled zeolite were tested. The performed analysis was based on determined plasticity, cation exchange capacity, coefficient of saturated hydraulic conductivity after compaction, several shrinkage and swelling characteristics as well as, finally, saturated hydraulic conductivity after three cycles of drying and rewetting of tested specimens and the reference samples. The obtained results showed that addition of zeolite to clay soils allowed reduction in their saturated hydraulic conductivity to meet the required threshold (≤1 × 10−9 m/s) of sealing capabilities for compacted clay liner. On the other hand, an increase in plasticity, swelling, and in several cases in shrinkage, of the clay–zeolite mixture was observed. Finally, none of the tested mixtures was able to sustain its sealing capabilities after three cycles of drying and rewetting. Thus, the studied clayey soils mixed with sustainable recycled zeolite were assessed as promising materials for compacted liner construction. However, the liner should be operated carefully to avoid extensive dissication and cracking.
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Churchman, GJ, and KR Tate. "Effect of slaughterhouse effluent and water irrigation upon aggregation in seasonally dry New Zealand soil under pasture." Soil Research 24, no. 4 (1986): 505. http://dx.doi.org/10.1071/sr9860505.
Full textAbstract:
Studies of the long-term (>25 years) treatment of a silt loam soil under pasture with slaughterhouse effluent showed that effluent did not affect macroaggregate stabilities as measured by wet-sieving, but increased the stability of clay aggregation as measured after selective disaggregation treatments. Highly humified organic matter was associated with the soil clays as a result of slaughterhouse effluent treatment. Studies of the similarly long-term irrigation of the same soil type with water showed that water decreased the stabilities of macroaggregates as long as they were kept wet, but increased their stabilities after air-drying. Scanning electron microscopy showed a web that became firmly bound to soils only after drying. Stabilities of aggregated clays were largely unchanged by water irrigation, though their sensitivity to the removal of polysaccharides and organically bound cations was increased by this treatment. Changes in stabilities could not be related to earthworm numbers or to the extent of mycorrhizal infection. Macroaggregate stabilities did not reflect obvious visual changes that occurred to the soil structure upon a major change in composition of the effluent. The effects of seasonal drying processes were very likely obscured by the stabilising effects of air-drying prior to wet sieving analyses for macroaggregate stabilities.
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Shorin, V. A., A. Y. Velsovskij, and T. R. Akhmetov. "Application of an ionic stabilizer for reinforcing and ensuring frost resistance of clay soils." E3S Web of Conferences 220 (2020): 01037. http://dx.doi.org/10.1051/e3sconf/202022001037.
Full textAbstract:
This work is devoted to the study of applicability of the Underbold stabilizer for clay soils in the Vologda region, Russia. The influence of the stabilizer on maintaining the ultimate compressive strength of reinforced soils is shown. It depends on the content of clay particles (soil type) and can reach 30% if the appropriate technology (recommended by the manufacturer) is used. The use of the Underbold stabilizer according to our technology (treatment with a stabilizer - drying - reinforcing with cement) provides an increase in the strength of the reinforced soil after water saturation up to 2 or more times in comparison with samples without a stabilizer. It is shown that when designing a pavement using local clay soils reinforced by the Underbold stabilizer, it is necessary to make a water-insulating layer, and the necessary drainage system to improve the performance of the structural layer. It is noted that this stabilizer does not reduce the phenomenon of frost heaving.
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Gullà, Giovanni, Maria Clorinda Mandaglio, and Nicola Moraci. "Effect of weathering on the compressibility and shear strength of a natural clay." Canadian Geotechnical Journal 43, no. 6 (June 1, 2006): 618–25. http://dx.doi.org/10.1139/t06-028.
Full textAbstract:
In situ, seasonal changes expose soils to frequent wettingdryingfreezingthawing cycles. Such processes can favour and trigger shallow instabilities controlled by the weathering process. This paper presents an experimental study carried out to investigate the effects of the weathering process, caused by the wettingdryingfreezingthawing cycles, on the compressibility and shear strength of a natural clay. Several specimens were trimmed from block samples of overconsolidated clays taken from a slope in south Calabria, Italy. Specimens were subjected to wettingdryingfreezingthawing cycles of different durations and then tested with standard equipment (oedometer and direct shear). Test results show that the wettingdryingfreezingthawing cycles caused a change in the initial microstructure that produced a decrease in the compression index and an increase in the swelling index. Moreover, the direct shear test results show a decrease in the peak shear strength and demonstrate that a larger reduction occurs in the first month of weathering cycles. The intense cycles performed in the laboratory produced a decay of compressibility and a shear strength approaching reconstituted values. The conclusions are important when choosing the shear strength parameters required when studying shallow landsliding in clay slopes.Key words: weathered clay, structure, cycle of degradation, shallow instability.
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Muneer, M., and JM Oades. "The role of Ca-organic interactions in soil aggregate stability .III. Mechanisms and models." Soil Research 27, no. 2 (1989): 411. http://dx.doi.org/10.1071/sr9890411.
Full textAbstract:
Serial additions of glucose after drying-wetting cycles led to substantial aggregation of the surface soil from a red-brown earth. Addition of glucose and Ca compounds resulted in up to 80% of the soil bound in particles >2000�m with only a small portion of the soil in particles 4 0 �m. Treatment of the soils with Na4P2O7 caused dispersion of most of the clay but did not disrupt larger aggregates. More disaggregation was caused by treatments with HCI (0.02 M and 0.1 M), indicating the presence of pyrophosphate-resistant binding mechanisms which were presumed to be due to Ca bridging. Addition of Ca to the soil reduced the efficiency of extraction of organic materials by NaOH. This effect was eliminated by a pretreatment with 1 M HCl, indicating a 'bridging' effect of Ca between polycarboxylic macromolecules (humic acids) and clays. The role of Ca in clay and organic matter flocculation, the bridging of clay aggregates to organic materials and interactions of these colloidal aggregates with the biologic cycle is illustrated in some pictorial models.
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RASA, K., R. HORN, and M. RÄTY. "Water repellency of clay, sand and organic soils in Finland." Agricultural and Food Science 16, no. 3 (December 4, 2008): 267. http://dx.doi.org/10.2137/145960607783328218.
Full textAbstract:
Water repellency (WR) delays soil wetting process, increases preferential flow and may give rise to surface runoff and consequent erosion. WR is commonly recognized in the soils of warm and temperate climates. To explore the occurrence of WR in soils in Finland, soil R index was studied on 12 sites of different soil types. The effects of soil management practice, vegetation age, soil moisture and drying temperature on WR were studied by a mini-infiltrometer with samples from depths of 0-5 and 5-10 cm. All studied sites exhibited WR (R index >1.95) at the time of sampling. WR increased as follows: sand (R = 1.8-5.0) < clay (R = 2.4-10.3) < organic (R = 7.9-undefined). At clay and sand, WR was generally higher at the soil surface and at the older sites (14 yr.), where organic matter is accumulated. Below 41 vol. % water content these mineral soils were water repellent whereas organic soil exhibited WR even at saturation. These results show that soil WR also reduces water infiltration at the prevalent field moisture regime in the soils of boreal climate. The ageing of vegetation increases WR and on the other hand, cultivation reduces or hinders the development of WR.;
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Goetz, Andrew J., Glenn Wehtje, Robert H. Walker, and Ben Hajek. "Soil Solution and Mobility Characterization of Imazaquin." Weed Science 34, no. 5 (September 1986): 788–93. http://dx.doi.org/10.1017/s0043174500067862.
Full textAbstract:
Imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} sorption and mobility were studied in five Alabama soils ranging from sandy loam to clay. Techniques included thinlayer soil chromatography, batch equilibrium, and soil solution recovery. Imazaquin was mobile in all soils with Rfvalues of 0.8 to 0.9. Sorption based on batch equilibrium was minimal with Kdvalues ranging from 0.001 to 0.21. The soil solution recovery technique was used to evaluate imazaquin sorption in each soil as influenced by imazaquin concentration, wetting and drying, and pH. As herbicide concentration added to the soils was increased from 0.1 to 10 mg/kg, the amount of14C-imazaquin in soil solution increased. Temporarily drying each soil to 25 or 50% of field capacity resulted in maximum sorption of imazaquin. Lowering the pH enhanced sorption in all soils such that the amount of imazaquin in solution ranged from 38 (low pH) to 100% (high pH). Soil sorption appeared to be governed by the pH-dependent charge surfaces from aluminum and iron oxyhydroxides (specifically hematite and gibbsite) and kaolinite.
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Ward, PR, and JM Oades. "Effect of clay mineralogy and exchangeable cations on water repellency in clay-amended sandy soils." Soil Research 31, no. 3 (1993): 351. http://dx.doi.org/10.1071/sr9930351.
Full textAbstract:
Artificial water-repellent sands were prepared in the laboratory from acid-washed sand and either cetyl alcohol or organics extracted from a natural water-repellent sand. Added clays (at 0.5% w/w) had no effect when gently mixed with a natural and the two artificial water-repellent sands. After a wetting and drying cycle, kaolinite reduced repellency to a low level in the natural sand and the artificial sand with extracted organics, but montmorillonite was not effective. Na+-saturated clays were generally more effective than Ca2+-saturated clays. In the cetyl alcohol sand, montmorillonite was more effective than kaolinite. Neither artificial sand was a perfect model of the natural system, although the extracted organic model was far superior. Kaolinite did not strongly adsorb hydrophobic molecules, but was effective because it was able to cover the hydrophobic sand surface. Application of kaolinite clay to a water-repellent sand appears promising.
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Ghembaza, Moulay-Smaïne, Said Taïbi, and Jean-Marie Fleureau. "Effet de la température sur le comportement des sols non saturés sur les chemins de drainage et d’humidification." Canadian Geotechnical Journal 44, no. 9 (September 2007): 1064–81. http://dx.doi.org/10.1139/t07-079.
Full textAbstract:
The behaviour of soils subject to suction on drying and wetting paths depends on the type of material and its initial state. Exposure to heat modifies the state of pore water and therefore the hydromechanical behaviour of the soil. A new experimental device has been developed to study the thermohydric behaviour of unsaturated soils. Salt solution desiccators and polyethylene glycol (PEG) osmotic solutions are dipped in thermostatic baths, whose temperature ranges from room temperature to 80 °C. Tests were carried out on a sandy clay prepared in the laboratory and on a natural undisturbed clay, extracted from an experimental site for deep underground storage of radioactive waste. Results show that temperature plays an important role in the shrinkage of soil, especially when subjected to high levels of suction. The results can be applied to observe the response of confining clay barriers submitted to hydric and thermal changes.
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Wilson, Brian, Subhadip Ghosh, Phoebe Barnes, and Paul Kristiansen. "Drying temperature effects on bulk density and carbon density determination in soils of northern New South Wales." Soil Research 47, no. 8 (2009): 781. http://dx.doi.org/10.1071/sr09022.
Full textAbstract:
There is a widespread and growing need for information relating to soil condition and changes in response to land management pressures. To provide the information needed to quantify land management effects on soil condition, monitoring systems are now being put in place and these programs will generate large numbers of samples. Streamlined procedures for the analysis of large sample numbers are therefore required. Bulk density (BD) is considered to be one of several key indicators for measuring soil physical condition, and is also required to estimate soil carbon density. The standard analytical technique for BD requires drying the soil at 105°C but this procedure creates several logistical and analytical problems. Our initial objective was to derive correction factors between drying temperatures to allow for rapid, low-temperature estimation of BD on large sample numbers. Soil samples were collected from 3 contrasting soil types (basalt, granite, and meta-sediments) in 4 land uses (cultivation, sown pasture, native pasture, woodland) in northern New South Wales to test the effect of soil drying temperature on BD determination. Cores were divided into 4 depths (0–0.05, 0.050–0.10, 0.10–0.20, 0.20–0.30 m), and oven-dried at 40, 70, and 105°C. Drying temperature had no significant effect on BD but the effects of soil type, depth, and land use were significant, varying according to expectations based on previous studies, i.e. higher BD in granite-derived soils and lower in basalt-derived soils, increased BD with depth, and increasing BD with increasing management intensity. These results indicate that lower drying temperatures (40°C) were adequate for the efficient determination of BD especially where analysis of other soil properties from the same sample is required. However, before this approach is applied more widely, further calibration of BD and drying temperature should be undertaken across a wider range of soils, especially on clay-rich soils.
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Pereira, Carlos, João Ribas Maranha, and Rafaela Cardoso. "A general mathematical framework for modelling soil-water retention behaviour." MATEC Web of Conferences 337 (2021): 02006. http://dx.doi.org/10.1051/matecconf/202133702006.
Full textAbstract:
A new constitutive model for the soil-water retention behaviour of unsaturated soils is proposed, able to reproduce the main drying and wetting paths, the cyclic retention behaviour and its dependence on the specific volume. The most significant aspect is the inclusion of the evolution, with the specific volume, of the degree of saturation when suction tends to zero in wetting paths considering the presence of entrapped air bubbles. The model is used to reproduce with success the drying/wetting cycles of two Pearl clay samples.
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Snyder, Victor A., and Miguel A. Vázquez. "Similarities in Evolution of Aggregate Size Distributions during Successive Wetting and Drying Cycles of Heavy Textured Soils of Variable Clay Mineralogy." Hydrology 9, no. 2 (February 9, 2022): 30. http://dx.doi.org/10.3390/hydrology9020030.
Full textAbstract:
A phenomenon causing instability of soil structure and associated hydraulic properties in recently tilled soils is aggregate fragmentation induced by wetting and drying cycles. We analyzed data from three experiments in Puerto Rico, the UK and China measuring fragmentation and resulting evolution of aggregate size distributions during successive wetting and drying cycles in heavy textured soils. Aggregate distributions were represented as the cumulative fraction F of aggregates passing through successively larger sieve sizes X. To a good approximation, all distributions exhibited similarity in that the aggregate diameter X(F) corresponding to F in a given test distribution was always a characteristic multiple α¯ of X(F) in a fixed reference distribution, where α¯ for a distribution was calculated as its mean weight aggregate diameter (MWD) divided by the MWD of the reference distribution. In most cases, α¯ for a given soil varied inversely with the square of the number of wetting and drying cycles. For different soils of similar initial aggregate sizes, α¯ for a given wet–dry cycle decreased with increasing activity coefficient, reflecting the enhancing effect of soil shrink–swell potential on fragmentation. Results highlight usefulness of the van Bavel mean weight diameter as a natural scaling parameter for characterizing aggregate distributions.
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NASCIMENTO, ÍCARO VASCONCELOS DO, THIAGO LEITE DE ALENCAR, CARLOS LEVI ANASTÁCIO DOS SANTOS, RAIMUNDO NONATO DE ASSIS JÚNIOR, and JAEDSON CLÁUDIO ANUNCIATO MOTA. "EFFECT OF SAMPLE RE-SATURATION ON SOIL-WATER CHARACTERISTIC CURVE." Revista Caatinga 31, no. 2 (June 2018): 446–54. http://dx.doi.org/10.1590/1983-21252018v31n221rc.
Full textAbstract:
ABSTRACT Soil-water characteristic curve (SWCC) is an important tool for water management in irrigated agriculture. However, factors such as texture and structure of soils influence SWCC behavior. According to the literature, wetting and drying cycles alter SWCC. A similar process of re-saturation and drying occurs during SWCC obtainment under laboratory conditions. Based on the hypothesis that re-saturation process alters SWCC due to clay loss in the sample, this study aimed to obtain the SWCC, S index, and pore size distribution from samples submitted to re-saturation cycles, as well as from not re-saturated samples but under higher matric potentials (-2, -4, -6, -8, and -10 kPa). For this, disturbed and undisturbed soil samples, collected from the A (sandy texture) and Btg (sandy clay loam texture) horizons of a Argissolo Acizentado, were used. After obtaining SWCC, each air-dried soil sample was submitted to particle size and clay dispersed in water analyses to verify whether the soil lost clay. The experimental design was a completely randomized design with two methods of SWCC constructing (with and without re-saturation) and eight replications. The re-saturation process generates a loss of clay in the sample, not causing significant changes in SWCC considering the assessed textural soil classes. In addition, sandy soil samples are more sensitive to changes in pore size distribution when submitted to re-saturation.
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Blyth, E. M., and C. C. Daamen. "The accuracy of simple soil water models in climate forecasting." Hydrology and Earth System Sciences 1, no. 2 (June 30, 1997): 241–48. http://dx.doi.org/10.5194/hess-1-241-1997.
Full textAbstract:
Abstract. Several simple soil water models with four layers or less, typical of those used in GCMS, are compared to a complex multilayered model. They are tested by applying a repeating wetting/drying cycle at different frequencies, and run to equilibrium. The ability of the simple soil models to reproduce the results of the multilayer model vary according to the frequency of the forcing cycle, the soil type, the number of layers and the depth of the top layer of the model. The best overall performance was from the four layer model. The two layer model with a thin top layer (0.1 m) modelled sandy soils well while the two layer model with a thick top layer (0.5 m) modelled clay soils well. The model with just one layer overestimated evaporation during long drying periods for all soil types.
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Shaw, David R., Stephen M. Schraer, Joby M. Prince, Michele Boyette, and William L. Kingery. "Runoff losses of cyanazine and metolachlor: effects of soil type and precipitation timing." Weed Science 54, no. 4 (August 2006): 800–806. http://dx.doi.org/10.1614/ws-05-095r1.1.
Full textAbstract:
The effects of time of precipitation and soil type on runoff losses of cyanazine and metolachlor were studied using a tilted-bed, microplot system. Two silt loam soils, Bosket and Dubbs, and a Sharkey silty clay were evaluated. Rainfall (22 mm h−1) was simulated at 0, 2, and 14 days after treatment (DAT). Time of precipitation did not impact herbicide losses or any of the runoff parameters evaluated in this study. Water runoff occurred sooner and in greater quantities from the surfaces of Bosket and Dubbs silt loam soils than from the surface of Sharkey silty clay. Runoff losses of cyanazine did not vary by soil type. Soil drying produced large cracks in Sharkey silty clay, which greatly reduced runoff in this soil. Combined runoff and leachate losses were highest from Dubbs silt loam. Runoff losses of metolachlor were not affected by soil type. However, regression analyses indicated that time of precipitation and soil type interacted to affect initial metolachlor concentration. At 14 DAT, initial metolachlor concentration was highest in runoff from Sharkey soil. Time of precipitation ranked with respect to initial metolachlor concentration in runoff from Bosket and Dubbs silt loam soils were 0 > 2 > 14 DAT and 0 = 2 > 14 DAT, respectively.
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te Brake, B., M. J. van der Ploeg, and G. H. de Rooij. "Water storage change estimation from in situ shrinkage measurements of clay soils." Hydrology and Earth System Sciences Discussions 9, no. 11 (November 21, 2012): 13117–54. http://dx.doi.org/10.5194/hessd-9-13117-2012.
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Abstract. Water storage in the unsaturated zone is a major determinant of the hydrological behaviour of the soil, but methods to quantify soil water storage are limited. The objective of this study is to assess the applicability of clay soil surface elevation change measurements to estimate soil water storage changes. We measured moisture contents in soil aggregates by EC-5 sensors, and in volumes comprising multiple aggregates and intra-aggregates spaces by CS616 sensors. In a prolonged drying period, aggregate-scale storage change measurements revealed normal shrinkage for layers ≥ 30 cm depth, indicating volume loss equalled water loss. Shrinkage in a soil volume including multiple aggregates and voids was slightly less than normal, due to soil moisture variations in the profile and delayed drying of deeper soil layers upon lowering of the groundwater level. This resulted in shrinkage curve slopes of 0.89, 0.90 and 0.79 for the layers 0–60, 0–100 and 0–150 cm. Under a dynamic drying and wetting regime, shrinkage curve slopes ranged from 0.29 to 0.69 (EC-5) and 0.27 to 0.51 (CS616). Alternation of shrinkage and incomplete swelling resulted in an underestimation of volume change relatively to water storage change, due to hysteresis between swelling and shrinkage. Since the slope of the shrinkage relation depends on the drying regime, measurement scale and combined effect of different soil layers, shrinkage curves from laboratory tests on clay aggregates require suitable modifications for application to soil profiles. Then, the linear portion of the curve can help soil water storage estimation from soil surface elevation changes. These elevation changes might be measurable over larger extents by remote sensing.
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Eltwati, Ahmed, Alaa Elkaseh, Fares Tarhuni, and Saleh Ahmeed Buagela. "POTENTIAL OF GRANITE DUST TO IMPROVE THE ENGINEERING PROPERTIES OF SOFT SOILS FOR ROAD CONSTRUCTION." Science Proceedings Series 2, no. 1 (April 25, 2020): 55–61. http://dx.doi.org/10.31580/sps.v2i1.1254.
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Soft soils such as clay soils, mostly if they comprise swelling minerals may produce great damage to structures, particularly when these soils are exposed to wetting and drying situations. The geotechnical properties of soft soils could be enhanced by utilizing chemical additives. In this paper, granite waste dust was used to adjust the properties of clay soils. This paper investigates the effect of granite rock dust on the geotechnical properties of soft soil. The particle size distribution, Atterberg limits, compaction, California bearing ratio (CBR) and direct shear strength characteristics of the soil when blended with various percentages of granite dust were evaluated. The findings show a great increase in the maximum dry density, optimum water content, direct shear strength and CBR with increasing the amount of granite dust. The best results obtained for CBR values were when the soils mixed with 8% granite dust. Although these findings indicate great improvement in the geotechnical parameters of clayey soils, the higher strength established is not enough for the enhanced soil to be utilized as a base material in the construction of heavily-trafficked flexible pavements. However, this modified material can be used as a base material for moderate traffic roads and as a sub-base material for high traffic roads.
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Wang, Hong Yu. "Design for Composite Liners of Landfill under Alternating Cycles of Wetting-Drying and Freezing-Thawing." Advanced Materials Research 163-167 (December 2010): 4464–69. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.4464.
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The design conception of composite liners consisting of a geomembrane (GM), geosynthetic clay liners (GCLs) and compacted gravel soils for landfill is presented based on the climate characteristic, gravel soils material storage in abundance, and GCLs having been exported all over the world for various applications. The analyses results suggested that the capacity to resist the collapse of wetting-drying and freezing-thawing, long-term barrier performance, and the general sliding stability of barrier system are enhanced obviously by using GCLs/GM as barrier and displacing clay by gravel soils as protector in this paper. It will be plausible as effective design for the barrier system of landfill under wet-dry and freeze-thaw alternating cycles in northwest China.