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Geotextile: It's Application to Civil Engineering Overview

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Geotextiles, a newly emerging field in civil engineering and other fields, offer great potential in varied areas of applications globally. Geotextiles play a significant part in modern pavement design and maintenance techniques. The growth in their use worldwide for transportation applications, in particular, has been nothing short of phenomenal. Geotextiles are ideal materials for infrastructural works such as roads, harbors, and many others. They have a bright future, thanks to their multifunctional characteristics. The paper provides an overview of various natural as well as synthetic textile fibers used for application as geotextiles
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GEOTEXTILE: IT’S APPLICATION TO CIVIL
ENGINEEERING – OVERVIEW
Dr. Bipin J Agrawal
Associate Professor
Department of Textile Chemistry, Faculty of Technology & Engineering,
The Maharaja Sayajirao University of Baroda, VADODARA-390 001; INDIA
E-mail address: bjagarwal@yahoo.com; Mob. 09924297828
ABSTRACT
Geotextiles, a newly emerging field in the civil
engineering and other fields, offer great potential in varied
areas of applications globally. Geotextiles play a significant
part in modern pavement design and maintenance
techniques. The growth in their use worldwide for
transportation applications in particular, has been nothing
short of phenomenal. Geotextiles are ideal materials for
infrastructural works such as roads, harbors and many
others. They have a bright future, thanks to their
multifunctional characteristics.
The paper provides an overview of various natural
as well as synthetic textile fibres used for application as
geotextiles
Key words: geotextiles; separators, drainage, filtration,
reinforcement, woven and non-woven fabrics
1. INTRODUCTION
Geotextiles were one of the first textile products in human
history. Excavations of ancient Egyptian sites show the
use of mats made of grass and linen. Geotextiles were
used in roadway construction in the days of the Pharaohs
to stabilise roadways and their edges. These early
geotextiles were made of natural fibres, fabrics or
vegetation mixed with soil to improve road quality,
particularly when roads were made on unstable soil. Only
recently have geotextiles been used and evaluated for
modern road construction. Geotextiles today are highly
developed products that must comply with numerous
standards. To produce tailor-made industrial fabrics,
appropriate machinery is needed.
Geotextiles have been used very successfully in
road construction for over 30 years. Their primary
function is to separate the sub base from the sub grade
resulting in stronger road construction. The geotextile
perform this function by providing a dense mass of fibres
at the interface of the two layers.
Geotextiles have proven to be among the most
versatile and cost-effective ground modification materials.
Their use has expanded rapidly into nearly all areas of
civil, geotechnical, environmental, coastal, and hydraulic
engineering. They form the major component of the field
of geosynthetics, the others being geogrids,
geomembranes and geocomposites. The ASTM (1994)
defines geotextiles as permeable textile materials used in
contact with soil, rock, earth or any other geotechnical
related material as an integral part of civil engineering
project, structure, or system.
Geotextiles should fulfill certain requirements like
it must permit material exchange between air and soil
without which plant growth is impossible, it must be
penetrable by roots etc. and it must allow rain water to
penetrate the soil from outside and also excess water to
drain out of the earth without erosion of the soil. To obtain
all these properties in geotextiles, the proper choice of
textile fibre is of paramount importance. The different
synthetic fibres used in geotextiles are nylon, polyester,
polypropylene while some natural fibres like ramie, jute
etc. can also be used.
In this paper, the types of fibres suitable for use
as geotextiles have been mentioned along with their basic
characteristics, functions and applications in various areas.
2. IMPORTANT CHARACTERISTICS OF
GEOTEXTILES
The characteristics of geotextiles are broadly classified as:
1. Physical properties:
a) specific gravity
b) weight
c) thickness
d) stiffness
e) density .
2. Mechanical properties:
a) tenacity
b) tensile strength
c) bursting strength
d) drapability
e) compatibility
f) flexibility
g) tearing strength
h) frictional resistance
3. Hydraulic properties:
a) porosity
b) permeability
c) permittivity
d) transitivity
e) turbidity /soil retention
f) filtration length etc.
4. Degradation properties:
a) biodegradation
b) hydrolytic degradation
c) photo degradation
d) chemical degradation
e) mechanical degradation
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f) other degradation occurring due to attack of
rodent, termite etc.
5. Endurance properties:
a) elongation
b) abrasion resistance
c) clogging length and flow etc.
3. SELECTION OF FIBRE FOR GEOTEXTILES
Different fibres from both natural as well as synthetic
category can be used as geotextiles for various
applications.
Natural fibres: Natural fibers in the form of paper strips,
jute nets, wood shavings or wool mulch are being used as
geotextiles. In certain soil reinforcement applications,
geotextiles have to serve for more than 100 years. But
bio-degradable natural geotextiles are deliberately
manufactured to have relatively short period of life. They
are generally used for prevention of soil erosion until
vegetation can become properly established on the ground
surface. The commonly used natural fibres are –
Ramie: These are subtropical bast fibres, which are
obtained from their plants 5 to 6 times a year. The
fibres have silky luster and have white appearance
even in the unbleached condition. They constitute of
pure cellulose and possess highest tenacity among all
plant fibres.
Jute: This is a versatile vegetable fibre which is
biodegradable and has the ability to mix with the soil
and serve as a nutrient for vegetation. Their quick
biodegradability becomes weakness for their use as a
geotextile. However, their life span can be extended
even up to 20 years through different treatments and
blendings. Thus, it is possible to manufacture
designed biodegradable jute geotextile, having
specific tenacity, porosity, permeability,
transmissibility according to need and location
specificity. Soil, soil composition, water, water
quality, water flow, landscape etc. physical situation
determines the application and choice of what kind of
jute geotextiles should be used. In contrast to
synthetic geotextiles, though jute geotextileas are
less durable but they also have some advantages in
certain area to be used particularly in agro-mulching
and similar area to where quick consolidation are to
take place. For erosion control and rural road
considerations, soil protection from natural and
seasonal degradation caused by rain, water, monsoon,
wind and cold weather are very important
parameters. Jute geotextiles, as separator, reinforcing
and drainage activities, along with topsoil erosion in
shoulder and cracking are used quite satisfactorily.
Furthermore, after degradation of jute geotextiles,
lignomass is formed, which increases the soil organic
content, fertility, texture and also enhance vegetative
growth with further consolidation and stability of
soil.
Synthetic Fibres: The four main synthetic polymers most
widely used as the raw material for geotextiles are –
polyester, polyamide, polyethylene and polypropylene.
The oldest of these is polyethylene which was discovered
in 1931 by ICI. Another group of polymers with a long
production history is the polyamide family, the first of
which was discovered in 1935. The next oldest of the four
main polymer families relevant to geotextile manufacture
is polyester, which was announced in 1941. The most
recent polymer family relevant to geotextiles to be
developed was polypropylene, which was discovered in
1954.
Polyamides (PA): There are two most important types
of polyamides, namely Nylon 6 and Nylon 6,6 but
they are used very little in geotextiles. The first one an
aliphatic polyamide obtained by the polymerization of
petroleum derivative ε-caprolactam. The second type
is also an aliphatic polyamide obtained by the
polymerization of a salt of adipic acid and
hexamethylene diamine. These are manufactured in
the form of threads which are cut into granules. They
have more strength but less moduli than polypropylene
and polyester They are also readily prone to
hydrolysis.
Polyesters (PET): Polyester is synthesised by
polymerizing ethylene glycol with dimethyle
terephthalate or with terephthalic acid. The fibre has
high strength modulus, creep resistance and general
chemical inertness due too which it is more suitable
for geotextiles. It is attacked by polar solvent like
benzyl alcohol, phenol, and meta-cresol. At pH range
of 7 to 10, its life span is about 50 years. It possesses
high resistance to ultraviolet radiations. However, the
installation should be undertaken with care to avoid
unnecessary exposure to light.
Polyethylene (PE): Polyethylene can be produced in a
highly crystalline form, which is an extremely
important characteristic in fiber forming polymer.
Three main groups of polyethylene are Low density
polyethylene (LDPE, density 9.2-9.3 g/cc), Linear low
density polyethylene (LLDPE, density 9.20-9.45 g/cc)
and High density polyethylene (HDPE, density 9.40-
9.6 g/cc).
Polypropylene (PP): Polypropylene is a crystalline
thermoplastic produced by polymerizing propylene
monomers in the presence of stereo-specific Zeigler-
Natta catalytic system. Homo-polymers and co-
polymers are two types of polypropylene. Homo
polymers are used for fibre and yarn applications
whereas co-polymers are used for varied industrial
applications. Propylene is mainly available in granular
form.
Both polyethylene and polypropylene fibres are creep
prone due to their low glass transition temperature.
These polymers are purely hydrocarbons and are
chemically inert. They swell by organic solvent and
have excellent resistance to diesel and lubricating oils.
Soil burial studies have shown that except for low
molecular weight component present, neither HDPE
nor polyethylene is attacked by micro-organisms.
Polyvinyl chloride (PVC): Polyvinyl chloride is
mainly used in geo membranes and as a thermo plastic
coating materials. The basic raw materials utilized for
production of PVC is vinyl chloride. PVC is available
in free- flowing powder form.
Ethylene copolymer Bitumen (ECB): Ethylene
copolymer bitumen membrane has been used in civil
engineering works as sealing materials. For ECB
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production, the raw materials used are ethylene and
butyl acrylate (together forming 50-60%) and special
bitumen (40-50%).
Chlorinated Polyethylene (CPE): Sealing
membranes based on chlorinated poly ethylene are
generally manufactured from CPE mixed with PVC
or sometimes PE. The properties of CPE depend on
quality of PE and degree of chlorination.
4. TYPES OF GEOTEXTILES
Geotextiles are a permeable synthetic material made of
textile materials. They are usually made from polymers
such as polyester or polypropylene. The geotextiles are
further prepared in three different categories woven
fabrics, non-woven fabrics and knitted fabrics
Woven fabrics: Large numbers of geosynthetics are
of woven type, which can be sub-divided into several
categories based upon their method of manufacture.
These were the first to be developed from the
synthetic fibers. As their name implies, they are
manufactured by adopting techniques which are
similar to weaving usual clothing textiles. This type
has the characteristic appearance of two sets of
parallel threads or yarns --.the yarn running along the
length is called warp and the one perpendicular is
called weft.
The majority of low to medium strength woven
geo synthetics are manufactured from polypropylene
which can be in the form of extruded tape, silt film,
monofilament or multifilament. Often a combination
of yarn types is used in the warp and weft directions
to optimize the performance/cost. Higher
permeability is obtained with monofilament and
multifilament than with flat construction only.
Fig 1. Woven Geotextile Fig 2. Non-woven Geotextile
Non-woven: Non woven geo-synthetics can be
manufactured from either short staple fibre or
continuous filament yarn. The fibers can be bonded
together by adopting thermal, chemical or mechanical
techniques or a combination of techniques. The type
of fibre (staple or continuous) used has very little
effect on the properties of the non woven geo
synthetics. Non-woven geotextiles are manufactured
through a process of mechanical interlocking or
chemical or thermal bonding of fibres/filaments.
Thermally bonded non-wovens contain wide range of
opening sizes and a typical thickness of about 0.5-1
mm while chemically bonded non-wovens are
comparatively thick usually in the order of 3 mm. On
the other hand mechanically bonded non-wovens
have a typical thickness in the range of 2-5 mm and
also tend to be comparatively heavy because a large
quantity of polymer filament is required to provide
sufficient number of entangled filament cross wires
for adequate bonding.
Knitted fabrics: Knitted geosynthetics are
manufactured using another process which is adopted
from the clothing textiles industry, namely that of
knitting. In this process interlocking a series of loops
of yarn together is made. An example of a knitted
fabric is illustrated in figure. Only a very few knitted
types are produced. All of the knitted geosynthetics
are formed by using the knitting technique in
conjunction with some other method of geosynthetics
manufacture, such as weaving.
Fig 3. Knitted Geotextile
Apart from these three main types of geotextiles, other
geosynthetics used are geonets, geogrids, geo-cells, geo
membranes, geo composites, etc. each having its own
distinct features and used for special applications.
5. FUNCTIONS OF GEOTEXTILES
Every textile product applied under the soil is a geotextile.
The products are used for reinforcement of streets,
embankments, ponds, pipelines, and similar applications
(Figure 4). Depending on the required function, they are
used in open-mesh versions, such as a woven or, rarely,
warp-knitted structure, or with a closed fabric surface, such
as a non-woven. The mode of operation of a geotextile in
any application is defined by six discrete functions:
separation, filtration, drainage, reinforcement, sealing and
protection. Depending on the application the geotextile
performs one or more of these functions simultaneously.
Fig 4. Application areas of Geotextiles
5.1. Separation:
Separation is defined as, “The introduction of a flexible
porous textile placed between dissimilar materials so that
the integrity and the functioning of both the materials can
remain intact or be improved”. In transportation
applications separation refers to the geotextile’s role in
preventing the intermixing of two adjacent soils. For
example, by separating fine subgrade soil from the
aggregates of the base course, the geotextile preserves the
drainage and the strength characteristics of the aggregate
material. The effect of separation is illustrated in figure 5.
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Fig 5. Concept of Separation function
They are used in all classes of roads and similar
civil foundation as the base of construction on
contaminated layer is the single most cause of premature
failure. The use of separator prevents pumping effect
created by dynamic load and also helps the passage of
water while retaining soil particles. In theses types of
geotextiles, thickness and permeability are most important
characteristic properties. Some of the applications areas
are: Between subgrade and stone base in unpaved and
paved roads and airfields
Between subgrade in railroads
Between land fills and stone base courses
Between geomembranes and sand drainage layers
Beneath sidewalks slabs
Beneath curb areas
Beneath parking lots
Beneath sport and athletic fields
5.2. Filtration:
It is defined as the equilibrium geotextile-to-soil system
that allows for adequate liquid flow with limited soil loss
across the plane of the geotextile over a service lifetime
compatible with the application under consideration”. In
filtration, fabrics can be either woven or non-woven, to
permit the passage of water while retaining soil particles.
Porosity and permeability are the major properties of
geotextiles which involves in filtration action. Application
helps the replacement of graded aggregate filters by a
geotextiles warping. These applications are also suitable
for both horizontal and vertical drains. A common
application illustrating the filtration function is the use of a
geotextile in a pavement edge drain, as shown in figure 6.
Fig 6. Filtration and Transmissivity functions
5.3. Drainage (Transmissivity):
This refers to the ability of thick nonwoven geotextile
whose three-dimensional structure provides an avenue for
flow of water through the plane of the geotextile. Figure 6
also illustrates the transmissivity function of geotextile.
Here the geotextile promotes a lateral flow thereby
dissipating the kinetic energy of the capillary rise of
ground water.
5.4. Reinforcement:
This is the synergistic improvement in the total system
strength created by the introduction of a geotextile into a
soil and developed primarily through the following three
mechanisms:
lateral restraint through interfacial friction between
geotextile and soil/aggregate
forcing the potential bearing surface failure plane to
develop at alternate higher shear strength surface
membrane type of support of the wheel loads.
In this method, the structural stability of the soil is greatly
improved by the tensile strength of the geosynthetic
material. This concept is similar to that of reinforcing
concrete with steel. Since concrete is weak in tension,
reinforcing steel is used to strengthen it. Geosynthetic
materials function in a similar manner as the reinforcing
steel by providing strength that helps to hold the soil in
place. Reinforcement provided by geotextiles or geogrids
allow embankments and roads to be built over very weak
soils and allows for steeper embankments to be built.
5.5. Sealing Function:
A non-woven geotextile performs this function when
impregnated with asphalt or other polymeric mixes
rendering it relatively impermeable to both cross-plane and
in-plane flow. The classic application of a geotextile as a
liquid barrier is paved road rehabilitation, as shown in
Figure 7. Here the non-woven geotextile is placed on the
existing pavement surface following the application of an
asphalt tack coat. The geotextile absorbs asphalt to become
a waterproofing membrane minimizing vertical flow of
water into the pavement structure.
Fig 7. Sealing Function
6. APPLICATIONS OF GEOTEXTILES
Civil engineering works where geotextiles are employed
can be classified into the following categories –
6.1 Road Works: The basic principles of incorporating
geotextiles into a soil mass are the same as those utilized in
the design of reinforced concrete by incorporating steel
bars. The fabrics are used to provide tensile strength in the
earth mass in locations where shear stress would be
generated. Moreover, to allow rapid dewatering of the
roadbed, the geotextiles need to preserve its permeability
without losing its separating functions. Its filtration
characteristics must not be significantly altered by the
mechanical loading.
6.2 Railway Works: The development of the railway
networks is being greatly boosted by the present state of
economy because of their profitability in view of
increasing cost of energy and their reliability as a result of
the punctuality of trains even in the adverse weather
conditions. The woven fabrics or non-wovens are used to
separate the soil from the sub-soil without impeding the
ground water circulation where ground is unstable.
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Enveloping individual layers with fabric prevents the
material wandering off sideways due to shocks and
vibrations from running trains.
6.3 River Canals and Coastal Works: Geotextiles protect
river banks from erosion due to currents or lapping. When
used in conjunction with natural or artificial enrockments,
they act as a filter. For erosion prevention, geotextile used
can be either woven or nonwoven. The woven fabrics are
recommended in soils of larger particle size as they usually
have larger pore size. Nonwovens are used where soils
such as clay silt are formed. Where hydrostatic uplift is
expected, these fabrics must be of sufficiently high
permeability.
6.4 Drainage: In civil engineering, the need for drainage
has long been recognized and has created the need for
filters to prevent in-situ soil from being washed into the
drainage system. Such wash in soil causes clogging of the
drains and potential surface instability of land adjacent to
the drains. The use of geotextiles to filter the soil and a
more or less single size granular material to transport water
is increasingly seen as a technically and commercially
viable alternative to the conventional systems. Geotextiles
perform the filter mechanism for drainages in earth dams,
in roads and highways, in reservoirs, behind retaining
walls, deep drainage trenches and agriculture.
6.5 Sports field construction: Geotextiles are widely used
in the construction of Caselon playing fields and Astro turf.
Caselon playing fields are synthetic grass surfaces
constructed of light resistance polypropylene material with
porous or nonporous carboxylated latex backing pile as
high as 2.0 to 2.5 cm. Astro Turf is a synthetic turf sport
surface made of nylon 6,6 pile fibre knitted into a backing
of polyester yarn which provides high strength and
dimensional stability. The nylon ribbon used for this is of
55 Tex. It is claimed that the surface can be used for 10
hr/day for about 10 years or more. Modern Astro Turf
contains polypropylene as the base material.
6.6 Agriculture; It is used for mud control. For the
improvement of muddy paths and trails those used by cattle
or light traffic, nonwoven fabrics are used and are folded
by overlapping to include the pipe or a mass of grit.
7. GEOTEXTILES & THE ENVIRONMENT
Environment and ecological sustainability become one of
the prime issues in the modern developmental strategy.
Without positive ecological sustainability the
technology/product becomes obsolete. Utilization of
geotextile in civil engineering is not a new technology. But
their modern uses have started with the advancement of
synthetic and polymeric products and their ever increasing
application in different forms and areas of civil engineering
was initiated only a few decades ago. Again uses of natural
fibrous materials in the field of bioengineering, erosion
control and agro-mulching are also recent practices. In
geotechnical uses like fibre drain, separator, filter and
reinforcing materials are mostly synthetic and non
biodegradable with longer span of life. Woven, non-
woven, composite geosynthetics are used in the
construction of roads-highways, railways, water-bodies,
river banks erosion controls and other areas. On the other
hand in soil bioengineering, permanent and self
propagating vegetation is required with environmentally
desirable and aesthetically pleasing appeal besides being
economical and self sustainable. The roots bind the soil
and counteract surface erosion for which natural
geotextiles are more acceptable due to their better
performance. Synthetic geotextiles are made of polymers
and plastics. Hydro-carbon, petrochemicals, fossils are the
basic raw materials for their production. Thus, all green
house gases and effects are some how related with their
manufacturing. Moreover, non-destructible nature of these
synthetic geotextiles has direct effect on soil, water air and
other biotic and a biotic system. These geotextiles may
often come in contact with life cycles of animals, fishes,
insects, and pests along with various micro organisms and
create imbalance in the ecosystem. Thus, synthetic
geotextiles may have direct negative impact on climate and
ecology as a whole for which extensive research is
essential in this area.
8. FUTURE OF GEOTEXTILES
When looking to future generations of geotextiles, an
examination of the role of nanotechnology in the functional
enhancement of geotextiles is in order. By reducing fiber
diameter down to the nanoscale, an enormous increase in
specific surface area to the level of 1000 m2/g is possible.
This reduction in dimension and increase in surface area
greatly affects the chemical/biological reactivity and
electroactivity of polymeric fibers. Because of the extreme
fineness of the fibers, there is an overall impact on the
geometric and thus the performance properties of the
fabric. There is an explosive growth in worldwide research
efforts recognizing the potential nanoeffect that will be
created when fibers are reduced to nanoscale.
CONCLUSION
Textiles are not only clothing the human body but also our
mother land in order to protect her. Extensive awareness
should be created among the people about the application
of geotextiles. Geotextiles are effective tools in the hands
of the civil engineer that have proved to solve a myriad of
geotechnical problems. To explore the potential of
geotextile more researches are needed in this field.
REFERENCES
1. ASTM (1994), Annual Books of ASTM
Standards, American Society Testing and
Materials, Philadelphia, Pennsylvania. Volume
4.08 (1), Soil and Rock, Volume 4. No. (8), Soil
and Rock, Geosynthetics, Volume 7, No. 1,
Textiles.
2. Abdullah, A. B. M., A Hand book of Geotextiles
Particularly natural goetextiles from jute and
other vegetable fibers, FAO-2000
3. Gregory, R. N., Barry, C. R., Geotextiles in
Transportation Applications, Featured Short
Course, 1998.
4. Rankilor, P. R., Membranes in Ground
Engineering, John Wiley and Sons, New York,
1981.
5. Koerner, R. M., Designing with Geosynthetics,
Third edition, Prentice Hall, 1993.
National Conference on Recent Trends in Engineering & Technology
13-14 May 2011 B.V.M. Engineering College, V.V.Nagar,Gujarat,India
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6. Ayres, D. J., “The Treatment of Unstable Slopes and
Railway Track formation”, The Journal of the
Society of Engineers, Vol. 52, No. 4 (Oct./Dec),
1961.
7. Terzaghi, K. and Peck, R. B., “Soil Mechanics in
Engineering Practice”, John Wiley & Sons, New
York, 1967.
8. Ko, F.K., “Nanofiber Technology: Bridging the
Gap between Nano and Macro World”, in NATO
ASI on Nanoengineeered Nanofibrous Materials,
Anatalia, Turkey, Kluwer Academic Publishers,
2003.
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13-14 May 2011 B.V.M. Engineering College, V.V.Nagar,Gujarat,India
... Geotextiles are widely used and will continue to be used in all aspects of geotechnical engineering, particularly in the roads, airports, railways, and waterways. Reinforcement, separation, filtration, drainage, and environmental protection are some of the worth-mentioning functions performed by different types of geotextiles (Agrawal, 2011). Therefore, the objective of this chapter is to review the fabrics in particular knitted fabric for geotextile. ...
... Geotextiles have been used in the history of human civilization since prehistoric times. Excavations at the ancient Egyptian sites revealed the use of various geomats made of grass and linen (Agrawal, 2011). Different types of naturally occurring materials such as grass, fibers, leaves, etc., were used with soil as the reinforcement materials. ...
... The thickness of the mechanically bonded nonwoven geotextiles is in the range of 2e5 mm, while chemically bonded structures are usually around 3 mm thick. On the other hand, geotextiles bonded thermally are usually 0.5e1 mm thick (Agrawal, 2011). Some of the widely used nonwoven geotextile structures have been discussed below. ...
Chapter
Geotextiles are used in many geotechnical applications due to their effective functions such as reinforcement, separation, filtration, sewage, and environmental protection. Various types of significant properties and functions of geotextiles including geosynthetics which determine their suitability for the end uses including advantages of using knitted geotextiles and the most popular application areas are discussed with practical examples. Two-dimensional knitted geotextile was mainly warp-knitted fabrics which has loops in a zigzag pattern having laid warps at fabric plane. It has also three-dimensional forms including in-plane and out-of-plane multiaxial reinforcements. It was pointed out that the knitted geotextiles being used are only approximately 5% of the total geotextile consumption; the demand for knitted geotextile has been increasing exponentially in recent times due to their structure and associated critical mechanical properties. Finally, this chapter concludes with explaining the survivability and durability aspects of geotextiles.
... Within the geosynthetic systems, high-strength synthetic fabrics and sand or mortar, etc. are used for filling up the synthetic nets or bags as well. The geosynthetics are synthetic products, thin, flexible and sheet like materials made of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and polyester (PET) and also ethylene copolymer bitumen (ECB) and chlorinated polyethylene (CPE) (Agrawal 2011 to their non-polar nature, polyethylenes are resistant to chemicals and they also have very low permeability to liquids and gases and are almost insoluble at the temperature below 60 C. High density polyethylene (HDPE) and low density polyethylene (LDPE) are used in geosynthetic applications like geonets, geogrids, etc. Geotextiles are made of knitted or stitch-bonded fibers or yarns. ...
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This Wiley classic presents both theoretical and practical knowledge of soil mechanics in engineering. Written by Karl Terzaghi, universally recognized as ``the father of geotechnical engineering,`` it has long been the standard in the field. It offers a fundamental understanding of how to determine and use soil properties needed for design and construction; points out appropriate nature and benefits of exploration and soil tests under various conditions; and discusses most suitable methods and types of equipment for fills, excavations, and foundations. It also features expanded coverage of vibration problems, mechanics of drainage, passive earth pressure, and consolidation. This book contains information on the following. Part 1: physical properties of soils; index properties of soils; soil exploration; and hydraulic and mechanical properties of soils. Part 2: theoretical soil mechanics; hydraulics of soils; plastic equilibrium in soils; and settlement and contact pressure. Part 3: problems of design and construction; ground improvement; earth pressure and stability of slopes; foundations; settlement due to extraneous causes; and dams and dam foundations.
Annual Books of ASTM Standards
ASTM (1994), Annual Books of ASTM Standards, American Society Testing and Materials, Philadelphia, Pennsylvania. Volume 4.08 (1), Soil and Rock, Volume 4. No. (8), Soil and Rock, Geosynthetics, Volume 7, No. 1, Textiles.
The Treatment of Unstable Slopes and Railway Track formation
  • D J Ayres
Ayres, D. J., "The Treatment of Unstable Slopes and Railway Track formation", The Journal of the Society of Engineers, Vol. 52, No. 4 (Oct./Dec), 1961.
Nanofiber Technology: Bridging the Gap between Nano and Macro World
  • F K Ko
Ko, F.K., "Nanofiber Technology: Bridging the Gap between Nano and Macro World", in NATO ASI on Nanoengineeered Nanofibrous Materials, Anatalia, Turkey, Kluwer Academic Publishers, 2003.