Geogrid: Combigrid®

Combigrid® geogrids

Combigrid® is a composite of a laid geogrid made of stretched, monolithic flat bars with welded junctions and a mechanically bonded and calendered filter geotextile welded within the geogrid structure. Combigrid® is used for stabilisation and reinforcement of soils in many fields of infrastructure, environmental protection, and hydraulic engineering applications.

Typical solutions with Combigrid®

Geogrid solutions for unpaved roads
  • Reduced surface deformation (less rutting)
  • Reduced base course thickness (vs. unreinforced sections)
  • Reduced maintenance cycles
  • Extended service life
Geogrid solutions for paved roads and- storage yards
  • Reduced surface deformation (less cracks)
  • Reduced base course thickness (vs. unreinforced sections)
  • Reduced maintenance cycles
  • Extended service-life
Geogrid solutions fo railway construction
  • Reduced surface deformation (less cracks)
  • Reduced base course thickness (vs. unreinforced sections)
  • Reduced maintenance cycles
  • Extended service life
Geogrid- solutions for working platforms
  • Improved bearing capacity on soft ground
  • Reduced surface deformation (less differential settlement)
  • Reduced base course thickness (vs. unreinforced sections)
  • Economic alternative to deep foundation solutions (e.g., piles)

Advantages of Combigrid®

Combigrid® is a geocomposite stabilisation and reinforcement solution. The unique manufacturing process produces structured, high strength, monolithic, pre-stressed polypropylene or polyester bars with a continuous molecular orientation. The extraordinary high extensional stiffness of Combigrid® efficiently reduces deformations in the subgrade which extends the service life of modern infrastructure.

Stress / Strain behaviour

Geocomposites like Combigrid® are used wherever high strength is required at low elongation. The stress-strain behaviour (also known as tensile stiffness) of the geogrid is important when selecting, which type of geogrid is to be used. Geogrids will typically have a maximum elongation at break of 6% up to 15%, depending on the choice of polymer and manufacturing technology. However, the internal angle of friction of medium to densely compacted soils is reduced when the soil is subjected to axial strains of less than 2%. It is necessary to align the stress-strain behaviour of the installed geogrid with the strain behaviour of the soil. The performance of the geogrid at strain levels around 2% is therefore important and here Combigrid® shows its strength. Combigrid® provides excellent tensile strength properties at low elongations and demonstrates its advantages to hold the soil particles together at this important strain range.

Soil separation

The three-dimensional fibre matrix of the needle-punched Secutex® nonwoven, acts as separation layer between fine grained subgrade soil and coarse aggregate base course layers and ensures long-term filter stability. The properties of separation, filtration and reinforcement are combined in the product Combigrid®.

Tests to simulate the traffic passages on an unreinforced base course resulted in 3 inch (75mm) deep ruts after 20 load cycles, and it took 540 load cycles when Secugrid® 20/20 Q1 was used. However, when Combigrid® was used, the maximum rut depth of 3 inches was not reached even after 100,000 load cycles. Using a composite product made of a geogrid and a needle-punched nonwoven firmly bonded between the longitudinal and cross bars at the interface between soft subgrade and base course layer worked really well. Combigrid® – not just a geogrid. THE solution for infrastructure projects on low bearing capacity subsoil.

Stress-strain curves of different geogrids. Scaled up detail illustrates typical working strain levels (≤ 2% elongation)
Stress-strain curves of different geogrids. Scaled up detail illustrates typical working strain levels (≤ 2% elongation).
Combigrid® and Secugrid® traffic benefit ratio (TBR) over a very weak subsoil, compared to an unreinforced section (for subsoils CBR 1%, for details see EuroGeo4, paper 229)
Combigrid® and Secugrid® traffic benefit ratio (TBR) over a very weak subsoil, compared to an unreinforced section (for subsoils CBR 1%, for details see EuroGeo4, paper 229).

Software & more geogrids

Online calculator Software - design base course thicknesses for Secugrid® or Combigrid® stabilised and reinforced base courses in different applications such as working platforms for tracked plants (e.g. piling rigs), hardstands for cranes and heavy equipment, storage areas, etc.

Platform

With the Naue Platform Software, you can design base course thicknesses for Secugrid® or Combigrid® stabilised and reinforced base courses in different applications such as working platforms for tracked plants (e.g. piling rigs), hardstands for cranes and heavy equipment, storage areas, etc.

Platform Software
Online calculator software SecuCalc - designing base course thicknesses for Secugrid® or Combigrid® stabilised and reinforced base courses in road construction as well as for parking and storage areas or similar applications

SecuCalc

With the Naue SecuCalc Software, you are designing base course thicknesses for Secugrid® or Combigrid® stabilised and reinforced base courses in road construction as well as for parking and storage areas or similar applications.

SecuCalc Software
Calculator software for comparison of Secugrid®-reinforced steep slopes, walls and abutments.

SecuSlope

Software for the comparison of Secugrid®-reinforced steep slopes, walls and abutments.

SecuSlope 3.0
Secugrid® geogrids for soil stabilisation and reinforcement

Secugrid®

Secugrid® geogrids for soil stabilisation and reinforcement

Secugrid®
High Strength Geogrid Secugrid®-HS

Secugrid® HS

Secugrid® HS geogrids are laid geogrids made of high tenacity polyester filaments with an extruded polyethylene protective coating and welded junctions

Secugrid® HS

Secugrid® m3 System

Secugrid® reinforced slope and retainig wall systems

Secugrid® m3
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