Geogrids have been used in a number of applications for civil engineering projects. With a principle function of reinforcing soil, it finds uses across industries due to its tensile strength, and ability to balance loads, across a variety of subgrades. But did you know that the aperture of a geogrid is not fixed? What is the best aperture size of geogrids suitable for your next project? In this blog we will discuss the geogrid aperture, and how it affects the outcomes across different geotechnical instances. There is no one size fit for all solutions when it comes to soil reinforcement, soil improvement or construction–each project brings its own unique challenges. That is why at Strata Global –our state of the art manufacturing facility—allows us to adapt to your needs.
A geogrid, as we know, is a geosynthetic material used to reinforce soil. By locking aggregate, sub-grade or other in-fill materials into place, it improves load distribution, reduces the overall thickness of paved roads, or subgrade, and helps with stabilizing the soil structure.
In the process of soil improvement, the aperture is one of the key element in conjunction with the soil or material being used as in-fill. A geogrid’s aperture is the void space within the grid-like structure of a geogrid. These apertures come in various shapes and sizes, designed to interlock with the surrounding soil and aggregate materials held in place. Strata Global have a wide range of aperture sizes available for geogrids. In the case of our uniaxial geogrids, the standard aperture size is 40mm to 400 mm and for biaxial geogrids is 20mm to 150mm.
The size of these apertures is a critical design element, as it dictates the level of interlock and confinement achievable with the soil. It influences geogrid’s ability to reinforce and stabilize the ground, making it a crucial factor in the design and selection process. It’s worth noting that ultimately, the aperture size impacts the tensile strength, and ultimate junction strength –which is why it’s a factor to consider. The physical properties of a geogrid roll affect how much load it can carry, over what area.
Aperture size is responsible for soil-geogrid interaction, and shear strength improvement. The right balance between aperture size and soil particle size or in-fill material ensures the geogrid layer can effectively confine the soil, improving its load-bearing capacity, preventing soil migration, and improving resistance to deformation under repetitive load. But, the biggest factor here is its compatibility with in-fill material. This singular factor –if not considered –makes the process ineffective.
The type of soil present at a construction site affects aperture selection. Factors such as soil particle size, shape, and gradation need to be taken into account to ensure geogrid apertures can effectively interlock with the soil. For example, in sandy soils, smaller apertures may be needed to prevent the sand from passing through the geogrid. Angular particles, such as those of crushed stone or gravel, interlock more effectively with larger apertures compared to rounded particles compared to sandy soils.
The distribution of soil particle sizes has to complement the aperture size to facilitate proper interlocking. This interaction is key to the stabilization process, as it prevents soil movement and provides a stable base for construction.
Aperture size directly impacts the level of soil confinement and reinforcement. Larger apertures tend to offer greater interlock with coarse soils, while smaller apertures may be better suited for finer soils to prevent particle migration and ensure effective reinforcement. This leads to a variable confinement stress that a geogrid can afford to the material it holds. Depending on the stiffness and tensile strength of the geogrid itself, its overall resistance to stress is affected. For example, in case of clayey soils, a smaller aperture is preferred since the soil itself has cohesive properties and tends to stick together, requiring the geogrid to have a higher tensile strength to resist the cohesive forces of the soil, and ultimate deformation under loads.
Geogrids are preferred for soil reinforcement particularly due to its ability to distribute or transfer applied loads, across the soil or confined material. This mechanism is inherently what makes geogrids an excellent choice for improving the bearing capacity and reducing deformations in soil structures.
The size of the apertures influences how loads are distributed within the soil mass. Properly sized apertures ensure that loads are spread evenly, reducing the risk of localized failure and enhancing the overall stability of the structure. For example, aggregate sizes make a difference to the shear strength of the soil it’s reinforcing.
For optimal performance, the aperture size must be balanced with the geogrid’s required tensile strength. This ensures that the geogrid can withstand the forces exerted on it while providing sufficient interlock with the soil. Aperture size affects both tensile strength and the ultimate juncture strength. The ultimate junction strength refers to the strength of the connections between the intersecting ribs of the geogrid
In India, the Bureau of Indian Standards (BIS) provides standards such as IS 17371 for geogrids in flexible pavements. It must be noted though that the guidelines focus on the tensile strength which ultimately affects the interaction between soil and the geogrid. Similarly, ASTM standards in the United States or BS standards in the United Kingdom –all work to create a unified measurement criteria for geogrid selections. At Strata Global, we’re proud to say that our products are certified across the EU, UK, USA, India and New Zealand.
To consider the different aspects before you choose the size of an aperture, one needs to first be clear about the geotechnical aspects of the project itself. Right from the soil chemistry, water content, water saturation, retention, compaction scores –all of these affect your geogrid choice. It makes sense that any project would commence with soil testing to determine the physical, and chemical properties of the soil at the site. Then comes the aspect of design and planning. For geogrid-reinforced structures, parameters such as aperture size, soil properties, and the quality of installation–all affect the performance of the geogrid. These factors must be carefully considered to ensure the success of a geogrid application.
The relationship between aperture size, soil confinement, and deformation characteristics is complex. Aperture size dictates the level of soil confinement and the geogrid’s capacity to interlock with soil particles. Relatively to the size of the in-fill material, smaller apertures enhance soil confinement, by achieving greater interaction between the soil and the geocell. This heightened confinement can improve load bearing capacity of the soil-geocell system by as much as 2-5x depending on the soil itself, leading to superior load distribution and minimized vertical and lateral deformations. Conversely, larger apertures or inadequate confinement can result in excessive soil movement, reduced stability, and increased deformation levels. As such, choosing the “right” aperture size is critical to the structural integrity of geogrid-reinforced systems.
Our case studies often provide us a chance to review the kind of issues we came across and the learnings from them. Here, we present two instances of how we worked with geogrids, to solve very specific problems.
In Riyadh, Saudi Arabia, the Riyadh Development Authority faced a challenge in constructing retaining structures for access to the metro station within the densely populated city. To solve this, StrataGrid™ 60 was selected for reinforcing a vertical mechanically stabilized earth (MSE) wall, providing a robust solution to the space constraints and structural demands of the area.
StrataGrid™ 60, with its specific aperture size and tensile strength, enabled the efficient use of local infill, reducing transportation costs and lowering the project’s carbon footprint. The aperture size also facilitated optimal soil interaction, critical for load distribution and long-term stability of the wall. This approach not only supported the wall’s load-bearing capacity but also offered an eco-friendly solution by minimizing resource consumption.
Using StrataGrid™ 60, the project achieved a cost-effective, sustainable reinforcement structure within the city’s limited space, successfully meeting both structural and environmental goals.
The Aqaba Development Authority, Jordan required a technically superior and economical solution for the movement of heavy trailers towards their container yards lying in marine areas with weak sub-bases. Strata’s geotechnical experts designed a block fascia retaining wall, using site-won material and previously-made blocks lying at the site. Design would accommodate the heavy load of fully loaded containers carrying vehicles of ~30 KPa. The toe of the RS wall was provided with three layers of stone-filled gabions to protect against scouring throughout the life of the structure. The high-performance geogrid product, StrataGrid™ from Strata was used for this project. Geogrids with different aperture sizes were used in a strategic way to achieve the required results. StrataGrid™ SGU 40 and SGU 120 were chosen for their optimal engineering characteristics. SGU 120 uniaxial geogrids gave more strength and load distribution characteristics as the primary reinforcement layer, and SGU 40 would provide more support and stability with minimum usage of materials and cost as the secondary reinforcement. Since the materials used were available on site, therefore project costs were saved besides saving on time, for which heavy machinery and skilled labor were not required. The blocks could be placed manually, and StrataBlock™ gave a pleasant aesthetic appearance conforming to the architectural requirement. Explore more about this case study here.
Strata Global can help you solve your doubts related to choosing the right aperture size for your next project involving geogrids. Our expertise in geogrid technology ensures that you get the optimal design for your soil reinforcement needs. Contact us today to explore how our geogrid solutions can enhance the stability and performance of your construction projects. Let us be your partner in achieving durable and efficient geotechnical solutions tailored to your specific requirements.
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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.
Director, General Manager, Strata Inc.
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.
COO – Projects and Sales
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.
COO – Technical Textiles
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.
CFO – Chief Financial Officer
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.
CDO – Chief Development Officer
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.
CEO – Chief Executive Officer
Strata tenure: 14 years
Total industry experience: 42 years
B Tech (Chemical) – IIT Delhi
Leads day-to-day business operations of the company with focus on capacity expansion, product and process improvement.
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