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Major Re-Write[edit]

I'm planning a major re-write of this article, as well as merging it with geosynthetics, contact me if you wish to get involved, hoping to have it on its feet by the end of next week. RegardsGrahams Child 10:46, 27 May 2006 (UTC)

The write up is done but is titled Geosynthetics. At present there is a disagreement about how the Geotextiles and the Geosynthetics article should be connected. Hopefully this will be resolved shortly Grahams Child 18:26, 2 June 2006 (UTC)


Relatively new product in civil engineering circles. Besides conventional concrete, steel and timber we now have plastics!

Applications are unlimited: - mining, waste, roads, ...

According to my geotech professor, linen geotextiles were used by the ancient Egyptians. I suppose that use was limited to arid climes due to rot until synthetic materials came around.--Triskele Jim (talk) 16:48, 19 June 2008 (UTC)

Some examples and/or photos of it's usage could improve the clarity, of what geotextile is and how it is used. JohnLM (talk) 18:57, 9 February 2010 (UTC)

Retrieved from Wikipedia:Tutorial (Formatting)/sandbox Author User:Marilyn475[edit]


- - Inclusions of different types mixed with soil have been used for thousands of years. They were used in Roman days to stabilize roadways and foundations. These early attempts were made of natural fibres, fabrics or vegetation mixed with soil to improve road quality, particularly when unstable soils were encounterd. They were also used to build steep slopes as with several pyramids in Egypt and military fortifications, i.e., walls, as well. In these early applications the natural materials were embedded within the soil as the structure was built. A fundamental problem with using natural materials (wood, cotton, wool, etc.) in any buried environment is the biodegradation that occurs from microorganisms in the soil. However, with the advent of polymers in the middle of the 20th Century a much more stable material became available. When properly formulated, lifetimes of centuries can be anticipated even for harsh environmental conditions. Polymeric materials in the form of fibers, yarns, rods and sheets used with or in soil are known as "geosynthetics". - - The first papers on geosynthetics (as we know them today) in the 1960’s were as filters in the U.S. [1] and as reinforcement in Europe [2]. The 1977 conference in Paris brought together many of the early manufacturers, practitioners and a few academics [3]. The International Geosynthetics Society (IGS) founded in 1982 has subsequently organized worldwide conferences every four years and its numerous chapters have additional conferences. Presently there are separate geosynthetic institutes, trade-groups, and standards-setting organizations which are all very active. Approximately twenty universities teach stand-alone courses on geosynthetics and almost all include some aspects of the subject in their geotechnical, geoenvironmental, and hydraulic engineering courses. Geosynthetics are presently available worldwide and the activity is robust and steadily growing. - - - - - - - - - - - - - Figure 1 - Collage of geosynthetic products [3] - - == Categories == - - ===Geotextiles=== - Geotextiles form one of the two largest categories of geosynthetic materials. Their rise in growth during the past 40-years has been nothing short of outstanding. They are indeed textiles in the traditional sense, but consist of synthetic fibers (all are polymer-based) rather than natural ones such as cotton, wool, or silk. Thus, biodegradation and subsequent short lifetime is not a problem. These synthetic fibers are made into flexible, porous fabrics by standard weaving machinery or they are matted together in a random nonwoven manner. Some are also knitted. The major point is that geotextiles are porous to liquid flow across their manufactured plane and also (to a limited extent) within their thickness. There are hundreds of specific application areas for geotextiles that have been developed; however, the fabric always performs at least one of four discrete functions; separation, reinforcement, filtration and/or drainage. - - ===Geogrids=== - Geogrids represent a rapidly growing category within geosynthetics. Rather than being a woven, nonwoven or knitted textile fabric, geogrids are polymeric materials formed into a very open, gridlike configuration, i.e., they have large apertures between individual ribs in the machine and cross machine directions. Geogrids are (a) homogeneously stretched from perforated polymer sheets in one or two directions for improved physical properties, (b) made from yarns on weaving or knitting machinery by standard textile manufacturing methods and then coated, or (c) by bonding polymeric rods or straps together. There are many specific application areas, however, they function almost exclusively as reinforcement materials. - - ===Geonets=== - Geonets, called geospacers by some, constitute another specialized category within the geosynthetics area. They are formed by continuous extrusion of parallel sets of polymeric ribs at preset angles to one another. When the ribs are opened, relatively large apertures are formed into a netlike configuration. They are usually factory fabricated with one or two geotextiles on their surfaces. Their design function is completely within the in-plane drainage area where they are used to convey all types of liquids. - - ===Geomembranes=== - Geomembranes represent the other largest category of geosynthetics and in dollar volume their sales are even greater than that of geotextiles. Case histories of reservoir liners date from the 1950's [4], but the major growth in the USA and Germany was stimulated by governmental regulations originally enacted in the early 1980’s [5]. The materials themselves are relatively thin impervious sheets of polymeric materials used primarily for linings and covers of liquid- or solid-storage facilities. This includes all types of landfills, reservoirs, canals, tunnels and other containment facilities. Thus the primary function is always containment thereby functioning as a liquid and/or vapor barrier. The range of applications is very great, and in addition to the geoenvironmental area, applications are rapidly growing in geotechnical, transportation, hydraulic, and private development engineering. - - ===Geosynthetic Clay Liners=== - Geosynthetic clay liners, or GCLs, are an interesting juxtaposition of polymeric materials and natural soils. They are rolls of factory fabricated thin layers of bentonite clay sandwiched between two geotextiles or bonded to a geomembrane. Structural integrity of the subsequent composite is obtained by needle-punching, stitching or physical bonding. GCLs are used as a composite component beneath a geomembrane or by themselves in geoenvironmental and containment applications as well as in transportation, geotechnical, hydraulic, and many private development applications. - - ===Geofoam=== - Geofoam is a product category created by a polymeric expansion process resulting in a “foam” consisting of many closed, but gas-filled, cells. The skeletal nature of the cell walls is the unexpanded polymeric material. The resulting product is generally in the form of large, but extremely light, blocks which are stacked side-by-side providing lightweight fill in numerous applications. The primary function is dictated by the application; however separation is always a consideration and geofoam is included in this category rather than creating a separate one for each specific material. - - ===Geocomposites=== - A geocomposite consists of a combination of geotextiles, geogrids, geonets and/or geomembranes in a factory fabricated unit. Also, any one of these four materials can be combined with another synthetic material (e.g., deformed plastic sheets or steel cables) or even with soil. As examples, a geonet with geotextiles on both surfaces and a GCL consisting of a geotextile/bentonite/geotextile sandwich are both geocomposites. Soil filled honey combed cells made from geomembranes or geotextiles are also considered as geocomposites. This specific category brings out the best creative efforts of the engineer and manufacturer. The application areas are numerous and constantly growing. The major functions encompass the entire range of functions listed for geosynthetics discussed previously; separation, reinforcement, filtration, drainage, and containment. - - - == Functions == - - The juxtaposition of the various categories of geosynthetics just described with the primary function that the material is called upon to serve allows for the creation of an organizational matrix for geosynthetics; see Table 1. In essence, this matrix is the “scorecard” for understanding the entire geosynthetic field and its design related methodology. In Table 1, the primary function that each geosynthetic can be called upon to serve is seen. Note that these are primary functions and in many cases (if not most) there are secondary functions, and perhaps tertiary ones as well. For example, a geotextile placed on soft soil will usually be designed on the basis of its reinforcement capability, but separation and filtration might certainly be secondary and tertiary considerations. As another example, a geomembrane is obviously used for its containment capability, but separation will always be a secondary function. - - The greatest variability from a manufacturing and materials viewpoint is the category of geocomposites. The primary function will depend entirely upon what is actually created, manufactured, and installed. - - Table 1 - Identification of the Usual Primary Function for Each Type of Geosynthetic [6] - - - {| class="wikitable" - |- - ! Type of Geosynthetic (GS) - ! Separation - ! Reinforcement - ! Filtration - ! Drainage - ! Containment - |- - | Geotextile (GT) - | yes - | yes - | yes - | yes - | - |- - | Geogrid (GG) - | - | yes - | - | - | - |- - | Geonet (GN) - | - | - | - | yes - | - |- - | Geomembrane (GM) - | - | - | - | - | yes - |- - | Geosynthetic Clay Liner (GCL) - | - | - | - | - | yes - |- - | Geofoam (GF) - | yes - | - | - | - | - |- - | Geocomposite (GC) - | yes - | yes - | yes - | yes - | yes - |} - - - - == Applications == - - Geosynthetics are generally designed for a particular application by first considering the primary function that can be provided. Design then proceeds by adapted forms of civil engineering practice. As seen in the accompanying table there are five primary functions given, but some groups suggest even more [7]. - - - ===Separation=== - Separation is the placement of a flexible geosynthetic material, like a porous geotextile, between dissimilar materials so that the integrity and functioning of both materials can remain intact or even be improved. Paved roads, unpaved roads, and railroad bases are common applications. Also, the use of thick nonwoven geotextiles for cushioning and protection of geomembranes is in this category. In addition, for most applications of geofoam, separation is the major function. - - ===Reinforcement=== - Reinforcement is the synergistic improvement of total system strength created by the introduction of a geotextile or a geogrid (both of which are good in tension) into a soil (that is good in compression, but poor in tension) or other disjointed and separated material. Applications of this function are in mechanically stabilized earth walls and steep soil slopes. Also involved is the application of basal reinforcement over soft soils, deep foundations or karst rock formations for embankments and heavy surface loadings. - - ===Filtration=== - Filtration is the equilibrium soil-to-geotextile interaction that allows for adequate liquid flow without soil loss, across the plane of the geotextile over a service lifetime compatible with the application under consideration. Filtration applications are highway underdrain systems, retaining wall drainage, landfill leachate collection systems, as silt fences and curtains, and as flexible forms for bags, tubes and containers. - - ===Drainage=== - Drainage is the equilibrium soil-to-geosynthetic system that allows for adequate liquid flow without soil loss, within the plane of the geosynthetic over a service lifetime compatible with the application under consideration. Geonets, geocomposites and (to a lesser extent) thick geotextiles accommodate this function. Drainage applications for these different geosynthetics are retaining walls, sport fields, dams, canals, reservoirs, and capillary breaks. Also to be noted is that sheet, edge and wick drains are geocomposites used for various soil and rock drainage situations. - - ===Containment=== - Containment involves geomembranes, geosynthetic clay liners, and (some) geocomposites which function as liquid or gas barriers. Landfill liners and covers make critical use of these geosynthetics. All hydraulic applications (tunnels, dams, canals, reservoir liners, and floating covers) use these geosynthetics as well. - - - == Advantages == - - * The manufactured quality control of geosynthetics in a controlled factory environment is a great advantage over outdoor soil and rock construction. Most geosynthetic factories are ISO 9000 certified and have their own in-house quality programs as well. - - * The thinness of geosynthetics versus their natural soil counterpart is an advantage insofar as light weight on the subgrade, less airspace used, and avoidance of quarried sand, gravel, and clay soil materials. - - * The ease of geosynthetic installation is significant in comparison to thick soil layers (sands, gravels, or clay liners) requiring large earthmoving equipment. - - * Published standards (test methods, guides, and specifications) are well advanced in standards-setting organizations like ISO, ASTM, and GSI. - - * Design methods are currently available in that many universities are teaching stand-alone courses in geosynthetics or have integrated geosynthetics in traditional geotechnical, geoenvironmental, and hydraulic engineering courses. - - - == Disadvantages == - - * Long-term performance of the specific formulated resin being used to make the geosynthetic must be assured by using proper additives including antioxidants, ultraviolet screeners, and sometimes fillers. - - * Clogging of geotextiles, geonets, and/or geocomposites is a challenging design for certain soil types or unusual situations. For example, loess soils, fine cohesionless silts, highly turbid liquids, and microorganism laden liquids (farm runoff) are troublesome and generally require specialized testing evaluations. - - * Due to the inherent thinness of geosynthetics, handling, storage, and installation must be assured by careful quality control and quality assurance of which much as been written [8]. - - - == References == - - # Agerschou, H. S. (1961), "Synthetic Materials Filters in Coastal Protection," Journal American Society of Civil Engineers, Waterways and Harbours Division, Vol. 87, No. WW1, pp. 111-24. - # Rankilor, P. R. (1981), Membranes in Ground Engineering, J. Wiley and Sons, Chichester, U.K., 377 pgs. - # ----- (1977), Proceedings of International Conference on the Use of Fabrics in Geotechnics, Paris, France, Vol. 1,2,3. - # Staff, C. E. (1985), “The Foundation and Growth of the Geomembrane Industry in the United States,” Proc. Intl. Conf. on Geomembranes, IFAI Publ., Roseville, MN, pp. 5-8. - # Koerner, R. M. (2008), “A Worldwide Perspective on the Impermeabilization of Solid Waste Landfills: Past-Present-Future,” International Congress on Protection, Construction, and Impermeabilization of Hydraulic Structures, CEDEX, Palma de Mallorca, 23-25 April, 2008, 13 pgs. - # Koerner, R. M. (2005), Designing With Geosynthetics, 5th Edition, Pearson-Prentice Hall Publishing Co., Upper Saddle, NJ, 796 pgs. - # IGS, “Geosynthetic Functions”, Accessed 28 May 2006. - # Daniel, D. E. and Koerner, R. M. (2007), “Waste Containment Facilities: Guidance for Construction Quality Assurance and Construction Quality Control of Liner and Cover Systems,” Second Edition, ASCE Press, Reston, Virginia, 352 pgs. - - - == External Links == - - International Geosynthetics Society [1] - Geosynthetics Materials Associations [2] - Geosynthetic Institute [3] - International Association of Geosynthetic Installers [4] - Geosynthetica via I-Corp [5]