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5. civil engineering textile


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civil engineering textile

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5. civil engineering textile

  1. 1. Textiles in Civil Engineering (Geotextile) Granch Berhe 2015 1
  2. 2. Definition The word ‘Geotextiles’ is a combination of two words. The word ‘Geo’ comes from the Greek word, meaning ‘Earth’, and textiles “permeable textiles used in conjunction with soil, foundation, rock, earth or any geotechnical engineering- related material” “Any permeable textile material used for filtration, drainage, separation, reinforcement and stabilisation purposes as an integral part of civil engineering structures of earth, rock or other constructional materials” 2
  3. 3. History Geotextiles can be made from either natural or synthetic fibres The exploitation of the use of natural fibres in construction can be traced back to the fifth and fourth millennia BC as described in the Bible (Exodus chapter 5, verse 6–9) Babylonians 3000 years ago constructed this Ziggurat using reeds in the form of woven mats and plaited ropes as reinforcements The Great Wall of China, completed circa 200 BC, utilised tamarisk branches to reinforce mixtures of clay and gravel 3
  4. 4. Any permeable textile natural or synthetic, used with foundation soil, rock, earth, or any other geotechnical engineering related material. What is a Geotextile? Geosynthetics are manufactured (not naturally occurring) materials that are used to withstand and/or enhance the forces of the in-place earth. 4
  5. 5. Method of production Process Form of fibre Polymer PP/PE bi-component Continuous filament PP Heat-bonded Staple fibre PP PP/PE mix Nonwovens PP PET Staple fibre HDPE Needle-punched Continuous filament PP PET Nonwoven Geotextiles Needle Punched nonwoven Thermally bonded nonwoven 5
  6. 6. Non woven • More than 75% of the market utilises geotextiles made from various nonwoven fabrics, chiefly staple-fibre needlepunched and continuous-filament spunbonded nonwovens. • Nonwoven materials are normally 25–30% cheaper than woven materials 6
  7. 7. Method of production Process Form of fibre Polymer Slit-flat tape PP (HDPE) Wide loom (beam) Fibrillated yarn PP Wide loom (creel) Multi-filament yarn PET (PA) Woven <3.8m loom (beam) Medium mono filament with yarn PP HDPE PA Woven Geotextiles film tape extruded tape PET multifilamentMonofil 7
  8. 8. Woven • They have a surprisingly wide range of applications and they are used in lighter weight form as soil separators, filters and erosion control textiles. • In heavy weights, they are used for soil reinforcement in steep embankments and vertical soil walls; the heavier weight products also tend to be used for the support of embankments built over soft soils • Advantage - stress can be absorbed by the warp and weft yarns and hence by fibres, without much mechanical elongation 8
  9. 9. Method of production Process Form of fibre Polymer Stitched-bonded Nonwoven base with multi- filament stitch yarn PP or PET nonwoven PET stitching Knitted Weft insertion filament yarn PET Warp knitted Multi-filament yarn PET Knitted Geotextiles Knitted base Upper surface 9
  10. 10. The mode of operation of a geotextile in any application can be defined by the following functions: Functions of Geotextile :Functions of Geotextile : Separator Reinforcement Drainage Filter Energy absorberContainer
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  12. 12. Functions of geotextiles Filtration – liching of water Drainage - collects and redirects liquid or gas Separation – layer between fine soil and coarse material Reinforcement - when the stability of the weak subgrade or soil is complemented by higher tensile strength of fabric. Container - when it holds or protects the materials such as sand, rocks, fresh concrete12
  13. 13. Applications 1. River bank protection. 2. Seabed protection. 3. Sea coastal protection. 4. Coastal protection/sea defences. 5. Drainage. 6. Perpendicular versus in-plane water flow applications. 7. Reservoirs and lakes. 8. Concrete mattresses. 9. Vertical screens. 10. Geobags. 11. Reclaimed land. 12. Anchoring. 13. Paved and unpaved road subgrade separation. 14. Embankments. 15. Reinforced earth. 16. Reflective cracking. 17. Railways. 18. Landfills. 19. Slit fences. 13
  14. 14. 14 Applications of Geotextile :Applications of Geotextile : Reservoirs, damsReservoirs, dams Liquid wasteLiquid waste Solid wasteSolid waste RoadsRoads RailroadsRailroads Erosion protectionErosion protection Retaining wallsRetaining walls Drainage systemsDrainage systems
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  16. 16. 1. Physical properties: a) specific gravity b) weight c) thickness d) stiffness e) density . 2. Mechanical properties: a) tenacity b) tensile strength c) bursting strength d) drapability e) compatibility f) flexibility g) tearing strength h) frictional resistance 3. Hydraulic properties: a) porosity b) permeability c) permittivity d) transitivity e) turbidity /soil retention f) filtration length etc. 16 4. Degradation properties: a) biodegradation b) hydrolytic degradation c) photo degradation d) chemical degradation e) mechanical degradation f) other degradation occurring due to attack of rodent, termite etc. 5. Endurance properties: a) elongation b) abrasion resistance c) clogging length and flow etc. Performance Requirements of Geotextile
  17. 17. Properties • mechanical responses, – ability of a textile to perform work in a stressed environment and its ability to resist damage in an arduous environment – The ability to perform work is fundamentally governed by the stiffness of the textile in tension and its ability to resist creep failure under any given load condition • filtration ability – function is to hold intact a freshly prepared soil surface, so that water may exude from the soil surface and through the textile without breaking down that surface • chemical resistance – use of textiles in contact with highly acidic peat soils, where in tropical countries, pH values down to 2 have been encountered – Industrialised countries – Ultraviolet light They are all developed from the combination of the physical form of the polymer fibres, their textile construction and the polymer chemical characteristics 17
  18. 18. Fibers used Natural fibres offer high strength, high modulus, low breaking extension and low elasticity. Some of the plant fibres that can be used in geotextile manufacture are jute, sisal, flax, hemp, abaca, ramie and coir 18
  19. 19. Advantages of natural fibers • low cost, • robustness, • strength/durability, • availability, • good drapeability • biodegradability/ environment friendly 19
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  21. 21. Synthetic • Synthetic fibres are the main raw materials for the manufacture of all types of geotextiles – polypropylene, polyester, polyamide and polyethylene • polyester widely used – exhibits superior creep resistance and tenacity values – is almost inevitably used when high strengths are required – applications where the geotextile is subjected to high stresses and elevated temperatures – susceptibility to hydrolytic degradation in soils exceeding pH 10. 21
  22. 22. • PP – low cost, acceptable tensile properties and chemical inertness – disadvantages of polypropylene are its sensitivity to ultraviolet (UV) radiation and high temperature and poor creep and mineral oil resistance • PA – cost and overall performance render it inferior to polyester. 22
  23. 23. Limitations of synthetic • Synthetic geotextiles can cost over 10 times as much per unit area as natural ones • non-biodegradable and may cause soil pollution • The material composition of geotextiles determines their longevity in the field: natural products last about two to five years, whereas synthetic products last >25 years 23
  24. 24. • Erosion control geotextiles are made from natural (jute, coir, sisal, cereal straw and palm leaves) or synthetic (nylon, polypropylene, polyester and polyethylene) materials • Geotextiles are used for separation of two distinct ground layers, slope stabilization, vegetation management and soil erosion control. • Geotextiles are widely used to control on-site and off-site soil erosion of human-disturbed lands 24
  25. 25. PET Vs PP in Geotextile Applications 25 Property PET PP g/cm3 1.38 0.91- 0.93 Melting Point 265 165 Strain 10 -15 > 100 % Creep < 2% 5% Modulus (Gpa) 10 2.8 Breaking Elongation 20-50 % 40 -70 % Breaking Tenacity (gm/d) 9 6 UV Resistant High Susceptible Polar solvents Degrade Resistant pH > 9.5 Hydrolysis 3 -13 Moisture Regain 0.4 0
  26. 26. Polypropylene Polymer has distinct advantages 1. Resistant to chemical attack 2. Stable to pH between 3 and 13 3. Non-biodegradable 4. Resistant to soil-bound chemicals, landfill leaches, mildew and insects. 5. Lightest fibre Polyethylene Terephthalate (PET) Polymer has : 1. Superior Breaking Tenacity (Strength) 2. Superior creep characteristics required in some critical reinforcement materials.  PET must not be used in contact with soils with pH >9.5  For PET made Geotextiles hydrolytic resistance is required to be observed.  For Geotextile application in case of PP Oxidative resistance is required to be observed.
  27. 27. 27 Temperature resistance PET is winning with a melting point of 265o C versus the 165o C of PP. This means that for applications which need temperature resistance e.g. resistance to reflective cracking in roads, PET is preferable. Creep PET by far the best choice. Chemical resistance Generally PP is better. PP is preferred for landfills. Alkali resistance Again PP is the better choice e.g. in touch with fresh concrete. UV resistance This is a PET domain. PP geotextiles should be improved with carbon black for a better behavior to UV.
  28. 28. Technical Requirement for use in subsurface drains • Breaking load not less than 10 kN/m • Minimum Failure strain of 10% • Apparent opening size 0.22mm – 0.43 as soil properties • Allow water flow @ not less than 10lit/sqm/sec • Minimum puncture resistance of 200 N • Minimum tear resistance of 150N PET is Preferable Than PP 28
  29. 29. Technical Requirement for use in Highway Pavement • Minimum Tensile strength 36.3 Kg • Elongation 50% • Asphalt Retention 10 kg/10sqm • Melting Point 150C • Surface Texture- heat Bonded on one side only PP is Preferable Than PET 29
  30. 30. Technical Requirement for use in Protection Works • Aperture : Rectangular, square or oval • Colour : Black • Strength : Min 10kN/m • Elongation: Max 15% • Life : Min 8 years PET is Preferable Than PP 30
  31. 31. 31 Silt Fence• Prevents storm water from transporting sediment off- site • Alternate for hay bales • Low elongation (stretch) important for more support • Filtration and tensile strength properties most important • Commonly light weight woven (higher strength) geotextiles PET is Preferable Than PP
  32. 32. 32 Roadway Separation / Stabilization • Prevents subgrade from intermixing with base course • Alternate to undercutting • Low elongation for higher modulus PET is Preferable Than PP
  33. 33. PP is Preferable Than PET if pH is >9.5 33
  34. 34. PET is Preferable Than PP 34
  35. 35. 35 Geotextiles in Drainage Geotextile around pipe Geotextile around pipe Geotextile lining trench Lining pipes not preferred method PP is Preferable Than PET
  36. 36. 36 Filtration w/ geotextile w/o geotextile - loss of fines PP is Preferable Than PET
  37. 37. Avoid granular material penetration Puncture resistance PP is Preferable Than PET 37
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  40. 40. 40 Thank You!
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