15 November 2019

Spotlight-TechFab India

Techgrid PP Biaxial Geogrids

 

TechFab India a major manufacturer of geosynthetics, is among few companies to have GAI-LAP (Geosynthetics Accreditation Institute Laboratory Accreditation Programme), awarded by the Geosynthetic Institute USA. One of its products, TechGrid PP, has multiple applications in the construction sector.

 

 

TechGrid PP – A World-Class Biaxial Geogrid

 

TechGrid PP is a family of integrally formed biaxial geogrids manufactured from superior grades of polypropylene using a precisely controlled punching and drawing process. The product is manufactured in Techfab India’s state-of-the-art manufacturing facility in Daman, Union Territory and Dadra & Nagar Haveli. Stringent controls on raw materials and manufacturing process ensures a high quality product with consistent geometry, integral junctions, superior mechanical properties, and excellent durability.

 

TechGrid PP’s aperture dimensions and rib geometry ensures extremely efficient interlocking with a wide range of soils and granular materials including sands, gravel, crushed stone, moorum, granular subbases and bases in roads, and blanket and ballast in railway tracks. The monolithic nodes with very high junction strength enable full load transfer between the ribs in both machine and transverse directions. TechGrid PP with its high tensile strength and modulus, high junction strength and aperture rigidity mobilizes high tensile loads at small strains and is extremely efficient in reinforcing soils and granular materials. Reinforcing with TechGrid PP, greatly enhances the structural strength and stiffness and load distribution capacity of granular layers. TechGrid PP has excellent durability with its high resistance to weathering, most chemicals, and biological organisms normally present in soils. TechGrid PP is the ideal choice for reinforcement of soils and granular materials for applications which require multi-directional load dispersion.

 

TechGrid PP is available with tensile strength of 20, 30, and 40 kN/m (in both machine and transverse directions), and with aperture dimensions of 38 x 38 mm and 65 x 65 mm.

 

 

 

Virtues of TechGrid PP

 

Incorporation of TechGrid PP at the bottom and/or within a granular layer can result in an appreciable improvement in the system performance through four effects:

  • Separation effect
  • Lateral restraint effect
  • Tension membrane effect
  • Bearing capacity improvement effect.

 

 

 

Separation Effect

 

When granular materials like gravels or aggregates are placed on weak and compressible soils like soft clays and silts and subjected to load, there is a tendency for the granular particles to penetrate into the soft soil below. This happens during initial placing, spreading, and compaction, and also due to trafficking during service. Loss of aggregates into the soft soils below results in a reduction in the designed thickness of the layer and consequently its structural capacity. However, if a biaxial geogrid like TechGrid PP is positioned at the bottom of the granular layer, the grid resists the downward movement of the granular particles and functions as a separator between the granular layer and the soft soil, preserving the as-placed thickness of the granular material. In cases, which require filtration in addition to separation, a nonwoven needle-punched geotextile like TechGeo Nonwoven Geotextile could be used in combination with TechGrid PP Biaxial Geogrid.

 

 

 

Lateral Restraint Effect

 

When granular layers are subjected to repeated traffic loads, the applied vertical stresses tend to push the granular particles laterally away from under the load. Reinforcement of granular layers with geosynthetics offers lateral restraint to the granular particles thereby directly resisting the lateral movement of granular particles and resulting in an increase in average confining stress. Lateral restraint results in the following benefits:

  • Horizontal and vertical strains within the aggregate layers are significantly reduced.
  • Because of higher confining stress the modulus of granular layer is increased enabling it to distribute stresses over a wider area. Vertical stresses and strains in the subgrade are reduced.
  • Shear stresses and shear strains in the subgrade are reduced.

TechGrid PP with its extremely efficient interlocking with granular materials and high tensile strength, stiffness, and junction strength, provides a very high degree of lateral confinement and greatly enhances the structural efficiency of granular layers.

 

 

Tension Membrane Effect

 

The deformations of the soil below induce compatible strains in the geosynthetic reinforcement leading to development of tension in the geosynthetic. The upward component of tension developed in the reinforcement directly below the loaded area resists the vertical loads, while the downward component of tension immediately beyond the loaded area confines the soil. For tension membrane effect to develop to a significant degree, appreciable deformations are required. This effect could be made use of in applications like unpaved roads, working platforms, load transfer platforms, subsidence prone areas etc.

 

 

 

Bearing Capacity Increase Effect

 

The geosynthetic reinforcement intersects potential bearing capacity failure surfaces, which instead of passing through the weaker soils below, now passes through the stronger granular layers. This results in a considerable increase in the bearing capacity of the system.

 

 

 

Benefits of using TechGrid PP

 

Reinforcement of soils and granular materials with TechGrid PP Biaxial Geogrids results in several benefits:

 

  • Functions as a separator - preserves the designed thickness and integrity of granular layers placed over weak soils
  • Acts as a working platform and capping layer over weak soils supporting the movement of construction plant, preventing excessive deformation of subgrade, and facilitating proper compaction of the granular layers
  • Enhances the structural performance of granular subbase and base courses in unpaved roads and flexible highway and airport pavements
  • Improves the performance of ballast and sub-ballast/blanket layers of railway trackbeds
  • Strengthens the foundations of hard standages, factory and warehouse floors, and storage areas
  • Improves the performance of load transfer platforms for pile/column supported embankments
  • Spanning voids in subsidence prone areas – mining, sink holes, etc.
  • Prevents surficial slope face failures when used as secondary reinforcement

 

TechGrid PP can be used to engineer efficient and economic solutions by minimizing replacement of soft soils, facilitating construction by ensuring access to and trafficabilty of the site, making possible substantial savings in granular materials, improve performance, reducing maintenance, increasing service life, etc. TechGrid PP can be used to achieve immediate cost savings by reducing granular layer thickness and/or to reduce the whole life cost.

 

 

 

Applications of TechGrid PP

 

TechGrid PP has a large number of applications in highways, railways, airports, ports, construction, mining, industries, logistics etc. The important applications are summarized below:

 

  • Unpaved roads: Rural roads, access roads, mine haul roads, forest roads
  • Flexible pavements: Highway, airport and port pavements; below or within granular subbase or granular base
  • Rail trackbeds: below and/or within blanket and/or ballast; construction of new lines and also rehabilitation of existing lines
  • Hard standages: Below/within granular subbases or base layers of parking lots, storage yards, container stations, ports
  • Floors: Below/within granular layers below heavily loaded floors of factories and warehouses.
  • Working platforms: To support movement of construction equipment and plant on sites underlain by soft soils
  • Load transfer platforms: Embankments supported on granular columns or concrete piles
  • Void spanning: Roads, railways and other facilities in subsidence prone areas with abandoned mines sink holes and other underground cavities
  • Secondary reinforcement in reinforced soil slopes and embankments

 

 

 

TechGrid manufacturing process:

 

TechGrid biaxial geogrid are manufactured from carefully selected grades of polypropylene .A long duration life is required in civil engineering applications and the grade of PP used in TechGrid associations the optimum values of the strength, stiffness, toughness, and durability.

 

Biaxial geogrids are made by extruding a sheet of PP to very precise tolerance, punching an accurate pattern of holes, than stretching the sheet under controlled temperature, firstly in the longitudinal direction, than in the transverse direction.

 

This process creates a geogrid with square and rectangular apertures, called a biaxial grid because it is stretched in two directions.

 

 

TechGrid Quality Control Testing:

 

TechGrid biaxial geogrid’s quality control testing parameter is carried out using the International Standard, we followed following testing at our TFI In-house laboratory.

ASTM D 4595, ASTM D 6637 Method A & B, ENISO 10319,ASTM D 7737,ASTM D 4355,EN ISO 12224,ASTM D 1603,

 

The TFI quality control testing laboratory is accredited in accordance with ISO/IEC: 17025:2005, GAI-LAP, International Geosynthetics Society, and Association of Indian Laboratories.

 

 

 

Conclusions

 

TechGrid PP is a world-class integrally formed polypropylene biaxial geogrid manufactured in India by Techfab India Industries and is ideal for the reinforcement of soils and other granular materials in applications which require load transfer in multiple directions.

 

TechGrid PP strengthens and improves granular layers through separation, lateral restraint, tension membrane and bearing capacity improvement effects.

 

Techrid PP enables engineers to find proven, economic, constructible and sustainable solutions to diverse problems in the sectors of highways, railways, airports, ports, construction, mining, industries and logistics.

 

 

 

 

 




Leave a Comment

Name  
Email Address
(will not be published)    
Website
Comment