J U T E
G E
O T E X T I L E
S |
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| Jute, one of the
oldest surviving agro-industries in India, has been traditionally in use for flexible
packaging, specially sacks. Its special physical attributes have opened up new avenues for
diversification promted mostly as a result of global concerns for environment. Jute
Geotextile is one such diversified product of jute which has proved to be highly effective
in addressing a number of soil-related problems in civil engineering. |
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| Functionally, Jute
Geotextile (JGT) does not have any dissimilarity with man-made Geotextiles-commonly known
as Synthetic Geotextiles - made of artificial fibres with various petro-chemical
derivatives as their source. The functions are - separation, filtration, drainage and
initial reinforcement. |
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| Besides,
biodegradablility of JGT helps in quick growth of vegetation by coalescing with the soil,
increasing its permibility, retaining the appropriate humidity as "mulch" and
creating a micro-climate that is conductive to vegetative growth. In fact, JGT is the most
acclaimed natural fabric that provides biotechnical solutions to vulnerable exposed soil. |
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| Biodegradability
is considered by some as a disadvantage. This is to be borne in mind that all geotextiles
act as catalyst in the process of improving engineering properties of soil. An effective
life span of two season-cycles is found to be sufficient for natural consolidation of soil
known as "filter cake" formation from extensive laboratory tests by leading
academics and field trials. Biodegradability of JGT is, therefore, not a discouraging
factor. |
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| Types
of Jute Geotextile |
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| Generally
three types of Jute Geotextile are there, viz., open mesh ,woven and non woven |
|
OPEN MESH JUTE GEOTEXTILE |
|
Type |
Weight |
Width |
Open area |
Strength |
Water holding
capacity(%) |
Expected Durability
(Year) |
| I |
292 |
122 |
60 |
75x75 |
400 |
1 |
| II |
500 |
122 |
50 |
10x10 |
500 |
1 |
| III |
730 |
122 |
40 |
12x12 |
500 |
1 |
|
|
| Application
Areas |
|
| - Protection of slopes in road and railway
embankments, bridge approaches, terraces in hilly terrains. |
- Stabilisation of sand dunes, mine spoils,
O.B. dumps in open cast mines, PFA dumps in thermal power plants,
slag heaps. |
| - Promotion of quick vegetation in areas denuded by
natural calamities like cyclones, earthquakes, landslides. |
| - Stabilisation of waste – dumps. |
| - Prevention of reflection cracks. |
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| Advantages |
|
| -
Price advantage over any type of Geotextile – natural or synthetic. |
| -
Unquestionable eco compatibility. |
| -
Easy availability and transportation. |
| -
Easy installation. |
|
WOVEN JUTE GEOTEXTILE |
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| Varieties
available off-the shelves : |
|
| Type |
Weight
(gsm) |
Width
(cm) |
Porometry
(O90)micron |
Strength
(MDxCD)
kN/m |
Permittivity at
10cm water head
(1/
m2 /sec) |
Durability
(Yrs) |
I
Grey
(Untreated) |
760 |
76 |
300 |
20x20 |
50 |
1 |
| Bitumen treated |
1200 |
76 |
150 |
20x20 |
25 |
4 |
II
Grey
(untreated) |
900 |
200 |
250 |
40x40 |
30 |
1 |
Treated
(Rot resistant) |
900(+) |
200 |
250 |
40x40 |
30 |
1 |
|
|
| Application Areas |
|
| - Protection of river bank |
| - Strengthening of road when used as an intervening layer between subgrade
and subbase |
- Filtration by retaining soil particles on the one hand and ensuring
permeability of water through and along it
on the other . |
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| Advantage |
|
 |
Easy
to transport, handle and install. |
|
|
Easily
available with customised specifications. |
|
|
Economical.
|
|
|
Eco-compatible
|
|
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Helps
natural protection by fostering vegetation over it. |
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| A P P L I C A T I O
N................................................................................................................................................ |
|
Jane Rickson of Silsoe
College identified three current main applications for jute:
- Erosion
control and vegetation establishment
- Agroplant
mulching
- Rural road
pavement construction
The salient
properties which determine the effectiveness of ageotextile are percentage cover, water
holding capacity, the thickness and roughness of fibres and yarns, their orientation
across the slope and installation procedures which do not disturb the site. Testing over
12 years at Silsoe has proved the technical excellence of jute compared with other natural
and synthetic geotextiles under a range of environmental conditions, showing that
vegetation establishment is highly effective when jute is used. |
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| A newly developed wick drain,
formed from a jute sleeve packed with coir, showed how combinations of geotextile types
provide benefits greater than the sum of each. Professor Bob Sarsby of Bolton Institute
reported on full-scale trials of soil walls incorporating jute rope reinforcement. This
work graphically demonstrated the strength of jute in supporting walls of 4m or more. He
went on to describe the use jute in road construction especially over areas of poor
ground. Not enough attention has yet been paid to this potentially extensive application. |
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| The micro-climate surrounding
jute geotextiles has been explored by Yves Henri Faure of Grenoble University who has
tested the efficiency of jute sheets in preventing loss of soil in shallow and steep
slopes. Earth works were built on a test-bed capable of being rotated to various
inclinations and subjected to simulated rainfall, varying from light to heavy tropical
downpours. The amount of soil lost to erosion was measured. The faces were then protected
by various geotextiles and the soil erosion again measured. The tests simulated wash out
of vegetated soil slopes and provided data of use in landscaping projects. Over the whole
range of rainfall intensities and slope angles jute geotextiles outshone the other
materials. A jute of approximately 500g per m2 appeared to be cost effective. |
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| Using jute to protect large
areas from erosion, including high-altitude ski-slopes with significant precipitation, has
been trialed by Francoise Dinger of CEMAGREF. The ability of jute to absorb five times its
own weight of water ( 3kg per m2 of slope ) was demonstrated. The retained
water firstly attenuates the run-off into the drainage system and is then released
gradually to soak into the adjacent soil to nourish the vegetation from severe frosts, so
aiding growth. |
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| Mike Hyder of Hy-Tex Ltd.
commented that prevention of soil erosion was better and more cost effective than remedial
works. The most vulnerable sites were over steepened slopes, exposed highly erodible
sub-soil, and disturbed or badly compacted ground. |
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| Consequences of soil erosion
were: poor growing conditions, additional costs for remedial works, blocked drains and
flooding, pollution of waterways and increased maintenance. Many applications of jute made
by his company were illustrated by ‘before and after’ photographs showing the
dramatic improvement in vegetation growth and erosion control. |
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| Barbara Lois of SIRAS Company
described the extensive environmental works undertaken in France using jute geotextiles,
including rehabilitating mine dumps, restoring the Rhone river banks and the vegetating
high altitude steep slopes at the Winter Olympic ski jump in Savoie. Landscaping of slopes
alongside the TGV rail line and along highway cuttings and embankments showed the
effectiveness of the geotextiles. |
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| Dr. Finn Terkelsen from
Denmark felt that the partners in this field are playing a waiting game. The jute mills
are waiting for the engineers to tell them what to do, whilst the engineers are waiting
for the jute mills to show them what is available. Much research has been carried out by
several institutes in jute producing countries as well as in Europe. Interesting results
were seen but wider use did not materialise. It will be important to address this issue
and to use past experiences as stepping stone for future work. There is currently a very
wide gap. Erosion control, foundations, sound barriers, filters, and reinforcement and
drainage were suggested as the most appropriate target uses of jute geotextiles. |
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Mills
Engaged
 |
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| S T E E P S L O P E
S............................................................................................................................................. |
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| Steep slopes present
particular erosion control problems. Eight soil erosion plots were established on a South
facing slope in a trial carried out by Dr.David Mitchell of Wolverhampton University
Experimental Station at Hilton, Shropshire. Soil erosion of sections protected slope
reduced the erosion by 54% whereas the jute geotextile reduced erosion by 99% compared
with the bare slope. |
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| Using jute to resolve the
difficulties of vegetating the steep faces of reinforced soil slopes would be helped if
the salient technical aspects were drawn together and published in a form more accessible
to users. For example, jute blended with synthetic fibres has been processed on the
existing non-woven production machinery at British Textile Technology Group (BTTG),
ManchesterA range of technical products of widely varying properties and with weights from
100 to 2000gm per m2 and with thicknesses up to 60mm can be produced by this
method. |
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| F U T U R E L I N K
S.............................................................................................................................................. |
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| The two seminars held in
London and Geneva in 1997 under auspices of JMDC forged links between all sides of
industry which will be instrumental in helping jute to be accepted and applied more widely
in environmental schemes. The clear need for concise technical information of direct
relevance to users was established and the next phase of the work will address this. |
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| Note:
This is reproduction of an article written by Mr. Red Smith, Director,
Elwood Consultants Ltd., Albrighton (UK) which was published in the Autumn’98 issue
of ENACT , a UK-based land management magazine. JMDC utilised the expertise of Mr.
Rod Smith for promotion of jute geotextiles in Europe. |
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(Sourse : INDIAN
JUTE newsletter, March 1999) |
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