TYPES OF REINFORCEMENT

MATERIALS

IN GROUND IMPROVEMENT TECHNIQUES

REINFORCEMENT MATERIALS

STEEL

FIBRE

GEOGRIDS

THERMOPLASTICSGEOTEXTILE GLASS

GEOCOMPOSITE

MAIN OBJECTIVE :

To change unfavorable conditions into more suitable for the support of structures.

To reduce downdrag forces.

To reduce Seepage loss.

To protect against uplift pressures.. etc.,.

MATERIAL CONCERN:

• Strength

• Durability

• Stability

• High coefficient of friction

• Low cost

• Availability

STEEL:

Reinforcement steel is a common steel bar, and is commonly used as a tensioning device in reinforced concrete and reinforced masonry structures holding the concrete in compression. It is usually formed from carbon steel, and is given ridges for better mechanical anchoring into the concrete.

Concrete is a material that is very strong in compression, but relatively weak in tension. To compensate for this imbalance in concrete's behavior, rebar is cast into it to carry the tensile loads.

While any material with sufficient tensile strength could conceivably be used to reinforce concrete, steel and concrete have similar coefficients of thermal expansion.

Fiber-reinforced polymer rebar is now also being used in high-corrosion environments. It is available in many forms, from spirals for reinforcing columns, to the common rod, to meshes and many other forms. Most commercially available rebars are made from unidirectional glassfibre reinforced thermoset resins.

Steel reinforcement:

Steel reinforcement:

FIBRE:

Fibre is a filament or thread like piece of any material.

Fibre-reinforced plastic (FRP) are composite materials made of a polymer matrix reinforced with fibres.

Fibre reinforced plastics are a category of composite plastics that specifically use fibrous materials to mechanically enhance the strength and elasticity of plastics.

PROPERTIES:

•Corrosion resistance•Light weight•Durable•Least maintenance required

ADVANTAGE:

•FRP can be applied to strengthen the beams, columns and slabs in buildings. It is possible to increase strength of these structural members even after these have been severely damaged due to loading conditions.

Fibre reinforcement:

Fibre reinforcement:

GEOTEXTILE:

Geotextiles have similar properties to fabrics and are flexible.

Geotextiles (also called geofabrics) have a very wide range of applications in geotechnics and drainage.

Continuous sheets of woven, non-woven, needle punched or thermally bonded fibres or yarns.

Geotextiles can be used as reinforcing layers in the construction of embankments and are laid between layers of compacted fill.

ADVANTAGE:

•Geotextiles were successfully used in the construction of an embankment over the floodplain, i.e. soft alluvial soil with high water table.

•The geotextile was placed to separate the subgrade from the imported granular fill forming the drainage blanket .

•Filtering properties of geotextiles are also exploited by manufacturing them in tubular form for use as vertical drains.

Geotextile:

Geotextile:

GEOCELLS:

A deep (1m) layer of interconnecting strips of geogrids/geofabrics filled with granular material to create a stiffened basal layer which can be used to control differential settlement under embankments constructed on compressible ground.

Geocells provide three dimensional reinforcement to soil by physical confinement into a honeycomb like structure.

Geocells might be made of polymeric fabric or grids and are delivered to site flat-packed.

ADVANTAGE:

•Geocells can be used as basal reinforcement to embankments or as sub-base reinforcement to paved and unpaved roads.

•They can be used over soft compressible soils or to limit the thickness of the subbase layer required.

Geocell:

Geocell:

Geocell (tree root protection):

GEOCOMPOSITES:

A generic description for products made from any combination of two or more geosynthetic components to fulfill a specific function or functions.

Thus providing savings in construction time and enhanced performance.

Depending on the composite design, they can work as a barrier, drainage, filtration, protection, separation or reinforcement layer.

ADVANTAGE:

•Geocomposites might be used as barriers/separation layers to separate and contain polluted soil or waste and avoid migration of pollutants to the surrounding soil or water.

•In railways applications, geocomposites can replace the sand layer separating the track ballast from the foundation, performing the same function of stopping the upward migration of fines.

Geocomposites:

Geocomposites

Geocomposites

GEOGRIDS:

Open grid-like meshes formed of different polymers.

Usually produced with a range of strengths in either a biaxial orientation (meaning strength in both directions), or uni-axial, (meaning strength in one direction only), or tri-axial (with a honeycomb appearance and strength in all directions).

The apertures within the grids may therefore be square, rectangular or triangular.

ADVANTAGE:

•For embankment construction using reinforced soil techniques, layers of geogrid are used to reinforce the fill and connect to a soft or hard facing at the slope surface.

•Geogrids can be used for erosion control at the surfaces of embankment and cutting slopes.

•hey protect and retain the surface soil from the actions of rain and water run-off and assist in preventing debris slides.

Geogrid:

Geogrid:

Geogrid:

THERMOPLASTIC:

RTP is a generic term referring to a reelable high strength synthetic fibre (such as Glass, Aramid or Carbon) reinforced thermoplastic pipe.

Primarily, the pipe provides benefit to applications where steel may rupture due to corrosion and installation time is an issue.

Typically, the materials used in the construction of the pipe might be Polyethylene (PE), Polyamide-11 or PVDF and may be reinforced with Aramid or Polyester fibre although other combinations are used.

ADVANTAGE:

•The great advantage of this pipe is also its very fast installation time compared to steel pipe when considering the welding time as average speeds up to 1000m/day (>3000ft/day) have been reached installing RTP in ground surface.

Thermoplastic reinforcement:

Thermoplastic reinforcement:

Engineering Consideration:

Great care should be taken while installing this reinforcement materials.

Material which is selected for reinforcement should match the soil conditions.

Analysis of the site should be made before any reinforcement work get started.

REFERENCES:

Books:

Ground Improvement Techniques - Dr.P.Purushothama Raj

Geosynthetic soil reinforcement testing procedures - S.C.Jonathan cheng

Websites:

aggregain.wrap.org.uk/geosystems/geocomponents/geonets.

THANK YOU…