PRS Geo-Technologies

- 3D Cellular Confinement System | Neoloy Geocells

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PRS-Neoweb (Tough Cell) is a groundbreaking soil stabilization and reinforcement technology for civil engineering and transportation infrastructure. The PRS-Neoweb geocell is a composite 3D honeycomb structure created by the interaction of infill soil, strip material and cell geometry.  The high-strength, creep resistant cellular confinement system technology maintains soil compaction to provide long term and reliable soil reinforcement.

Due to its unique Neoloy® composition, PRS-Neoweb provides more structural geosynthetic reinforcement for the subgrade and/or base of any pavement than any other geosynthetic solution. PRS-Neoweb improves the moduli of infill materials (MIF Modulus Improvement Factor) to strengthen the pavement layers. PRS-Neoweb geocell is the only high-strength, creep-resistant geocell with a design life aligned to the needs of today’s transportation infrastructure for long-term base reinforcement for highways, railways and ports.

PRS-Neoweb Sustainable Solution

PRS-Neoweb (Tough Cell) improves the strength (layer modulus) of non-cohesive, inferior fill, such as fine granular soils and sand. Not only does this reduce the layer thickness of each structural layer and reduce the amount of required infill. PRS-Neoweb cellular confinement systems enables high-quality ‘imported’ aggregate to be replaced with less expensive locally-available granular soils for infill. Whereas, the cost or availability of aggregate can be crucial to projects, with PRS-Neoweb infill costs are lowered, construction is faster, and a more durable road is constructed.

These benefits decrease the amount of excavation, hauling, and placement and compaction resulting in significant economic and environmental gains. Reinforcement with PRS-Neoweb also increases the service life of pavement structures, thereby reducing their operational and maintenance cost requirements.
 
Benefits

Engineering

  • 3D geocell “beam effect” with high flexural strength and stiffness
  • Use available native, sandy or recycled soil for base infill instead of high cost aggregate
  • Distribute loads evenly and increase bearing capacity
  • Reduce structural layers’ thickness and bituminous wearing course by 5-25%
  • Outperforms any geogrid

Material

  • High dimensional stability
  • Very high creep resistance
  • Very long-term allowed stress for design under high temperatures (60°C)
  • Outperforms any HDPE geocell

Operational

  • Fast all-weather installation
  • Reliable long-term performance
  • Decrease surface degradation, rutting, fatigue
  • Less repairs and downtime

Economic

  • Lower construction costs – initial savings
  • Increase pavement lifespan – long term savings
  • Extend maintenance schedules and reduce costs
  • Shift limited road resources/budgets from repairs to new construction

A 3D cellular confinement system, such as PRS-Neoweb™ is a honeycomb geocell structure created by the 3D interaction of soil, cell walls and geometry.  Geocell cellular confinement system maintains soil compaction, thereby increasing the structural strength of the infill and pavement layer.

The key geocell reinforcement mechanisms are lateral and vertical cellular confinement, beam effect and improved load distribution. When the confined soil within a geocell is subjected to loading, it causes lateral stresses on the cell walls. The 3D zone of cellular confinement reduces the lateral movement of soil particles while vertical loading on the contained infill results in high lateral stress and resistance on the cell-soil interface.

The  high-strength geocell mattress created by PRS-Neoweb (Neoloy based geocells), acts as a flexible beam, which reduces stress and settlement. In addition cellular confinement increases the elastic modulus values of granular infill materials, particularly inferior fill, such as fine granular soils and recycled materials.

These mechanisms highlight the importance of geocell stiffness – a key difference between PRS-Neoweb and other geocells.
 
Benefits

Technology

  • Lateral confinement – of infill materials prevents movement and shearing of infill under loading.
  • Infill stiffness – transfers vertical forces to hoop stresses and by passive resistance.
  • Vertical confinement – due to frictional resistance between infill, cell walls & base acting as mattress
  • Distribution – of lateral and vertical stresses is maximized
  • Aggregate – movement and attrition are minimized

Engineering

  • Excellent hoop strength and stiffness – prevents deformation and increases durability
  • 3D zone of influence – to maximize the reinforcement mechanism
  • High creep resistance – enables reliable long-term performance
  • Better load transfer – by reducing applied load settlements
  • Reduced aggregate attrition – from traffic vibrations
  • Subbase spreads applied traffic loads – thereby reducing vertical stresses on subgrade
  • Lower vertical stresses – increase subgrade strength and reduce thickness of structural layers

Economic

  • Lower construction costs – initial savings
  • Increase pavement lifespan –lifecycle savings

Although the runners in a marathon start together, their performances differ as the race goes on. The same is true for geocells. Geocells must retain their performance over time, e.g., maintain their 3D geometry (dimensional stability), for the reinforcement mechanisms (wall stiffness, beam effect and elastic modulus) to function. Deviation in geocell geometry will weaken the pavement and cause fatigue failure.

The advanced Neoloy polymer alloy provides the PRS-Neoweb™ geocell with the optimal combination of strength, stiffness and durability. PRS-Neoweb maintains its stiffness and geometry for the geotechnical project lifespan under dynamic loading, thermal cycling and high temperatures. Pavement layers and subgrade reinforced by PRS-Neoweb improve the level of pavement stability and uniformity, thereby increasing the performance and life of the pavement.

The result is significantly less road repairs and rehabilitation, as well as decreased use of raw materials, making road construction more sustainable and more economical. The end result is reduced maintenance, a cost-effective solution and fast return on investment.

The high modulus PRS-Neoweb has been calibrated for use with today’s mechanistic empirical models (MEPDG) for road design (e.g., AASHTO Roadside Design Guide). PRS-Neoweb's long-term strength makes it a 'perpetual geocell', suitable for the base of perpetual pavements and perpetual railway superstructures.

Benefits

Engineering

  • Stiff and Strong – very high tensile strength, up to 28 MPa, prevents fatigue
  • Confinement – increases pavement layer strength (modulus) regardless of bearing capacity (CBR)
  • Reinforcement – reduces layer thickness and wearing course by up to 50%
  • Beam effect – improves load transfer and bearing capacity by up to 50%
  • Improves elastic modulus – by factor of 2-5 for heavier traffic and longer pavement lifespan

Economic

  • Simple logistics – and fast all-weather installation
  • Lower costs – of infill, compaction, construction
  • Reduce maintenance – repairs, maintenance cycles and downtime
  • Extended lifespan – lowers life cycle costs and suitable for perpetual pavements

Environmental

  • Lower grade infill – Use locally available, ungraded or recycled materials for infill
  • Reduce pollution – quarrying, hauling, fuel, pollution, carbon footprint
  • Green – sustainable construction method

Novel Neoloy Polymer Alloy

  • Patented technology – provides very high stiffness, dimensional stability, creep resistance
  • Durable – long-term performance under heavy dynamic loading
  • Advanced engineering – suitable for very perpetual pavements
  • High performance– outperforms any other HDPE geocell

The goal of geosynthetic reinforcement is to optimize the resources used to construct a solid, stabilized base and subbase for the pavement or other construction. Failure to provide an adequately stabilized base results in frequent and expensive repairs. PRS-Neoweb geocell is an ideal geosynthetic soil stabilization and reinforcement solution for geotechnical engineering. PRS-Neoweb cellular confinement creates a reinforced mattress with a beam effect with unbounded base material.

  • Compared to 2D geosynthetic products, such as geogrids and geotextiles, geocell confinement in three dimensions better minimizes the lateral as well as the vertical movement of soil particles. This results in a higher locked-in confining stress and thus a higher modulus of the base.
  • Conventional ground stabilization solutions (soil replacement, additives, or thicker base layers) either do not provide sufficient long-term stability and strength for transportation engineering and/or entail higher costs and environmental impacts.

PRS-Neoweb reinforcement outperforms any other geocell, geogrid or geosynthetic solution. See for yourself how PRS-Neoweb compares:

Benefits of PRS-Neoweb

  • Improve layer modulus – using lower quality, local available or recycled infill
  • Reduce layer thickness – more than any other solution
  • Long-term performance – extend pavement life more than other solutions
  • Easy and fast deployment – all-weather installation and all-weather roads
  • Sustainable solution – reduce aggregate use as well as labor, equipment, resources
  • Minimize maintenance – stronger pavement reduces ongoing repairs and rehabilitation cycles.
  • Cost effective – lower construction costs and lifecycle costs

PRS invests considerably in research, development and in-situ field testing. The goal of PRS R&D was to create a tough new generation of geocell technology and performance. The result of this intensive program was the development of a patented novel polymeric alloy called Neoloy®.

Research and testing on PRS-Neoweb geocells from Neoloy was conducted in collaboration with leading international researchers, geotechnical engineering universities, industry research institutes and government transportation agencies in the US, Canada, Japan, Russia, England, Poland, Germany, Holland and India, among others. These helped test and refine the new generation Neoloy geocell technology by:

  • Determining performance parameters and engineering proofs for reliability
  • Modeling and calibrating design methodologies
  • Establishing standards and specifications along with academic, professional and industry accreditation, such as the Geosynthetics Institute (GSI);TRI Environmental (Texas
  • Research International); and ASTM technical committee D35 on geosynthetics.

As noted in Geosynthetics Magazine, PRS R&D efforts set an example of a fruitful iterative process between private industry and academia:

“Professor Leshchinsky and I note that this article…departs from...policy in an effort to offer a guideline, an example, of how product development for the geosynthetics industry can be done effectively. We hope these lessons can further advance the geosynthetics industry into the 21st century with much success.”  - Editors of Geosynthetics magazine.

PRS-Neoweb is revolutionizing the use of geocells for engineers and contractors. How? Because the high-strength of PRS-Neoweb geocells is manufactured in several different categories according to strength and other design factors. Now you can select the PRS-Neoweb type that fits the project requirements. The result is increased performance at lower cost, no matter which project type. PRS offers:

  • New design methods - Extensive R&D with PRS-Neoweb included calibration of design methods for use in unpaved roads (modified Giroud and Han method) and paved roads (layered elastic model method) integrating the PRS-Neoweb modulus improvement factor (MIF).
  • New specifications and standards - PRS developed new performance based specs that more accurately reflect the performance of geocells in the field than traditional methods.
  • Engineering consulting - as an engineering and technology company, PRS provides geotechnical engineering and design services to you maximize its effectiveness of PRS-Neoweb in each project.
  • New PRS-Neoweb categories - PRS developed four main types of geocells for each general application category. This enables optimization of the geocell (and maximizes cost-effectiveness) by matching the tensile strength and durability of PRS-Neoweb to the project requirements. 

Benefits

Engineering

  • Confinement increases layer strength (modulus)
  • Reinforcement reduces layer thickness and wearing course
  • Beam effect improves load transfer and bearing capacity
  • Modulus Improvement Factor (MIF) allows more traffic and for longer time
  • More reinforcement than any geogrid

Economic

  • Simple logistics and fast all-weather installation
  • Lower construction, infill costs
  • Improve pavement lifespan
  • Reduce repairs, maintenance cycles and downtime

Environmental

  • Use locally available, ungraded or recycled materials for infill
  • Reduce quarrying, hauling, fuel, pollution, carbon footprint
  • Green sustainable construction method

Novel Neoloy Polymer Alloy

  • Provides very high stiffness, dimensional stability, creep resistance
  • Long-term performance under heavy dynamic loading
  • Outperforms any other HDPE geocell

One shoe doesn’t fit all. Neither does one geocell fit all projects. PRS enables you to customize your geocell to fit the project thereby maximizing your cost-efficiency. PRS-Neoweb is manufactured according to several project profiles so you can match it with the specific requirements of your project.

First analyze the project according to typical stresses, loading, environmental durability and temperatures. Then match the project requirements with the PRS-Neoweb Category Table and Flow Charts below to choose the appropriate PRS-Neoweb type, according to the tensile strength and durability.  Of course, each geocell type is available in different size cells and wall heights to fine-tune the solution.

Benefits

Project Optimization & Costs

  • Customized geocell –  according to project requirements and design-life
  • Optimize project costs – can be reduced by up to 50%
  • High long-term performance – Neoloy® geocell technology inside each cell

Improved logistics and handling

  • Up to 50% more sections / pallet / container
  • Ease of installation
  • Sections are easier to carry, handle, layout
  • Available section sizes  up to 50% larger
  • Installation time decreased significantly

Table of PRS-Neoweb Categories A B C D

The following chart explains how to select the PRS-Neoweb that matches the actual needs of the project categories, pre-calculated by typical stresses, loading, photochemical durability, elevated temperatures and design-life and not just the cell dimension.  Different cell sizes and wall heights are available according to design objectives.

PRS-Neoweb is manufactured from Neoloy, a novel polymeric alloy developed by PRS, based on polyester nano-fibers in a polyolefin matrix. Neoloy enables a strong and stiff PRS-Neoweb geocell with high durability, higher tensile strength, resistance to creep and high temperatures, and dimensional stability than commonly-used HDPE-based geocells.

PRS together with experts in geosynthetics (TRI, GRI, ASTM) has adopted new test methods for geocells, based on widely-accepted testing methods for polymer plastics in other industries. In addition to conventional seam weld and tensile strength properties, the advanced test methods utilized by PRS predict long-term behavior and accumulated plastic strain in a geosynthetic under loading with different mechanical stresses, frequencies and temperatures. These methods include:

  • TMA – Thermo-Mechanical Analysis
  • DMA – Dynamic Mechanical Analysis
  • SIM  – Stepped Isothermal Method
  • CTE – Coefficient of Thermal Expansion
  • DSC – Differential Scanning Calorimetry

These test methods more accurately reflect 3D geocell geometry and material performance in the field rather than tests of individual strips and virgin materials. Although not yet adopted by the geocell industry these commonly used ASTM/ISO standards have been adopted by PRS for reliable and verifiable assessment of geocell properties and long-term performance.

The PRS-Neoweb design methodology is based on using the Tensile Strength at Yield to calculate the Long-Term (allowable) Design Strength - LTDS, according to the design life of each project. This value however, is the maximum tensile strength at maximum deformation, and therefore needs to be limited by the following commonly-accepted design reduction factors:

  • Creep Reduction factor
  • Oxidation & Photochemical Reduction Factor
  • Installation Damage Reduction Factor
  • Elevated Temperatures (optional)

Whereas the applied tensile forces acting upon a geocell in different applications can be determined, each general application category has different requirements. Therefore, PRS developed four main types of geocells for each general application category. This enables optimization of the geocell (and maximizes cost-effectiveness) by matching the tensile strength and durability of PRS-Neoweb to the to the application project requirements. 

This approach departs from commonly accepted practice of using standard, traditional geocells (of different sizes and heights) for all types of slopes, roads and retaining walls, and never taking into account design requirements, which leads to over/under design performance.

The extensive research, development, testing, and patents and the novel Neoloy polymeric alloy for PRS-Neoweb™ geocells are evidence of PRS’ leadership in the field of geocells. These efforts included collaborative research with world renowned geotechnical experts and researchers, with over 40 professional papers published and presented in the last few years alone.

The collaborative testing and certification program also included leading institutes and transportation authority’s around the world, such as the US Federal and state Departments Of Transportation (DOTs), The Mid-America Transportation Center, the US Federal Railroad Administration (FRA), RZD Russian National Railways, KOAC-NPC Road Standards Institute, Holland, Indian Roads Congress and other standards, geosynthetics and transportation bodies around the world.

Below are the categories of published research with PRS-Neoweb.

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