Written By: Samantha Justice, P.E., Bryan Wedin, P.E. Geocells provide one of the most powerful solutions available to engineers and contractors when designing and constructing roadways over soft and weak subgrades. With a successful track record of over 40 years, geocells have proven effective in load support applications over challenging conditions. If you’ve ever wondered how geocells work in load support applications – and the relationship between lateral confinement, hoop stress and wall tension – you’ve come to the right place. Geocells are used to alter vertical stresses beneath an applied cyclical load. When a vertical, cyclical load is applied over geocells, active earth pressures develop in the loaded cell. These pressures arise due to the friction between the infill material and the cell wall. This friction pushes back against the passive earth pressure in the adjacent cells, helping to support the load. Refer to Figure 1. The balance of active and passive earth pressures activates the hoop stress in the cell walls, which increases the stiffness and bearing capacity of infill material. The infill material is confined within the individual cells with no chance of displacement, or lateral or vertical spreading and the result is increased stiffness. In effect,… Read more »
Posts Categorized: Geosynthetics Industry
Using GEOWEB® Geocells in Landfill Capping Applications
Written by: Cory Schneider, Business Development Manager When contaminated material such as landfill waste or contaminated soil is encountered, there are typically two options available—removal of the material or placing a “cap” over it. In most cases, capping is the easier and more cost-effective of the two options. Caps serve to isolate the contaminated material, preventing people and wildlife from coming into contact with it. Factors Influencing Landfill Cap Design Landfill cap design for any particular site depends on many factors, including the type and quantity of contaminants, size of site, amount of rainfall, and future use of the area. It can consist of one or several of the following: asphalt or concrete, vegetative layer, drainage layer, and/or an impervious layer (geomembrane or compacted clay). Preventing Slope Erosion with Advanced Geosynthetic Technology When using vegetative covers, especially in sloped areas, one of the best ways to prevent long-term erosion of the cap is to confine the topsoil component using geosynthetics like the GEOWEB Soil Stabilization System (geocells). The GEOWEB Geocells, which are three-dimensional ultrasonically welded strips of high-density polyethylene (HDPE), create small pockets to hold soil in place. By doing so, the system prevents erosion or sloughing when the soil… Read more »
Energy Infrastructure and Climate Change: Protecting Erodible Slopes in Fire-Prone Areas
Energy infrastructure is critical to the functioning of modern societies, and its protection against natural disasters and environmental threats is a top priority. Climate change exacerbates these disaster risks, with extreme weather conditions and wildfires being of particular concern, considering potential damage to the energy infrastructure and disruption of energy supply. Wildfires cause rapid, severe destruction, and, aside from damage to infrastructure, can impact our climate, vegetation, and atmosphere. To measure the size and impact wildfires have, scientists use observations from several low Earth-orbit satellites, including the Copernicus Sentinel-3. These tracking satellites gather shortwave-infrared data combined with other techniques to differentiate between burned areas and other low reflectance covers such as clouds. The European Space Agency (ESA) compiles that long-term dataset to analyze global fire trends. According to the ESA, fire affects an estimated four million square kilometers (1.5 million square miles) of Earth´s land each year [1]. That is 400,000,000 hectares (990,000,000 acres) yearly—about half the size of the United States of America, an area larger than the country of India. The United Nations Environment Programme (UNEP) Rapid Response Assessment on Wildfires compiles findings from over 50 experts from research institutions, government agencies, and international organizations around the globe, and… Read more »
White House Provides Clarification on Build America, Buy America (BABA)
The White House released guidance on the Build America, Buy America (BABA) initiative, an important component within the $1.2 trillion Infrastructure Investment and Jobs Act (IIJA) from 2021. BABA stipulates that certain products must be manufactured in the U.S. to qualify for federal funding in infrastructure projects and emphasizes the use of domestically produced construction materials. As the faucet opens for IIJA projects, make sure your project has certainty and you are building with quality materials you can trust, 100% made in the USA. BABA Highlights: Scope: The BABA guidelines apply to federally funded infrastructure projects, including those under the IIJA. Material Categories: BABA focuses on three primary categories: iron and steel products, manufactured products, and construction materials. Notably, the list has been expanded to include engineered wood but excludes coatings, paint, and bricks based on feedback. Made in America Criteria: To wear the “Made in America” badge, a product must be produced in the U.S., with at least 65% of the cost of its components sourced domestically. This will further increase to 75% in the calendar year 2029. Included Materials: The guidance specifically lists plastic and polymer-based products, non-ferrous materials, glass, fiber-optic cable, engineered wood, drywall and lumber. Implications… Read more »
A Week of Celebration and Inspiration: Engineers Week 2024
“Welcome to the Future!”: Engineers Week 2024 From February 18 to 24, 2024, the engineering community will come together to celebrate Engineers Week. This year’s theme, “Welcome to the Future!”, is a nod to the incredible advancements that have been made and a look forward to the innovations yet to come. It’s a week to celebrate, reflect, and inspire the next generation of engineers. The Roots and Relevance of Engineers Week Initiated in 1951 by the National Society of Professional Engineers (NSPE), Engineers Week has grown into a global celebration. It acknowledges the vital role engineers play in progressing our society. The week aligns with the birthday of one of history’s great engineers, George Washington, who was also a surveyor. This connection underscores the deep roots and enduring impact of engineering in our world. Why “Welcome to the Future!” Matters This year’s theme emphasizes the forward-looking essence of engineering. It’s not just about honoring past achievements; it’s about shaping the future. Engineers are instrumental in developing innovative solutions to some of the world’s most complex challenges, from climate change to advancing technology in renewable energy and communications. This week is an opportunity to showcase how engineering keeps us moving forward,… Read more »
Using Geosynthetics to Stabilize Soils in a Harsh Environment
By Dhani Narejo, PE, Bruno Hay, and Bryan Wedin, PE Mine Site Erosion Problems One of the largest nickel mining sites in the world is located on the South Pacific island of New Caledonia. Due to the size of the mining project and the terrain of the site, significant cut-and-fill work for civil engineering structures was unavoidable. Given the magnitude of the site, the challenge of safeguarding the structures against erosion is formidable. Inaction is not an option due to the sensitive nature of the structures, environmental concerns, and a keen desire by the owners to protect the environment. A typical example of the erosion at the site is the slope in Figure 1. Such slopes require continuous maintenance if the erosion problem is not addressed. In some cases, erosion can cause interruption in the mobility of materials and personnel at the site. Several erosion-control measures had been successfully used at the site, including riprap and concrete. An alternate erosion control system was desired by the owner that would meet the following objectives: Be cost-effective, Require little or no maintenance, Utilize local labor and materials, Have a design life exceeding 50 years. Soil, topography, weather Ultrabasic soils cover about one-third… Read more »
The Dangers of Breaking Specs and Bid Shopping
Written by Sam Justice, P.E. Building roads, housing, and other critical infrastructure is a great responsibility taken on by engineers, architects and project owners. Ensuring that these structures are safe and reliable for years and decades is of the utmost importance at all stages of design and construction. The Challenge of Maintaining Quality in Construction The design team creates building plans and the associated specification that capture the essence of their vision as they work to write the guiding documents for their project. They make decisions about product types, grades, and take great pains to build into their documents citations of certifications and standards to assure only quality materials are allowed on the site. However, product competition and budget demands are a concern seen in many projects that can challenge the specifications intended to produce the best possible structure. Substandard “or equal” substitutions can be encountered in the critical moments between design, bid awards, and construction. It is up to the specifying engineers and architects to hold their spec in all phases of the process to ensure the right materials and installation procedures are used. The Bidding Process and Material Selection Contractors often produce bids with the materials indicated by the… Read more »
Why Geocells Outperform Geogrids for Road Construction
Geocells (cellular confinement system CCS) offer a more effective and practical 3D design solution to load support challenges than multilayered 2D geogrid efforts. Geocells transfer applied loads instantaneously, delivering practical soil stabilization in a product that is fast and easy to install. How do geogrids work? Geogrids rely on rutting, displacement and lateral movement of the road material to activate the load support reaction of the product. As shown below, failure of the driving surface must occur before the geogrid reacts. As a result, rutting and soil displacement is a prerequisite reality to the system. Since the geogrid is two-dimensional, material not located directly within the plane occupied by the geogrid is free to move, shift and displace. It is essential that geogrids are placed in a flat or a pre-tensioned manner—but that is not practical in a construction environment. It is common to see geogrids unrolled over a prepared grade with an undulating surface. As aggregate is placed over the top of the geogrid, the material kinks and waves, further warping the 2D plane. The geogrid is rarely pulled tight during installation which does not allow full tension under load. Geogrids are difficult to… Read more »
Addressing Microplastics: How GEOWEB® Geocells Contribute to Eco-friendly Soil Stabilization Practices
Written by: José Pablo George, M.S., CPESC-IT, International Business Manager Microplastics, tiny plastic particles smaller than five millimeters, present a potential hazard to both wildlife and marine organisms. As revealed by a global microplastics database provided by the National Centers for Environmental Information (NCEI) and published by the National Oceanic and Atmospheric Administration (NOAA), plastic is the dominant type of marine debris in the ocean and the Great Lakes. These microplastics, usually originating from single-use, disposable plastics on land, are transported via rivers and wind into global circulation systems where they accumulate. International Measures and Guidelines: A Proactive Response to Plastic Pollution The United Nations Environment Programme´s Intergovernmental Negotiating Committee and Environment Assembly have adopted an international legally binding instrument on plastic pollution to address plastic pollution throughout its life cycle. Given the array of different types of plastics, the Sea Studios Foundation, in conjunction with Earth911.org, the Institute of Agriculture and Trade Policy, the WHO International Programme on Chemical Safety, and the US EPA, has published a Smart Plastics Guide. This guide outlines seven commonly used plastic types and their potential health hazards. There are some plastics (often used for disposable packaging) that are not easily recycled and may contain… Read more »
“Or Equal” Substitutions in Geosynthetics: Evaluating the Contractor’s Proposed Alternative Amidst Global Supply Chain Disruptions & Rising Costs
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… Read more »
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