Geogrids are now regularly used in engineering applications to assist in stabilising soil, enhancing a site’s load bearing capacity and helping structures endure. There are many types of geogrids on the market today, with mono-oriented geogrid and bi-directional geogrid being two of the most specified options for soil reinforcement applications.
While both may be geogrids, mono-oriented and bi-directional seek to satisfy different engineering needs and choosing the wrong type can have serious consequences for project performance, construction cost and on-going serviceability.
In this article we look at the big differences between mono-oriented geogrids and bi-directional geogrids. Looking at the way they are manufactured, their mechanical properties, applications and the way they are selected.
What Is A Mono-Oriented Geogrid?
Also known as a Uniaxial Geogrid, throughout manufacture a Mono–oriented Geogrid (more commonly called mono-oriented) is formed following the punching of polymer sheets which are ideally drawn in a single longitudinal direction during the drawing process.Only developed very high tensile strengths in terms of their “machine” direction of manufacture.Most mono-oriented geogrids are either available in high-density polyethylene (HDPE) or polypropylene (PP), which will not only resist environmental attacks and chemical attack, but also considerably control the time dependent long-term creep effect present with geogrids.Where tensile forces are acting in one predominant direction to be resisted
What Is A Bi-Directional Geogrid?
Commonly known as Biaxial Geogrid; Bi-directional geogrids are drawn and stretched times across both the longitudinal and transverse directions. To increase the distribution of the load attempts across the reinforced soil mass.Biaxial geogrids are typically made of polypropylene (PP), HDPE or other engineered polymers. The square aperture aids interlocking of the aggregates and granular fill at the time of construction. As loads in many ground stabilization operations act in more than one plane, these types of geogrids are often used for the reinforcement of pavements and foundations. Production DifferencesMono Oriented GeogridsThe impt seeking of production is simply to adequately orient themacromolecular structure of the polymer only in one direction. The long thermi sheet is extruded and the apertures punched, and subsequently it is stretched longitudinally whilst the polymer is retained warm. This assists in orientating the polymer itself, and so gives the greatest optimum strength in the length of the grid. Then all final geogrids have very long apertures and ribs today best viewed as essentially one way signals.Production DifferencesBi-directional GeogridsThe bi-directional geogrids have thenegativevalues in the stretching (above mentioned) both along and athwart the way the grid is made. This tends to make a better balanced structure, and the grid will therefore exhibit similar properties in both ways. The apertures are often square or rectangular to assist restricting the aggregates, and help distribute out both the loads and transmittant s of the aggregates. Tensiogenic CharacteristicsMono Oriented GeogridThe one most notable is the high strength there only in one way. TGDG120KN, TGDG160KN and TGDG200KN are typical products.Grade High strength GeogridsThese high strength grades are used in wall retaining and in reinforced earthy structures. Strength concentrated in one way, and therefore satisfactorily resist lateral earth pressures.Bi-directional geogrid
These bi-directional geogrids enjoy the manufacturer’s claim of tensile strength being provided in both directions. Typical products are TGSG3030, TGSG3535, TGSG4040, TGSG5050. Yet the bi-directional geogrids, although weaker in ultimate strength than the high-strength uniaxial products, are more evenly weighted. The number of applications of a soil stabilisation application, utilising a multidirectional geogrid, are many.
Load Transfer
Monooriented
The way in which the loads are transferred is entirely different. Mono-oriented geogrids transfer the loads, in the main, from one direction, through tensile resistance, and act in a sense as reinforcing tendons to the mass of earth itself. Where the earth pressures which are involved in the problem of retaining walls are chiefly horizontally orientated this method of transfer is perfectly satisfactory.
Bi-directional
These incorporate the additional design capability of developing an interlock with the aggregate, the aggregate being tethered within the aperture. Therefore the confinement effect allows the gradation of the aggregate, through the apertures if you like, to mitigate lateral movement of the mass of soil to further aid load distribution, to increase the bearing capacity of weak soil.
Applications of Mono-oriented Geogrid Retaining Wall Reinforcement
Mono-oriented geogrids are widely used in retaining walls where unweighting of the back wall by reinforcement is desired, and the high tensile strength assists the stability of the masses being contained by the walls.Resist soil movement, which helps to provide a sounder earth retaining wall.
Steep Slope Reinforcement
Reinforcement for the level slope constructions (roads, paths tracks) made steeper as prevented by failure often have to resist considerable tensile force.Uniaxial geogrids enhance the stability of steep embankment and cut walls.
Reinforced Soil Structures (RSS)
The premise behind many of these structures is that mono oriented geogrids reduces the depth of required overall stability construction thus reducing the cost of being built.
These can replace retaining walls and are often used in walls of higher materials such as precast concrete.
Embankment Reinforcement
Often Reinforced Soil Structures of the taller of the embankments built on poorer ground are raised in height with a Uniaxial geogrids to uplift them sufficiently to eliminate best of settlement.
Application of a Bi-directional Geogrid
Biaxial is utilized for flat Road bed road miles.
Road Base Stabilization
The grid confines the aggregate the aggregates of the whole pavement spreading the traffic loading over a greater area to decrease the ruts and prolong to the end that a bit of a life of the rut road.
Parking Lots and Industrial Yards
The harder and lot of load the load the heavier the shifting and the more will be the damage to road traffic lot surfaces of the lot.
Bi-directional geogrids will sometime put into the ground, to be buried in “present base.Soil stabilisation in powder differs in its et al, and might do as a difference or support in bad of its part then can work at least as on maintenance if proves to work.
Soft Soil Stabilization
The ground under as on may not be difficult of carrying surface, and wheel chronicle of. Stabilized is of the soft soil, through improved bearing capacity soil, less liable to eccentric dos differential settlement.
Railway and Airport Construction
When do build of structure the required best performance of recent even for a number more reason they constructed. Working on the principle of confinement of.
Material Options
More the sorts of both is fair, project good: as kind of material to choose.
Having around as HDPE a Geogrid, that is resistant to chemicals and good in choice as in service.
They’re commonly utilized in landfill improvements and environmental applications.
PP Geogrid
PP geogrids offer good stiffness and are cost-effective. Consequently, they are commonly used for roadways and soil reinforcement.
PET Geogrid
PET geogrids are polyester geogrids, which offer great tensile strength with low creep. They are ideal for long-term reinforcements.
Fiberglass Geogrid
Fiberglass geogrids are another geogrid commonly used for asphalt pavement reinforcements. They help to reduce reflective cracking and enhance the overall performance of the pavement.
Installation Considerations
Correct installation is crucial for both types of geogrids.
With mono-oriented geogrids, it is critical to make sure the direction of primary strength is with the anticipated load direction. If oriented in the wrong direction, and the efficiency in that case significantly reduced.
Bi-directional geogrids are usually simpler to install as they’re giving reinforcement for both directions in general principal strength both the.
Regardless of this proper tensioning, overlapping, and compaction of the backfill is important to get that ‘most of its out performance’ from the geotextile.
Cost Comparison
Total costs of a project could depend on a number of facets, the type of geogrid, strength, and load and other requirements.
Mono-oriented geogrids tend to come at a higher unit cost because they are a specialised high-strength ext. However they can often be the most economical buy, however, of project. Particularly for things like retaining walls, etc, and reinforced soil structures types.
Bi-directional geogrids are more generally going to work out much more economical for projects using that road and foundation stabilize.
In most cases can lead to a lower overall cost by putting less of that in itself of fresh earth included and having it even less to maintain by simply selecting the right.
How to Brave Between Mono-and the same Bi-direction Geogrids.
You should start with an understanding of the loading on conditions.
Selecting a Mono-oriented Geogrid when:
- Reinforcement is required chiefly in one direction.
- When building retaining walls.
- When building steep slopes.
- Reinforcing embankment.
- For situation of designing reinforced soil structures.
Selecting Bi-directional Geogrid where: - These loads likely present themselves to come for various in multiple either directiones.
- for “that of the stabilizing’ partly the base layer of a your road.
- When “parking lots strengthening’.
- When they’re going laying does appear on of the sub grades either.
- All transport infrastructure tied in between of lays.
Ultimately, should be also described homes by guiding with engineer calculation dictated the soil conditions and of the project what the extreme specifications.
Conclusion
Mono-oriented Geogrids and Bi-direction Grids are different, but equally important functions.