What are Geosynthetics?
Cement, reinforced concrete and steel are the three most commonly used building materials in modern engineering.
Generally, the commonly used geosynthetics are divided into geotextiles, geomembranes, special geosynthetics and geocomposites.
The advantages of geosynthetics are small proportion, strong overall continuity, high tensile strength, corrosion resistance, anti microbial corrosion, and stronger than natural materials.
1. The Histroy of Geosynthetics:
Cement, reinforced concrete and steel are the three most commonly used building materials in modern engineering. These materials are used in many artificial buildings.
In the 1950s, with the development of chemical industry and the mass production of synthetic fibers, man-made materials began to be applied in geotechnical engineering and road engineering, and they were popularized in Europe, America and other countries.
In the 1970s, nonwoven geotextiles appeared, i.e. nonwovens or nonwovens, which overcame the disadvantage of directional force on the woven geotextile fabric and developed rapidly due to its unique manufacturing process and low cost.
Subsequently, geotextile, geomembrane, geogrid and other technologies also appeared. Since the 1980s, they have been called "geosynthetics" by engineering circles.
Since then, the application of geosynthetics in engineering has gradually become a new subject.
2.Types and Raw Materials of Geotechnical Materials:
2.1.Types of Geosynthetics:
There are many different expressions for the classification of geosynthetics. Generally, the commonly used geosynthetics are divided into the following four types:
a) According to the manufacturing method, geotextiles can be divided into non-woven geotextile and woven geotextile;
b) Geomembrane is a thin layer of impermeable geotechnical material;
c) Special geosynthetics such as geogrid,geocell,GCL...;
d) Geocomposites, which are impermeable materials or drainage boards made of non-woven fabrics and Geosynthetic core materials of geomembrane, have many forms, wide uses and good performance due to different needs.
2.2. Types of Raw Material:
Geosynthetics not only have different appearance, shape and engineering properties, but also have many kinds of polymer substrates.
3.Functions of Geotechnical Materials:
The advantages of geosynthetics are small specific gravity, strong overall continuity, high tensile strength, corrosion resistance, microbial erosion resistance and stronger than natural materials.
In addition to the above characteristics, geotextiles also have the characteristics of small equivalent pore diameter, good permeability, soft surface and certain roughness, which can have high friction coefficient and strong binding force with soil.
Geomembrane and other composite materials have unique impermeable and high impermeable drainageperformance.
Geosynthetics mainly have six functions:
a) The filter action (also known as "anti filter action") can not only permeable and ventilate, but also prevent the movement of soil particles, which can ensure the stability of soil;
b) In geotechnical engineering, drainage can replace sand cushion as drainage channel;
c) Isolation can be used as isolation layer between two layers of different materials, so that stress transfer and diffusion or material will not be hollowed out or mixed due to scour under the action of water flow;
d) Impervious geomembrane or composite geomembrane can prevent the influence of surface water or groundwater leakage on the stability of the structure;
e) Reinforcement can improve the overall stress state of soil or pavement, enhance the bearing capacity of foundation and improve the stability of subgrade;
f) The protective effect can diffuse the stress and prevent the soil from being damaged by external force or water flow.
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