Ballast Stabilization Using Geocells

Posted July 27, 2023 by Katie Bocskor

The Often Overlooked Importance of Junction Efficiency as a Key Design Consideration

A significant number of research studies have been carried out to investigate the benefits of using geocells in railway track bed applications. Combined with an ever-expanding list of successful projects from around the world, the benefits of using geocells in rail ballast stabilization is well-documented. Rail operators understand that durable track geometry starts with a solid foundation, and geocells have emerged as a powerful value engineering tool for reinforcing ballast and sub-ballast layers while optimizing layer thicknesses.

Many practitioners may not be aware of the critical role that geocell junctions (both mechanical and internal) play in ensuring that the installed system performs in a uniform and consistent manner. In track bed stabilization applications, non-uniform junction performance can lead to differential settlement and localized subsidence—which in turn can lead to serviceability issues, damage to the overlying structure/pavement, and a reduction in overall design life. In essence, poor junction performance can nullify all the intended benefits of a geocell system.

This article will succinctly discuss the different types of junctions present in geocell systems, failure mechanisms and test methods, and the concept of junction efficiency as a performance parameter.

Types of Geocell Junctions

There are two types of junctions present in any geocell system: internal junctions, the factory-welded seams that create the interior cells of the panel, located within the body of a geocell panel; mechanical junctions located around the perimeter of an individual panel, formed during installation when adjacent panels are connected in the field, creating mechanically joined cells along panel joints. Since a primary mechanism by which geocells provide benefit is through lateral confinement of the infill, it is vital that both types of junctions remain intact during construction and throughout the design life of a project.

Junction Performance: Failure Mechanisms, Current Test Methods

Dating back to original research performed by the U.S. Army Corps of Engineers in early geocell development, much of the focus on junction performance was limited to peel strength of these internal junctions, with less consideration for mechanical junctions or other potential modes of junction failure. International Standard ISO 13426-1, “Strength of Internal Structural Junctions – Part 1: Geocells” presents standard test methods for evaluating several possible failure mechanisms for geocell junctions, including failure in shear, peeling, and cell splitting. What is lacking in ISO 13426-1 and similar standard test methods is a way to relate these failure mechanisms to the tensile characteristics of the cell wall itself.

Geocells are comprised of single strips of high-density polyethylene (HDPE) joined together. From a structural integrity perspective, these junctions should be expected to perform at a level that is equal to or better than that of the cell wall itself to ensure uniform and consistent performance. This is where the concept of junction efficiency comes in.

What is Junction Efficiency?

Junction Efficiency is a ratio (typically presented as a percentage) accounting for all three primary modes of potential junction failure (shear, peeling, splitting), and compares measured junction strength values to the tensile properties of the perforated cell wall. Separate values must be determined for internal and mechanical junctions.

In the case of mechanical junctions, the type of connection must be specified, with laboratory samples consistent with in-field installations. If the mechanical junctions will use staples, then representative laboratory tests must incorporate all relevant aspects of the stapling method, including material (stainless steel vs. aluminum), gauge, minimum number per junction, and vertical/horizontal spacing necessary to achieve junction performance requirements. Similarly, if cable ties or two-piece connectors are the recommended connection device, then their break strength, material composition, durability, length, and assembly instructions must be specified and tested.

In the case of GEOWEB® geocells, mechanical junctions utilize Presto Geosystems’ patented ATRA® Key. ATRA Keys are simple to use and provide consistent, reliable mechanical junction performance for the life of the project. As shown in the table below, GEOWEB geocells facilitate junction efficiencies in excess of 100% for both internal and mechanical junctions, offering robust protection against the primary modes of junction failure.

“Or Equal” Substitutions in Geosynthetics: Evaluating the Contractor’s Proposed Alternative Amidst Global Supply Chain Disruptions & Rising Costs

Posted June 9, 2023 by Ashley Beyer

truck driving over sand filled geoweb road

As supply chain issues and project delays continue to wreak havoc in the global geosynthetics industry, Presto Geosystems has prepared this “reboot” of our tips for evaluating “or equal” substitutions to help you navigate the decision-making process when confronted with a proposed alternative geosynthetic product.

According to a recent special feature article from Geosynthetic News Alerts (GNA), more oversight and diligence is needed—now more than ever—as deceptive products and inferior raw materials continue to find their way into global markets.

According to GNA “Distributors and installers that place orders in good faith—particularly with overseas vendors—may wind up with rolls of geosynthetics they can’t use, and no wriggle room in compressed delivery timelines to find alternatives or otherwise rectify errors.” To protect against this, GNA goes on to emphasize the importance of vetting geosynthetics suppliers to maintain quality metrics. In light of this, Presto offers this reboot of our five tips for evaluating “or equal” substitutions to help you keep your project on the path to success amidst the chaos.

Tip #1: Review Product Datasheets Closely (Be Wary of Disclaimers)

Many design professionals tend to focus on the numbers shown on a product datasheet and may even have an implicit trust in the information provided. Unfortunately, some geosynthetics manufacturers and distributors will use this to their advantage.

After an initial review of the product data, you will have a sense of whether the product at least appears to meet the project specs on the surface. However, it is imperative to dig a little deeper. Pay close attention to any disclaimer language in the fine print at the bottom of the page.

Disclaimers that include statements such as “…specifications may change without notice” are a red flag.

Manufacturers who invest in quality assurance programs typically don’t need to provide this type of disclaimer, and are willing to stand behind their published product data.

Tip #2: Learn More About the Product Manufacturer

Starting with a few simple questions, you can obtain a sense of whether or not the product is “tried-and-true,” relatively new, or entirely unproven. Below are a few questions that can help you learn more.

Who actually manufacturers the product? This is particularly important when working with organizations that claim to be both a distributor and manufacturer of geosynthetics products. It is important to understand specifically which products they make versus those they distribute or offer under private label agreements (or OEM license agreements). Most importantly, remember that just because a company’s logo is on a product datasheet does not mean they are the manufacturer. Only accept product datasheets with the manufacturer’s information on it—not the distributor!
Can the manufacturer provide project references or case studies demonstrating the proposed substitution has been successfully used on similar projects elsewhere?
Can the manufacturer provide calculations demonstrating the proposed alternative will meet design objectives?
Can the manufacturer provide technical assistance during installation and provide support if unexpected challenges should arise during construction?

Tip #3: Look for Markings of Product Quality & Manufacturer Integrity

Indications of product quality such as the CE marking and ISO certification are useful in establishing an increased level of confidence that the manufacturer holds product quality and data integrity in high regard.

CE Mark – The CE Mark is an EU-mandated regulatory mark declaring the manufacturer’s product data is trustworthy and must be carried on products sold in the European market. While not required for geosynthetic products sold outside of the EU, it can provide a quick “gut check” as less reputable manufacturers will have difficulty obtaining this mark. The CE mark should include the number of the certification body beneath it, and the manufacturer should be able to provide a valid Certificate of Conformity of Factory Production Control upon request. The CE certificate will identify which products are included, as well as the location where the products were manufactured.
ISO 9001 Certification – For a manufacturer, obtaining certification under the ISO 9001 standard requires a significant commitment (and investment) in establishing and maintaining a comprehensive quality management program. Comprised of quality management procedures (QMPs), the program must consider every step of the production process, from the receipt and handling of raw materials to the finished product. Manufacturers who are ISO-certified should be able to provide a valid Certificate of Registration upon request. The ISO certificate will identify the name of the manufacturer, certificate number, certifying body, and a statement indicating the manufacturer’s quality management system complies with the requirements of ISO 9001 for the specific products of interest.
Certificate of Analysis (COA) – Implementing a robust ISO-certified quality management program typically requires continuous quality assurance and quality control testing in order for produced goods to be approved for release from the manufacturing facility. As part of this testing, a Certificate of Analysis, or COA, should be available for all manufactured lot numbers. Accordingly, reputable geosynthetics manufacturers should be able to provide COAs for products that ship to your project site, thereby providing documentation that the goods received were tested and approved in accordance with their ISO-certified quality management program.

Tip #4: Get Third-Party Data

This typically begins with a request to the contractor or manufacturer to provide third-party data to confirm the results are consistent with the product datasheet, and that the proposed substitution will perform as advertised. With manufacturer-provided data, it is important to verify that the results are from an accredited third-party laboratory.

If you are not comfortable with the data provided, or have lingering doubts, request that the contractor provide representative samples of the material for further inspection and testing. Provided the project budget allows, an ideal laboratory test program would include analysis of the samples of the proposed substitution as well as the originally-specified product. Including the originally-specified product as the baseline for comparison allows for a comprehensive evaluation of the results, and ultimately supports in making a well-informed decision.

Tip #5: Prepare a Summary of Your Evaluation

Before responding to project stakeholders, it can be helpful to prepare a summary of your evaluation laying out your findings and providing the rationale behind your assessment. We’ve prepared a checklist and product scoring sheet incorporating the considerations above that can be used as a starting point for completing your evaluation. You can download this form using the link below.

Download the Checklist >>

Read “The Significance of High-Quality Standards” >>

Conserving Natural Resources Using Geosynthetics

Posted March 1, 2023 by Katie Bocskor

Written By: Cory Schneider, Environmental Scientist, Presto Geosystems

Natural resources are finite, or at a minimum, can easily be consumed faster than they can be replaced. As such, the conservation of natural resources is a pragmatic endeavor. Geosynthetics—widely available materials used in construction, civil engineering, and environmental protection—can be useful in promoting the conservation of these resources. When used as intended, geosynthetics can enhance soil properties and reduce the demands placed on natural resources.

Types of Geosynthetics

Geosynthetics are typically made from synthetic polymers, such as polyethylene, polypropylene, and/or polyester, and are designed to be durable and resistant to weathering and other environmental factors.

General groupings of geosynthetics include:

geotextiles,
geogrids,
geomembranes,
geocells,
erosion control blankets (ECBs),
and turf reinforcement mats (TRMs).

Geotextiles (permeable) and geomembranes (impermeable) provide separation, while geogrids and geocells provide varying degrees of stabilization and confinement. ECBs and TRMs, made with a combination of natural and synthetic fibers, resist surficial erosion by preventing seed washout prior to germination.

Application areas where these geosynthetic materials are used typically include:

load support,
slope, shoreline, and channel protection,
and earth retention.

Using Geosynthetics in Load Support Applications to Conserve Natural Resources

In load support applications, geogrids, geotextiles, and geocells can all be used to reduce structural cross-section depths, thereby conserving natural resources. The figure below illustrates this benefit and provides a comparison of four structurally equivalent unpaved road sections over a very weak subgrade with a CBR of 0.5%.

As shown, the conventional cross-section in this case would require more than 36 inches of aggregate to achieve minimal stability, while the planar geosynthetic option (geogrid + geotextile) would require 26 inches of aggregate. Most notably in this case is that geocells—specifically the GEOWEB® Geocells—can be used to achieve an optimal section thickness of only 15 inches, and where suitable on-site material (OSM) is available, it is possible to limit imported aggregate to just the wearing course.

How Geocells Conserve Natural Resources

Through full-depth confinement, geocells allow for the use of lower-quality, non-cohesive soils and recycled materials (concrete, asphalt), further conserving resources through beneficial reuse. Beneficial reuse of any of the aforementioned reduces imported material requirements, thereby conserving aggregate, and with the additional benefit of less truck traffic to the site, conserves oil and gas and puts less stress on local roadways. Properly designed geosynthetics can also increase your roadway´s useful life and reduce or eliminate maintenance needs.

In slope, shoreline, and channel applications, ECBs, TRMs—and to a further extent—geocells, help prevent surficial soil erosion—a process that can cause significant damage to natural ecosystems and lead to the loss of valuable topsoil. While ECBs and TRMs are suitable to protect the surface, adding geocells to the cross-section can prevent supersaturated soils below these products from washing downslope or downstream, and can improve the hydraulic performance of the materials used in the geocells.

Finally, geosynthetics can be used in constructing retaining walls and embankments, which can help conserve resources by reducing the need for land excavation and fill. In retaining wall construction, geogrids—and occasionally geotextiles—are used as tiebacks in Mechanically Stabilized Earth (MSE) structures, while geocells and TRM wraps are just a few of the many different geosynthetic facing options available. Geocells can not only be used to create living green walls to help stormwater infiltrate naturally and add an aesthetically pleasing finish to a structurally sound engineering solution, but research has also shown that geocells can withstand high levels of seismic shaking and may be a suitable option in many earthquake-prone parts of the world.

Let Our Engineers Run Design Calculations on Your Next Geocell Project.

See the Cost and Material Savings for Yourself!

Presto Geosystems’ engineering team works closely with you to provide free project evaluations, with engineering support from the preliminary stages through construction. The project evaluation will deliver a technically sound, cost-effective solution based on four decades of accredited research and project experience.

Contact our knowledgeable staff and network of qualified distributors to discuss your project needs today and see how we can help you save money while conserving natural resources. Responsible use of engineered materials designed for long-term performance in the environment can help you achieve a more sustainable approach to construction.

Use our free online tools to keep your projects moving forward.

7 Key Factors to Choosing the Right Geocell

Posted November 4, 2022 by Ashley Beyer

Choosing the Right Geocell

Does excellent quality and support matter to you? Of course it does. But, you are smart enough to know that there is no free lunch. Low cost alternatives are less expensive for a reason. So, what do you need to look for to recognize the right geocell for your project?

Quality Feedstock
Insist upon verifiable proof that your geocell is manufactured only with virgin high density polyethylene. While it is possible to achieve poor weld strength with virgin materials, it is impossible to achieve consistently excellent weld strength unless only virgin high density polyethylene is used.
Integral Components
Choose a geocell that offers connection components, tendons, stakes, load transfer clips and installation tools that are specifically tailored for the system. Using rope, staples, bent rebars (J hooks) and zip ties that are not specifically designed for use with a geocell engineered solution is unwise and potentially catastrophic. Use only designs that recognize the critical nature of these components to the overall success of the project.
Experience and Warranty
Choose a manufacturer who has thousands of projects and decades of experience. It is shocking how little some manufacturers understand about the principles and practices of engineering and soil stabilization solutions. Consider the value of a warranty offered by a company who just appeared on the scene or from private label pass through companies who source from numerous suppliers (unknown to you). Pass through private label resellers source from different manufacturers (from different countries) and you have no ability to control the quality of your material if you don’t know where it is being made. The value of a warranty is directly proportional to the stability and longevity of the company offering it.
Certification and Testing
Look for indications of product quality such as CE marking or manufacture certification under the ISO 9001 standard. Ask for proof of certification to make sure that you are not buying “empty acronyms”. Insist on a Certificate of Analysis (COA) that certifies the resin lot number, seam peel strength, and other key criteria of your geocell run to ensure the material shipped to the jobsite meets printed specifications. Everyone has a spec sheet. The value of a spec sheet is that it represents the characteristics of the product. Does the material that shows up at the site meet those specs? Make sure that higher quality “special run” material is not used for testing, while lower quality material is shipped to the job site. Test samples should be taken from warehouse floors, not made special for testing requests.
Design Support
If your geocell provider does not employ full time engineers and provide free design evaluation….ask yourself, why not? Excellent geocell manufacturers are solution providers….not just material mills.
Installation Support and Distributor Network Strength
Contractors should insist that their resellers be trained in construction methods so that geocell is properly placed and so that the contractor can get in and get out quickly. Good providers have tips, methods and custom tools to speed installation. Great manufacturers care about installation……not just moving material.
Certainty
There should be no question about any detail and NEVER a question about the success of a project. Contractors and engineers deserve reputation assurance. Insist upon only geocell providers who are market leaders and who champion the category.

Follow these guides and you will sleep well knowing that your project will be a success.

Building Climate-Resilient Infrastructure Using Geosynthetics

Posted October 18, 2022 by Ashley Beyer

When extreme weather events occur, communities are often left to grapple with the devastating effects. An increase in extreme weather patterns, coupled with aging or inadequate infrastructure, amplifies the often dangerous and costly damage that ensues—especially for vulnerable communities living in low-lying areas.

According to a recent study, the United States could see a 26.4% increase in flood risk by 2050, which could cause significant damage to existing infrastructure. For this reason, it is vital to build resilience into infrastructure projects to mitigate climate risk and ensure the long-term reliability of critical infrastructure.

Incorporating geosynthetics into infrastructure can improve the ability of communities to withstand and recover from extreme weather events. For example, in hurricane-prone parts of the country, designing robust access roads along power transmission lines allows repair crews to safely and quickly restore power to communities that might otherwise be without electricity for days or even weeks. Geosynthetic products, such as geocells, can be used to construct reliable access roads along transmission infrastructure, which often traverse very remote areas with difficult terrain and very soft ground conditions. Through an interconnected honeycomb-like network, geocells confine and stabilize soils that would otherwise be unstable under loading.

When used in load support, slope stabilization, channel protection, and retaining wall applications, geocells are a powerful weapon against the long-term effects of climate change. This article discusses several examples where GEOWEB geocells were successfully used to help communities adapt to, and recover from, extreme weather events.

GEOWEB Porous Pavements Used for Rebuilding Roads, Replacing Transmission Lines Damaged During Hurricane Michael in Florida’s Panhandle

Hurricane Michael caused extensive damage to Florida’s power grid network, leveling more than 100 transmission towers in a 34-mile right-of-way from Port St. Joe to Callaway. This right-of-way crosses swampy, remote, and hard-to-reach areas, making rebuilding the grid even more challenging. This extremely wet, muddy ground prevented repair vehicles from accessing the area. Helicopters were employed to transport the new steel towers installed on-site.

Accessing the lines for maintenance would require a stronger roadway to support heavy vehicles in the wettest areas. The GEOWEB Load Support System was used to make the roads operational and improve performance in saturated conditions.

The GEOWEB system was placed over an enhanced geotextile and filled with crushed aggregate to create access roads across critical wetlands and stabilize pole pads. The access roads and pads are permanent.

GEOWEB Geocells Repair Storm-Ravaged Trail & Maintenance Road

In the spring of 2018, several storms violently swept through areas along southern Maine’s coastline, devastating the beaches and trails of Fort Foster—a town-owned park in Maine. Known as “nor’easters,” these destructive storms form along the east coast, bringing strong winds, rain, and flooding to the New England states. As the storms rolled past, the damage was visible to Fort Foster and Kittery Point’s 2.1-mile-long shoreline walking trail and maintenance road, as well as on the slopes leading down to the beach.

The park’s goal was to repair the damage and protect the slopes, maintenance road, and recreational trail from future storm damage. The GEOWEB® Soil Stabilization System was chosen to restore and protect two sections of the park’s shorelines and trails.

By using the GEOWEB System, the park was able to armor the maintenance road, recreational trail, and slopes from future storm events. Since being installed in 2018, the GEOWEB Load Support and Shoreline Protection Systems continue to perform as designed, allowing the community to once again enjoy the trail system and local beaches.

shoreline trail with geoweb geocells cutout

GEOWEB Hard-Armored Shoreline Protection System Protects Vulnerable Riverbank from Erosive Forces

The extreme El Niño event caused the western Pacific to warm, developing atmospheric convection and increased rainfall. The storm events caused catastrophic flooding and severe erosion in the eastern equatorial region of Ecuador and Northern Peru. A portion of the Zarumilla River, located in the remote Tumbes region in Northwestern Peru, was experiencing severe erosion and required a shoreline protection solution to prevent further deterioration of the riverbank.

The GEOWEB® Shoreline Protection System was selected to protect the Zarumilla riverbank against future storm events. The GEOWEB system with concrete infill provides economical, hard-armored protection of slopes and channels exposed to high flow velocities and high shear stresses. The system has been proven to withstand sustained flow velocities over 36 ft/s (11 m/s) and shear stresses of 20.9 psf (1.0 kPa), outperforming rip-rap, gabions, and other conventional hard armor strategies.

The product was shipped to the site in September 2020, and installation was complete by December 2020. The project was completed on schedule and within budget. The GEOWEB® Shoreline Protection System is performing to expectations and will provide much-needed protection to the Zarumilla River and the communities that depend on it when the next major storm hits.

GEOWEB Geocells Used for Erosion Protection of Canal Floodwall

Erosion of the 17th Street Canal’s flood protection system was a major concern for the Southwest Louisiana Flood Protection Authority-East. The Authority required a solution to protect the canal’s slope against erosive forces and prevent a floodwall breach in the event of a tropical storm event.

To mitigate channel slope erosion, engineers chose the GEOWEB Confinement System to stabilize the slopes along the Metairie side of the drainage channel. By confining the infill material, the GEOWEB system prevents flow from causing scour and erosion on slope surfaces.

The construction company installed approximately 380,000 square feet of GW40 (mid-cell size, six-inch deep panels) over a woven geotextile along the canal’s slope and infilled the cells with crushed aggregate sized based on research and testing at Colorado State University hydraulics lab.

The GEOWEB System:

Allows the use of smaller, less expensive rock—even waste rock which decreases installation and transportation costs.
Creates a permeable, cover when drainage is desired but vegetation cannot be established.
Resists high velocities and tractive forces.

Design Support & Resources for the GEOWEB System Applications

The engineering team at Presto Geosystems works closely with engineers and project planners, offering free project evaluation services and on-site support. Our recommendations will deliver a technically sound, cost-effective solution based on four decades of accredited research and testing data.

Please contact our knowledgeable staff and network of qualified distributors and representatives to discuss your project needs today.

Meet the Presto Geosystems Team: Get to Know Bryan

Posted October 4, 2022 by Ashley Beyer

How long have you been with Presto Geosystems?

Time flies when you are having fun! I have been with Presto Geosystems going on 14 years. In that time, I got to work with some really great people and enjoyed speaking with Gary Bach on how geocells were invented back in the late 70s and early 80s.

Can you tell us a bit about your background?

I grew up in the Upper Peninsula of Michigan and enjoyed doing all things outdoors. My father was an Olympic ski jumper, so I had no choice but to strap on a pair of skis and follow in his footsteps. I became pretty good and was in three junior Olympics before a bad fall ended that part of my life. I grew up before video games, so we were always outside playing football, baseball or just riding bikes.

After a year at Michigan State University, I attended college at Michigan Tech University in Houghton, MI and graduated with a degree in Environmental Engineering. After graduation, I moved to Green Bay, WI, and worked for Foth & Van Dyke and then Robert E. Lee engineering consulting firms before joining Presto Geosystems.

What attracted you to the world of engineering and geosynthetics?

I was lucky enough to land a wonderful job out of college at Foth & Van Dyke in Green Bay, WI. Foth was a growing consulting firm at the time and the staff was always at the leading edge of technologies. When I started in consulting, geosynthetics were just becoming an option for roadway and earth retention projects. I got to see early on how engineers included geosynthetics in their projects and how the approval agencies accepted them. I guess I’m really showing my age…

What does your job entail? Can you take us through a day in the life as the Chief?

The best part of my job is that every day is different and it seems there are no “typical” days. Our products can solve so many soil stabilization problems that I am blessed to work with engineers all over the world on their challenging projects. It is rewarding to walk away from my computer at the end of the day knowing that the Geosystems Team and our worldwide distribution network work together to make a difference.

What do you like most about your job and/or what do you like most about this industry?

The people and relationship building through the years has been enjoyable. Our industry really works closely to ensure successful geosynthetic projects. I enjoy working on the AREMA, ASTM, and ISO committees and the discussions with the industry experts.

What is the most challenging part of your job?

How do you turn it off? When I first started consulting 35 years ago, we didn’t have the technology we have today. We didn’t even have AutoCAD or personal computers at the time! Everything was done by hand, and I think we understood the calculations better. When you left work, it allowed you to unwind. Today, it seem it is 24/7, especially with the advancements in technology. It can be a challenge to turn it off.

What do you enjoy doing when you aren’t out helping solve the world’s soil stabilization and erosion challenges?

My wife and I stay pretty active, especially in the summers. We live on a golf course, and you will always find us out playing or enjoying a cocktail on the 19^th hole! Family is a big part of our life. We are lucky to have four wonderful kids who have moved out of the house and are employed! They have given us three beautiful grandchildren (one more on the way in December) that we love to spend time with and spoil which is what grandparents are supposed to do.

What is your favorite place in the world to visit?

I have been lucky to have traveled all over the world for leisure and work. A few of my favorites include Austria, Switzerland, Australia, and Banff in Canada. If had to pick one it would have to be Punta Cana since my wife and I have the best of times when we visit. We have so many great memories there. We both have stressful jobs, so it is nice to get away, relax on the beach, enjoy some cocktails and let someone else do the cooking.

If you could meet anyone, living or dead, who would you meet?

This is an easy one but hard to decide which person. I am a huge old western movie fan. It is to the point that if I am watching tv and scrolling through the channels and come across one, my wife just gets up and goes to another tv. I would have to pick my top 20, throw them in a hat, and just pick one and would be fine.

What would you name the autobiography of your life?

Never a Dull Moment.

Are material shortages delaying your road construction projects? Here is how to stay on schedule and within budget.

Posted August 30, 2022 by Ashley Beyer

Written by: Bryan Wedin, P.E., Chief Design Engineer

Road construction is booming, and this trend is expected to remain strong due to high demand and the Infrastructure Investment and Jobs Act (IIJA), which includes investments across many sectors, including public infrastructure.

Along with this boom, the road construction industry has been dealing with inflation-related cost increases and limited availability of construction materials. The industry has been impacted by supply-chain interruptions and shortages for many roadway materials including lime, cement, and even aggregate. These materials are typically used for roadway base construction, which means road construction projects that use these materials may be subject to delays. Due to these shortages and delays, on-site material or sand-filled GEOWEB® geocells can provide a cost-effective, readily available substitute for base materials–especially where native subgrade conditions consist of weak or soft soils.

GEOWEB® Geocells for Roadway Base Stabilization

The GEOWEB geocells have been used for load support and foundation applications worldwide for more than 40 years. Developed in collaboration with the U.S. Army Corps of Engineers (USACE) in the late 1970s, Presto co-invented the technology now known as geocells or a cellular confinement system (CCS). The early applications of geocells consisted primarily of stabilized, expedient sand roads for military vehicles. In the early 1990s, the U.S. Army deployed over 6 million square feet of the geocellular system to stabilize the shifting desert sands and provide mobility for troops and military vehicles. At the time, the system was dubbed Sandgrid due to its readily available sand infill.

Both the USACE and Desert Storm forces found a solution for building fast access roads across sand landscapes. By utilizing the principle of soil confinement to enhance soil strength, the GEOWEB System turns sand into a load-supporting composite structure that can support heavy-loaded vehicles under repeated load cycles. Since then, the GEOWEB System has also been adopted by State and Federal roadway authorities for domestic road construction across the United States.

Presto Geosystems has endeavored to improve and innovate geocell technology, creating the modern-day GEOWEB® Soil Stabilization System. The GEOWEB geocells are made of 100% high-density virgin polyethylene (HDPE) and do not contain any recycled material, fillers, or exotic polymers—all of which can negatively affect performance. Complete with a full line of accessories for ease of installation and long-term performance, the GEOWEB Soil Stabilization System is the most advanced geocell technology in the industry.

Sand-Filled GEOWEB Geocells for Soil Stabilization

sand filled geocells Geocells are three-dimensional honeycomb-like structures made of ultrasonically welded strips of HDPE that confine infill material over a specified cell depth and diameter. Through confinement, the GEOWEB system distributes loads laterally and controls shearing, as well as lateral and vertical infill movement.

Compared to planar geosynthetic products such as geogrids—which commonly rely on expensive imported high-quality aggregate—geocells are highly versatile and can be filled with a variety of commonly available and economical infill materials, including sand.

In many cases, geocells allow for the beneficial reuse of on-site materials, eliminating the need to purchase expensive aggregate or imported structural fill. These advantages not only offer the potential for savings in overall construction costs but also contribute to a significant reduction in carbon emissions due to less aggregate/fill processing, transportation, and handling.

The illustration below provides a comparison of four structurally equivalent aggregate sections over a subgrade with a CBR of 0.5%.

As shown, the unreinforced aggregate option would require more than 36 inches of aggregate to achieve minimal stability, and the planar geosynthetic option (geogrid + geotextile) would require 26 inches of aggregate. In contrast, the GEOWEB geocells reduce the total section thickness to only 15 inches, and where suitable on-site material is available, it is possible to limit imported aggregate to just the wearing course.

The GEOWEB geocells dramatically increase the shear resistance of the infill, which allows the use of lower-quality fill to carry concentrated loads that would otherwise require crushed aggregate to prevent localized, near-surface shear failure. The cellular structure also distributes concentrated loads to surrounding cells, thus reducing the stress on the subgrade directly beneath the load and the required total thickness of the structure.

Let Our Engineers Run Design Calculations on Your Next Project. See the Cost Savings For Yourself!

Presto Geosystems’ engineering team works closely with you to provide free project evaluations and on-site installation support. The team at Presto Geosystems is here to provide engineering support from the preliminary stages through construction. Use our free online tools to keep your projects moving forward. The project evaluation will deliver a technically sound, cost-effective solution based on four decades of accredited research and project experience. Please contact our knowledgeable staff and network of qualified distributors to discuss your project needs today.

Presto Geosystems Announces Launch of the ATRA® Wall Key

Posted July 20, 2022 by Ashley Beyer

We are thrilled to announce our newest innovation at Presto Geosystems: the patented ATRA® Wall Key for the GEOWEB® Retaining Wall System.

The ATRA Wall Key is used to connect adjacent GEOWEB Retaining Wall sections through the GEOWEB material slots (I-slots). The ATRA Wall Key includes an integrated washer at the base of the handle for coverage of the I-slots when connecting adjacent wall sections, frictional barbs for an improved interlock with the GEOWEB sections, and an ergonomic handle with S-shaped contouring for ease of installation.

The ATRA Wall Keys are the most effective way to connect the GEOWEB Retaining Wall sections, ensuring the long-term success of your project. Made of non-reactive, chemically inert high-density polyethylene, the ATRA Wall Keys provide a more secure and permanent mechanical connection over staples or zip ties, and they are the only geocell connector specifically designed for use in exposed wall face applications. Formulated to withstand weathering and ultraviolet radiation, the ATRA Wall Keys will not corrode or photodegrade, even when exposed to harsh environments. Securing sections with the Wall Keys is faster than using staples or zip ties, requires no tools, and can be completed by one installer with one easy turn.

The new ATRA Wall Keys offer a natural-looking aesthetic by blending seamlessly into our green or tan wall fascia options.

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How Geosynthetics Are Uniquely Poised to Help Alleviate Congestion at U.S. Ports

Posted June 1, 2022 by Ashley Beyer

Written by: Michael J. Dickey, PE, Director and Bryan Wedin, PE, Chief Design Engineer

On May 6, 2022, the Maritime Administration (MARAD) released an amended Notice of Funding Opportunity (NOFO), allocating over $234 million for port infrastructure development in 2022. Adding to the previously appropriated amount of $450 million from the Infrastructure Investment and Jobs Act (IIJA, or Bipartisan Infrastructure Law), this will bring the total amount available for port improvement projects to $684 million for FY2022.

The significance of this investment comes at a crucial time. According to the American Association of Port Authorities, the pandemic has laid bare the need for a transport system that is able to surge and stretch across all links—from sea, to land, to rail, to warehouse, to consumer. The question is, how can this funding be used to meet this need quickly and cost-effectively? The answer may lie in a strategy implemented in 2021 in the state of Georgia to alleviate congestion at the Port of Savannah. The Georgia Port Authority, in partnership with Norfolk Southern, implemented a solution that has caught the attention of other U.S. port authorities and Class I railroads using what is being referred to as “pop-up container yards”.

What Is a Pop-Up Container Yard?

In a recent article featured on Freightwaves.com, pop-up container yards are described as “mini-versions of inland ports where containers are brought to strategically located sites by intermodal rail, shortening the distance trucks have to travel to collect imports or drop off exports and reducing traffic in and around busy seaports. The concept essentially brings the seaport closer to manufacturing, agriculture and population centers.” While, on the surface, pop-up container yards may seem like a very pragmatic solution to a complex problem, developing one of these sites can come with its own set of unique challenges.

One such challenge relates to existing ground conditions. From a geotechnical perspective, the ground conditions may not be suitable for the heavy demands of container handling and storage operations. And unless an alternate location has been identified that is better suited, project engineers and designers must often evaluate the need for ground improvement options capable of supporting heavy vehicle loads over soft or unstable soils. The good news is that the GEOWEB® Soil Stabilization System was invented specifically for this purpose. The GEOWEB Cellular Confinement System (CCS) is an American-made geosynthetic product manufactured by Presto Geosystems that has been in use for over forty years.

GEOWEB Geocells Improve Bearing Capacity Over Soft or Unstable Soils

Created through a collaboration between the U.S. Army Corps of Engineers (USACE) and Presto Products Co., the GEOWEB system was designed to address the needs of the U.S. military to build access roads capable of supporting heavy vehicle loads over soft or unstable soils. The system’s deep cellular network controls both the horizontal and vertical movement of unstable base soils. In load-support applications, when a static or dynamic load is applied to a geocell-reinforced layer, lateral earth pressures are mobilized and transferred across a three-dimensional network of interconnected cells. The layer essentially performs like a composite material, facilitating a phenomenon known as the mattress effect.

Success Story: CSX Intermodal Facility in Charleston

The CSX Charleston Intermodal Yard required base reinforcement due to poor and unstable subgrade conditions. Shallow surficial soils comprised very loose sandy soils that were inadequate to support the operation of reach stackers used in regular lifting and moving containers. In addition, a similar condition was prevalent in another area of the site designated for chassis parking. Both areas were prone to significant rutting due to the inherent instability of shallow surficial soils.

The Presto Geosystems’ design staff worked closely with CSX to provide design recommendations based on sub base strength, vehicle loadings, and frequency of traffic. After a thorough review of the geotechnical report, it was determined that on-site material could be beneficially reused as infill in the GEOWEB system.

Eliminating the need to import costly aggregate and structural fill led to significant cost savings, and yard downtime was substantially reduced. Minimizing downtime was especially important due to the high volume of tractor-trailers the facility handles daily. The reach stacker area used an enhanced woven geotextile, three-inch base, six-inch GEOWEB panels, and a three-inch wearing surface. The chassis parking area utilized a high-strength woven geotextile, six-inch GEOWEB panels, and a two-inch wearing surface. The GEOWEB system stabilized a total of 1.75 acres. Both areas have required minimal maintenance and continue to function as designed. Both areas have required minimal maintenance and continue to function as designed.

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Protect Your Project Schedule and Reduce Costs with GEOWEB® Geocells

As demonstrated by the success at the CSX intermodal facility, where a suitable source of clean sand is available, the GEOWEB cells can be infilled with on-site material in place of expensive aggregate, drastically reducing imported aggregate volumes altogether. Even at sites where a suitable source of clean sand is not readily available, geocells offer the potential to reduce the required thickness of the base layer in a load support application by as much as 50%. In both cases, project stakeholders can realize cost savings, as well as a potential reduction of schedule-related risks, particularly where the availability of suitable aggregate, or availability of truck drivers to transport said material, might otherwise be outside of the project decision-maker’s control.

Compared to planar geosynthetic products such as geogrids—which commonly rely on expensive, imported high-quality aggregate—geocells are highly versatile and can be filled with a variety of commonly available and economical infill options. Infill options include sand, crushed aggregate, recycled concrete, pulverized debris, recycled asphalt, or other locally sourced materials. The illustration below provides a comparison of four structurally equivalent aggregate sections over a subgrade with a CBR of 0.5%.

As illustrated, the unreinforced aggregate option would require more than 36 inches of aggregate to achieve minimal stability, and the planar geosynthetic option (geogrid + geotextile) would require 26 inches of aggregate. In contrast, the GEOWEB geocells reduce the total section thickness to only 15 inches, and where suitable on-site material (OSM) is available, it is possible to limit imported aggregate to just the wearing course.

A Value-Engineered Solution for Your Pop-Up Container Yard Project

The GEOWEB geocells can be added to pop-up container yard projects to provide a value-engineered solution for both paved and unpaved areas. This not only reduces construction costs, but can also help keep your project on track when aggregate shortages and limited availability of truck drivers threaten your project schedule.

Project-specific recommendations are influenced by loading, subgrade soils, traffic frequency, and infill type. The engineering team at Presto Geosystems works closely with engineers and project planners, offering free project evaluation services and on-site installation support. Our recommendations will deliver a technically sound, cost-effective solution based on over four decades of accredited research and testing data. Please contact our knowledgeable staff and network of qualified distributors and representatives to discuss your project needs today.

Contact: Bryan Wedin, PE, Chief Design Engineer

Sustainable Vegetated Channels = The Death of Rip Rap

Posted April 28, 2022 by Katie Bocskor

Rip rap is a common channel protection method because of its resistance to most flows with appropriate rock size; however, it does have significant drawbacks. Material can be expensive, not locally available, and placement requires heavy equipment. Additionally, rip rap channels are prone to regular maintenance, collection of debris and garbage, erosion at boundaries, undermining, and movement.

Naturally vegetated channels are grassed greenways that offer substantially lower maintenance and cost but are limited in their ability to resist moderate-high flows and shear forces even for short durations—unless the soils and vegetation can be stabilized.

High-Performing Vegetated Solution

The GEOWEB® Soil Confinement System offers protection to channels with continuous low flows—as well as moderate-to-high flow intermittent channels. The system’s honeycomb-like network creates check-dams that protect the soil layer from hydrological erosive forces and resulting erosion that impacts unconfined soils. Cell wall perforations lock up with the vegetative root for further stabilization.

The GEOWEB single-layer vegetated channels can withstand ~9 ft/s (2.7 m/s), more than doubling the resistance of typical unsupported vegetated channels (4 ft/s (1.2 m/s). The GEOWEB channels can withstand even higher velocities—as high as 30 ft/s (9m/s)—with an overlying Turf Reinforcement Mat (TRM) when fully vegetated. This is a significant improvement, essentially doubling performance resistance to shear stress and velocities for TRMs and Erosion Control Blankets (ECBs). Rigorous flume testing at Colorado State University (CSU) with varying shear stresses and flow rates substantiated resistance of high shear stresses up to 15.9 lbf/ft2 (77.6 kgf/m2).

Vegetated GEOWEB TRM System Compared to Rip Rap

The GEOWEB TRM System offers advantages over rip rap for vegetated channels:

Streamlined Transition with Boundaries: Smooth integration with boundaries reduces undermining and erosion at boundary points
Higher Permeability: Ideal for environmentally low-impact design
Easier Integration in Landscape Plan: Less obtrusive and can be incorporated as a “soft” solution (i.e., grassed conveyances) with capabilities of some hard-armored systems

Sustainable Solution for Vegetated Conveyances

Sustainable vegetation in channels can be achieved with the GEOWEB TRM system. Applications that benefit include roadside ditches, stormwater channels, shoreline embankments, dams, spillways, and pond overflow systems. The GEOWEB/TRM system is a more sustainable—and environmentally friendly solution than rip rap for these common applications.

Presto offers full design and specification tools and a free project evaluation service to determine applicability.

Geosystems’ Blog