by Bryan Gee, P.E., on September 06,
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Geogrids first came on the scene in the early s when Tensar introduced &#;extruded, punched and drawn&#; (&#;Tensar Process&#;) biaxial (BX) and uniaxial geogrids. Over time, these products have become widely accepted with proven success in a variety of civil and geotechnical applications requiring soil stabilization and reinforcement. The triaxial form was developed and introduced in the late s as an improvement to the biaxial form, particularly for civil and geotechnical engineering applications where the applied loads are not limited to one or two directions (for example, pavements, haul roads, working platforms and general soil stabilization). In , after decades of performance testing and product development, InterAx geogrids were introduced. InterAx is currently the most advanced geogrid on the market for trafficked surfaces. Its advanced materials science and revolutionary geometry maximize performance in stabilization applications.
Each type of geogrid is a unique and distinct engineering material with its own in-application performance capabilities. The obvious differences in geometry are significant among biaxial, triaxial, and InterAx geogrids. Each type of geogrid interacts uniquely with the aggregate that is placed and compacted to complete the mechanically stabilized layer, or MSL. This means that one type of geogrid should not be substituted for another without fully redesigning the application. Further, the mechanisms that create aggregate confinement in roadbed applications are very complex, and no two geogrids are the same. While biaxial, triaxial, and InterAx geogrids can all be used across many of the same applications, there are impacts on the other materials (i.e., aggregate, asphalt) involved in the application. For example, a haul road over soft ground can be designed with biaxial, triaxial, or InterAx geogrid (provided the product used has undergone appropriate performance validation testing). It&#;s important to remember &#; if the same level of performance is necessary, there will be different thicknesses of aggregate material required for each product. A lower performing BX geogrid may cost less but the additional aggregate requirement could quickly negate any geogrid cost savings compared to the high performing InterAx geogrid.
Even products that appear to be very similar may not perform the same. For example, Tensar has performed rolling wheel traffic testing on a Tensar biaxial geogrid and another non-Tensar biaxial geogrid of equal tensile strength; this testing showed the two products do not perform the same. As a result, each product must stand on its own data. Attempts to apply property data from one product to other &#;similar&#; products introduces the risk of non-performance. Further, and despite much research and effort, there are no proven correlations between the physical properties of geogrids and performance in roadbed and stabilization applications. To assure performance of geogrids in these applications, designs must be based on performance validation data for the specific geogrid product under consideration.
If you are considering substituting one geogrid for another, keep the following in mind:
Want a more in-depth look at comparing geogrids? Check out our webinar and earn professional development credit.
It&#;s important to have all of the necessary information before substituting a geogrid in a project. Contact your local Tensar rep for a complimentary project review to ensure you don&#;t make a costly mistake.
There are dozens of geogrids and other geosynthetic products on the market. How do you know which is right for your project's needs? When it comes to roadway construction, the keys are proper design and testing to validate performance.
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Geogrids is a polymeric material in addition to many polymers like polyethylene, polyvinyl alcohol polypropylene, etc. It is one of the most substantial inventions in synthesis which is used as a reinforcing material. They are formed by bonding intersecting ribs. They have huge open spaces in between the ribs known as &#;apertures&#;.
Geogrids can be classified as geosynthetic materials that are accustomed in the construction industry in the frame of reinforcing materials. It can be accustomed in the soil reinforcement or accustomed in the reinforcement of retaining walls and even more applications of the material are on their way to being developed.
The great demand and application of Geogrids in construction are due to their being good in rigidity and having a higher ability to distribute load across a broad area.
Type of Geogrids established on Pattern
Uniaxial geogrids is chased by macromolecule polymers, and constructed by longitudinal tension. This category of geogrids is integrity with evenly distributed elliptical net structures. It has more flexible strength and tensile modulus. With this type of structure, the geogrids gives an ideal interlock system for the soil. It has high one-sided strength and capacity, and high lateral constraint for soil-rock mixtures. All property indexes of it are superior to geogrids without tensity. It is an ideal reinforced material currently, like reinforced earth structures in strengthened retaining walls, reinforced steep slopes, bridged support, and highways, railways, and airports.
It is stretched just in the longitudinal direction. Hence the stress is transferred only by that axis; even the tensile strength is higher in the longitudinal direction in contrast to the transverse direction in uniaxial geogrids.
The material of biaxial geogrids is alike with the material of unidirectional geogrids. Its chemical property isn&#;t active as well. It is chased by macromolecule polymers and constructed by longitudinal and horizontal tensions. This type of material has a more tensile strength in both longitudinal and horizontal directions. This kind of structure gives an interlock system for the soil and is fitted for the improvement of roadbeds with wide areas of permanent loads, for instance, treatment of soft soil foundation and augmented earth structures.
It is stretched in two directions (longitudinal and transversal), hence the stress is equally distributed in both directions. In biaxial geogrids, the longitudinal direction is known as machine direction (MD) and the transverse direction is known as cross-machine direction (CMD). Since the strength is equal forth both axis these geogrids are particularly preferred in construction.
Triaxial is a revolutionary afresh geogrids product. The triangular design of triaxial geogrids, associated with the increased rib thickness and junction ability, greatly enhances aggregate interlock and confinement &#; resulting in the optimal structural performance of the mechanically stabilized layer. Research signifies that triaxial geogrids can lessen aggregate base/sub-base requirements by 25% to 50%.
Triaxial geogrids supplies performance in three dimensions:
Multidirectional Load Distribution
Multidirectional Load Distribution
Junction stability and ability
Chief Performance for Surfaced and Unsurfaced Roads
Fewer Stress on Subgrades
They are built from polypropylene accustomed for ground stabilization and soil reinforcement applications. They are plane structures in a polymer that are extruded and next pulled: this might either be done in one direction or the two major directions. They are applied in soil and road paving reinforcement.
It is manufactured by combining polymeric&#;generally polyester or polypropylene&#;and bending them into a mesh pattern that is further coated with a polymeric lacquer.
It is constructed by bonding, typically at right angles, two or more sets of strands or other components.
Fiberglass geogrids is a new supreme material used for reinforcing road surfaces and bases, it is produced of fiberglass filament, and shielded with special solutions and High longitudinal and horizontal intensity, moderate elongation rate, anti-alkaline, and aging resistance, broadly used in the asphalt road surface, concrete road surface, and reinforcing road infrastructure.
PET Geogrids Terylene geogrids is an afresh material for reinforcing road infrastructures; it is produced of terylene filament, and shielded with a special solution and High longitudinal and horizontal strength, moderate elongation rate, anti-alkaline, and aging resistance.
Warp Knitted Fiberglass Geogrids is woven by great Tensile Modulus fiberglass filament as the raw material is protected with adhesive.
Geogrids have been greatly used for the construction of earth-sustained and earth-supported structures like mechanically stabilized earth (MSE) retaining walls, steep slopes, and further structures. Its application areas comprise.
Geogrids for pavements
Geogrids applications in pavement and roadway are made up of subgrade improvement, reinforcing the core course, sub-infrastructure, and surface courses. The outward displacement of railway ballast is apprehended and the settlement is shortened when they are reinforced with geogrids soft subgrade, the stiffer geogrids function better than flexible geogrids as the latter instantly reacts to the applied load.
Geogrids for retaining wall
Geogrids are accustomed to stabilizing the backfill in retaining walls. The stability of the earth retaining wall counts on the friction angle. Creep and stress relaxation properties influence the performance of geogrids in a retaining wall.
Geogrids for soil foundation
Both Uniaxial and Biaxial geogrids are typically used in foundation works. The main condition to attain good stability is the interlocking capacity of geogrids and aggregates.
Geogrids for slope stabilization
The geogrids reinforcement in slope prompts primarily the slope deformation and stability. The bearing capacity majorly depends on the length of the geogrids. To attain the best performance the aperture size should be closely equal to 0.2 times the width of the footing.
Geogrids for structural elements
In structural elements, the geogrids are used as further reinforcement and as shear reinforcement. To obtain good strength fibers such as polypropylene and steel are used. The geogrids reinforcement brings about high ultimate load-bearing capacity], enhanced energy absorption and reduced slippage, shear, and bond strength, lesser drying shrinkage, and shortened degradation rate.
Link to Shuangcheng New Material
Geogrids are a subgroup of geosynthetics notable for their open apertures for use in reinforcement. They comprise three main categories based on construction style; knitted and woven polyester or fiberglass grids that have been coated with PVC or other additives, extruded polypropylene and HDPE plastic geogrids, and welded rod or strap geogrids.
Also known as geogrid mesh, geogrid is a type of geosynthetic primarily used for soil or ground stabilization and reinforcement. Commonly used in construction, it offers a solid base that can help stabilize the soil. In pavement structures, the geogrids are placed at the bottom or within the layers of the pavement system, improving its load capacity under repeated foot or vehicle traffic.
Geogrids can also increase the service life of pavements by stabilizing the subgrade and reducing their vulnerability to the elements such as water, sunlight and chemicals. Geogrids can help prevent cracking and potholes which can damage pavements. When building roadways, thick bases are needed for the foundation to improve stability, but this can cost a lot of money. Installing geogrids for soil reinforcement is a cost-effective solution that offers the same level of stability and increases the roadway's service life at the same time.
Geogrids are also used in retaining walls by reinforcing the soil backfill, preventing movement from behind the wall. It's safe to build steeper and higher walls with geogrids since they can hold the backfill together. Using geogrids for slope reinforcement such as in a retaining wall is more cost-effective because there's no need to purchase additional materials to hold back the soil behind it, since geogrids can achieve this task. Walls with geogrid systems are also more flexible and resistant to the effects of earthquakes.
Geogrids are made with polymeric or polymer materials and are resistant to UV radiation, chemicals and mechanical damage. Easily installed, geogrids serve as reinforcing material that prevents soil movement behind a retaining wall or beneath a pavement. They achieve this through their apertures &#; the open spaces between the ribs &#; which help create interlocking pockets that hold the material better. Geogrids also help distribute weight evenly, keeping the structure safer and more stable.
Visualize holding compacted soil in one hand and using the other hand to press down on it. The soil loses its shape; it may spread out or become flatter. When the compacted soil is placed in a mold, it prevents it from crumbling or spreading. If installed in a structure, the mold prevents soil movement, creating a solid, stable base. This is what a geogrid does.
The polymer material in geogrids is stretched out to strengthen the ribs, ensuring it can withstand the tension and pressure from the materials filling up the apertures. When buying geogrids, look at the thickness of the rib, tensile loads and the aperture area to determine if it can withstand the pressure or tension. Contact us for high-quality geogrids for construction projects.
Geogrids stabilize the soil through the tension membrane effect which is based on vertical stress distribution. When the sheet is placed within the soil, it acts as a supporting structure, creating a tension membrane that helps even out soil distribution. The framework helps prevent issues such as differential settlement or subsidence.
Compared to other geotextiles, the load-bearing capacity of geogrids is much higher, ensuring the stability of the structure above it. Geogrids also increase road performance and safety of the pavements through lateral restraint. Without a geogrid, a large vehicle driving over the pavement can move the soil beneath, affecting the stability of the pavement. Geogrids prevent this shift, since they hold the soil firmly in place via the apertures, ribs and nodes.
Several types of geogrids are available in the market and are manufactured for different construction projects or applications. Two of the most common geogrids are uniaxial and biaxial.
Ideal for slope reinforcement or wall applications, uniaxial geogrids have rectangular apertures and offer high tensile strength in just one direction. While it's more affordable, it's not suited for roads or pavements where the pressure is distributed in both directions. Landfill liner systems, retaining walls and steep slopes can benefit from this type of geogrid.
Designed with square apertures, a biaxial geogrid is ideal for pavements or road applications because it offers high tensile strength in both directions. Like uniaxial geogrids, biaxial versions are suitable for use in slope or wall applications. When compared to uniaxial geogrids, biaxial geogrids are more economical because there's no need to increase aggregate layer thickness, which costs more money. Contractors can use biaxial geogrids when working on weak subgrades, unpaved roads and airport runways.
Are you wanting to know more about geogrid in hardscape? If you are preparing to install pavers in your yard, you&#;ve likely been advised to implement geogrid in whatever hardscape you install. But when should you use geogrid? What is its purpose? How long does geogrid last?
In this blog post, we&#;ll answer the most frequently asked questions about geogrid so that you can be equipped with knowledge before you begin your hardscape project.
Geogrid is used in almost every type of hardscape&#;from driveways to walkways to patios and everything in between. However, it is essential in retaining walls, particularly those above three or four feet.
Pro Tip
Geogrid should be implemented whenever you want your hardscape to last and stay structurally sound.
It is better to install geogrid and learn later that it might not have been necessary than to skip using it and have your wall crumble a few years later.
Geogrid is used in slope stabilization, soil stabilization, and soil reinforcement. Geogrid is crucial in keeping your hardscape interlocked while the environment around it naturally swells, shrinks, and shifts in response to climate and seasonal changes.
Yes, it is ideal to use geogrid in all retaining applications. For most man-made retaining wall blocks, geogrid is desired at 36&#;-48&#; exposed wall heights.
If steep slopes are near the wall, loading above the barrier, tiered walls, or poor soil, geogrid becomes even more necessary, regardless of wall height.
Products such as a weed barrier or orange safety fencing are not the same thing as geogrid. Geogrid is intentionally designed with specific ribs and patterns to minimize shifting and settling.
Pro Tip
The cost of implementing geogrid in your initial installation is well worth the alternative of rebuilding your hardscape after only a few years.
Woven textiles can provide a highly efficient and cost-effective alternative to rigid polypropylene geogrids for base stabilization applications. However, if the instructions for your retaining wall block tell you to use geogrid&#; do use geogrid.
Your geogrid will essentially last forever.
Tests have shown that geogrid has virtually no degradation for exposure in an outdoor environment for 12 months. This means that degradation will not happen even if geogrid is left exposed to the elements.
There is even less chance of degradation when geogrid is underground in a dense aggregate environment, as it usually is. Your geogrid will last as long as your hardscape&#;likely longer than you!
Yes, you can and probably should. Geogrid reinforcement can be used in thin Portland cement concrete (PCC) members and overlays in pavements and other structures where steel reinforcement cannot be set due to constructability and strength impediments.
Incorporating geogrids into the roadway section effectively creates a stiffer, more uniform foundation that will maintain well and for a long time. You can read more in this article where the Arizona Department of Transportation describes how it used geogrid in the paving of US 89T.
If you use geogrid, you can reduce the depth of excavation required on unsuitable subgrades. This means less digging and excavation, making your project more straightforward.
Geogrid does wonders to strengthen the soil and provide enhanced safety and excellent seismic durability by stabilizing slopes. Geogrid ensures that your retaining wall won&#;t fall over!
Another advantage of geogrid is that it reduces differential settlement. Geogrids lessen the need for maintenance and extend the lifetime of paths, roads, walls, and more.
Geogrids have higher tensile strength than the soils they contain and, depending on their size, can endure heavy loads. With a tensile strength of lbs/sq ft, geogrid can easily withstand heavy vehicular traffic (even trucks carrying heavy loads), aid in retaining solid walls and steep driveways, and hold up under an extremely high volume of foot traffic.
Geogrid is placed atop the subgrade (the primary layer of earth below your project) and below the AB (aggregate base). In other words, dirt, sand, or large rock should be below the geogrid and ¾&#;-0 road base gravel installed on top of it.
Geotextiles are for separation, filtration, and drainage purposes, while geogrids are used specifically for reinforcement. If you want to build a strong hardscape, use geogrid.
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