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27 July 2016 1 Coir Geotextiles G V RAO

Coir Bhoovastra (Geotextiles)

for

Civil Engineering Applications –Experiences & Potential

Dr. G.Venkatappa Rao

Guest Professor,

Indian Institute of Technology, Gandhi Nagar Chairman

Saimaster Geoenvironmental Services P Ltd Hyderabad

Historical

• Use of coconut leaf mattresses in Kerala in road construction

• Dragging a bogged down vehicle using leaves, brushes etc

• Cordruoy roads using tree trunks packed next to one another and levelling with gravel for traffic in forest areas

• Natural erosion control by vegetation – turfing, trees etc

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Coconut groves


COIR FIBRE

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Coir – Essential features

Coir fibres length : 50 --150 mm

diameter : 0.2 – 0.6 mm

High production in India : Social welfare

Woven coir geotextiles and

non-woven coir blankets :Erosion control

Biodegradability : 5 years life in

saturated condition


DURABILITY

• BUNDENSTAT’S results:

Whereas cotton degrades totally in six weeks and jute in 8 weeks, coir has retained 2% strength even after one year, and

It takes 15 times longer than cotton and 7 times longer

than jute to degrade.

• The growth of micro -organisms depends on their chemical composition. The longer resistance of coir due to its high lignin content (about 35%) compared to say 12% for jute.

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SEM MICROGRAPH OF COCONUT HUSK

COIR FIBRE BROKEN IN LIQUID NITROGEN

CLOSE UP VIEW OF SAME COIR FIBRE 27 July 2016 Coir Geotextiles G V RAO 15

H2M6

400gsm

H2M5

700gsm

H2M9

900 gsm

Coir woven geotextiles


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Property Coir geotextile

Roll width (m) Roll length (m) Roll weight (kg) Runnage of yarn

Aperture size (mm*mm) Thickness (mm)

Mass per unit area (g/m*2) Tensile strength m/c (kN/m)

%Elongation m/c Tensile strength X-m/c (kN/m)

% Elongation X-m/c Initial tangent Modulus at 5 mm

deformation (kN/m)

E 1.2 25 10

45*30

7.3 335 3.86 20 2.5

27.5 30

F 1,2,4

50 1/20,2/40,4/80

240 25*25

6.7 360 6.34

19.17 4.38

31.67 48

G 1,2,4

50 1/35,2/70,4/140

240 6.25*6.25

8 610

10.63 31.67

7.5 26.25

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H 1.2 24 42 7*4 9.5 1335 31.50 42 12.73 18 100

Physical and mechanical properties of woven Coir geotextiles


Non-woven coir geotextiles

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Non-woven coir geotextiles - types

Studies carried out

at

Indian Institute of Technology,

New Delhi Venkatappa Rao, G., Dutta, R. K. and Balan, K.


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Property Non-woven coir geotextiles

Roll width (m) Roll length (m) Roll weight (kg) Thickness (mm)

Mass per unit area (g/m*2) Tensile strength m/c (kN/m)

%Elongation m/c Tensile strength x-m/c (kN/m)

% Elongation x-m/c Initial tangent Modulus at 5 mm

deformation (kN/m)

A 2.2 25 33 12

865 7.6 11.3

3 9.7 68

B 2.2 25 22 8.9 420 1.7 35 0.8

15.8 10

C 2.2 42 69 9 750 2.3 27.5 0.7 19.2 13.8

D 2.0 25 50

13.6 1175 15.4 27 8.3 24 49

Physical and mechanical properties of non-woven coir geotextiles


Strength reduction for coir when submerged in soft saturated clay

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APPLICATION POTENTIAL

1. Erosion Control

2. Rural Roads

3. Road Edge Drains

4. Silt fence

5. Ground Improvement

6. Reinforcement



RILL and GULLY SLOPE

EROSION

EROSION

CONTROL

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EROSION

• Surface Soil Erosion - dislodgement of soil particles and their transportation down slope as a series of events...

• Erosion control - restraining the initial movement of soil particles by wind and water.

• An effective erosion-control material will reduce the impact of raindrops on the soil and impede overland water flow.

• So, fewer soil particles become dislodged during rainfall.

• Slowing the flow of water down slope accomplishes two things

1. Reduction in the transport capacity of the thin sheet flow , thereby minimising the displacement of dislodged soil particles,

2. Infiltration of more rainfall into the soil, providing desirable

moisture to newly planted seedlings.



• ROLLED EROSION CONTROL PRODUCTS (RECPs).

Expected to serve mitigation of erosion both in the short term as well as long term

through the establishment and maintenance of vegetation

cover Such solutions are also known as Biotechnical Engineering Solutions.

• Before the advent of RECPs MULCHING has been in use for acceleration of vegetation establishment.

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Rolled Erosion Control Product


Being

installed in a ditch


Figure illustrates the overlap provisions schematically.

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Additional anchorage is achieved by installing a row of staples along the crest and toe

Bridge across Vasista Godavari –Chinchinada, W.G.Dt., A.P.

• 20 m – 25 m thick black cotton soil deposit

• 12m high embankment

• Basal Geocell Mattress

• 3 m high reinforced soil wall

• Erosion control Blanket in place of pitching


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ROLLED EROSION CONTROL PRODUCTS

• These products can be classified as:

I. Erosion Control Nettings (ECN)

II. Erosion control meshes (ECM)

III. Erosion Control Blankets (ECB) with single/double net

IV. Geosynthetic (polymeric) Mattings or Turf Reinforcement Mats (TRM)


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EROSION CONTROL TECHNOLOGY COUNCIL (ECTC) CLASSIFICATION

Low velocity degradable RECPs

High-velocity degradable RECPs

Long term nondegradable RECPs

ECPS HAVE MAJOR APPLICATIONS IN:

• Shore-line stabilization

• Beautification of lakes and ponds

• Landscaping and Golf Courts

• Plant and tree protection systems

• Sand dune stabilization

• Ski slope and high altitude vegetation

• Protection and revegetation of waste dumps

• Wasteland development

• They could also be highly useful in controlling dust and vegetating ash-pond dikes and dams with ore tailings.


CSEB - KORBA SITE (Gar-mat with grass turfing)

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THE OLD WAYS (cordrouy roads)


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Soft soils in construction

- low bearing capacity

- excessive rutting

- compressible layers

- uneven settlements

- …

soil reinforcement needed !

Coir Geotextiles G V RAO


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Membrane Tension Support



Coir Geotextile in Road Structure

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Studies carried out

at

Indian Institute of Technology,

New Delhi Venkatappa Rao, G. and Dutta, R. K. (2006),

Coir geotextiles in rural roads , Highway Research Bulletin,

Indian Road Congress, No. 74, pp. 9-15.


APPLICATION IN RURAL ROADS

• The use of closely woven geotextiles as an interface

between the subgrade and the sub-base

– increases the strength of the pavement and

– prevents intermingling of the soils and the

granular sub-base and improves drainage.

• Under the weight of the base layer and the

compactive effort, the subgrade loses water,

draining out through coir fabric, and gains in

strength. 27 July 2016 Coir Geotextiles G V RAO 52

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RURAL ROADs (contd).

• Once the coir geotextile is placed on the weak

subgrade,

– the subgrade stiffens and

– becomes stronger on consolidation within about

a year or so under the action of

• the granular sub-base surcharge,

• self-weight of pavement,

• construction rolling

• and traffic loads.


Rural Roads (contd)

• With time, the subgrade becomes less and less

dependent on the fabric for its stability

• Therefore, the long-term durability aspect of coir

should not deter its use as a geotextile for various

applications in road construction.


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Model test tank


0

10

20

30

40

50

60

0 45 90 135 180

Bearing pressure, kPa

De

form

ati

on

, m

m

Type D

Type C

Type B

Type A

Unreinforced

Static load versus deformation behavior of

models reinforced with different types

of woven geotextiles

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0

10

20

30

40

50

60

0 50 100 150 200


De

form

ati

on

, m

m

Type G

Type F

Type Hf

Type Hb

Type E

Unreinforced

Static load versus deformation behaviour of models

with different types of non-woven geotextiles


0

10

20

30

40

50

60

0 50 100 150 200


De

form

ati

on

, m

m

Type D

Type G

Type F

Type Hf

Type Hb

Type E

Type C

Type B

Type A

Unreinforced

Static load versus deformation behaviour of

models reinforced with different non-woven

and woven coir geotextiles

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BCR versus deformation behaviour of models reinforced With non-woven and woven coir geotextiles


0

10

20

30

40

50

60

70

1 10 100 1000 10000

Number of cycles

Perm

an

en

t d

efo

rm

ati

on

, m

m

Unreinforced at 35.88 kPa

Type C at 35.88 kPa

Type E at 35.88 kPa

Type C at 71.76 kPa

Type E at 71.76 kPa


Permanent vertical deformation versus

number of load repetitions

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0

7.5

15

22.5

30

1 10 100 1000

Number of cycles

Ap

pa

ren

t re

sili

en

t m

od

ulu

s ,

kP

a/m

m


Type C at 35.88 kPa Type E at 35.88 kPa

Unreinforced at 17.94 kPaType C at 71.76 kPa

Type E at 71.76 kPa

Apparent resilient modulus versus number of load repetitions

27

Ju

ly 2

01

6

62


Number of cycles

Percentage reduction in permanent deformation

Geotextile type A

Geotextile type B

10 200 700

21.19 58.85 76.68

21.19 55.68 74.62

Percentage reduction in permanent

deformation

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STATIC AND CYCLIC

BEHAVIOUIR OF POND ASH

REINFORCED WITH

COIR GEOTEXTILE

MVS Sreedhar,

Osmania University

The pond ash.

• Collected from NTPC, Ramagundam in AP

• Collected close to the discharge point and

hence a coarser pond ash, classified as SP

• Non-plastic

• Spherical in shape with intra-particle cavities

• Crushable to considerable extent with notable

modification in particle size.


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The coir geotextile

Product name CCM-700 H2M2

Produced by M/s Charankattu Coir Manufacturing Company Pvt. Ltd., Shertallay, Kerala, India.


Test facility


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0

20

40

60

80

100

120

140

160

0 3.2 6.4 9.6 12.9 16.1 19.3

LO

AD

(x 1

0 )

(N

)

SETTLEMENT (mm)

LOAD VS SETTLEMENT CURVE 50 MM SQUARE MODLE FOOTING ON

POND ASH AT 70% OF MDD EFFECT OF CGT-700 WITHOUT SURCHARGE

ONLY PA

CGT-700 AT 2.0 B (100mm)

CGT-700 AT 1.0 B (50mm)

CGT-700 AT 0.50 B (25 mm)


0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

CYCLIC LOAD APPLICATION

CYCLE NUMBER (N)

DO

UB

LE

AM

PL

ITU

DE

OF

CY

CL

IC L

OA

D (

x10)

(N

)


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0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

DEFORMATION (Vs) CYCLE NUMBER PLOT

CYCLE NUMBER (N)

DE

FOR

MA

TIO

N

(m

m)

FOR PA + CGT AT (u/B)=0.50


Comparative observations

• The ability to reduce the cyclic deformations

by CGT are lesser than that of WGT

• The ARM of PA+CGT composite is less than

that of PA+WGT composite

• This is essentially due to low elastic modulus

that govern the cyclic behaviour


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Conclusions

• CGT has potential to serve the reinforcement

function in frictional material like Pond Ash

• However, low elastic modulus of CGT and hence the

PA+CGT composite is resulting in higher level of

strain than allowable both under static and cyclic

loading.

• This may be due to the inherently low elastic

modulus of the fibers/yarns in the CGT


The future prospects

• Efforts need to be made to increase the

modulus of CGT such that it serves the

reinforcement function at allowable strain

levels AND improve its cyclic behaviour.


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LOCAL SOIL

• May be unsuitable for construction.

• Low bearing capacity or CBR Value.

• CBR < 2% causes shear failure and rutting.

Site condition benefit from Geotextile Stabilisation

• Poor soil – Clayey sand/silt, organic fatty clay,inorganic silt etc. • Soils with low undrained shear strength, c < 100 kPa. • Water table near ground surface. • Seasonally wet subgrade. • High sensitivity soil.

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Functions played by coir geotextiles

1) Separation

2) Drainage

3) Uniform load distribution (Reinforcement)

Design Approaches Using Geotextiles

• Separation, filtration, and Reinforcement

when subgrade CBR < 3.

• Only for separation, when subgrade CBR between 3 and 7.

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Field studies with

Coir Geotextiles

Dr.Sheela Evangeline,

Dr.Mariamma Joseph, Ms.Saida

College of Engineering Trivandrum

Field studies with Coir Geotextiles by

College of Engineering Trivandrum

• Sponsored by

NCMRI

Coir Board- NRRDA

• Construction by Rural Roads Dept (PMGSY)

• 100m stretch test road constructed at Chirakkad -Kumbakad road in Varkala Block


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Schematic diagram of the cross section with coir geotextiles


COIR GEOTEXTILES USED FOR RURAL ROAD PAVEMENT


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Unrolling coir geotextiles in Attukal Pambadi road on 23-9-11


Laying of coir geotextiles in Attukal Pambadi road on 23-9-11


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Fixing of Coir Geotextiles to ground


Coir geotextiles Laid on Attukal Pambadi road on 23-9-11


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Laying GSB layer over coir geotextiles in Attukal Pambadi road


Laying of GSB over coir geotextiles in Attukal Pambadi road on 23-9-11


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Photograph of Chirakkad -Kumbakad road in Varkala Block

- Before construction


Photograph of Chirakkad -Kumbakad road in Varkala Block –

During construction


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During construction – Laying of coir Geotextile



After laying of Premix bituminous concrete layer


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ROAD EDGE DRAINS

The poor performance of roads in India is partly due to construction on soft soils, at ground level, without considering the high ground water level.

This is more so where black cotton soils are present.

The road condition can be significantly improved by constructing

geotextile lined trench drains.

In some cases a non-woven coir blanket is of high potential, particularly in rural roads.



Coir Geotextile in Road Structure

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GROUND IMPROVEMENT

Pre-fabricated Vertical Drains (PVD) using synthetic polymeric

products (composing of non-woven geotextile sleeve) and

core/mesh in vogue the world over

for consolidating soft clays to improve the ground.

Successfully used in India at Kakinada Port and Kandla Port

recently.

A simple machine developed at the Textile Technology department

of IIT Delhi

uses coir and jute yarns to manurfacture 100% natural fibre PVDs.



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Maintenance of Silt Fences

• Inspection - physical condition, depth of soil behind fence, base pullout, fabric condition

• Clean-out when half-full.

• Allow soil to overtop and install additional downhill fences


Silt Fence - Installation


Coir Fibres Type A1 Coir Fibres Type A2

Type A1 25 mm long

Type A2 25 mm long

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Placing Fill on Geotextile



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BIS

Specifications for Coir Geotextiles[Bhoovastra]

1. Coir Felt – Specification, 2003, IS 15340.

2. Natural fibre geotextiles (jute geotextile and coir Bhoovastra) - Methods of test, 2008, IS 15868: Parts 1-6.

3. Open weave coir Bhoovastra-Specification, 2008, IS 15869.

4. Use of coir geotextiles (coir Bhoovastra) in unpaved Roads – Guidelines, 2009, IS 15871.

5. Application of coir geotextiles (coir woven Bhoovastra) for rain water erosion control in roads, railway embankments and hill slopes-Guidelines, 2009, IS 15872.


CONCLUSIONS

Separator Yes, Rural Roads

Reinforcement Yes Rural Roads, Low Embankments

Filteration & Good Erosion control

Drainage Silt fence

Life As required (5 – 10 yrs)

Environmental friendly

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Acknowledgements

Coir Board

Indian Institute of Technology, Delhi

College of Engineering, Trivandrum

Kerala State Coir Corporation

Kerala State Rural Road Development

Agency

NCMRI

27 July 2016


116

A presentation by

Sai Master Geoenvironmental

Services Private Limited

Serving the EnvironmentSAI MASTER ACHARYA SRI EKKIRALA BHARADWAJA