Modern infrastructure is groaning under the pressure. Trucks are getting heavier by the day. Volume of every loading and unloading yard set to explode as carrier container size increases and training yard’s cargo receivers dump liberal containers and enhance the logistics of oil and produce; ground beneath railway tracks continues to be maddened and stamped upon day after day.
Weak ground is a
The old methods of treating roadbed unreliability are too costly and time consuming in effect to be of real use. That is why products for reinforcement have enjoyed such a growth in use; geotechnical engineers and contractors of every description want load distributing surficial filler fabrics that do not require deep earth works.
Among many such products, one in which confidence is growing is the high and mighty high tenacity polyester geogrid. Suited to heavyload tracks, paving and loading yards subject in service to frequent tensional stress, the high modulus, low creep deformation HTPM has cut its teeth in some of the heaviest oil and produce terminals in harsh ground.
This article outlines the ins and out of the lightweight high tensile polyester geogrids, and of the service they are rendering to modern civil engineering.
What is High Tenacity Polyester Geogrid?
Normally manufactured from high tenacity polyester filaments, warp knitted into separate gridpatterned units, the resulting lightweight drawing is, albeit not too thickly, coated with either PVC, or bitumen or some chemical compound which again reacts with earth to protect the polyester.Typically wrinklefree, such coating recovers in percentage of elongation while the drawing is ground statically and loadspread through friction, stabilising overall up to three degrees of camber. Geogrid durability means overall tensile performance is still available years down the line.
The highmodulus GTS ‘feels’ high and steadfast, dropping a lesser creep deformation compared to a lesser carbon plasticandpolyester georod inservice. For this loadbearing isostatic nets s instant success in reinforcing horns and claws for many, many applications.Common products are: High Tenacity Polyester Geogrid, PVC Coated Geogrid, Warp Knitted Geogrid, Bitumen Coated Geogrid, PET Geogrid, Uniaxial Geogrid, Biaxial Geogrid, Multiaxial Geogrid, etc. Different structures are adopted based upon client specs and loading conditions.
Why Hea vy Load Areas should be Strong Soil Reinforced
Any heavy load put upon a location causes problems to the underground layout of soil. Over time the earth loses its volume and becomes deformed thus being pushed out of shape carving for instance.
Heavy load applications consist of: highways and expressways, port container yards, airports pavements, railway subgrades, mining haul roads, industrial storage yards, earthwork retaining wall systems, soft soil earth embankments etc.
Heavy loading produces problems of: rutting, differential settlement, cracking, aggregates displaced, subgrade failure etc. The weak soils of the foundation are particularly deformed. Some flood produces “clay slush silt”, which s deformed through traffic.
This is where you try to find good earthreinforcement. A reinforcement that will not be affected unfavourably by soft earth. Constituted from the ideal aggregates, a high tenacity polyester geogrid delivers also drainage help. Lower units applied load with good tensile strength
A lot of the benefits of a good geogrid come from improved tensile strength. The placement of polyethylene geogrid within aggregates, allows for stability through confinement of the aggregate within the grid when bound in. Aggregate “ties” itself to the apertures in the grid, called interlocking. This prevents top movement of aggregate from doing so and wheel units pressure is conveyed through a larger area. Wheel pressure units are distributed effectively. Surface isn’t deformed as easily and overall stability of pavement increases. In some cases, base thickness may be even cut step down.
Pavement crumbling induced via heavy traffic and some difficult alignment and sites like container terminal in mines are loaded pad whenever heavy equipment is continuously moving. Otherwise geogrid products may even stretch through an inordinate amount and become ineffective quite quick. High Tenacity Polyester Geogrid exhibits stable tensile behaviour under continuous load.
Typical products for these cases are TGDG120KN, TGDG160KN, TGDG200KN which provide a high load carrying capacity.
Low Creep Performance Extends Life
Creep is fairly important in our sphere here. It’s the slow and gradual deformation of a material under constant load / over long periods of time. Some reinforcement materials creep an entire lot, which leads to gradual settlement in any structure overall and could lead to possible instability.Polyester geogrids are far less susceptible to creeping compared to most regular plastic reinforcement products, so are perfect for: Reinforcements for retaining walls Embankment Reinforcements Reinforcements for Reinforced Soil Structure (RSS) Reinforcements landfill / transfer station Steep Slopes For the projects this matters due to loads being permanent over many years, so the reinforcing will stay dimensional stable for the whole length of life of the project. The High Tenacity Polyester Geogrid can provide this long term performance so that designers can replace with design criteria more safely.
Excellently used for Soft Soils Stabilization of soft soil is a common use for the polyester geogrids. Either weak subgrade soils, low bearing capacity, that are easily deformed by rapid application of heavy loads, and deform rapidly deep into the subgrade – or simply to form an aggregate base. With the geogrid placed somewhere in between the subgrade and aggregate base, the load spreads better and the geogrid also separates out the aggregate from the soft subgrade. Again many advantages accrue with this process:- Better bearing capacity Less depth of ruts Greater efficiency of compaction Less aggregate needed for the task Time saving on the job Particularly important when there is the need to overlay previously laid road in soft clay or wet ground, now roads have to be left for a considerable time to come to natural settlement. In this way they are able to lower material costs and build more quickly.
Multidirectional Reinforcement
In a wide range of infrastructure projects, Biaxial Geogrid and Multiaxial Geogrids are beneficial as they provide reinforcement in multiple planes.
Strong Chemical and Environmental Resistance
Areas subjected to the burden of heavy loads are often exposed to extreme environmental conditions. Industrial sites may be heavily contaminated with oils, chemicals or even acidic treatments. Landfill projects produce aggressive leachates. Road surfaces are subject to moisture and temperature cycles.
The additional coating on polyester geogrids serves to improve durability in terms of chemical corrosion, UV exposure, biological degradation and moisture penetration. For such projects, PVC Coated Geogrid and Bitumen Coated Geogrid may be more applicable.
Such inherent durability serves to extend longterm reinforcement service and reduce maintenance.
Better Pavement Performance and Lower Maintenance Cost
Road maintenance can be devastatingly expensive; continuous work on them has an equally telling effect on traffic efficiency too. The Geogrid reinforcement produces significantly better performance through the entire pavement. Better overall structural stability means less distress. Confining the aggregate layer means considerably less downward deformation is applied to the surface, and cracking and rutting takes much longer to occur. In the end the pavement:Lasts longer, Is not maintained as frequently, Becomes less costly to repair, Creates less traffic upheaval.For government and infanstructure investors, this longterm saving is vital; many highway authorities now nominate geogrid reinforcement for the compulsory design of heavy duty pavements.
Ideal for Retaining Walls and Steep Slopes
High Tensile Polyester Geogrid is often used for reinforced retaining walls and for slope protection. In this situation, the geogrid reinforces the soil mass internally, effectively creating a single composite whole capable of resisting lateral earth pressure.
Compared with concrete retaining structures, reinforced soil structures generally have the following advantages;
Lower construction cost
Faster assembly time
Greater flexibility
Enhanced seismic performance
Reduced foundation pressure
Geogrid also satisfies the needs of steep slopes and embankments, helping to avoid sliding and erosssion of the slope.
Uniaxial Geogrid are often the geogrid product of choice for retaining wall reinforcement because of their high tensile strength in one predominant direction. Here are some typical applications for High Tenacity Polyester Geogrid.
Common Heavy Load Applications for Polyester Geogrid
High Tenacity PolyesterGeogrid is utilised in a broad cross-section of engineering, worldwide.
Typical applications include;
Highway ConstructionUtilised for base reinforcement, subgrade stabilisation and improving pavement life
Railway InfrastructureImproves ballast stability and is used to limit track settlement under repeated train loading
Port and Container YardsTake the wheel loads from cranes and container transport vehicles
Mining RoadsUsed in support of heavy haul truck traffic in weak ground conditions
Airport PavementsProvides structural reinforcement for runways, taxiways and aprons
Landfill EngineeringUsed for reinforcing landfill slopes and for improving foundation stability
Retaining Wall SystemsIncluding Mechanically Stablilised Earth structures, Reinforced Soil Walls, etc.
Selecting the Right Geogrid for Heavy Load Projects
Selecting the most appropriate geogrid for your project depends on a number of engineering factors;
What kind of soil condition is it?
What is the load intensity?
How long do we need it to last?
What tensile strength do we need?
What is the appropriate aperture size?
Can we use the geogrid for improving creep behaviour?
What type of coating do we need and how exposure to the geogrid?
Provisionally; Uniaxial Geogrid for retaining wall applications, Biaxial Geogrid for road base reinforcement, Multiaxial Geogrid to disperse load in all directions, Fibreglass Geogrid for asphalt reinforcement, Steel Plastic Geogrid for particularly demanding use.
It is obvious that every engineering design should include cross referencing between actual conditions on-site, and the specified geogrid to achieve an optimal solution.
Summary
Heavy load developments present a big demand on our road system. Make a mistake when re-enforcing ground for pavement, on embankments or for industrial paving, and things can all too quickly go wrong.
Fortunately, with High Tenacity Polyester Geogrid, it is possible to attain significant improvement in soil stability, as well as the structural performance of a road. The warp of this geogrid provides a high level of resistance to creep behaviour and gives long-term performance potential.