Introduction of geogrid
Geogrid is a major geosynthetic material, which has unique properties and efficacy compared with other geosynthetics. It is often used as a reinforcing material for reinforced soil structures or a reinforcing material for composite materials.
Geogrids can be divided into the following four categories: plastic geogrids(including PP and PE geogrids), steel-plastic geogrids, fiberglass geogrids, and polyester warp-knitted polyester geogrids. The grid can be a single or Biaxial grid or a three-dimensional grid screen with a certain height made of polypropylene, polyvinyl chloride, and other macromolecular polymers by thermoplastic or molding. The grids usually are used in civil engineering, so it is called geogrids.
Type of geogrid
Plastic Geogrids have two kinds in the following, one is Uniaxially stretched geogrid and, the other is Biaxial Geogrid.
Uniaxially stretched geogrid or single dimension geogrid is a kind of high molecular polymer as the main raw material, adding certain anti-ultraviolet and anti-aging additives inside, through the uniaxial stretching process, which will make the scattered chain-shaped molecules reoriented in a linear arranged state. Then the geogrid is a high-strength geotechnical material that is extruded and pressed into a thin plate, punched into a regular mesh, and then stretched in the longitudinal direction. In this process, the macromolecules of the material are brought into a directional linear direction and make an oblong network-like integral structure with uniform distribution and high node strength is formed. This kind of structure has a quite high and strong tensile strength which tensile strength reaches 100-300KN/m, which is close to the level of low carbon steel, As we all know low carbon steel can be much better than traditional or existing reinforcement materials, especially when it is companied with such products have high early-stage (2%-5% elongation) tensile strength and tensile modulus that exceed the most common level. Provides the ideal force bearing and diffusion interlock system for the soil. The product of geogrids has a high tensile strength (>150Mpa) and can be suitable for different soil applications. So it has a very wide range of applications.
Biaxial Geogrid is a high-polymer mesh material with a square or rectangular frame produced by stretching. According to the different drawing orientations of its production, it can be divided into two types: one-way stretching and Biaxial Geogrid stretching. It is a punching machine on the extruded high-polymer board (the raw materials are polypropylene or high-density high-pressure polyethylene), and then the final drawing is carried out under the heating standard. The stretched polypropylene geogrid is only stretched along the length of the plate, while the stretched grid is made by drawing the stretched grid again in the vertical direction rather than the length. Plastic biaxial geogrid is the geosynthetic material widely used to reinforce retaining walls, subbases, or subsoils below roads or structures
Because the high-polymer polymer materials of plastic geogrids will be re-ordered with the whole process of heating and widening in the production and manufacture, the connection force between the molecular structure chains is improved, and the purpose of improving its compressive strength is achieved. Its tensile strength is only 10% to 15% of the original board. If anti-aging materials such as carbon black are added to the geogrid, it can have good performance properties such as acid resistance, alkali resistance, corrosion resistance, and aging resistance.
Biaxial Geogrid technical parameters
|Item||Yield Strength KN/M≥||Elogation (at 2%)KN/M≥||Elogation(at 5%) KN/M≥||Longitudinal nominal
Application scope and advantages of Biaxial Geogrid
1) Used to strengthen weak foundations: Biaxial Geogrid can increase the bearing capacity of the foundations, control the development of settlement, and the confinement effect on the road base can distribute the load to a wider subbase, thereby reducing the thickness of the base. Reduce project cost, shorten the construction period and prolong service life.
Biaxial Geogrid used for reinforced asphalt or cement pavement: geogrid is laid at the bottom of asphalt or cement pavement, which can reduce the depth of rutting, prolong the fatigue life of pavement, and reduce the thickness of asphalt or cement pavement to save costs.
It is used to reinforce the embankment, dam, and retaining wall: the filling of traditional embankments, especially high embankments, often needs overfilling and the edge of the shoulder is not easy to compact, which leads to the later flooding of the slope and the phenomenon of collapse and instability. At the same time, it needs to use a gentle slope, which covers a large area, and the retaining wall has the same problem. The use of Biaxial Geogrid to reinforce the embankment slope or retaining wall can reduce the floor space by half, prolong the service life, and reduce The cost is 20-50%.
Used to reinforce rivers and seawalls: It can be made into gabions, which can be used together with grilles to prevent the dams from being swept away by seawater and causing collapse. The gabions are permeable, which can slow down the impact of waves, prolong the life of the dams, save manpower and material resources, and shorten the construction period.
For landfill disposal: Biaxial Geogrids are used in combination with other soil composite materials to treat landfills, which can solve the problems of uneven foundation settlement and derived gas emissions, and can maximize the storage capacity of the landfill.
Special use of one-way geogrid: low-temperature resistance. Adapt to a -45℃—50℃ environment. It is suitable for the poor geology of less frozen soil, rich frozen soil, and high ice content frozen soil in the north.
2)Biaxial Geogrid is suitable for all kinds of river embankment and roadbed engineering reinforcement, slope greening, cave wall reinforcement, large and medium-sized airports, underground parking lots, port freight stations, and other installed roadbed reinforcement.
1. Expand the bearing capacity of the road (ground) foundation and increase the service life of the road (ground) foundation.
2. Avoid the road (ground) surface from collapsing or causing cracks, and keep the road surface beautiful and neat.
3. The construction is convenient, time-saving, and labor-saving, reducing the construction period and maintenance costs.
4. Avoid cracks caused by tunnels.
5. Raise steep slopes to avoid soil erosion.
6. Reduce the thickness of the foundation cushion and save engineering costs.
7. Reliability of support point slope protection planting grass net-pad landscaping natural environment
Construction of Biaxial Geogrid for Road projects in Thailand
1 Treatment of pavement
The use effect of the two-way grille is related to the treatment of the pavement. Before laying, the substances on the pavement that may affect the bonding strength of the grille and the bottom layer, such as grease, paint, sealing material, water stains, dirt, etc., must be removed. , keep the laying surface clean and dry.
2 Laying and fixing of Biaxial Geogrid
The Biaxial Geogrid can be laid by tractors or special equipment modified by automobiles, and can also be laid. When the grille is laid, it should be kept flat and taut, without wrinkling, so that the grille has effective tension, and then roll it again with a clean drum roller after laying.
①The fixed iron sheet of 50×50×0.3mm is required to be flat and not warped, and the periphery should be chamfered;
②2-inch steel nails.
When using the fixed steel nail method to lay the Biaxial Geogrid, first fix one end of the fixed iron sheet and steel nails on the lower structure that has been sprinkled with adhesive layer asphalt, and the steel nails can be injected by hammering or nailing. The Biaxial Geogrid is then tensioned and fixed in sections, each section having a length of 2 to 5m. It can also be divided into sections according to the spacing of the shrinkage joints, and the position of the steel nails is set at the joints. When the Biaxial Geogrid is required to be tensioned, the glass fiber is in a straight tension state in both longitudinal and transverse directions.
The Biaxial Geogrid overlap is vertical overlap, the overlap width is not less than 20cm, and the horizontal overlap width is not less than 15cm. The longitudinal overlap should be based on the asphalt paving direction, and the former should be placed on top of the latter one. When fixing, the steel nails cannot be nailed to the two-way grille, and the grille cannot be hit with a hammer. After fixing, if the steel nails are broken or the iron sheet is loose, it needs to be fixed again. After the Biaxial Geogrid is laid and fixed, it must be rolled and stabilized with a rubber roller so that the grille and the original road surface are bonded.
In actual construction, some construction units spread the Biaxial Geogrid after spraying the sticky layer oil, and the road roller is followed by rolling, the effect is better, and the Biaxial Geogrid le is not easy to wave.
Thus, it is particularly important to strengthen quality supervision and improve the technical level of construction personnel.