Historically, engineers have had their share of challenges posed by unstable soil formations. Weak soil conditions lead to delays, increased costs, and even structural failures of construction projects. Before the invention of geogrids, the more conventional solutions involved using large quantities of expensive aggregate materials or implementing complex soil reinforcement techniques.
Dr. Brian Mercer pioneered the invention of geogrids in the 1950s. Mercer’s initial “Netlon process” entailed extruding molten plastic into a grid-like structure that resembled a fishing net. Although this was commercially successful, Mercer set his sights on a wide range of uses for geogrids. He believed that through the development of stronger geogrids, their reinforcement capabilities could be improved tenfold. With this goal in mind, he relentlessly pursued advancements in technology, which resulted in the invention of the “Tensar process” in 1978. This process produced geogrids with superior strength and durability. Geogrids have since become the cornerstone of most land reinforcement projects.
Geogrids are polymeric grids manufactured from high-strength materials like polyester, polyethylene, or polypropylene. These grids reinforce soil, transfer loads across a wider area, and prevent soil from pulling apart under tension.
Geogrids have become a mainstay of any construction project where soil reinforcement is necessary. The following points provide an overview of the optimal geogrid installation process:
An engineer assesses the subgrade’s readiness for geogrid installation. It involves gauging elevations and analyzing unsuitable materials. You may employ proof rolling to locate weak areas, and any ruts can be smoothed out by backdragging.
Achieving a smooth grade might be difficult in soft grounds like swamps or peat. In such cases, make it a priority to create positive drainage away from the construction zone. The subgrade must be free of any damaging debris.
Unroll the geogrid following the prepared surface’s contours. Project specifications dictate the direction of laying and spacing of multiple layers. Generally, geogrids are placed parallel or perpendicular to a road centerline.
Geogrid rolls adjacent to each other should overlap at sides and ends as per specified guidelines. Overlaps are to be “shingled” in the direction of the fill to prevent them from peeling under the advancing fill. Consider starting with rolls at the far end of the coverage area and working toward the fill placement point.
Use shears or a utility knife to cut geogrids for curves, manhole covers, or other obstructions. Do not forget to wear gloves and eye protection.
The first lift of aggregate fill over the geogrid should be 150mm (6 inches) thick at the minimum. You can avoid rutting by using a thicker layer on soft ground surfaces.
The aggregate fill can be dumped directly onto the geogrid. Rubber-tired trucks can be driven over the geogrid at low speeds (less than 5 mph) to dump fill as they move forward.
The next step involves the trucks backing up and dumping fill onto the previously placed layers. Be prudent in the case of very soft subgrades to avoid stressing the soil. A qualified geotechnical engineer can be consulted in such situations.
Avoid having tracked equipment directly on the geogrid. Ensure at least 150mm (6 inches) of aggregate fill between the geogrid and tracked equipment is maintained. If the subgrade is firm enough to resist rutting, you may use rubber-tired equipment on the geogrid.
Use a low-ground-pressure dozer to spread the fill evenly on soft ground surfaces. The dozer blade is to be raised gradually as each lift is pushed out to create a cascading effect on the geogrid. Prioritize working from stronger to weaker areas while maintaining the shingle pattern for fill overlaps.
Standard compaction is suitable for most projects. In the case of soft soils, static compaction with a light roller is recommended to negate subgrade disturbance. Maintaining optimal moisture content in the fill helps with compaction. For soft soil foundations, the initial layer of compacted material may be looser than usual. This prioritizes a stable work surface for construction activities before focusing on achieving maximum density.
In roadway improvement projects, unstable subgrade soils pose serious hurdles. Strata tackles these challenges with its array of geosynthetics solutions like StrataWeb® geocell and StrataGrid™ uniaxial geogrid. StrataWeb® and StrataGrid™ work by reinforcing the subgrade, creating a more sturdy foundation for the roadway. These geosynthetics curtail the need for a thick base and sub-base layers which greatly saves on construction costs.
Contractors can implement appropriate measures to mitigate risks by understanding the potential barriers to geogrid installation. Here are some of the challenges listed below:
The preparation of a smooth and uniform subgrade is essential. Uneven surfaces tear geogrids during the installation process. Proof rolling can pinpoint these areas, but backdragging might be required to create a level surface for proper placement.
Geogrids tend to shift during installation if secured inadequately. This is due to substandard anchoring or uneven placement of the backfill.
It is important to overlap adjacent geogrid rolls according to project requirements and fully secure them. Improperly seamed geogrids can reduce their reinforcement capabilities, making them less effective at distributing stress.
Colder weather conditions can make geogrids prone to fracturing under dynamic loads. Avoid deploying geogrids at low temperatures to prevent durability issues.
Poorly chosen materials used in the aggregate fill can cause a separation between the fill and the subgrade. It is recommended that well-graded crushed aggregate with maximum particle size and fine content within specified limits be used.
These regulations focus on reducing the impact on the ecosystem throughout the project lifecycle. The key considerations include appropriate waste disposal protocols, particularly for hazardous materials. Adhering to environmental guidelines garners ecological welfare and public trust.
The standard geogrid solutions in the market require skilled labor for the best subgrade reinforcement. StrataGridTM, on the other hand, is designed to ensure successful installation even in the absence of a skilled workforce. The geogrid’s lightweight construction makes handling and deployment much more effortless when compared to other geogrids in the market. It boasts a sturdy design that diminishes any risk of accidental laceration during installation by less experienced crews. These advantages help less skilled workers install StrataGrid™ with ease. Strata empowers contractors to find success on a broader range of projects as they allow for geogrid installation with an unskilled labor force.
Strata Geosystems is the first choice for most engineers thanks to its commitment to innovation in engineering. Their expansive portfolio showcases numerous cases where their expert guidance and top-of-the-line products provided solutions to challenges faced by their clients.
The construction of a reinforced soil wall on NH 227 in Trichy, India, presented Strata with several tricky hurdles. The flood-prone paddy land required an elevation above ground level. The design needed a curved wall that reached up to 11 meters in height while incorporating a 6-meter-wide slip road for access to the village. To add to the challenge, the project involved a critical junction where the highway transitioned from four to two lanes.
Strata’s innovative solution made use of “select fill” to raise the ground level and curtail any risk of floods. To achieve the curved wall design with an integrated slip road, StrataBlock™ segmental blocks were deployed. This ingenious block system provided a smooth, curved aesthetic while also accommodating the access road within the wall structure. The StrataGrid™ was employed to avoid overlapping in curved sections, particularly at the junction. Finally, a strategically positioned cross wall made construction frictionless at the lane bifurcation. With the guidance of their expert engineers, Strata delivered a functional and visually appealing curved reinforced soil wall.
The Villena Municipal Solid Waste (MSW) Treatment Plant Landfill in Spain needed an enclosure that did not hinder the ecological makeup of that area in any way. Strata’s challenge was to design and install anchor trenches within some space constraints. The design also had to ensure efficient rainwater drainage, gas collection, and slope stabilization.
Strata developed an ingenious installation methodology for the anchor trenches that worked within the limited workspace. StrataDrain™ drainage composite was implemented to improve the flow rate, design efficiency, and reduce overloads. The revamped drainage system improved upon the existing rainwater management and gas collection systems. StrataGrid™ geogrids were also plied to reinforce and stabilize the landfill slopes. Strata ensured successful landfill capping that met all environmental requirements by adapting their geosynthetic solutions to the complex landfill terrain. The project is a testament to Strata’s expertise in delivering innovative solutions for environmental projects.
Strata Geosystems is world-renowned for its commitment to innovation and exceptional engineering. Through a combination of their high-performance products and a focus on client needs, Strata consistently delivers successful projects.
Strata’s dedication to innovative solutions and exceptional client service make it a trusted partner for any civil engineering venture. Are you considering Strata for your next project? Take a peek at our roster of geosynthetic products to find the perfect fit for your specific needs. Reach out to our team of experts today to discuss how Strata can help you achieve success.
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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.
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Strata tenure: 13 years
Total industry experience: 24 years
MBA – University of Gujarat
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Strata tenure: 13 years
Total industry experience: 33 years
BE (Mechanical) – Nagpur University
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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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Leads day-to-day business operations of the company with focus on capacity expansion, product and process improvement.
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