UNIVERSITY OF NAIROBI

A STUDY ON THE EFFECTS OF THE REPLACEMENT OF

COCONUT SHELL AS COARSE AGGREGATE IN CONCRETE

By Imani Yusuf Taherali, F16/28904/2009

A project submitted as a partial fulfillment for the award of the

degree of

BACHELOR OF SCIENCE IN CIVIL ENGINEERING

2014

[i]

Abstract

In this constructed environment, the rising cost of building construction materials is the factor of

great concern. The prices of building materials are rising day by day. The coarse aggregates are

the main ingredients of concrete.

In this study, coconut shell is used as lightweight aggregate in concrete. The properties of coconut

shell and coconut shell aggregate concrete is examined and the use of coconut shell aggregate in

construction is tested. Coconut shell exhibits more resistance against crushing compared to

conventional aggregate. Density of coconut shell is 521.5 kg /m3 and these is within the specified

limits for lightweight aggregate. There is no need to treat the coconut shell before use as an

aggregate. A water cement ratio of 0.5has been used throughout the project.

Properties of coconut shell aggregate concrete were studied and compared with the control

concrete. Compressive and tensile tests on hardened concrete was performed.

Use of coconut shell aggregate concrete as structural lightweight concrete is recommended.

Coconut shell aggregate is a potential construction material and simultaneously reduces the

environmental problem of solid waste and is readily available at a lower cost than normal

aggregates.

[ii]

Dedication

I dedicate my work to my family and friends who have continuously supported me in my quest

for excellence. I also heartily thank and dedicate this work to my Supervisor who has imparted

invaluable knowledge and time dedication to my work.

[iii]

Acknowledgement

I wish to acknowledge all those who made this project a success.

First and foremost, I wish to acknowledge my supervisor Dr (Eng.) S.O. Abuodha for his

continuous guidance, invaluable advice, endless assistance and knowledge which lead to the

successful completion of this project.

Secondly, I wish to thank all my lecturers for the knowledge they shared with me in my five years

of study at the University of Nairobi.

Special thanks to Mr. Muchina, Mr. Martin and Mr. Nicholas for their assistance in this project.

I would also like to extend my gratitude to my colleagues who have helped me through this

journey.

Lastly, I wish to thank my parents, brothers and sisters for their endless support throughout my

life.

May you all be blessed.

[iv]

Table of contents

ABSTRACT ................................................................................................................................................. i

DEDICATION ............................................................................................................................................ ii

ACKNOWLEDGEMENT ....................................................................................................................... iii

TABLE OF CONTENTS ......................................................................................................................... iv

LIST OF ILLUSTRATIONS ....................................................................................................................ix

LIST OF ABBREVIATIONS ..................................................................................................................xi

Chapter one

1.0 Introduction .......................................................................................................................................... 1

1.1 Background knowledge....................................................................................................................... 1

1.2 Coconut growing regions .................................................................................................................... 1

1.3 Physical properties of coconut ........................................................................................................... 1

1.4 Chemical properties of the coconut shell.......................................................................................... 1

1.5 Uses of the Coconut Plant .................................................................................................................. 1

1.6 General Introduction ............................................................................................................................ 1

1.7 Aim of the Research ............................................................................................................................ 1

1.8 Objective ............................................................................................................................................... 1

1.9 Research Hypothesis ........................................................................................................................... 1

Chapter Two

2.0 Review of Literature ............................................................................................................................ 1

2.1 Lightweight concrete ........................................................................................................................... 1

2.2 Lightweight Aggregate ....................................................................................................................... 7

[v]

2.2.1 Naturally occurring aggregates ....................................................................................................... 8

2.2.2 Artificially produced aggregates .................................................................................................... 8

2.2.3 Aggregates from Industrial By-products ....................................................................................... 9

2.2.4 Aggregates from organic solid waste ........................................................................................... 10

2.3 Properties of Aggregate .................................................................................................................... 11

2.3.1 Particle shape (angularity and flakiness) and Surface texture .................................................. 11

2.3.2 Particle size distribution ................................................................................................................ 12

2.3.3 Loose bulk, compacted bulk and relative density ...................................................................... 13

2.3.4 Water Absorption ........................................................................................................................... 14

2.3.5 Aggregate Strength ......................................................................................................................... 14

2.3.6 Chemical characteristics of Aggregates ...................................................................................... 14

2.4 Properties of Fresh concrete ............................................................................................................. 15

2.4.1 Workability ...................................................................................................................................... 15

2.5 Other aspects of Concrete ................................................................................................................. 16

2.5.1 Fire Resistance ................................................................................................................................ 17

2.5.2 Mixed Design .................................................................................................................................. 17

2.5.3 Water Cement Ratio ....................................................................................................................... 18

2.5.4 Mixing of Concrete ........................................................................................................................ 18

2.5.5 Curing ............................................................................................................................................... 19

2.5.6 Permeability of Concrete ............................................................................................................... 19

2.5.7 Testing of Concrete ........................................................................................................................ 20

Chapter Three

3.0 Methodology ...................................................................................................................................... 21

[vi]

3.1 Introduction ........................................................................................................................................ 21

3.2 Materials ............................................................................................................................................. 21

3.2.1 Cement ............................................................................................................................................. 21

3.2.2 Sand .................................................................................................................................................. 21

3.2.3 Coarse Aggregate ........................................................................................................................... 22

3.2.4 Water ................................................................................................................................................ 22

3.2.5 Coconut Shell Aggregate ............................................................................................................... 23

3.3 Tests on aggregates ............................................................................................................................ 25

3.3.1 Sieve Analysis ................................................................................................................................. 25

3.3.2 Aggregate crushing value (ACV) ................................................................................................. 27

3.3.3 Bulk Density .................................................................................................................................... 31

3.3.4 Flakiness Index ............................................................................................................................... 32

3.3.5 Water Absorption ........................................................................................................................... 33

3.4 Mix Design ......................................................................................................................................... 33

3.5 Test on Fresh Concrete ..................................................................................................................... 36

3.5.1 Slump test ........................................................................................................................................ 36

3.6 Tests on Hardened concrete.............................................................................................................. 38

3.6.1 Casting of Cubes ............................................................................................................................. 38

3.6.2 Curing of Cubes .............................................................................................................................. 39

3.6.3 Compressive Test ........................................................................................................................... 41

3.6.4 Split Tensile Test ............................................................................................................................ 44

Chapter Four

4.0 Results ................................................................................................................................................. 46

4.1 Sieve Analysis .................................................................................................................................... 46

[vii]

4.1.1 Fine Aggregate ................................................................................................................................ 46

4.1.2 Coarse Aggregate ........................................................................................................................... 47

4.1.3 Coconut Shell Aggregate ............................................................................................................... 48

4.2 Aggregate crushing value ................................................................................................................. 50

4.2.1 Aggregate crushing value for normal aggregates ....................................................................... 50

4.2.2 Aggregate crushing value for coconut shell aggregate .............................................................. 50

4.3 Bulk Density ....................................................................................................................................... 51

4.4 Flakiness Index .................................................................................................................................. 51

4.5 Water Absorption ............................................................................................................................... 52

4.6 Mix Design ......................................................................................................................................... 53

4.6.1 Proportions of different replacement ratios................................................................................. 54

4.7 Slump Test ............................................................................................................................................. 55

4.8 Compressive Test ............................................................................................................................... 56

4.8.1 14 day Compressive Cube Test Results ...................................................................................... 56

4.8.2 28 day Compressive Cube Test Results ...................................................................................... 57

4.9 Split Tensile Test ............................................................................................................................... 60

Chapter Five

5.0 Discussion ........................................................................................................................................... 63

5.1 Sieve Analysis .................................................................................................................................... 63

5.2 Aggregate Crushing Value ............................................................................................................... 64

5.3 Bulk Density ....................................................................................................................................... 64

5.4 Flakiness Index .................................................................................................................................. 64

5.5 Water Absorption ............................................................................................................................... 65

5.6 Slump Test .......................................................................................................................................... 65

[viii]

5.7 Compressive Test ............................................................................................................................... 65

5.8 Split Tensile Test ............................................................................................................................... 67

Chapter Six

6.0 Conclusion .......................................................................................................................................... 69

Chapter Seven

7.0 Recommendations .............................................................................................................................. 71

REFRENCES .............................................................................. 72

[ix]

List of illustrations Page

Figure 1 coconut growing regions 2

Figure 2 Man plucking coconut from a full grown tree 2

Figure 3 Cross-section of a coconut fruit 3

Table 1 Estimated production of coconut in Kenya 4

Figure 4 Classifying the particle shape by “sphericity” and roundness 11

Figure 5 true, shear and collapsed slump 16

Figure 6 Samples of coarse and fine aggregates 22

Figure 7 coconut shell halves 23

Figure 8 Crushing of coconut shells 24

Figure 9 Sizes of crushed coconut shell aggregate sample 24

Figure 10 Sieve analysis of coconut shell aggregate 27

Figure 11a,b aggregate crushing value test 29

Figure 11c loading of aggregate sample for ACV test 29

Figure 12 Crushed sample for ACV test 29

Figure 13 sieving of sample on sieve size 2.36mm 30

Figure 14 Weighing balance for weighing small masses 30

Figure 15 Dry mixing of concrete in a rotational drum 35

Figure 16 true,shear and collapse slump 36

Figure 17 slump test 37

Figure 18 slump test showing true slump 38

Figure 19 casting of cubes 39

Figure 20 curing of cubes and cylinders 40

Figure 21 loading area for compressive test 42

Figure 22 compressive machine dial gauge 43

Figure 23 cylinder specimen ready to be loaded 45

Figure 24 splitting of cylinder 45

[x]

Table 2 Sieve analysis for fine aggregate 46

Graph 1 particle size distribution for fine aggregate 47

Table 3 sieve analysis for coarse aggregate 47

Graph 2 Particle size distribution of coarse aggregate 48

Table 4 Particle size distribution for coconut shell aggregate 49

Graph 3 Particle size distribution of coconut shell aggregate 49

Table 5 Results for ACV test on coarse aggregate 50

Table 6 Results for ACV test on coconut shell aggregate 50

Table 7 results for determination of bulk density of the coconut shell aggregate 51

Table 8 Flakiness index of coconut shell aggregate 51

Table 9 Results for test for water absorption of coconut shell aggregate 52

Table 10 Mix design for concrete 53

Table 11 Mass required for different percentage replacement of coarse aggregate with coconut shell aggregate 54

Table 12 Slump for different percentage replacement of coarse aggregate with coconut shell aggregate 55

Graph 4 slump for different percentage replacement of coarse aggregate with coconut shell aggregate 55

Table 13 14 day compressive strength and densities of different percentage replacement 56

Table 14 28 day compressive strength results 57

Graph 5 Compressive strength for 14 and 28 days 59

Graph 6 strength development of different percentage replacements of coarse aggregate 59

Graph 7 Densities of concrete for different percentage replacement 60

Table 15 28 day tensile test results 60

Graph 8 Tensile strength for different percentage replacement 62

Figure 25 stone crusher 63

Figure 26 crack path around coconut shell aggregate 66

[xi]

List of abbreviations

SSD - saturated surface dry

OD – oven dry

CS – coconut shell

CSA – coconut shell aggregate

W/c – water cement ratio

LWA - lightweight aggregate

LWC – lightweight concrete

FI- Flakiness index

ACV – Aggregate crushing value