Geogrids vs. Geotextiles: Choosing the right geosynthetic
Geogrid vs. Geotextile
Civil engineers are the ones responsible for deciding which category of geosynthetics to use in their projects, as each material has specific properties tailored for certain purposes. Geogrids are polymeric grids in uniaxial and biaxial configurations. Strength characteristics of each configuration are concentrated in the principal direction(s) of the ribs. Their main function is reinforcement. The open mesh structure allows it to infill with the soil, making it a composite system of increased load-bearing capability. A quality like this makes geogrids very suitable for applications that include the reinforcement of weak soils, support of retaining walls, and the stabilization of slopes.
On the other hand, geotextiles are permeable fabrics made of woven, non-woven, or knitted synthetic materials. Unlike geogrids, their structure emphasises the flow of water while at the same time separating individual layers of soil. This barrier prevents soil mixing, maintaining the structural integrity of the project. Geotextiles are used in drainage systems for roads and landfills as separating layers between waste and soil and as an erosion control measure in riverbanks.
What are the advantages of using geogrids?
1. Slope stabilization and erosion protection:
- Reduced erosion: The square mesh or grid like structure of geogrids provides a stable matrix for topsoil. By reinforcing the soil mass, geogrids improve internal stability, which helps prevent shallow failures and sloughing, thereby contributing to overall erosion resistance. A geogrid’s open mesh contributes to healthy root growth within the slope, consequently improving its resistance to erosion.
- Coastal and reservoir slope protection: Geogrids protect unstable slopes exposed to water. In coastal and reservoir slope protection, geogrids can reinforce the soil mass beneath armor layers or vegetation; for creating a direct sturdy wave erosion barrier by infilling, geocells filled with pebbles are typically used. In a similar vein, in reservoir applications, geogrids reinforce layers of granular material, which provides erosion protection; if weed suppression is also needed, a nonwoven geotextile is typically used in conjunction with the geogrid.
2. Surface stabilization:
Geogrids reduce the amount of aggregate material required to stabilize weak soils. The open mesh structure of the geogrid interlocks with aggregate, distribute applied loads over a wider area, decreasing localized stresses.
3. Soil retention on steep slopes:
Engineered for installation on steep slopes, geogrids allow the use of on-site soil as structural fill, reducing the need for expensive imported aggregate.
4. Retaining wall reinforcement:
Geogrids are implemented in retaining wall construction, specifically in the soil backfill. A reinforced backfill soil contributes to an improvement in the structural integrity of the retaining wall. They confine backfill material and distribute loads evenly, which is beneficial for retaining walls built on soft backfill or sloping ground.
What are the disadvantages of not using geogrids?
1. Higher construction costs:
Large quantities of aggregates are required when geogrids are not used for soil reinforcement. Consequently, there is added pressure on the budget to source and transport these additional materials. Also, standard methods may be more labor-intensive, which further inflates project costs.
2. Increased site disturbance:
Generic techniques for soil reinforcement involve intensive excavation and manipulation of the existing soil. The surrounding systems often get disrupted because of these activities.
3. Reduced load distribution and soil reinforcement:
Without the reinforcing properties of geogrids, soil structures are unable to distribute loads evenly. Uncontrolled settlement and stress concentrations can cause premature failure in structures.
What are the advantages of using geotextiles?
Filtration and drainage:
The porous structure of geotextiles acts as a selective barrier, allowing water to pass through while retaining soil particles. This proves invaluable in road construction, where proper drainage is essential to prevent cracking and rutting.
Separation:
Geotextiles show proficiency in separating dissimilar soil layers. This prevents intermixing, which is important in applications where different soil types serve specific functions.
Erosion control:
Geotextiles stabilize the soil surface, supporting root systems and promoting foliage growth to combat erosion. They can also be used to filter runoff water, preventing the transportation of sediment in the process.
What are the disadvantages of not using geotextile?
Reduced soil stability:
Without the separation and filtration qualities of geotextiles, different soil layers tend to intermingle. Improper filtration causes the migration of fines, compromising their strength and stability. Moreover, the absence of proper drainage within the soil can act as a catalyst for these issues.
Increased construction cost:
An absence of geotextiles may require alternative solutions to achieve desired filtration, drainage, or separation functions. This may mean using additional granular materials or labor-intensive techniques, inflating project costs.
How do you choose between geogrids and geotextiles?
Geogrids and geotextiles are versatile tools, each offering unique functionalities. However, choosing the right geosynthetic necessitates a thorough understanding of their key differences. Here’s a detailed breakdown to guide your selection process:
Property |
Geogrids |
Geotextiles |
|---|---|---|
Purpose and functionality: |
A grid-like structure created from high-tensile-strength polymers. Geogrids strengthen the soil, improving its load-bearing capacity. |
Synthetic fibers that excel in filtration, drainage, separation, and erosion control. They allow water to pass through while retaining soil particles. |
Material composition and strength: |
The materials used to manufacture geogrids for soil reinforcement include high-strength polymers like polyethylene (HDPE), polypropylene (PP), or polyester (PET). Their manufacturing process, involving extrusion, knitting, or weaving, yields a grid-like structure with exceptional tensile strength and stiffness. |
Geotextiles are crafted from synthetic fibers like polyester, polypropylene, or nylon. The manufacturing process, either woven or non-woven, influences their properties. Woven geotextiles offer better strength and tear resistance, while non-woven geotextiles are preferable for filtration applications because of their increased pore space. |
Installation Considerations: |
Geogrids are unrolled and placed in the designated location, requiring a properly graded and compacted subgrade to ensure full contact and performance. Seams between geogrids can be fastened mechanically or overlapped. |
Geotextile installation may require grading and subgrade preparation, especially in erosion control or drainage applications. For instance, in erosion control, proper grading and subgrade preparation is necessary to ensure a stable surface for geotextile placement. |
Water permeability and drainage: |
Due to their open grid-like structure, geogrids allow for the free passage of water within the soil, which is beneficial in preventing excessive hydrostatic pressure buildup when used in conjunction with appropriate drainage systems in applications like retaining walls |
The permeability of geotextiles is specifically engineered for and dependent on their specific purpose. For drainage applications, highly permeable geotextiles are chosen to facilitate water flow. Conversely, for erosion control, geotextiles with lower permeability are chosen to impede water flow and stabilise the soil. |
Durability and longevity: |
Geogrids are exceptionally strong and have a long service life. High resistance to ultraviolet radiation, chemical degradation, and temperature fluctuations. |
Geotextiles are adequately durable and prioritise filtration and separation over raw strength. The specific material and the environmental conditions influence their longevity. |
Strata Geosystems' geogrids and geotextiles for your project
Geogrids and geotextiles share some common factors, but they are fundamentally different in their nature. The differences between the geotextiles and geogrids are crucial to be able to choose the material best suited for your project.
Strata Geosystems geogrids i.e., StrataGrid uniaxial (SGU) and StrataGrid biaxial (SGB) geogrids, which are planar synthetic structures formed by a network of connected tensile elements, would be the best application for projects involving soil reinforcement. With tensile elements that provide extraordinary strength and stabilisation, Strata’s geogrids are ideal for projects like retaining walls and embankments.
On the other hand, our geotextiles i.e., StrataTex HSR would be very suitable for projects requiring filtration, drainage, or separation. Strata’s synthetic geotextiles provide excellent permeability, allowing water to pass through while retaining soil particles.
Strata Geosystems’ experts ensure a hassle-free selection process for your project needs. At Strata Geosystems’ your construction needs will be matched with the right geosynthetic solution to ensure the success of your project. Contact us today to get started.