Geogrids are a type of geosynthetic material used for mechanical stabilization and soil reinforcement in construction. These large, flexible rolls of polymers follow a grid-like pattern with intersecting openings called apertures. Depending on the application, geogrids are inserted within the subgrade material itself or as a layer between the subgrade and base, based on the California Bearing Value of the soil on site.
Geogrids mechanically strengthen the unbound layers of aggregate and other subgrade materials by confining them within the apertures, creating a mechanically stabilized layer. This layer manages differential settlement, decreases necessary fill depths, caps weak deposits, and enhances dynamic traffic loading and bearing capacity, ultimately leading to a more stable pavement structure.
Geocell is a cellular-like net structure known as a cellular confinement system. These geocells are manufactured using long-lasting materials that provide uniform stability and are environmentally friendly. The geocell’s three-dimensional honeycomb design compacts the soil, providing a robust configuration in the infill and the pavement. This design also allows the geocell to divide the load and increase the bearing capacity uniformly.
At times, we also recommend adding a layer of geotextiles to ensure adequate separation between layers to avoid migration of soils, reducing the risk of rutting, cracking, and other forms of distress. It’s worth noting that the use of geotextiles and geogrids should not be confused.
We delve into why geogrids are a good choice for pavement designs, and what benefits they offer by being included in the project.
Subgrade stabilization enhances the properties of the subgrade – the natural soil or aggregate layer beneath roadways, highways, or railway tracks. The subgrade is akin to the foundation of the structure. The purpose behind subgrade stabilization is to reduce or minimize rutting, increase the stiffness of the subgrade, and distribute loads more evenly to prevent differential settlement.
Whether a geogrid is necessary or not is determined by the subgrade being reinforced. An overlooked factor is the quality of the subgrade itself which although may have soil with a robust Resilient Modulus (MR), can lose its strength when it’s saturated with water, or subjected to iterative dynamic loads. Another reason this may occur is the presence of low-plasticity fines or fine sands in the subgrade itself, leading to contamination of the subgrade. With the load being distributed at the junctures, and tensile strength which spreads the load, we see improved shear strength of the soil by up to 50%. The benefits of geogrids for stabilization therefore can be in the following ways:
The primary role of geogrids in pavements is to provide mechanical stability to weak subgrade soils. By locking the subgrade into apertures, the confined movement minimizes the lateral pressure, allowing for more uniform load to be carried from top. As the paved road ages, this is key since the subgrade will be subject to temperature changes, and other fluctuations which must be accounted for to avoid failures, cracking, rutting and other maintenance-led challenges.
Geogrids reduce the amount of aggregate required in the pavement structure by 15-20%. This makes it an economical choice and offers a more sustainable construction process. By improving the shear strength, we no longer need thick layer upon layer of aggregate material. Instead a thinner layer works to distribute loads well enough.
Geogrids are easy to install when compared to other subgrade stabilization methods. Geogrids installation doesn’t require skilled labor or specialized equipment. This is another lever which helps bring down the overall cost of the project.
The use of geogrids in subgrade stabilization can help extend pavement life structure by providing a strong and durable foundation. With reduced maintenance costs, minimized degradation of the paved structure, and longer maintenance cycles, we see longer lifespans for pavements using geogrids
By reducing the amount of aggregate needed for the project, geogrids automatically reduce the amount of quarrying activity needed to create subgrade, apart from the very real logistical cost of moving materials around from the quarry site to the project site. This not only affects the net carbon footprint of the project, but is an important consideration for geographies which are ecologically sensitive and are unable to support extensive excavation, but also can reduce the extent of deep mixing needed in specific instances. This is of value to mountainous regions prone to landslides, water saturation, or coastal regions with specific soil challenges.
For pavement design, at the design stage, various factors that impact the lifespan of the pavement must be considered. Factors such as traffic volume, traffic load, CBR value, environmental conditions must all be taken into account when developing project plans. This is where Strata Geosystems’ extensive experience in global projects becomes valuable. Our manufacturing and application experience provide us with unique insights into projects that may present unforeseen challenges. When choosing the right manufacturer and partner for your project, we help you determine what is needed for the site, from design to final implementation. We guide partner with you through the following aspects:
Geogrids have three key benefits: improve the trafficking performance, longevity and cost of a given project. These benefits are essentially interlinked. In subgrades which would typically need high levels of mechanical stabilization, today geogrids deliver high value over the life of a project. For example, for the Kohima-Bypass Road in Nagaland, there were project goals which needed to be met. Essentially, design that supports the dynamic load, and also reduced maintenance cycles given the remoteness of the site itself.
The initial parameters included a subgrade California Bearing Ratio (CBR) of 10% and a traffic intensity of 50 MSA. The optimized design ultimately featured two layers of SGB Grid –our biaxial geogrid: one within the Wet Mix Macadam (WMM) and the other within the granular sub-base. The design approach followed the LCR method. The inclusion of SGB Grid had a confining effect that minimized both vertical and lateral aggregate movement, resulting in superior stability under traffic loads compared to unreinforced sections. This is where one can compare the superior difference in introducing geogrids.
Our solution allowed for easy installation using unskilled labor (another cost saving measure), reduced layer thickness to conserve natural materials, and decreased maintenance needs. The flexibility of SGB Grid promoted better interaction with aggregates in the pavement, enhancing fatigue and rutting design life, and facilitating economical and rapid construction.
In summary, geogrids play a crucial role in optimizing pavement performance and durability by providing reinforcement, separation, improved physical properties, reduced base layer thickness, enhanced load distribution, and cost-effective construction practices within the pavement system. Choose Strata Geosystems for the best in class experience of end to end project management for all your geotechnical challenges. With certifications from ASTM, ISO, NTPEP, ISI, BBA, we’re poised to meet your requirements with independently tested lab reports and three decades history of experience.
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Director, President – Glen Raven Technical Fabrics
Strata/Glen Raven tenure: 10 years/28 years
Total industry experience: 35 years
MBA – Wake Forest University
Directs the strategic direction of Glen Raven’s automotive, protective apparel, military, geogrid, outdoor and logistic businesses.
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Strata/Strata Inc. tenure: 3 years/14 years
Total industry experience: 25 years
MBA – Georgia State University
Led the integration of Strata Inc. business operations into the headquarters of GRTF and transition from USA based to India based manufacturing.
Director
Strata tenure: 17 years
Total industry experience: 47 years
CA – ICA
Played a key role in the establishment of Strata’s India operations. Provides vision for product innovation and leveraging new technology trends.
Global Technical Sales Director
Strata tenure: 7 years
Total industry experience: 32 years
Civil & Geotechnical Engineer (First class)
Provides highly technical and innovative civil engineering solutions in India and around the world. Responsible for the design and execution of large-scale geotechnical projects around the world including Australia, Asia, Europe, Africa, Middle East, and South America.
CTO – Chief Technology Officer
Strata tenure: 9 years
Total industry experience: 48 years
BTech (Hons), MTech (Civil) Both IIT Bombay, DMS (Bombay University), FIE, FIGS, Chartered Engineer
Streamlines the designs of Geosynthetics and has brought innovation in geogrid and geocell design application.
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Strata tenure: 13 years
Total industry experience: 24 years
MBA – University of Gujarat
Leads the monetization of products and solutions while ensuring highest execution quality and project profitability.
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Strata tenure: 13 years
Total industry experience: 33 years
BE (Mechanical) – Nagpur University
Drives excellence in process design, product features and cost effectiveness in production.
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Strata tenure: 8 years
Total industry experience: 35 years
CA – ICA, ICWA – ICWAI
Leads the finance, accounting, taxation, commercial, legal and IT functions and assisting on all strategic and operational matters.
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Strata tenure: 10 years
Total industry experience: 13 years
MBA – ISB, Hyderabad
Leads diversification of the product portfolio, monetizing the new products and ensuring successful sustained financial growth of the company top line.
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Strata tenure: 14 years
Total industry experience: 42 years
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