The recent history of geotextiles is inseparable from the development of polymers and synthetic fibers.
Since the 1970s, geotextiles have been widely used in various fields such as highways, railroads, water conservancy, and harbor buildings, etc. The mass production and application of geotextiles have been generally regarded as a kind of engineering material that can improve project quality, speed up construction, reduce project cost and prolong maintenance. The more desirable engineering materials of the cycle. China’s research and application of geotextiles started late, from the 80s onwards in the railroad, water conservancy sector began to apply, and has achieved promising results, has clearly shown the superiority of this material. Engineering design using geotextiles, deepen the personnel of geotextiles, with our understanding of the performance of this material on the improvement and the application of the actual project, and constantly summarize the exchange, geotextiles will be widely used and universal attention.
Let’s dive right in now, and you can click on the question that interest you,
1 Characteristic of geotextiles
1) Characteristic of geotextiles
Geotextile is a kind of chemical fiber product, whose raw materials are polypropylene, polyester, poly wash amine (woolen), etc. In terms of product types, they can be divided into two categories: textile (spun) fabrics and nonwoven fabrics. The so-called textile fabrics are obtained from polymers, then spun into threads and woven into cloth with the regular organization on a loom. The so-called non-woven fabrics, is not through the textile process, directly with synthetic fibers to needle-punch bonding, thermal bonding, and chemical bonding. Since the raw material of geotextile is polypropylene and other chemical fiber products, it has the advantages of strong chemical resistance, high melting point, and high strength, while the nonwoven fabric has a lower cost than woven fabric, simple process and high yield in its tensile strength without significant directionality, so nonwoven fabric is a widely used geotextile in the world at present.
2) Function and application of geotextile
The functions of geotextiles as construction materials are multifaceted, and the following basic functions and applications have been recognized by experts, design people, and manufacturers.
- Separation: Geotextiles can effectively prevent the mixing of two different sizes of soil materials to avoid mixing with each other or loss of soil particles, which is very important for building a road or railroad foundations on soft soils. The economy shows that in some cases it would be practically impossible to build on such foundations without geotextiles because the filling material would sink directly into the subsoil. Therefore, the application of geotextiles is an economical and effective solution.
- Filtration role: The use of geotextiles as a filter layer and the role of graded gravel layer is the same, geotextiles can make water flow freely through with almost no pressure, but also to prevent the loss of soil fines, so as not to lead to instability and erosion of certain projects, such as in the hydraulic structure, river, lake shore embankment by wave impact or wave water level changes, will reduce the stability of soil erosion, between the river bank and masonry laid geotextile filter layer, it can stop the erosion of soil, to prevent the river bank collapse.
- Drainage role: so that the geotextile itself form a drainage channel, the moisture in the soil gathered within the fabric, along with the fabric slowly discharged from the soil, in the water content of soft soil areas to build roads, you can use special machinery to insert the geotextile into the soil, groundwater along the geotextile column out of the ground, into the permeable sand layer or geotextile excluded roadbed.
- Reinforcement role: geotextile sandwiched in the aggregate – geotextile – soil base system, can disperse the vehicle load to a larger area, reduce the pressure of the load on the soil base, under the load, the soft soil base deformation because the geotextile fabric has a certain toughness and elongation, so the geotextile fabric with the deformation embedded in the soil base, so that the whole system to create a continuous structure, improve the stability of the structure, improve the bearing capacity of the soil base.
2 Construction precautions
1) Preparation of surface layer
First, clean the pavement so that there is no debris on it, and it is better to clean it with water. Repair the cracks on the pavement larger than 0.6 cm, and the repair material can be asphalt concrete, asphalt sand, cement concrete according to the unused situation.
2) Spraying sticky layer oil
Spray sticky layer oil on the pavement with a hot asphalt sprinkler, the amount of oil depends on the oil absorption rate of the pavement, and the general amount is between 0.9-1.2 kg/㎡. Oil number is generally better with 60 or more asphalt.
If you take two times sticky layer oil method, the first dosage between 0.5-0.7 kg/㎡, then lay asphalt geotextile, in the asphalt geotextile on the sprinkling of sticky layer oil, the dosage between 0.4-0.5 kg/㎡.
3) Paving surface layer
When laying geotextile, ensure that the coil is at a certain height from the ground, and when the nuisance-free geotextile is tensioned and straightened in bonding with sticky layer oil, brush it flat and roll it with a steel roller.
When geotextile laying, should try to make it flat and straight, which can give a certain tension. When the bonded fabric appears more than 1.27 cm wrinkle, use a knife to cut it and lap it along the laying direction. When laying the fabric at the road bend, it should be cut open on the inside of the fabric bend, and lap along the laying direction. The lap length required between the fabric width and the fabric width is 4-7.5 cm.
4) Spreading stone chips
After the fabric is fully combined with the sticky layer oil, sprinkle stone chips on it, stone chips can generally be used melon pieces or medium-coarse sand, the number of stone chips depends on the flooding oil on the surface of the fabric, generally in about 2 m³/K㎡.
5) When laying geotextile in a large area, at the lateral lap of the cloth, according to the specific situation can be considered fixed with a fixer
Fixer includes fixing nails and fixing iron. Fixed nails available cement nails, nails, nail length in about 8 cm, fixed iron with 1 mm thick, 3cm wide iron strip. Nail-fixed nails available hand hammer or nail gun, in the case of the grassroots comparatively dense room available high-speed nail gun.
At the same time, the geotextile should be kept dry, if it is rained on then it should be dried all before laying. When laying the geotextile, the construction personnel should not smoke. When the human asphalt is used to bond the geotextile cools, then do the top layer. In the geotextile is in a saturated state, hot asphalt has not yet cooled do not drive on it, in the paved geotextile vehicles do not turn around and brake.
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