geosynthetics engineering: in theory and practice 6.pdflecture - 6 an overview of geosynthetics...

GEOSYNTHETICS ENGINEERING: IN THEORY AND PRACTICE

Prof. J. N. Mandal

Department of Civil Engineering, IIT Bombay, Powai , Mumbai 400076, India. Tel.022-25767328email: [email protected]

Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay

Module - 2LECTURE - 6

AN OVERVIEW OF GEOSYNTHETICS


Introduction Categories of geosynthetics

Geosynthetics scope and definitions

Raw materials and machineries

Composition of geosynthetics

Types of geosynthetics and functions

Geosynthetic functional applications

Multiple functions of geosynthetics

Design of geosynthetic

Sustainability using geosynthetics

OUTLINE


INTRODUCTION

In the past four decades, extensive research has beencarried out on geosynthetics around the world.

It is required to attain good design, good research and atthe same time good material and good constructiontechnique to overcome the educational and technicalchallenges. The dynamic and rapid growth of geosynthetic is exciting,emerging and vibrant in the field of civil engineering.

Today, more than twenty billion square meters ofgeosynthetics have exclusively been used in several millionprojects (Giroud, 2012).


The jute geotextile was successfully used on Strand roadin Kolkata in 1934 by Bengal PWD and subsequently inMyanmar during 2nd world war. The jute geotextile had alsobeen used for erosion control in 1980.

The revolutionary development of geosynthetics has beenstarted in the early 1970s in the field of construction industry.

Geosynthetics provide proper solution to design andconstruction problems in spite of climatic, geographic ortechnological differences.

The uniqueness of geosynthetics is that they ensuremultifunctional performances and simple to use and providegreat economical potential advantages.


Unmodified Reinforced Spun bonded

Melded stabilized e. g. calendared

Non stabilized

stabilized Non stabilized e. g. calendared

Melded Reinforced

Needle-punched (thick) Needle-punched (thin) Monofilament Multifilament Silt film

Non-oven knitted woven

Geotextiles

Permeable Impermeable

Synthetic Natural Synthetic Natural

Textiles Webbings

Combination products

Steel, polymers Palm leaf, wood, bamboo

Cotton, jute, reeds, grass

Geomembrane

Closed mesh

Open mesh

Strips

Geogrids Reinforced earth

Combination products

polymers

Geosynthetics classifications (After Rankilor 1981)


GEOSYNTHETICS SCOPE AND DEFINITIONS What are Geosynthetics?

Geosynthetic is a product made of polymeric/natural material usedwith soil and rock, or any other related geotechnical engineeringmaterials for the construction of Civil Engineering structure, orsystem.

Why would we want to use them?

Sustainable development and environment protection can go hand - and – hand.

It reduces maintenance cost and increases life. It saves substantial cost over alternative solutions. The quality can be controlled as manufactured in a factory It is widely available. It has generic specifications and easy to install.


Optimum technical properties of Geosynthetics:

It has excellent stress-strain behavior

It has good flexibility

It has excellent filtration characteristics

It has high water permeability

It can provides excellent mechanical protection

It can be welded together

It does not form by-products

It is highly resistant to chemical and biological attack, and

It is chemically ultraviolet stabilizedProf. J. N. Mandal, Department of Civil Engineering, IIT Bombay

When can we use them?

Low bearing capacity of the soil Excessive Settlement of soil Soft soil treatment (Reclamation of Land) Limited space for construction Land Saving To control and protect the environment Swelling soil Faster Construction Saving in time Saving in cost Sustainable environmental safety To maintain quality assurance / quality control (QA/QC)


Where can we use them?

Geotechnical Engineering

Transportation Engineering

Geo environmental Engineering

Coastal/Hydraulics/Water Resources Engineering

Mining Engineering

Agricultural Engineering

Earth quake Engineering

Bio Engineering


How can we use them?

We can use geosynthetics based on their major functionsand specifications. There are six major functions:

Separation

Filtration

Drainage

Reinforcement

Protection, and

SealingProf. J. N. Mandal, Department of Civil Engineering, IIT Bombay

Who produce Geosynthetics?

Around the world there are many manufacturing companiesthat produce comprehensive range of Geosynthetics andany other related products used in Civil engineering andconstruction systems.

CATEGORIES OF GEOSYNTHETICS• Geotextiles (Knitted, Nonwoven, Woven)• Geogrid (Bonded, Extruded, Knitted, Woven)• Geomembrane (Bituminous, Elastomeric, Plastomeric)• Geonets• Geosynthetics Clay Liner• Geocomposite drains (PVD, Geonets or Geospacers)• Geopipes


• Geostrips

• Geospacers

• Geocomposite

• Glassgrid

• Geoarmour

• Geoblanket

• Geofoam

• Geomats

• Geocombs

• Geotextile container

• Geotextile bags

• Geotextile tubes •Geo coir

• Geo jute

• Bamboo

• Geocell / Geoweb

• Gabion

• Fiber

• Hybrid geosynthetics

• Electro kinetic geosynthetics

• Smart Geosynthetics

• Geo straw


RAW MATERIALS USED FOR THE PRODUCTION OF VARIOUS TYPES OF GEOSYNTHETICS

• Polypropylene (PP)• Polyethylene (PE)• Polyamide/ Nylon (PA)• High density polyethylene (HDPE)• Low density polyethylene (LDPE)• Linear low density polyethylene (LLDPE)• Medium density polyethylene (MDPE)• Very low density polyethylene (VLDPE)• Chlorinated polyethylene (CPE)• Chloro-sulphonated polyethylene (CSPE)


• Polystyrene (PS)

• Polyester or polyethylene terephthalate (PET)

• Polyvinyl chloride (PVC)

• Chlorinated Polyethylene (CPE)

• Ethylene Propylene diene terpolymer (EPDM)

• Expanded polystyrene (EPS)

• Geo Jute (GJ)

• Geo Coir (GC)

• Bamboo (B)

• Sisal (S)

• Straw (SW)Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay

RAW MATERIALS USED FOR THE PRODUCTION OF VARIOUS TYPES OF GEOSYNTHETICS

Raw materials Geosynthetics

PP, PET, PE, PA, GJ, GC, S, SW Geotextiles

PET, PP, HDPE, GC, B, S Geogrids

PVC, PP, HDPE, LLDPE, VLDPE,

CPE, CSPE, GJ

Geomembranes

HDPE, MDPE,GJ, GC, S, SW Geonets

HDPE, PP, PVC Geopipes

EPS Geofoams


COMPOSITION OF GEOSYNTHETICS

Geosynthetics are made of different types of fibers or yarns:

Monofilament Silt-film monofilament Multifilament Silt-film multifilament Staple fibers Staple yarnStable fibersFilamentsSilt films


Woven geosynthetics and knitted geosynthetics can bemade of yarns as follows:

A monofilament yarnA spun yarnA multifilament yarnA fabricated yarn andA slit film yarn

The nonwoven geosynthetics can be made of stablefibers or filaments. The arrangement of fibers is randomand bonded together with the following systems: Mechanical bonding Chemical bonding Heat/ Thermal bonding Resin bonding

Spray bonding Spun bonding Stitch bonding


Manufacturing of Geogrid

Strata India (Courtesy to Mr. N. Dalmia)Prof. J. N. Mandal, Department of Civil Engineering, IIT Bombay

Tensar International (1996, 1997 and 1999)


DIFFERENT TYPES OF GEOSYNTHETICS

GEOTEXTILES (GT) Nonwoven geotextileWoven geotextile

Woven geotextiles supplied by manufacturers

Nonwoven geotextiles supplied by manufacturers


Nonwoven Geotextiles:

Mechanically bonded non-woven

Thermally bonded non-woven


Woven Geotextiles:

Monofilament-on-multifilament Multifilament-on-multifilament


GEOGRIDS (GG)

Woven geogrids: Yarns are weaved perpendicular toeach other

Bonded geogrids: Two or more sets of strands arebonded together perpendicular to each other

Knitted geogrids: Yarns are knitted togetherperpendicular to each other

Extruded geogrids: Geogrid polymer is made of sheetform


GLASS GRIDS


GEONETS


GEOMEMBRANE

Geomembranes are of two types:

Calendared geomembranes are polyvinyl chloride (PVC),polyethylene (PE) and ethylene interpolymer alloy (EIA).

Extruded geomembranes are high-density polyethylene(HDPE), Low-density polyethylene (LDPE), very flexiblepolyethylene (VFPE) and polypropylene (PP).

Geomembranes are made of relatively impermeable thincontinuous flexible plastic sheets or rubber materials. It hassmooth or rough surfaces either on one or both sides.


Different types of geomembranes supplied by the manufacturers


GEOCOMOPITES (GC)


GEOCOMPOSITE EROSION CONTROL MATS

Geocomposite Erosion control mat supplied by manufacturers


GEOSPACERS / GEOSTRIPS


GEOSYNTHETIC CLAY LINERS (GCL)


GEOTEXTILE TUBES

Schematic view of geotextile tube

GEOPIPES


GEOFOAMGeofoam blocks or slabs are made of expandedpolystyrene (EPS) or extruded polystyrene (XPS). It is avery lightweight material with high void content and itsdensity is very low compared to the soil.


GEOCELL/ GEOWEB


GEOTEXTILE CONTAINERS

GEOMATTRESS/ GEOTEXTILE BAG


NATURAL GEOTEXTILE

Geojutes supplied by manufacturers

Geocoirs supplied by manufacturers


GABIONS

FIBERS


ELECTROKINETICS GEOSYNTHETICS: These arebasically quick drainage materials. These are electricallyconductive geosynthetics. It performs soil consolidation byelectro-osmosis process.

GEOBLANKET: It is made of synthetic or naturalbiodegradable permeable materials. It is used fortemporary erosion control with vegetations.

GEOMAT: It is a three dimensional permeable material. Itis made of bonded filaments. It can be used for permanenterosion control problems. The roots of grass and smallplants act as reinforcement for vegetation.


Please let us hear from you

Any question?


Prof. J. N. Mandal

Department of civil engineering, IIT Bombay, Powai , Mumbai 400076, India. Tel.022-25767328email: [email protected]


geosynthetics engineering: in theory and practice 6.pdflecture - 6 an overview of geosynthetics...

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