type of geosynthetic

Types of geosynthetic

 

In 1977, GiroudJR and PerfettiJ first referred to permeable geosynthetic materials as "geotextiles" and impermeable materials as "geomembranes". In the 1980s, in order to better meet the needs of geotechnical engineering, the application of geosynthetic materials gradually increased, and other types of geosynthetic materials using synthetic polymers as raw materials emerged one after another, which has exceeded the scope of "fabric" and "membrane", and the two categories are difficult to include. The International Society of Geotextiles proposed a classification system for geotextiles, geomembranes, and related products, and the classification method proposed by Giroud et al. in 1983 is a typical representative of it. The current trend in the classification of geosynthetic materials is to abandon the idea of using geotextiles as the main classification line and establish classification methods that are convenient for engineering applications.

 

Geosynthetic materials are usually divided into four categories:

 

 

 

 

I  Geotextiles belong to permeable geosynthetic materials, formerly known as geotextiles, and the raw materials used are generally polypropylene, polyester, or other synthetic fibers.

Geotextiles include woven geotextiles and non-woven geotextiles.

Weaving geotextiles: Organic woven geotextiles and knitted geotextiles.

Non woven geotextiles include needle punched non-woven geotextiles, hot bonded non-woven geotextiles, and chemically bonded non-woven geotextiles.

 

Common geotextiles include:

• Polyester short fiber needle punched nonwoven geotextile: It is made by laying polyester short fibers into a mesh through different equipment and processes, and then processing them through needle punching and other processes.
• Polypropylene short fiber needle punched nonwoven geotextile: a geosynthetic material made mainly from polypropylene fibers through combing, laying nets, needle punching, and solidification.
• Polyester filament needle punched nonwoven geotextile: made by the method of polyester filament forming a web and solidifying, with its fibers arranged in a three-dimensional structure.
• Polypropylene woven fabric: Using polypropylene flat filaments as raw materials, it is composed of at least two sets of parallel yarns (or flat filaments), and woven into a cloth shape by interweaving warp and weft yarns using different weaving equipment and processes.
• Polyester woven fabric: Made from high-strength and low elongation synthetic fiber filaments such as polyester and polypropylene, it has superior water retention, filtration, durability, corrosion resistance, and high tensile strength through weaving technology. It is suitable for coastal rivers, slope protection, beach protection, and soft soil foundation treatment, and is a practical new material in modern foundation engineering.
• Polyester composite geotextile: composed of high-strength polyester fiber and non-woven fabric woven by warp knitting, it perfectly combines the high-strength performance of geogrid and the drainage performance of non-woven geotextile, making it an excellent geotextile.

 

II Geomembrane belongs to relatively impermeable geosynthetic materials, which use raw materials such as asphalt and synthetic polymers, as well as certain fillers and additives. The fillers include mineral powder and polymer powder, etc. In order to improve its durability and reduce its cost, additives include plasticizers, anti-aging agents, antibacterial agents, various stabilizers, etc. The commonly used geomembrane thicknesses include 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.75mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.5mm, and 3.0mm From 0.2mm to 3.0mm. Width: 1m-12m. Colors: black, green, blue, white. Materials: HDPE, LDPE, LLDPE. The classification of geomembranes is as follows:

Classified by surface effect:

• Smooth geomembrane: A geomembrane with a flat and smooth appearance on both sides.
• Textured geotextile film: a geotextile film produced by certain techniques with a uniform rough appearance on one or both sides. There are single-sided textured geotextiles and double-sided textured geotextiles.

 

Classified by production raw materials:

• High density polyethylene geomembrane: geomembrane produced from medium density polyethylene resin or high-density polyethylene resin, with a density of ≥ 0.940g/cm3
• Low density polyethylene geomembrane: geomembrane produced from raw materials such as low-density polyethylene resin (PE-LD), linear low-density polyethylene resin (PE-LLD), ethylene copolymer, etc., with a geomembrane density of ≤ 0.939g/cm3
• Linear low-density polyethylene geomembrane: a geomembrane produced from linear density polyethylene resin (PE-LLD) as raw material, with a geomembrane density of 0.939g/cm3.

 

III Composite geosynthetic materials refer to geosynthetic materials composed of two or more materials, such as geotextiles and geotextiles, including composite geotextiles, composite geotextiles, composite waterproofing materials (drainage belts, drainage pipes, drainage waterproofing materials, etc.).

 

IV Special geosynthetic materials refer to new geosynthetic materials developed in the past decade, in addition to geotextiles and geomembranes, which can better meet the requirements of geotechnical engineering. The package includes geogrid, geosynthetic belt, geosynthetic cell, geosynthetic mesh pad, geosynthetic mesh, geosynthetic bag, geosynthetic fabric bentonite pad, polystyrene board, composite drainage network, filter plate, vegetation network, grass planting grid, etc.

The most commonly used polymer materials in geosynthetics are:

•  Polyethylene (abbreviated as PE);
•  Polypropylene (abbreviated as PP);
•  Polyester (abbreviated as PET);
•  Polyamide (abbreviated as PA);
•  Polyvinyl alcohol (PVA);
•  Polyvinyl chloride (abbreviated as PVC);
•  Polystyrene (abbreviated as PS), etc.

 

Fibers are divided into natural fibers and chemical fibers. Natural fibers include cotton, wool, silk, linen, etc; Chemical fibers are made from various raw materials that have undergone chemical treatment and mechanical processing, including artificial fibers and synthetic fibers. Synthetic fibers are made from polymers as raw materials, which are melted or dissolved into a viscous spinning solution. They are then sprayed by a spinneret under a certain pressure and processed into a final product. Compared with artificial fibers, synthetic fibers have higher strength and lower moisture absorption.

 

In business, the short fibers of synthetic fibers are referred to as fibers, while the short fibers of synthetic fibers are referred to as nylon. The long fibers of synthetic fibers and synthetic fibers are collectively referred to as silk. The commercial product names uniformly refer to polyester fiber as polyester, polyvinyl alcohol fiber as vinylon, polyacrylonitrile fiber as acrylic, polyethylene fiber as chlorinated fiber, and polypropylene fiber as polypropylene. Sometimes adding a grease character after the product name refers to adding resin to the fibers to prevent shrinkage, waterproofing, etc; Sometimes, some plastic resin is added to increase elasticity.