LB/von/\2./o3 
USE OF COIR FIBRE AS A RAW MATERIAL FOR 
GEOTEXTILES 
8BIVERSITY OF iWORATUUSA. SRI 
MORATUWA 
G7- 7 . is 
N.S.NAWARATHNA 
This thesis was submitted to the Department of Textile and Clothing 
Technology of the University of Moratuwa in partial fulfilment of the 
requirements for the Degree of Master of Science 
Department of Textile and Clothing Technology 
University of Moratuwa 
Sri Lanka 
January 2003 
University of Moratuwa 
77394 
77394 
The work presented in the thesis in part or whole, has not been submitted for 
any other academic qualification at any institution. 
N.S.Nawarathna Dr. Nirmali de Silva 
(Candidate) (Supervisor) 
n 
ABSTRACT 
Geotextiles are defined as 'permeable textile material used with foundation, soil, rock, 
earth or any other geotechnical engineering related material, as an integral part of a 
man-made project, structure or system' where Geotextiles are used in the separation, 
reinforcement, drainage and filtration. Geotextiles are of two main types, namely 
natural and synthetic. The more popular ones are made from polyester, polyamide, 
polyethylene and polypropylene. The synthetics are preferred because of their high 
strength, extensibility and resistance to microorganisms when used in various 
applications usually in contact with soil particles. 
There is a rapid growth in the use of bioengineered soil erosion and sedimentation 
control designs especially in environmentally sensitive areas. Most of these designs 
incorporate coir products to provide the required initial structural stability until the 
establishment of sustainable vegetation. Design criteria in these designs assume a 
certain rate of degradation in the coir products. As a result, there is a growing concern 
about durability and strength retention in field applications of coir erosion control 
products. Coir, jute and coir-jute blends are natural geotextiles commonly used use in 
geotechnical engineering applications. Natural geotextiles are totally biodegradable 
and provides excellent microclimate for plant establishment & growth, easy to install 
and economical. 
iii 
ACKNOWLEDGEMENT 
(1). I gratefully acknowledge the time and effort of Dr.Nirmali de Silva in supervising 
this research project. I appreciate the constant guidance and continued support give to 
me. 
(2). I would like to thank Prof. Lakdas D. Fernando, Senior Professor and former 
Head of the Department of Textile and Clothing Technology and Dr. U.S.W. 
Gunasekera, Senior Lecturer in the Department for their valuable contribution and for 
their vital suggestions to improve this project. 
(3). I wish to thank Mr. Saman Indrajith the General Manager of the Sancta Maria 
Coir Export for generously supplying coir geotextile samples to carry out the research 
work. 
(4). I wish to extend my sincere thanks to the staff members of the Department of 
Textile and Clothing technology who helped me in various ways to complete the 
project successfully and especially to the technical officers Mrs. D. Dissanayake, Mrs. 
P. Wanniarachchi, Mr. CP. Malalanayake and lab attendant Mr. W.Chandradasa for 
their co-operation extended to me during my work. 
(5). Further, I wish to sincerely thank and acknowledge the support given by Lecturer 
in-charge Mr. V.S.C. Weragoda and technical officer Mr. S.D. Karunarathne of the 
Material Tensing Laboratory of the Department of Material Engineering of the 
University of Moratuwa. 
(6). I would like to thank my friend Kumudini for the many useful discussions we 
had while we were studying together. 
(7). The contributions from the Senate Research Grant to purchase chemicals and 
accessories for the research is appreciated. 
(8). Finally I wish to gratefully acknowledge the Asian Development Bank, Science 
and Technology Personnel Development Project for the financial assistance that 
enabled me to undertake a research project leading to Masters Degree. 
TABLE OF CONTENTS 
Abstract 
Acknowledgement 
Table of Contents 
List of Figures 
List of Tables 
List of Annexes 
List of Abbreviations 
CHAPTER ONE 
Introduction and Description of Geotextiles 
1.1 Introduction 
1.2 Historical Background of Geotextile Applications 
1.3 Types of Geotextile 
1.3.1 Materials Used 
1.3.2 Woven Geotextiles 
1.3.3 Knitted Geotextiles 
1.3.4 Non-oven Geotextiles 
1.4 Functions and Applications of Geotextiles 
1.4.1 Separation 
1.4.2 Filtration 
1.4.3 Drainage 
1.4.4 Reinforcement 
1.5 Applications of Biodegradable Geotextiles 
1.5.1 Special Applications of Coir Geotextiles 
1.6 Major Users of Geotextiles in Sri Lanka 
1.6.1 Sri Lanka Land Reclamation and Development Corporation 
1.6.2 Road Development Authority 
1.6.3 Railways Department 
1.6.4 Coast Conservation Department 
1.7. Scope of the Project 
CHAPTER TWO 
Materials and Methods 
2.1 Introduction 
2.2 Production of Coir Geotextiles 
2.2.1 Retting and Extraction of Coir Fibre 
2.2.2 Production of Coir Ropes 
2.2.3 Production of Coir Geotextiles 
2.3 Experimental 
2.3.1 Coir Fibre 
2.3.1.1 Length and Linear Density 
2.3.1.2 Strength and Extensibility at Break 
2.3.1.3 Moisture Regain and Moisture Content 21 
2.3.1.4 Creep Properties 22 
2.3.2 Coir Rope 22 
2.3.2.1 Variation of Strength with Twist 22 
2.3.2.2 Strength and Extension in Conditioned State 23 
2.3.2.3 Strength and Extension in Wet and Dry States 23 
2.3.2.4 Retention of Strength and Extension at Break Under 23 
Normal Weather Conditions 
2.3.2.5 Retention of Strength and Extension at Break in 23 
Acidic Medium 
\i 2.3.2.6 Retention of Strength and Extension at Break in 24 
Alkaline Medium 
2.3.2.7 Retention of Strength and Extension at Break in 24 
Seawater Medium 
2.3.2.8 Retention of Strength and Extension at Break in 24 
Distilled Water Medium 
2.3.2.9 Creep Properties 24 
2.3.3 Coir Geotextile/s Mat 25 
2.3.3.1 Sampling and Preparation of Test Specimens 25 
2.3.3.2 Mass Per Unit Area 26 
2.3.3.3 Tensile Properties of Geotextiles in Conditioned 26 
State 
2.3.3.4 Tensile Properties of Geotextiles in Wet/Dry State 27 
CHAPTER THREE 
^ Results and Discussion 
3.1 Coir Fibre 29 
3.1.1 Length and Linear Density 29 
3.1.2 Calculation of Tensile Properties of Coir Fibre 34 
3.1.3 Moisture Regain and Moisture Content 39 
3.1.4 Creep Properties 41 
3.2 Coir Rope 44 
3.2.1 Strength Variation with Twist 43 
3.2.2 Strength and Extension in Conditioned State 46 
3.2.3 Strength and Extension in Wet and Dry States 48 
3.2.4 Retention of Strength and Extension in Normal Weather 49 
3.2.5 Retention of Strength and Extension in Alkaline/ Acidic/ 49 
^ Seawater/Distilled-water Medium 
3.2.6 Creep Properties 52 
3.3 Coir Geotextile 54 
3.3.2 Tensile Properties of Geotextiles 55 
3.3.2.1 Calculation of Tensile Strength, Initial Modulus and 55 
Extension in Conditioned States 
3.3.2.2 Calculation Of Tensile Strength, Initial Modulus and 57 
Extension in Wet/Dry and Conditioned States 
vi 
3.3.3 Comparison of Properties of Coir Geotextile with Synthetic 
Geotextiles 
58 
CHAPTER FOUR 
Conclusions 60 
References 63 
Annex 01 65 
Annex 02 73 
Annex 03 80 
List of Figures 
Figure No. 
4 
1.1 Types of Geotextiles 
1.2 Application of Geotextiles on the Unpaved Road 
1.3 Geotextile Stabilization of an Unpaved Road 
1.4 Application of Geotextiles as a Filter Material 
1.5 Application of Geotextiles in Drainage System 
1.6 Application of Geotextiles in Reinforcement System 
1.7(a-d) Application of Coir Geotextiles 
2.1 General Classification of Natural Fibres 
2.2 Design of set of Clamps for Testing 
3.1 Distribution of Coir Fibre Length 
3.2 Fibre Array Diagram of Cotton Fibres 
3.3 Variation of Fibre Length with Frequency 
3.4 Variation of Fibre Linear Density with Frequency 
3.5 Strength-Extension Diagram of a Coir Fibre 
3.6 Variation of Tenacity with Frequency 
3.7 Work of Rupture 
3.8 Variation of Work of Rupture with Frequency 
3.9 Variation of Initial Modulus with Frequency 
3.10 Variation of Extension % with Frequency 
3.11 The Hysteresis of a Material 
3.12 Creep Curve of Coir Fibres 
3.13 Creep Curve s for Polypropylene, Polyamide and Polyester 
3.14 Variation of Tenacity with Twist of Ropes 
3.15 (a,b)Twist factor vs Strength of some Natural Fibres and Coir fibre 
3.16 Variation of Strength vs Extension% of a Rope 
3.17 Variation of Strength vs Extension% of Ropes 
3.18 (a) Variation of Retained Tenacity % with Time 
3.18 (b) Variation of Retained Extension% at Break with Time 
3.19 (a)Variation of Retained Tenacity with Time 
3.19 (b) Variation of Extension at Break with Time 
3.20 (a) Variation of Retained Tenacity with Time 
viii 
4 
3.19 (b) Variation of 
3.21 (a) Variation of 
3.20 (a) Variation of 
3.21 (a) Creep Curve 
3.21 (b) Creep Curve 
3.21 (c) Creep Curve 
3.21 (d) Creep Curve 
3.21 (e) Creep Curve 
3.21 (f) Creep Curve 
3.21 (g) Creep Curve 
3.21 (h) Creep Curve 
3.22 (a) Variation of 
2.22 (b) Variation of 
with Average Indicated 
Retained Extension % at Break with Time 
Retained Average Tenacity with Time 
Extension % at Break with Time 
for 50% Loaded Coir Ropes 
for 40% Loaded Coir Ropes within First Two Days 
for 30% Loaded Coir Ropes 
for 20% Loaded Coir Ropes 
for 50% Loaded Coir Ropes within First Two Days 
for 40% Loaded Coir Ropes within First Two Days 
for 30% Loaded Coir Ropes within First Seven days 
for 20% Loaded Coir Ropes within First Day 
strength vs extension% of one specimen 
strength vs extension% of one specimen all Specimens 
ix 
List of Tables 
4 
•if 
Table No. 
1.1 Comparative Properties of General Polymer Families 
1.2 Geotextile Applications and Functions 
2.1 Composition of Coconut Fibres 
2.2 Applied Load on the Specimens 
3.1 Class Intervals Vs Frequency of Length 
3.2 Length Range of Natural Textile Raw Materials 
3.3 Types of Coir Fibre 
3.4 Results of Class Intervals and Frequency of Linear Density 
3.5 Results of Class Intervals and Frequency of Tenacity 
3.6 Results of Class Intervals and Frequency of Work of Rupture 
3.7 Results of Class Intervals and Frequency of Initial Modulus 
3.8 Results of Class Intervals and Frequency of Extension 
3.9 Comparison of Properties of Fibres 
3.10 Moisture Regain and Moisture Content 
3.11 Twist and Tenacity Values 
3.12 Twist Factors of Coir for different Tex Values 
3.13 Frequencies of Tenacity 
3.14 Frequencies of Extension % 
3.15 Strength & Extension% at Break of Ropes 
3.16 Extension Values of Ropes 
3.17 Mass Per Unit Area Values of Geotextiles 
3.18 Mass per Unit area values of Fabrics 
3.19 Properties of Geotextiles in conditioned State 
3.20 Properties of Geotextiles in Wet and Dry States 
3.21 Comparison of Properties of Coir Geotextile with Synthetic Geotextiles 
> 
X 
List of Annexes 
Annex 1 Length and Weight of Coir Fibres 
Annex 2 Breaking Strength, Extension at Break, Work of Rupture 
and Slop of the Strength vs Elongation of Coir Fibres 
Annex 3 Extension of Coir Fibres 
xi 
List of Abbreviations 
figure 
frequency 
hours 
relative humidity 
turns per meter 
versus 
xn