TEXTILES.ORG
By Jingkui Chi
Editor’s note: Part 1 of this 2-part series ran in the August/September issue of Geosynthetics. Following the Abstract, Part 2 concludes with sections 3 and 4 of this manuscript.
Abstract
This article presents an introduction to the development of China’s geosynthetic production, applications, testing, and research, and discusses the market supply and demand as well as development trends.
3. Testing and standards
3.1 Testing technology for geosynthetics
Currently in China, there are no unified domestic product testing standards, even as the development and application of geosynthetics continues.
Knowing the performance indexes of geosynthetic products is crucial and it is essential to test them. Early products were mainly geotextiles, so many of them adopted the textile test methods. Synthetic and composite materials adopted the plastic products test methods. However, geosynthetics mainly used in geotechnical engineering follow the test methods of soil mechanics and hydraulics.
European companies mainly use the International Organization for Standardization (ISO) standards, while American and Southeast Asian companies primarily use ASTM International standards. In China, as early as the late 1980s, the organization called the Geosynthetics Technology Collaboration compiled the “reference standards of geosynthetics test methods,” then compiled Geosynthetics Testing Manual, published in March 1991. The main content includes testing methods, testing principles, test instruments and equipment, and data sorting methods for geosynthetics (physical, mechanical, hydraulic characteristics, etc.—18 items total are included). It accumulates much practical data and lays a foundation for establishing more complete specifications.
State leaders have paid great attention to flood-control emergencies, particularly because China suffered severe flooding disasters in 1998. An industry standard, Test Procedure of Geosynthetics by the Ministry of Water Resources, and Test Specification for Geosynthetics used in Highway Projects by the Ministry of Communications were published successfully. All these standards are warranted and they played an important role in quality control. Meanwhile, they push forward the application selection, research, and the development of geosynthetics in projects. Although there are national standards and industry standards, China still has some problems of application practice.
- Currently, when standards are made, they refer to the ISO and ASTM standards, but they all choose all the contents, not only the test content, but also the test method. While test equipment differs, there is a lack of comparability between the test results of Chinese products and the national standards. It is also an important reason why foreign countries cannot always accept Chinese products.
- As a relatively new material in geotechnical engineering, geosynthetic materials have unique characteristics. The testing results will be different if different testing methods, testing equipment, or the condition or medium is different. In the past, all references were to the textile test standards or geotextile product test standards. Some of them are feasible, but there are some differences and impracticalities. Some of the norms are limited and lagged by the practical testing methods. However, there is not a revision and supplement of these norms, so it’s difficult to raise the level.
- There is a lack of systematic and planned research on test technology. A scientific basis for the establishment of some special tests is not provided.
3.2 Technical standards for geosynthetics
The implementation of the industry standard, Application Technical Standard for Geosynthetics used in Water Resources and Hydropower Engineering, was started in November 1998. It includes the design methods and key points of construction technology using geosynthetics as filters, for drainage, anti-seepage, bank protection, anti-scour, and soil reinforcement. The principle is that application design is the priority and the construction requirement should also be taken into consideration.
- The establishment of the application technical standard provides a scientific basis for engineering design and construction and ensures engineering quality. After years of the application, it is proved to be feasible and promotes the application of geosynthetics. The standard had been revised and some new content was added in 2004, and now it is reporting for pending trial.
- Because the application time for geosynthetics in China is short, there is little accumulated data from scientific experiments and practical engineering applications, so the revision of standards is limited to some extent. This is the most important thing to be strengthened.
- When geosynthetics are used in large engineering projects, construction requirements are made accordingly, while smaller projects are constructed with simpler tools, equipment, and experience. More data about this should be collected and summarized, and then feasible construction standards can be made to improve the quality of construction.
4. Future
4.1 The market prospects for geosynthetics
Currently, China is in the midst of large-scale infrastructure construction projects, especially important projects that require different types of high-quality products.
The out-of-date production mode, or “family workshop” from the past, cannot meet current requirements for both quantity and quality, so it forces the enterprise to reform and innovate. Among them, reinforced materials, anti-seepage materials, and some kinds of the geotextiles develop quickly.
1. Reinforced materials
With the construction requirements of railways, highways, and environmental projects, a large amount of reinforcement materials are needed. Currently, many products, such as uniaxial geogrid, biaxial geogrid, fiberglass geogrid, and warp-knitted geogrid can be produced and widely applied to projects.
2. Anti-seepage materials
With the development of hydraulic engineering, environmental engineering, and construction engineering, the requirement for anti-seepage materials becomes much higher, and the single thin-type geomembranes cannot meet the high demand.
All these promote the vigorous development of geomembranes. Currently, both calendering and blow molding geomembranes are produced in China. Production includes: PVC geomembrane, polyethylene geomembrane (PE), high-density polyethylene geomembrane (HDPE), and low-density polyethylene geomembrane (LDPE). Smooth geomembrane, single-textured geomembrane, double-textured geomembrane, composite geomembrane, reinforced geomembrane, and geosynthetic clay liner (GCL) can also be produced according to engineering requirements. There are fewer calendering geomembrane production factories.
Currently, the usage of geomembranes is very large. According to some statistics, the annual demand of all types of geomembranes reaches up to 150,000,000m2, about 35,000 tons. Therefore, it is necessary to further reform and improve the production of geomembrane.
3. Geotextile materials
Geotextiles mainly include braided, woven, and nonwoven. With the requirements of reclamation land from the sea in coastal areas in recent years, plus waterway regulation and municipal construction projects, the demand for geosynthetics increases yearly and the variety and specification also increases.
Among braided geosynthetics, high-strength circular knitting fabrics, reinforced braiding fabrics, anti-aging braiding fabrics, and nano-braiding fabrics have been put into the market successfully except for the plain fabrics. Weaving fabrics are mainly combined with nonwovens and fabricated into large, sand-filled bags, then used in reclaiming land from the sea. The application quantity is quite large; the amount in the Deep-Water Channel Project on the flow field of the Yangtze Estuary reached more than 3.4 million m and a large quantity was also used in Yangshan Deep-Water Sea-Filling Project.
In recent years, nonwoven products are made mainly of staple fiber needlepunched nonwoven. They are generally used as filtration layers and also used as the component of composite geomembrane. The application and production quantity of polyester long-staple needlepunched nonwovens is increasing; there are more than 10 manufacturing enterprises. The equipment investment for long-staple nonwoven materials is large, the process is complicated, and the domestic development is slow.
In short, both the output and the usage of geosynthetic materials in Chinese engineering projects is increasing greatly. The development of the output, quality, and quantity of reinforced materials and anti-seepage materials is significant, although there are different degrees of development in drainage, pervious hose, plastic blind drain, three-dimensional geonet, geocells, and other products. The production scale is small, the technology is not high, the product is unstable, and the market competition ability is low. Some products may not be the main material in projects, but are related to the project quality and stability and, at the same time, concern the whole development of geosynthetics.
4.2 The development ofgeosynthetics technology
Geosynthetics is a new geotechnical engineering material as well as a new multidisciplinary technology.
With the rapid development of the polymer chemical industry, new varieties of synthetic fibers and new synthetic materials are continuously emerging and are used in geotechnical engineering successfully. These developments took 40 years abroad, but only 20 years in China. There is a certain gap between domestic and overseas. Overseas, the United States develops products. In Europe, Germany, France, the Netherlands, Italy, and other Western European countries also develop rapidly. In Asia, Japan, South Korea, and Thailand develop rapidly.
In recent years, we have attended international academic conferences and exhibitions in Europe, North America, Japan, South Korea, and other locales. At the same time, we also visit factories and construction projects and meet some dealers and scholars from many countries. By doing this, we gain understanding of the development of geosynthetics abroad, and find the characteristics of many varieties, good quality, series of products, product stability, data integrity, popular engineering applications, and high-technology quality dealers. All these should be considered in China’s future development. At the same time, combining with our national condition, the development is accelerated.
1. Product development
This development is mainly new varieties and series products.
New product varieties are developed for use rather than retrofitting the existing ones. We should design scientific and rational products according to the engineering applications. Due to a wide range of projects, there is a great demand and potential for these products.
In addition, we should enhance series product development; ideally, every type of product should be made into series systematically. By doing so, designers can choose the product that is suitable for the design requirements by series when they use geosynthetic materials. This will change the unscientific and unreasonable demands that appear in current design, and also reduce the burden and unnecessary troubles of the production enterprises.
2. Product function development
A major advantage of geosynthetics is that when a primary function is taking effect in an application, the other functions work at different degrees to produce the ideal effect.
When the same product is used in different projects or different parts of one project, it can have different functions. The product function development can expand the range of the finished and semifinished products. Therefore, it can reduce the burden of construction and increase the product’s sales and profits.
Application technology is key to the development and popularization of geosynthetic materials because it allows geosynthetics to be used more reasonably, effectively, and widely, to help solve problems in projects, and to expand the application of geosynthetics.
Corresponding to expanding the sales market, there must be complete representative testing standards. However, the current standards have some disadvantages, so they must be revised and the test equipment must be reviewed.
Only when the design and application criteria are perfected and unified, the construction equipment reviewed, the technical level improved, and the construction standards set up, can we create conditions and basis for design application development.
Product market development conclusions
The market is complex with many factors, such as systems and interpersonal relationships, as well as natural and man-made disasters. Some small and less competitive enterprises have difficulties. In any case, we should utilize all opportunities to enter the market and create conditions for the market development with favorable factors.
First of all, we should base our efforts on the domestic market. China is undergoing large-scale infrastructure construction. Local, national, and international consortia have increased investment in engineering construction and provided funding. However, new engineering materials are needed. All these form a good opportunity and provide a wide product market for geosynthetics.
Many projects require a large number of geosynthetic materials, particularly geomembranes, such as the Western Development Project, the South-to-North Water Diversion Project, and other environmental engineering and municipal construction. The key to the western development is to solve the water problems, which requires transporting water, collecting water, and storing water, and all these have to solve the anti-seepage problem with geomembranes. At the same time, it promotes the sales of other materials correspondingly.
In addition, Beijing (the host city of the 2008 Olympics), Shanghai (the host city of the World Expo–2010), and the surrounding area of Shanghai and the Yangtze River delta area are ideal markets for geosynthetics. It isn’t easy to enter these markets, and enterprises should change their marketing methods and launch joint sales and network sales through sale platforms in addition to direct sales. Some competitive enterprises can sell their products abroad and put them into international markets. Some have already done it.
Currently, enterprises have to establish their own brand as quickly as possible, promote their own brand, and increase their brand’s popularity through customers, designers, experts, and project examples, as well as through professional conferences and exhibitions to maintain and expand their market share.
The production, application, and research of geosynthetics in China developed very quickly. Production develops toward series, synthesis, and compounds. Applications develop toward medium and large projects. Relevant theoretical research, testing technology, design criteria, and construction technology are modified, perfected, and improved. All of these fully reflect that China has strong production capacity and a high technological level with a strong team in geosynthetic fields.
Geosynthetic products offer new, viable geotechnical engineering materials, and the economic and social benefits are significant. Also, they have strong application values. Therefore, we have to seize the current favorable opportunity and work together to push the usage of geosynthetics to a new stage.