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Nonwovens / Technical Textiles

Geotextiles: The Concrete Alternative

Geotextiles offer flexible, cost-effective solutions for civil engineering applications requiring reinforcement, erosion control, barrier and other functions.

Jürg Rupp, Executive Editor

G eotextiles were one of the first textile products in human history. Excavations of ancient Egyptian sites show the use of mats made of grass and linen. Geotextiles are ideal materials for infrastructural works such as roads, harbors and many others. They have a bright future, thanks to their multifunctional characteristics.

Geotextiles today are highly developed products that must comply with numerous standards. To produce tailor-made industrial fabrics, appropriate machinery is needed. Germany-based Trützschler Nonwovens Fleissner GmbH and Dilo Maschinensystem GmbH produce nonwovens machinery, and Lindauer Dornier GmbH manufactures weaving machines. All three companies plus the Geosynthetic Materials Association (GMA), Roseville, Minn., and the Association of the Nonwoven Fabrics Industry (INDA), Cary, N.C., provided useful information for this article.

GeoPic1
Geotextile application areas
All illustrations: courtesy of Lindauer Dornier GmbH


Functions
Every textile product applied under the soil is a geotextile. The products are used for reinforcement of streets, embankments, ponds, pipelines, and similar applications. Depending on the required function, they are used in open-mesh versions, such as a woven or, rarely, warp-knitted structure, or with a closed fabric surface, such as a nonwoven. The basic geotextile functions include erosion control; protection; filtration; armoring; drainage; and separation, or barrier function.

Geotextiles with their built-in functions are virtually tailor-made based on end-use or application. Major requirements include: tensile strength; permeability to air, fluids and/or light; mesh size suited to end-use, such as filtration, sieve or separation; chemical, mechanical or thermal resistance; and durability.

Fibers
Most woven geotextiles are made of filament polyester (PET), polypropylene (PP), glass, basalt, aramid or carbon fibers; with the fiber chosen based on the required functions, mainly tensile strength and a very long product life. Typical end-use applications are roads, levees and railroad embankments, among other applications. Nonwovens, usually made of PP and PET, are mainly applied for barrier function end-uses such as filtration and separation. In addition, nonwovens made of natural fibers, for example, are suitable for covering grass slopes. It is possible to incorporate different kinds of seeds, such as grass, and the nonwoven cover will eventually decompose as a green and natural surface grows on the construction.

Bast fibers, with their non-uniform fiber qualities, are beginning to be used in certain nonwoven products. The same applies for recycled fibers. Currently, very few recycled fibers are used. Also, recycled fibers do not always have the uniform properties required to form an even product. When PET bottles are recycled in a way that produces uniform fibers, then recycled PET fibers could be processed using needlepunch technology, Dilo mentions.

Coating materials play a very important role in enhancing geotextile properties and functions. Primary coating materials used include polyvinyl chloride, bitumen, latex, plastisol, silicone and other similar materials.

Geopic2
Geotextile applications include reinforcement for road construction.

Global Market
According to information provided by Dornier, the global geotextiles market is estimated to have been worth $3 billion in 2009. The nonwovens sector accounts for 74.5 percent of the growth; wovens, 25 percent; and other systems, 0.5 percent. The global growth of geosynthetics alone is estimated at 5 percent annually.

According to GMA, the U.S. and Canadian geosynthetics market has a current estimated value of $2.1 billion, with the U.S. share of that market put at 90 percent and the Canadian share at 10 percent. The sector employs some 12,000 people. Within that market, geotextiles has a 32-percent share; geomembranes, 28 percent; geogrids, 14 percent; and drainage composites, 26 percent.

The nonwoven geosynthetics market has gone up and down in concert with the recent financial market ups and downs. "Geosynthetic nonwovens volume dropped precipitously during 2008 and 2009," said Ian Butler, INDA's director of market research and Statistics. "However, there has been considerable growth in 2010."

INDA estimates that in 2010, the North American nonwoven geotextiles industry had a production volume of some 350 million square meters, with a roll goods value of nearly $300 million. "Most of these products are made from needlepunched PP, but there is some small volume of of spunbonded PET used for asphalt overlay," Butler said. "What has boosted the sales in 2010 was the Obama administration's plan to invest in the highway, airport and similar projects to provide work and reinvest in the transportation infrastructure. In discussions with people in the industry, they indicated that the low inventories of geosynthetics nonwovens at the end of 2009 led to many very busy nonwoven needlepunch producers now catching up with demand."

While Textile World does not have access to specific data related to China's geotextiles market, that country has major infrastructure and erosion control projects planned, and the Chinese market will account for the largest portion of new geosynthetics demand worldwide in the next few years, according to information posted on the website of Cleveland-based industry research firm Freedonia Group Inc.

Dornier reports the growing Indian geotextiles market has a value of some $49.6 million, but it is expected to grow to nearly $66 million by 2012. Projected annual growth is 12 percent, and long-term, it will increase to 20 percent, thanks to the further development of the country's infrastructure.

Fleissner, Dilo and Dornier expect much better results for 2010 than they realized in the previous two years. This improvement is primarily thanks to structural adjustments, Dornier reports, but the markets as such are in much better shape than previously. In spite of the falling markets owing to the recent financial crisis, Fleissner reports constant demand for its machinery and expects to report a successful 2010. Dilo also is seeing strong recovery since first-quarter 2010 and is working at full capacity, with delivery times up to seven months.

Dornier's main markets are Germany, the Netherlands, Russia, China and India. Fleissner's markets include Germany and Russia as well, but also the United States. Dilo reports demand for complete production lines for geotextiles is at the moment very high around the globe, but particularly in Europe, the United States and Asia.

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Important Sector
For each company, the geotextiles sector is an important market. Trützschler Nonwovens is able to deliver lines for man-made fiber production as well as calenders or bonding machines such as its Omega machine. The company reports lines already delivered for geotextile production have a production capacity of more than 1,500 kilograms per hour and even at low fabric weights of 60 to 80 grams per square meter.
 
Dilo and Fleissner report there is an important upswing for nonwovens in general and geotextiles in particular. The advantage of nonwovens as geotextile products is first of all their high-volume and cost-effective production. A further criterion is their ability to stretch and adapt to bumpy surfaces. Of outstanding importance is the finished product's fabric width for effective and economical road — or, increasingly, harbor — constructions. Dilo needlepunch machines are constructed to allow a working width of 600 centimeters (cm).

On the other hand, geotextiles, which require high durability and strength, usually are made of woven fabrics. Dornier reports its weaving machines are especially suitable for production of open-mesh fabrics for armoring all kinds of constructions. Several layers of different constructions can be combined. Woven fabrics also need to be produced in a wide width. In general, machines with a nominal width of 540 cm and greater are used, while the hauling equipment for street construction is usually designed to have a 500-cm width. A rapier weaving machine with multiple weft insertion enables production of a defined product specific to the end-use.

The Future
The future for nonwoven and woven geotextiles is bright. However, for manufacturers to be successful in this market segment, there must be a lot of know-how and communication efforts with existing and potential customers. Comparing the difference between today's customer and one of 10 years ago, one could note such comments as: "Our old customers are true professionals; our new customers depend very much on our knowledge and experience." This means knowing exactly the markets, their requirements and possible civil engineering applications. Also, product requirements and the number of innovations are continually increasing, which makes the markets highly competitive and attractive, and creates more business.

Infrastructural programs are being undertaken mainly in emerging markets, but Europe and the United States are seeing increased demand. Especially in emerging countries such as Brazil, India, China and Russia, demand goes along with the rising mobilization and improved public transport facilities — including new airports. The use of geotextiles significantly reduces civil engineering construction costs and drastically extends the life of any road construction. "Textiles instead of concrete" is not only a slogan, but a fact. Geotextiles have flexibility, making them better and more economical than any other building materials.

January/February 2011

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Click here to view the Geogrid Calculation table