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Amit Rawal - One of the best experts on this subject based on the ideXlab platform.
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interface shear characteristics of jute polypropylene hybrid nonwoven Geotextiles and sand using large size direct shear test
Geotextiles and Geomembranes, 2014Co-Authors: M M A Sayeed, Janaki B Ramaiah, Amit RawalAbstract:Abstract In this study, large-size direct shear tests were conducted to determine the interfacial shear characteristics of sand–Geotextile under three different normal stresses. The Geotextiles used in the present study were hybrid needlepunched nonwovens containing defined weight proportions of jute and polypropylene fibers. Subsequently, the interfacial shear characteristics of hybrid and that of a nonwoven Geotextile consisting of solely polypropylene fibers with sand were compared and analyzed under different normal stresses. Initial higher shear stiffness of sand-polypropylene Geotextiles was observed corresponding to sand-hybrid Geotextiles specifically under higher normal stresses. Nevertheless, the contact efficiency of sand-hybrid nonwovens was similar to that of sand-polypropylene Geotextiles. The surface morphology of sand particles has been investigated based on the images obtained from scanning electron microscopy (SEM) and quantitatively analyzed by means of Wadell roundness and degree of angularity methods.
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a comparison of wide width tensile strength to its axi symmetric tensile strength of hybrid needlepunched nonwoven Geotextiles
Geotextiles and Geomembranes, 2013Co-Authors: Amit Rawal, Harshvardhan Saraswat, M Alamgir M Sayeed, Tahir ShahAbstract:Abstract Geotextiles are placed between the subbase and subgrade in order to enhance the bearing capacity of soft subgrades. The concentrated forces perpendicular to the plane of Geotextile as a result of subgrade surface irregularities can impart axi-symmetric loading to the Geotextile. In this study, a simple model of axi-symmetric tensile strength for anisotropic hybrid needlepunched nonwoven Geotextiles has been proposed by relating to its in-plane tensile properties obtained from wide-width tensile tests in the weaker direction. A range of hybrid Geotextiles has been produced from a blend of polypropylene/viscose fibers in defined weight proportions to validate the model of axi-symmetric tensile strength. In general, a good correlation has been observed between the theoretical and experimental results of axi-symmetric tensile strength of hybrid needlepunched nonwoven Geotextiles.
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Pore size distribution of hybrid nonwoven Geotextiles
Geotextiles and Geomembranes, 2011Co-Authors: Amit Rawal, Harshvardhan SaraswatAbstract:Abstract Pore size distribution has become a prerequisite in determining the performance of Geotextiles for various functions including filtration, separation and reinforcement. The pore structure and morphology in a nonwoven Geotextile are known to be complex and it becomes further complicated in hybrid nonwoven Geotextiles consisting of two types of fibers. In this study, a modified model of pore size distribution of hybrid nonwoven Geotextiles has been proposed based on sieving-percolation pore network theory. A comparison has been made between theoretical and experimental pore size distributions of hybrid needlepunched nonwoven Geotextiles consisting of predefined weight proportions of viscose and polyester fibers. The weight proportions of the constituent fibers have been theoretically analysed for obtaining the desired pore size distributions of hybrid nonwoven Geotextiles.
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Geotextiles production properties and performance
Textile Progress, 2010Co-Authors: Amit Rawal, Tahir Shah, Subhash AnandAbstract:The monograph critically reviews most commonly used Geotextile structures, their properties and performance characteristics. In general, both natural and synthetic fibres are used for the production of Geotextiles, and the advantages and disadvantages of each type of fibre are discussed for various applications of Geotextiles. The important functions of Geotextiles, i.e. filtration, drainage, separation and reinforcement have been identified and have been related to several properties and major applications of Geotextiles. Various Geotextile properties, namely mechanical, hydraulic and chemical and their test methods have been critically discussed. A process–structure–property relationship for most commonly used Geotextiles is also analysed. Furthermore, the design of a Geotextile is of paramount importance for any civil engineering application. Thus, the design criteria for various functions of Geotextiles have been addressed. Subsequently, the durability characteristics of Geotextile have been introduce...
Harshvardhan Saraswat - One of the best experts on this subject based on the ideXlab platform.
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a comparison of wide width tensile strength to its axi symmetric tensile strength of hybrid needlepunched nonwoven Geotextiles
Geotextiles and Geomembranes, 2013Co-Authors: Amit Rawal, Harshvardhan Saraswat, M Alamgir M Sayeed, Tahir ShahAbstract:Abstract Geotextiles are placed between the subbase and subgrade in order to enhance the bearing capacity of soft subgrades. The concentrated forces perpendicular to the plane of Geotextile as a result of subgrade surface irregularities can impart axi-symmetric loading to the Geotextile. In this study, a simple model of axi-symmetric tensile strength for anisotropic hybrid needlepunched nonwoven Geotextiles has been proposed by relating to its in-plane tensile properties obtained from wide-width tensile tests in the weaker direction. A range of hybrid Geotextiles has been produced from a blend of polypropylene/viscose fibers in defined weight proportions to validate the model of axi-symmetric tensile strength. In general, a good correlation has been observed between the theoretical and experimental results of axi-symmetric tensile strength of hybrid needlepunched nonwoven Geotextiles.
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Pore size distribution of hybrid nonwoven Geotextiles
Geotextiles and Geomembranes, 2011Co-Authors: Amit Rawal, Harshvardhan SaraswatAbstract:Abstract Pore size distribution has become a prerequisite in determining the performance of Geotextiles for various functions including filtration, separation and reinforcement. The pore structure and morphology in a nonwoven Geotextile are known to be complex and it becomes further complicated in hybrid nonwoven Geotextiles consisting of two types of fibers. In this study, a modified model of pore size distribution of hybrid nonwoven Geotextiles has been proposed based on sieving-percolation pore network theory. A comparison has been made between theoretical and experimental pore size distributions of hybrid needlepunched nonwoven Geotextiles consisting of predefined weight proportions of viscose and polyester fibers. The weight proportions of the constituent fibers have been theoretically analysed for obtaining the desired pore size distributions of hybrid nonwoven Geotextiles.
N Sanka - One of the best experts on this subject based on the ideXlab platform.
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laboratory performance of unpaved roads reinforced with woven coir Geotextiles
Geotextiles and Geomembranes, 2009Co-Authors: E A Subaida, S Chandrakara, N SankaAbstract:Abstract The results of an experimental study conducted to investigate the beneficial use of woven coir Geotextiles as reinforcing material in a two-layer pavement section, are presented. Monotonic and repeated loads were applied on reinforced and unreinforced laboratory pavement sections through a rigid circular plate. The effects of placement position and stiffness of Geotextile on the performance of reinforced sections were investigated using two base course thicknesses and two types of woven coir Geotextiles. The test results indicate that the inclusion of coir Geotextiles enhanced the bearing capacity of thin sections. Placement of Geotextile at the interface of the subgrade and base course increased the load carrying capacity significantly at large deformations. Considerable improvement in bearing capacity was observed when coir Geotextile was placed within the base course at all levels of deformations. The plastic surface deformation under repeated loading was greatly reduced by the inclusion of coir Geotextiles within the base course irrespective of base course thickness. The optimum placement position of coir Geotextile was found to be within the base course at a depth of one-third of the plate diameter below the surface.
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experimental investigations on tensile and pullout behaviour of woven coir Geotextiles
Geotextiles and Geomembranes, 2008Co-Authors: E A Subaida, S Chandrakara, N SankaAbstract:Abstract Results of an experimental programme to investigate the tensile and interface properties of woven coir Geotextiles are presented. Tension tests were conducted on coir fibres, yarns and woven Geotextiles at different gauge lengths and strain rates. Based on statistical analysis, a gauge length of 150 mm and a strain rate of 5%/min was adopted for the purpose of characterization of tensile properties. Tensile strength of woven coir Geotextile was expressed as a function of fibre strength, yarn properties and weaving pattern. Pullout test and modified direct shear test were conducted on Geotextiles in granular soils of different grain sizes. At low normal stress, bond resistance of coir Geotextile–sand interface obtained was more than shear strength of soil. But consistent values of bond resistance were not obtained at higher normal stresses. The opening size of mesh relative to the soil grain size influenced the pullout interaction between soil and Geotextile. For closely woven Geotextiles, the pullout resistance did not vary much in soils of different grain sizes, whereas for Geotextiles with open meshes, pullout resistance obtained was more in fine sand compared to coarse sand.
Barral C. - One of the best experts on this subject based on the ideXlab platform.
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Comparaison du comportement de plusieurs géotextiles utilisés pour la filtration de boues argileuses : étude expérimentale
'Elsevier BV', 2019Co-Authors: Stoltz G., Delmas Philippe, Barral C.Abstract:This paper presents the results of an experimental study of various Geotextiles used to filter clayey sludge. The use of Geotextiles to filter clayey sludge or suspensions of fine particles in water is more complex than that for filtering suspensions of granular soils. In practice, such applications generally use flocculants to postpone the formation of a low-permeability filter cake. The objective of the present study, which does not use flocculants, is to determine how Geotextile characteristics affect the capacity of the Geotextile to filter clayey sludge. Three key questions are addressed: (1) What are the main differences between vertical and horizontal filtration? (2) How do Geotextile characteristics (nature, opening size, permeability, etc.) affect its capacity to filter clayey sludge (3) How do clayey sludge characteristics (i.e., grain size distribution and concentration)? and the type of flow (i.e., constant head or constant flow) affect the filtering capacity of Geotextiles? To evaluate the capacity of a Geotextile to filter clayey sludge, we propose three relevant criteria and analyse two filtration phases induced by different cake-formation processes (controlled by the Geotextile and controlled by the filter cake). To determine the main differences between vertical and horizontal filtration, the settling of fines in the testing device and its influence on the results are analysed and discussed. This study shows that, for the various clayey sludge tested, the Geotextiles (needle-punched nonwoven and thermally bonded nonwoven) with the smallest opening sizes (O90≤60 µm) give the most promising results for filtering fines without the use of flocculants. Of these Geotextiles, the thermally bonded nonwoven structure seems to offer the best filtration performance for the largest range of fines concentration in the sludge
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Comparaison du comportement de plusieurs géotextiles utilisés pour la filtration de boues argileuses : étude expérimentale
'Elsevier BV', 2019Co-Authors: Stoltz G., Delmas Philippe, Barral C.Abstract:International audienceThis paper presents the results of an experimental study of various Geotextiles used to filter clayey sludge. The use of Geotextiles to filter clayey sludge or suspensions of fine particles in water is more complex than that for filtering suspensions of granular soils. In practice, such applications generally use flocculants to postpone the formation of a low-permeability filter cake. The objective of the present study, which does not use flocculants, is to determine how Geotextile characteristics affect the capacity of the Geotextile to filter clayey sludge. Three key questions are addressed: (1) What are the main differences between vertical and horizontal filtration? (2) How do Geotextile characteristics (nature, opening size, permeability, etc.) affect its capacity to filter clayey sludge (3) How do clayey sludge characteristics (i.e., grain size distribution and concentration)? and the type of flow (i.e., constant head or constant flow) affect the filtering capacity of Geotextiles? To evaluate the capacity of a Geotextile to filter clayey sludge, we propose three relevant criteria and analyse two filtration phases induced by different cake-formation processes (controlled by the Geotextile and controlled by the filter cake). To determine the main differences between vertical and horizontal filtration, the settling of fines in the testing device and its influence on the results are analysed and discussed. This study shows that, for the various clayey sludge tested, the Geotextiles (needle-punched nonwoven and thermally bonded nonwoven) with the smallest opening sizes (O90≤60 µm) give the most promising results for filtering fines without the use of flocculants. Of these Geotextiles, the thermally bonded nonwoven structure seems to offer the best filtration performance for the largest range of fines concentration in the sludge
Hani Nahlawi - One of the best experts on this subject based on the ideXlab platform.
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water retention of nonwoven polyester Geotextiles
Polymer Testing, 2006Co-Authors: Abdelmalek Bouazza, Michelle Freund, Hani NahlawiAbstract:Abstract Planar polymeric Geotextile materials are increasingly used in geotechnical and geoenvironmental engineering applications to perform various functions such as filtration, drainage and reinforcement. In most cases, they are placed above the groundwater table where soil and Geotextiles pores are filled with water and air (i.e. under unsaturated conditions). In this respect, the development of the Geotextile water-retention curves is of great importance to model the transient water flow in earthen systems containing Geotextiles where unsaturated conditions may prevail. This paper, presents the results of a study on the cross-plane and in-plane water-retention characteristics of two nonwoven, polyester Geotextiles. The Geotextiles’ cross plane water-retention data demonstrated their hydrophobic nature with both specimens being essentially non-conductive to water beyond suction heads of 0.2–0.3 kPa. Pore size and porosity seemed to have a controlling effect on both the desaturation and resaturation processes. The Geotextile with the larger apparent opening size and porosity de-saturated at very low suction pressure (0.4 kPa), whereas a slightly higher suction (0.9 kPa) was needed to de-saturate the Geotextile with smaller apparent opening size and porosity. Both specimens exhibited significant hysteresis in their water-retention function, such that at a given suction a Geotextile contained more water when drying than when wetting. The in-plane water retention of drying Geotextiles indicates that both Geotextile specimens absorbed no water at suctions greater than zero; thus the water retention of a dry specimen in the in-plane direction is effectively equal to zero. This implies that the Geotextiles used in the present study were more hydrophobic in the in-plane than the cross-plane direction during wetting.
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product performance water retention of nonwoven polyester Geotextiles
2006Co-Authors: Abdelmalek Bouazza, Michelle Freund, Hani NahlawiAbstract:Planar polymeric Geotextile materials are increasingly used in geotechnical and geoenvironmental engineering applications to perform various functions such as filtration, drainage and reinforcement. In most cases, they are placed above the groundwater table where soil and Geotextiles pores are filled with water and air (i.e. under unsaturated conditions). In this respect, the development of the Geotextile water-retention curves is of great importance to model the transient water flow in earthen systems containing Geotextiles where unsaturated conditions may prevail. This paper, presents the results of a study on the cross-plane and in-plane water-retention characteristics of two nonwoven, polyester Geotextiles. The Geotextiles’ cross plane water-retention data demonstrated their hydrophobic nature with both specimens being essentially non-conductive to water beyond suction heads of 0.2–0.3 kPa. Pore size and porosity seemed to have a controlling effect on both the desaturation and resaturation processes. The Geotextile with the larger apparent opening size and porosity de-saturated at very low suction pressure (0.4 kPa), whereas a slightly higher suction (0.9 kPa) was needed to de-saturate the Geotextile with smaller apparent opening size and porosity. Both specimens exhibited significant hysteresis in their water-retention function, such that at a given suction a Geotextile contained more water when drying than when wetting. The in-plane water retention of drying Geotextiles indicates that both Geotextile specimens absorbed no water at suctions greater than zero; thus the water retention of a dry specimen in the in-plane direction is effectively equal to zero. This implies that the Geotextiles used in the present study were more hydrophobic in the in-plane than the cross-plane direction during wetting. r 2006 Elsevier Ltd. All rights reserved.
