Phạm Duy Ánh (Andy, Mr), Eng
Director of Civil Engineering Department - VATEC
Nov 5th, 2023
What are Geogrids and the function of a Geogrid ?
Polymer-based geogrid (referred to as geogrid) has a flat, open-cell structure, consisting of integrated connected tendons forming a mesh or mesh-like structure, usually supplied in the form of a roll.
Geogrids mesh products are typically made from polymer materials, including polyester, polypropylene, polyethylene, or polyvinyl. They can be woven or knitted from yarns; punched into a polymer sheet; extruded through rotating die heads to create a net structure or welded from strips of material. From production or manufacturing technologies and polymer material origin, geogrids can be classified into stiff geogrids or flexible geogrids.
Geogrids are used to solve civil engineering and geotechnical problems in or on the ground. They primarily provide a stabilizing or reinforcing function, to supplement or enhance the properties of the soil or fill aggregate.
Geogrids do increase particle confinement and trafficking performance.
Development of Tensar stabilization geogrids
Tensar geogrid is a rigid geogrid, usually manufactured from high-density polyethylene (HDPE) or polypropylene (PP) using a process of punching, heating, and stretching technology to create a stiff grid structure. The joints between the formed, integrated ribs give them high strength and structural stability. The ribs have high molecular density, linked together into blocks through nodes.
Tensar InterAx geogrid is the latest piece of the development and research puzzle that started with a biaxial reinforced geogrid product, transitioned to a triaxial (TriAx) geogrid with reinforcement function. mechanical stabilization of the platform… and now Tensar InterAx NX.
Tensar InterAx combines coextrusion, advanced material science, and an optimized geometry to drive superior performance across a broader range and quality of aggregate types and gradations.
Is geogrid safe for the environment and its sustainability in construction?
Cradle to Grave' roughly translated as 'from cradle to grave', is a term that refers to existing throughout the life cycle, from beginning to end.
In order to create a more resilient future, we need infrastructure that optimizes construction efficiencies and performance, while minimizing environmental impact. An assessment of environmental impact is becoming a more common design criterion in a growing number of jurisdictions around the world. One of the tools created for this purpose is the Environmental Product Declaration (EPD). The use of EPDs to assess environmental impacts such as Global Warming Potential (GWP) is expanding rapidly in the construction industry.
Application of Tensar geogrid in construction.
Geogrids provide a stabilizing or reinforcing function to improve soil performance. In addition, Geogrid also acts as a separation layer between soil and aggregate layers and is widely used in civil engineering applications.
Geogrids can be used for the following applications:
- Construction of platform, improving load-bearing capacity in soft soil conditions.
- Optimize pavement structure: reduce structure thickness.
- Increase the service life of roads, sidewalks and traffic areas.
- Improves the long-term performance of paved and unpaved roads by minimizing aggregate movement.
- Reinforcing earth retaining walls and slopes.
- Foundation structure and mechanical stability of high embankment on soft soil.
- Reinforcing the railway platform.
For subgrade stabilization application to traffic areas and railway foundations, Tensar InterAx is very suitable to be applied with its unique design and optimization of grid structure shape to enhance stability. From there, improving the performance of the structure under the effect of load helps reduce investment costs and maintenance requirements.
For soil reinforcement applications, the load must be transmitted between the soil and the geogrid. The horizontal ribs of a uniaxial geogrid provide an effective mechanism for transferring loads through the meshes instead of just friction. High tensile loads in geogrids are carried by the longitudinal ribs. They must be able to withstand such high loads throughout the life of the structure (typically up to 120 years), requiring long-term durability and strength and stiffness. For reinforcing working floors in traffic areas and railway foundations, Tensar interaxial geogrids are very suitable for application with unique designs and optimization of grid structure shapes to improve performance. stable. From there, improving the performance of the structural layer under the effect of load helps reduce construction investment costs and maintenance requirements, reduce carbon emissions, and increase the lifespan of the pavement structure. , roadbeds, and other traffic and construction projects.
Comparing Tensar Geogrids with alternative soil reinforcement solutions
The openings or apertures between ribs allow the aggregate to strike through and interlock with the geogrid. Provided the geogrid is stiff enough, the rib profile deep enough and the junctions strong enough, the aggregate is confined within the apertures forming a new geogrid/aggregate composite material with improved strength and resistance to deformation.
The efficiency of the interlock and confinement provided by a geogrid is dependent upon its physical characteristics (in-plane stiffness, junction efficiency, rib profile) and compatibility with the aggregate (particle size and type). Different geogrids with the same short-term QC strength can have widely different characteristics depending on the method of manufacture, the joint type, the rib profile, and the polymer used.
a/ Generic Biaxial Geogrids and Tensar geogrid
|
Generic Biaxial geogrids |
Tensar geogrid |
|
Products suited to bi-directional reinforcement |
Products optimised for mechanical stabilisation of aggregates |
|
Lower confinement efficiency due to effect of rib profile or lower junction strength provides reduced performance |
Highly efficient aggregate confinement increases bearing capacity and limits surface deformations |
|
Design parameters typically based on small scale testing, or geogrid properties |
Design parameters developed from full-scale accelerated trafficking tests of mechanically stabilised layers |
|
Typically not proven for use in road base, primarily utilised over weak ground |
Proven suitability for base stabilisation in permanent roads as well as road foundations over weak ground |
b/ Neoweb and Tensar geogrid
|
Neoweb |
Tensar geogrid |
|
Aggregate or sand fill confined by cell walls to increase bearing capacity. |
Highly efficient aggregate confinement creates a mechanically stabilised layer with improved bearing capacity. |
|
Difficult to achieve compaction within cells |
Aggregate compaction is enhanced |
|
Complex installation requires more labour and time to open, secure and place first layer. Fill is difficult over weakest soils |
Installation costs are low. Quick and simple to roll out and commence fill. Over very weak soils access is made possible by ‘snowshoe effect’ |
|
Typically limited to installation over soft soils |
Proven suitability for base stabilisation in permanent roads to increase pavement life as well as for road foundations over weak ground |
c/ Geotextile reinforcement and Tensar geogrid
|
Geotextile reinforcement |
Tensar geogrid |
|
Mobilisation of geotextile strength to reinforce aggregate is limited by friction |
Product design optimised for mechanical stabilisation of aggregates by interlock and confinement |
|
Load support is developed by the tensioned membrane mechanism requiring higher surface deformation to mobilise the reinforcement effect |
Highly efficient aggregate confinement by interlock increases bearing capacity and limits surface deformations |
|
Typically limited to installation over soft soils where surface rutting is permissible |
Proven suitability for base stabilisation in permanent roads to increase pavement life as well as for road foundations over weak ground where surface rutting is to be limited |
Conclusion : It is important to note that although the application of geogrids to road works or roadbeds, yards, and technical infrastructure is said to bring many benefits, these benefits will not be the same for each person. for each type of technical mesh product. In fact, research has shown that the manufacturing method can have an influence on processing efficiency. However, Tensar geogrid is one of the products with many core benefits and is being applied in many construction projects around the world.
References:
(1): Visit on website: Tensar.com.vn
(2): Document Detail design about road and cranepad of Kosy wind power plant and Hacom wind power plant
(3): https://www.windfarmbop.com/tensar-triax-geogrid-use-in-wind-farms/
(4): https://www.geosyntheticssociety.org
(5): https://www.geosynthetica.com/
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