UNIVERSITY OF LAGOS

FACULTY OF ENGINEERING
DEPARTMENT OF CIVIL
AND ENVIRONMENTAL ENGINEERING

BEHAVIOUR OF ALKALINE ACTIVATED CONCRETE WITH

COCONUT SHELL ASH (CSA) AS PARTIAL REPLACEMENT
OF ORDINARY PORTLAND CEMENT (OPC)

BY:
EMESHIE, EBUBE JOSEPH
159042014

A Research Project Submitted To the Department of Civil and

Environmental Engineering, In Partial Fulfilment of the
Requirements for the Award of Master of Science (M.Sc.) Degree
(Structures Option) In Civil & Environmental Engineering

TITLE PAGE

JUNE, 2018

i
 CERTIFICATION

This is to certify that this project work is carried out by EMESHIE, Ebube Joseph with

matriculation number 159042014, in partial fulfilment of the requirements for the award of

Master of Science (M.Sc.) degree (Structures Option) in Civil and Environmental Engineering,

Faculty of Engineering, University of Lagos.

Dr. E.E. Ikponmwosa Date

(Project Supervisor)

Professor K.A. Aiyesimoju Date

(Head of Department)

ii
 DEDICATION

To my God, the Immortal, Invisible and only Wise One. I give all honour, thanks and sincere

adoration to Him and to His Son Jesus Christ to whom the Kingdom to come has been given and

my brethren in the Faith with whom I have partaken of Eternal Life.

iii
 ACKNOWLEDGEMENT

My special gratitude goes to God Almighty, the creator of all things and giver of life for his

grace, wisdom, and protection throughout my industrial training. May His name be praised now

and forever. Amen!

No achievement in life is without the help of many known and unknown individuals. Special

thanks to my parents, siblings and family friends who have been spiritual, physical, financial and

moral backbone.

To my Supervisor Dr. E. E. Ikponmwosa for his professional guidance and his fatherly touch

even beyond that required of him.

My in-depth gratitude goes to the Head of my Department Prof G.L Oyekan and all my

lecturers in the department, who have faithfully impacted their professional knowledge on me

and my colleagues (Structures Class 2015/2016) who have served to reshape my thoughts

through their positive influence.

Finally, I also wish to acknowledge my friends and colleagues; Martins, Lasisi, Emmanuel, Baba

Bolts, Ebuka, Isaac, Deji, Philips, Oluchi, Muyiwa, Opeyemi, Racheal, Saka, Joe, Femi,

Micheal, Obinna, etc. for their support and encouragement.

Grace and Peace to you all.

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 ABSTRACT

Sustainability in concrete production can be achieved by innovations in substitutions of material

used. Innovations are much needed to meet the increasing demand for new and quality materials.

This report presents the strength indices of structural concrete elements with ceramic waste as

coarse aggregate to achieve economy and reduce its impact on the environment. The work

investigated the physical properties, setting time of cement paste, workability, compressive and

tensile strength, flexural strength and failure pattern of concrete elements with ceramic waste as

coarse aggregate. Seventy-five (75Nos.) 150x150x150mm concrete cubes and Seventy-five

(75Nos.) 150x300mm cylinder moulds was cast and cured for a period of 7, 14, 28, 45 & 90 days

and tested on the specified age. Forty-five (45Nos.) Non-reinforced concrete beam of 750x150x

150mm and Ten (10Nos.) Reinforced concrete beam of 2.16m x150x250mm was cast and cured

for a period of 7, 14 & 28 days for non-reinforced beam while reinforced concrete beams was

cast and tested on the specified age to measure the correlation of strength parameter as observed

during the experiment. The concrete for this investigation was produced from cement, sand and

granite/ceramic waste in the ratio of 1:2:4 (Cement: Fine aggregate: Coarse aggregate) with

water/cement ratio of 0.45. The percentage replacement of granite with ceramic was varied from

0% to 100% at an incremental rate of 25%. The compressive and tensile strength of concrete

cubes and cylinder sample were determined using the Avery Dension Crushing Machine, while

the deflection of the reinforced concrete beams was determined by two-point loading test.

The results of the preliminary tests carried out shows that ceramic waste was found to have a

lesser ability to resist crushing. From the workability test results, it revealed an increase as the

content of ceramic waste increased from 70mm to 99mm at 0% to 75% replacement of granite

with ceramic waste but a decline was observed at 100% replacement. The results on compressive

v
strength shows that the strength value decreased as the percentage replacement increased from

control to 100% replacement. The strength values increased as the curing ages increased

progressively, and it was observed that from 25% to 75% replacement can be used for critical

structural works while 100% replacement are suitable for non-critical structural works. The

results show that tensile strength decreased as percent replacement increased, however as curing

age increases from 0 to 28 days, a gradual increase in tensile strength was observed and from 28

days to 90 days of curing, a decline in the values was noted. Results of non-reinforced beam

show the flexural strength increased as the curing ages are increasing but at 100% replacement a

declined was observed. Results of steel reinforced concrete beam, shows that the deflection

increased as percentage replacement is increased from control up to 75% and further replacement

led to a decrease in deflection as the load is applied at 10KN Interval.

vi
 TABLE OF CONTENTS

TITLE PAGE i

CERTIFICATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF PLATES xv

CHAPTER ONE INTRODUCTION 1

1.1 BACKGROUND STUDY 1

1.2 PROBLEM STATEMENT 2

1.2.1 Environmental Impact in Nigeria 2
1.2.2 Economy 3
1.2.3 Health Hazards 3

1.3 AIM AND OBJECTIVES 4

1.4 SIGNIFICANCE OF STUDY 4

1.5 JUSTIFICATION OF STUDY 5

1.6 SCOPE OF STUDY 6

1.8 LIMITATIONS AND CHALLENGES 8

1.9 PRESENTATION OF STUDY 8

1.10 DEFINITION OF TERMS AND TERMINOLOGIES 9

vii
CHAPTER TWO LITERATURE REVIEW 23

2.0 PREAMBLE 23

2.1 POZZOLANS 24
2.1.1 History 25
2.1.2 Classification of Pozzolans 29
2.1.3 The Pozzolanic Reaction 30

2.2 COCONUT 32
2.2.1 History, Spread and Cultivation 32
2.2.2 Production 35
2.2.3 Parts of Coconut and Their Respective Uses 37

2.3 WASTE PRODUCTS 38

2.3.1 Definition 38
2.3.2 Classification of Waste Products 39
2.3.3 Types of Waste Products 40

2.4 MECHANISM OF ACTIVATION 41

2.4.1 Alkali Activation 42
2.4.2 Sulphate Activation 45
2.4.3 Other Types of Activation 48

2.5 STRENGTH DEVELOPMENT USING VARIOUS CHEMICAL ACTIVATORS 50

2.5.1 Alkali Activators 50
2.5.2 Sulphate Activators 52
2.5.3 Other Types of Activator 55

2.6 CALCIUM HYDROXIDE (Ca(OH)2) CONTENT 57

2.7 CONCLUSIONS 58

CHAPTER THREE METHODOLOGY 60

3.0 PREAMBLE 60

3.1 PARENT MATERIALS 60

viii
 3.1.1 Cement 60
3.1.2 Fine Aggregate (Sharp Sand) 61
3.1.3 Coarse Aggregate (Granite) 61
3.1.4 Potable Water 61
3.1.5 Coconut Shell Ash 62
3.1.6 Sodium Hydroxide (NaoH) 62
3.1.7 Sodium Silicates (Na3SiO2) 62

3.2 PREPARATION OF ALKALINE ACTIVATOR 62

3.3 MIXING/CASTING OF CONCRETE 63

3.4 CURING OF CONCRETE 64

3.5 APPARATUS, TOOLS AND EQUIPMENTS 64

3.5.1 Avery Weighing Machine 64
3.5.2 Cube Moulds 64
3.5.3 Slump Mould 64
3.5.4 Concrete Mixer 65
3.5.5 Vicats Apparatus 65
3.5.6 Avery Dennison Compression Testing Machine (Capacity: 1500kN) 65
3.5.7 Wheel Barrow 65
3.5.8 Tamping Rod 65
3.5.9 Set of Sieves 66
3.5.10 Other Equipment 66

3.6 EXPERIMENTAL TEST PROCEDURES 66

3.6.1 Preliminary Investigation 66
3.6.1.1 Sieve Analysis/Gradation of Aggregates 67
3.6.1.2 Specific Gravity 68
3.6.1.3 Bulk Density 69
3.6.1.4 Moisture Content 70
3.6.1.5 Dry Density Test 71
3.6.1.6 Aggregate Crushing Value and Impact Value 71
3.6.2 Secondary Investigation 73

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 3.6.2.1 Consistency/Setting Time of Cement 73
3.6.2.2 Workability 74
3.6.2.3 Split Cylinder Test 75
3.6.2.4 Compressive Strength Test 76

3.7 MATERIAL QUANTITIES 93

3.7.1 Casting Schedule for Concrete Cubes 93
3.7.2 Casting Schedule for Concrete Cylinders 95

REFERENCES 99

x
 LIST OF TABLES
 Table 3.1: Showing Numbers of Cube for each Percentage Replacement of Ceramic

Waste

 Table 3.2: Showing Numbers of Cylinder for each Percentage Replacement of Ceramic

Waste

 Table 3.3: Showing Numbers of Beams without for each Percentage Replacement of

Ceramic Waste

 Table 3.4: Showing Numbers of Large Beams with for each Percentage Replacement of

Ceramic Waste

 Table 3.5: Showing Weights of Coarse Aggregate (Granite & Ceramic Waste) for each

Percentage Replacement.

 Table 3.6: Showing Weights of Coarse Aggregate (Granite & Ceramic Waste) for each

Percentage Replacement in Concrete Cylinder.

 Table 3.7: Showing Weights of Coarse Aggregate (Granite & Ceramic Waste) for each

Percentage Replacement in small Beam.

 Table 3.8: Showing Weights of Coarse Aggregate (Granite & Ceramic Waste) for each

Percentage Replacement in Large Beam.

 Table 4.1 Sieve Analysis for Fine Aggregate

 Table 4.2 Sieve Analysis For Coarse Aggregate

 Table 4.3 Sieve Analysis For Ceramic Waste

 Table 4.4 Showing Sieve Analysis for Ceramic Waste

 Table 4.5: Showing Some Physical Properties of Aggregates, Cement and Ceramic Waste

 Table 4.6: Showing Setting Time of Cement Paste

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 Table 4.7: Showing Slump Values and Degree of Workability

 Table 4.8: Average Compressive Strength Values for 7 Days

 Table 4.9: Average Compressive Strength Values for 14 Days

 Table 4.10: Average Compressive Strength Values for 28 Days

 Table 4.11: Average Compressive Strength Values for 45 Days

 Table 4.12: Average Compressive Strength Values for 7, 14, 28 & 45 Days

 Table 4.13: Average Tensile Strengths for each Percentage Replacement of Ceramic

Waste in Concrete Cylinder

 Table 4.14: Average Flexural Strengths for each Percentage Replacement of Ceramic

Waste in Concrete Beam

 Table 4.15: Average Flexural Strengths for each Percentage Replacement of Ceramic

Waste in Reinforced Concrete Beam

 Table 4.16: Load-Deflection Values for 28 Days Old Concrete Beam Replacement with

Ceramic Wastes.

 Table 4.17: Cost Analysis of Producing 1m3 of concrete.

 Table 4.18: Cost Analysis Difference between Control concrete and Ceramic Waste

Concrete.

xii
 LIST OF FIGURES
 Figure 4.1: Particle Size Distribution Curves for Sand, Granite and Ceramic Waste

 Figure 4.2: Variation of Workability with Percentage Replacement of Ceramic Wastes

 Fig 4.3: Graphical Representation of 7 Days Compressive Strength with Percentage

Replacement of Ceramic Wastes

 Fig 4.4: Graphical Representation of 14 Days Compressive Strength with Percentage

Replacement of Ceramic Wastes

 Fig 4.5: Graphical Representation of 28 Days Compressive Strength with Percentage

Replacement of Ceramic Wastes

 Fig 4.6: Graphical Representation of 45 Days Compressive Strength with Percentage

Replacement of Ceramic Wastes

 Fig 4.7: Graphical Representation of 90 Days Compressive Strength with Percentage

Replacement of Ceramic Wastes

 Fig 4.8: Superimposed Graphical Representation of 7, 14, 28, 45 & 90 Days Compressive

Strength of Specimen

 Fig 4.9: Superimposed Graphical Representation of Control, 25%, 50%, 75% & 100%

Replacement of Ceramic Waste in Concrete Cube Specimen

 Fig 4.10: Superimposed Graphical Representation of Control, 25%, 50%, 75% & 100%

Replacement of Ceramic Waste in Concrete Cube Specimen Showing Different Zones

 Fig 4.11: Superimposed Graphical Representation of 7, 14, 28, 45 & 90 Days Tensile

Strength of Specimen

 Fig 4.12: Graphical Representation Tensile Strength of Control, 25%, 50%, 75% & 100%

Replacement of Ceramic Waste in Concrete Cylinder Specimen

xiii
 Fig 4.13: Graphical Representation Flexural Strength of Control, 25%, 50%, 75% & 100%

Replacement of Ceramic Waste in Concrete Beam Specimen

 Fig 4.14: Chart Representation Flexural Strength of Control, 25%, 50%, 75% & 100%

Replacement of Ceramic Waste in Concrete Beam Specimen

 Fig 4.15: Load Deflection Curves for Control Specimen

 Fig 4.16: Load Deflection Curves for 25% Specimen

 Fig 4.17: Load Deflection Curves for 50% Specimen

 Fig 4.18: Load Deflection Curves for 75% Specimen

 Fig 4.19: Load Deflection Curves for 100% Replacement of Ceramic Waste in Reinforced Concrete

Beam Specimen

 Fig 4.20: Superimposed Load Deflection Curves for all Concrete Beam Specimen

 Fig 4.21: Graphical Representation of Load-Deflection in Reinforced Concrete Beam Specimens

xiv
 LIST OF PLATES
 Plate 3.1: Fine Aggregate (Sand)

 Plate 3.2: Coarse Aggregate (Granite)

 Plate 3.3: Cement (Elephant Superset)

 Plate 3.4: Ceramic Waste

 Plate 3.5: Sieve Analysis Apparatus

 Plate 3.6: Various Specimens of Cubes of Normal Concrete and those replaced with

Ceramic Waste

 Plate 3.7: Avery Crushing Machine

 Plate 3.8: Avery (Split Tensile) Crushing Machine

 Plate 3.9: Curing of Short Beams in a Judo Bag

 Plate 3.10: Tensile Strength Testing Machine

 Plate 3.11: Casting of Large Beam

 Plate 3.12: Load-Deflection Test Set-up

xv
 CHAPTER ONE INTRODUCTION

INTRODUCTION

1.1 BACKGROUND STUDY

Concrete is the premier construction material around the world and is most widely used in all

types of construction works, including infrastructure, low and high-rise buildings, and

domestic developments. It is a man-made product, essentially consisting of a mixture of

cement, aggregates, water and admixture(s).Ordinary Portland cement is conventionally used

as primary binder to produce concrete. The production of cement is increasing about 7%

annually. The cement through hydration acts as the binder while the fine and coarse

aggregates serve to improve workability and provide bulk and stability respectively [Zongjin

Li, 2011]. Traditionally cement has been available at exorbitant prices and of various types

(Ordinary Portland Cement, Blast-Furnace Slag/Sulphate Resisting Cement, Low heat

Cement, Masonry cements, Expansive cements, White blended cements etc. ) to suit all

purposes. However, the continued extensive extraction of its constituents (limestone, clay,

gypsum etc.) from nature has been questioned because of the depletion of limestone deposits

and the environmental concerns associated with its extraction and production. Environmental

concerns are the high energy consumption required to mine, manufacture, and transport the

cement; and the related air pollution, including the release of greenhouse gas (e.g., Carbon

dioxide- responsible for global warming), dioxin, Nitrogen dioxide, Sulphur (IV) oxide and

particulates.

Research on alternatives to cement, has so far centred on the partial replacement of cement

with different materials (Pozzolans). In Nigeria, the most common and readily available

materials that can be used to partially replace cement without economic implications are agro

based (in this case Coconut Shell Ash).

1
1.2 PROBLEM STATEMENT

Three major issues will be addressed here, and they are;

i) Environmental Impact in Nigeria.

ii) Economy

iii) Health hazards

1.2.1 Environmental Impact in Nigeria

A study carried out by Nigerian Environmental Society (NES), examined types of wastes and

their effect on the environment (Enugu state, Nigeria). Data was collected with the aid of

structured questionnaire from 100 respondents from the study area. Data analysis was by the

use of descriptive statistics. It was found that wastes of rice husk, sawdust waste, coconut

shell waste, waste of coconut fibre, plastic bottles and waste of pure water bags were the

predominant types of wastes identified in the study area. These wastes are deposited in the

environment with little effective method of waste management and recycling. The findings

revealed that waste refuse disposal causes traffic jam on the roads in Enugu state, waste of

materials together with waste of polythene materials is a predisposing factor to infectious

disease, drainage blockages, over flooding, possible water pollution and air pollution. Some

of these deposits are not easily decomposed and the accumulation has constituted an

environmental challenge hence the need to convert them into useful materials to minimise

their negative effect on the environment.

Global pollution coupled with resource depletion (which has led to ecological imbalance) has

challenged many researchers and engineers to seek these locally available materials with a

view to investigating their usefulness either wholly as a construction material or partly as a

substitute for conventional ones in concrete production.

2
1.2.2 Economy

The high cost of conventional building materials is a major factor affecting housing delivery

in Nigeria. This has necessitated research into alternative materials of construction. Coconut

shells are not commonly used in the construction industry but are often dumped as

agricultural wastes. However, with the quest for affordable housing system for both the rural

and urban population of Nigeria and other developing countries, various proposals focussing

on trimming down conventional building material costs have been put forward. One of the

suggestions in the forefront has been the sourcing, development and use of alternative, non-

conventional local construction materials including the possibility of using some agricultural

wastes and residues as construction materials. Coconuts shells (CS), are agricultural waste

products obtained in the processing of coconut, and are available in large quantities in the

tropical regions of the world, most especially in Africa, Asia and America. In Nigeria,

coconut shell is available in large quantities in the southern part of the country. Apart from its

use in production of fibre-roofing material, other possible use as pozzolan in mortar or

concrete production has not been extensively exploited.

1.2.3 Health Hazards

Bags of cement routinely have health and safety warnings printed on them because, not only

is cement highly alkaline, but the setting process is exothermic. As a result, wet cement is

strongly caustic (water pH = 13.5) and can easily cause severe skin burns if not promptly

washed off with water. Similarly, dry cement powder in contact with mucous membranes can

cause severe eye or respiratory irritation. Some trace elements, such as chromium, from

impurities naturally present in the raw materials used to produce cement may cause allergic

dermatitis. Reducing agents such as ferrous sulphate (FeSO 4) are often added to cement to

3
convert the carcinogenic hexavalent chromate (CrO42−) in trivalent chromium (Cr3+), a less

toxic chemical species. Cement users need also to wear appropriate gloves and protective

clothing. In this regard the need for a reduction in the use of cement during construction is

imminent and must be encouraged.

1.3 AIM AND OBJECTIVES

The aim of this research work is to investigate the behaviour of alkaline (NaOH+Na 2SiO3)

activated concrete with Coconut Shell Ash (CSA) as partial replacement of Ordinary Portland

Cement (OPC). The objectives are:

 To investigate the mechanical and physical properties of the parent materials in

concrete i.e. Grain size analysis, determination of bulk-densities, specific gravity,

coefficient of uniformity and curvature, dry density, moisture content, fineness,

soundness. Etc. .

 To determine the effects of varying concentrations of alkaline activator on the setting

time ( Initial and Final) of cement paste with a pozzolan(10% CSA)

 To investigate some engineering properties of both wet and hardened concrete with

varying proportions of alkaline activator.

 Determine the chemical (oxides) composition of coconut shell ash.

 To determine the optimum quantity of NaOH+Na2SiO3 needed.

1.4 SIGNIFICANCE OF STUDY

Coconut shell Ash (CSA) is a cheap alternative to supplement the use of OPC in normal

concrete production. Since the disposal of coconut shell ash constitute environmental

pollution, its reuse in normal concrete production will have the following useful effects:

The results of this study will prove to be of great importance and benefits to the economy in

quite a number of ways which includes:

4
  The study will help reduce the high demand for cement production, which causes

ecological imbalance associated with the mining of limestone.

 This study will help to curb or reduce the health hazards associated with working with

cement.

 This study could help improve some of the properties of concrete.

 This study could help improve some of the properties of mortar.

 Reduction in the cost of building development by reducing the amount of OPC

used in concrete production

 It will serve as a basis for further study and higher learning.

 This study will give an insight into the possible reduction of self-weight of concrete

produced from partially replaced OPC with CSA in the presence of Sodium

Hydroxide of NaOH+Na2SiO3

 The cost implications on the use of CSA as pozzolan in the presence of Sodium

Hydroxide (NaOH+Na2SiO3) in varying concentrations.

1.5 JUSTIFICATION OF STUDY

According to a report by FAO (Food and Agricultural Organisation), coconut is grown in

more than 86 countries worldwide, with a total production of 54 billion nuts harvest per

annum. Nigeria currently can boast of 265,000 metric tonnes of coconut production and it’s

in 18th position of the world coconut production index. Limited research has been conducted

on mechanical properties of concrete with coconut shell ash as possible replacement

substitute for cement (pozzolan). However, further research is needed for better

understanding of the behaviour of coconut shell as pozzolan. The main concern of this

research work is centred;

5
  Use of alternative, non-conventional local construction materials including the

possibility of using some agricultural wastes and residues as construction materials.

 On reducing cost while maintaining or enhancing structural integrity.

 Environmental/ health impacts are also taken into account

 Possible reduction of the self-weight of mortar and concrete itself.

 The optimum concentration of Sodium Hydroxide + Sodium Silicates

(NaOH+Na2SiO3) needed to get the best concrete.

1.6 SCOPE OF STUDY

This research work will investigate the possible effect of addition of Sodium hydroxide+

Sodium Silicates (NaOH+Na2SiO3) on the compressive strength of concrete produced using

coconut shell ash (CSA) as partial replacement for Ordinary Portland Cement (OPC) in

concrete. The variable in this research is Sodium Hydroxide+ Sodium Silicate

(NaOH+Na2SiO3). Other constituents of the concrete mixes will be held constant. The

OPC:CSA ratio will be at 90:10. The Sodium Hydroxide+ Sodium Silicate (NaOH+Na 2SiO3)

concentration will be varied in 4 steps of 4mol/dm3, 8mol/dm3, 12mol/dm3, and 16mol/dm3.

In summary, the scope of this work is as listed:

1. Evaluation of the physical and mechanical properties of the materials to be used. E.g.

Grain size analysis, determination of bulk-densities, specific gravity, coefficient of

uniformity and curvature, dry density, moisture content, fineness, soundness. Etc.

2. To determine the workability and structural characteristic of concrete both at fresh

and hardened stage. Concrete mix of 1:2:4 is to be adopted for normal concrete cubes,

cylinders and slabs.

6
 Prepare and cast Ninety 150mm by 150mm by 150mm concrete cubes divided into six

categories(representingNormal,Normal+10%CSA,Normal+10%CSA+4

molality(NaOH+Na2SiO3),Normal+10%CSA+8Molality(NaOH+Na2SiO3),

Normal+10%CSA+12molality(NaOH+Na2SiO3) and Normal+10%CSA+16molality

(NaOH+Na2SiO3 ) . Representing 3 cubes each for 7, 14, 28, 90 and 120 days)

respectively to be cured in normal water.

 Prepare and cast Ninety 150mm by 150mm by 150mm concrete cubes divided into six

categories (representing Normal , Normal+ 10%CSA, Normal+10%CSA+4

molality(NaOH+Na2SiO3),Normal+10%CSA+8Molality(NaOH+Na2SiO3),

Normal+10%CSA+12molality(NaOH+Na2SiO3) and Normal+10%CSA+16molality

(NaOH+Na2SiO3 ) . Representing 3 cubes each for 7, 14, 28, 90 and 120 days)

respectively to be cured in lagoon water.

 Prepare and cast sixty 300mm high by 150mm diameter short cylinders divided into

six categories(representingNormal,Normal+10%CSA,

Normal+10%CSA+4molality(NaOH+Na2SiO3),Normal+10%CSA+8Molality(NaOH+

Na2SiO3),Normal+10%CSA+12molality(NaOH+Na2SiO3)and

Normal+10%CSA+16molality(NaOH+Na2SiO3). Representing 2 cylinders each for 7,

14, 28, 90 and 120 days to be cured in normal water

 Prepare and cast twelve 1300mm by 500mm by 100mm reinforced concrete slabs

divided into six categories (representing Normal , Normal+ 10%CSA,

Normal+10%CSA+4molality(NaOH+Na2SiO3),Normal+10%CSA+8Molality(NaOH+

Na2SiO3),Normal+10%CSA+12molality(NaOH+Na2SiO3)andNormal+10%CSA+16m

olality(NaOH+Na2SiO3). Representing 2 slabs of each category for 28 days to be

cured with a jute bag.

7
 3. Conduct preliminary tests to determine the oxides composition of CSA, organic

impurities test on fine aggregate, moisture content of fine aggregate, specific gravity

of cement and aggregates, bulk density of aggregates, sieve analysis of aggregates,

setting time of cement (without sugar, with sugar and with sugar/CSA).

4. Workability test – Slump

5. Determination of the setting time (initial and final) of mortar produced from

pozzolanic cement, with and without Sodium Hydroxide (NaOH+Na2SiO3).

6. Determination of Compressive strength of the concrete cubes, from 2) above at

maturity ages 7, 14, 28, 90 and 120 days after curing.

7. Determination of Tensile strength of the concrete cylinders from 2) above at maturity

ages 7, 14, 28, 90 and 120 days, after curing them.

8. Discussion of the results obtained from all the tests conducted for conclusions and

recommendations.

1.8 LIMITATIONS AND CHALLENGES

Finance is the major limitation for this research work.

1.9 PRESENTATION OF STUDY

This research work is an add-on to works that precedes it; it contributes its own quota of

knowledge on the subject matter. It brings to bear the possibilities and potential inherent in

the partial replacement of Ordinary Portland Cement with pulverized Coconut Shell Ash

(CSA) in the presence of Sodium Hydroxide (NaOH+Na2SiO3) in the production of mortar

and concrete.

8
Chapter one gives a walk through on what to expect from the study and a form of general

knowledge on the terms and terminologies used i.e aims, objectives, background study,

problem statement, and its significance.

Chapter two gives a review of pertinent literature to the study e.g Coconut, Agro waste,

Pozzolans, alkaline activation.

Chapter three explains on the procedure, methodology used for the study and the test details

gotten.

Chapter four contains the test report where the test results are discussed and proper

comparisons are made to standard code of practice.

Chapter five discusses the overall project outlining the summary of the results and the

recommendations proffered.

The reference has the list of sources where some of the literature was gotten from. The

appendix contains graphs, tables and figures related to this work.

1.10 DEFINITION OF TERMS AND TERMINOLOGIES

1) Concrete is a composite material composed of coarse aggregate bonded together with

fluid cement that hardens over time. Most concretes used are lime-based concretes such

as Portland cement concrete or concretes made with other hydraulic cements, such as ciment

fondu. When aggregate is mixed together with dry Portland cement and water, the mixture

forms fluid slurry that is easily poured and moulded into shape. The cement reacts chemically

with the water and other ingredients to form a hard matrix that binds the materials together

into a durable stone-like material that has many uses. Often, additives (such as Pozzolans

or super plasticizers) are included in the mixture to improve the physical properties of the wet

mix or the finished material. Most concrete is poured with reinforcing materials (such

as rebar) embedded to provide tensile strength, yielding reinforced concrete

9
1) Composition of concrete: Many types of concrete are available, distinguished by the

proportions of the main ingredients below. In this way or by substitution for the cementations

and aggregate phases, the finished product can be tailored to its application. Strength, density,

as well as chemical and thermal resistance are variables. The constituents of concrete are;

2a) Cement: Portland cement is the most common type of cement in general usage. It is a

basic ingredient of concrete, mortar and many plasters. It consists of a mixture of calcium

silicates (alite, belite), aluminates and ferrites - compounds which combine calcium, silicon,

aluminium and iron in forms which will react with water. Portland cement and similar

materials are made by heating limestone (a source of calcium) with clay or shale (a source of

silicon, aluminium and iron) and grinding this product (called clinker) with a source of

sulphate (most commonly gypsum).

2b) Water: Combining water with a cementations material forms a cement paste by the

process of hydration. The cement paste glues the aggregate together, fills voids within it, and

makes it flow more freely. As stated by Abrams' law, a lower water-to-cement ratio yields a

stronger, more durable concrete, whereas more water gives a freer-flowing concrete with a

higher slump. Impure water used to make concrete can cause problems when setting or in

causing premature failure of the structure. Hydration involves many different reactions, often

occurring at the same time. As the reactions proceed, the products of the cement hydration

process gradually bond together the individual sand and gravel particles and other

components of the concrete to form a solid mass.

10
 Cement chemist notation: C3S + H → C-S-H + CH

Standard notation: Ca3SiO5 + H2O → (CaO)·(SiO2)·(H2O)(gel) + Ca(OH)2

Balanced: 2Ca3SiO5 + 7H2O → 3(CaO)·2(SiO2)·4(H2O)(gel) + 3Ca(OH)2 (approximately;

the exact ratios of the CaO, SiO2 and H2O in C-S-H can vary).

2c) Aggregates: Fine and coarse aggregates make up the bulk of a concrete mixture. Sand,

natural gravel and crushed stone are used mainly for this purpose. Recycled aggregates (from

construction, demolition, and excavation waste) are increasingly used as partial replacements

for natural aggregates, while a number of manufactured aggregates, including air-cooled blast

furnace slag and bottom ash are also permitted. The size distribution of the aggregate

determines how much binder is required. Aggregate with a very even size distribution has the

biggest gaps whereas adding aggregate with smaller particles tends to fill these gaps. The

binder must fill the gaps between the aggregate as well as pasting the surfaces of the

aggregate together, and is typically the most expensive component. Thus variation in sizes of

the aggregate reduces the cost of concrete.[27] The aggregate is nearly always stronger than the

binder, so its use does not negatively affect the strength of the concrete. Redistribution of

aggregates after compaction often creates inhomogeneity due to the influence of vibration.

This can lead to strength gradients

2d) Mineral admixtures and blended cements (Pozzolans):

Inorganic materials that have pozzolanic or latent hydraulic properties, these very fine-

grained materials are added to the concrete mix to improve the properties of concrete

(mineral admixtures), or as a replacement for Portland cement (blended cements). Products

which incorporate limestone, fly ash, blast furnace slag, and other useful materials with

pozzolanic properties into the mix, are being tested and used. This development is due to

11
cement production being one of the largest producers (at about 5 to 10%) of global

greenhouse gas emissions, as well as lowering costs, improving concrete properties, and

recycling wastes.

1) Alkaline Activation; Martinez-Ramirez and Palomo( 2001) defined alkali activation as a

process where amorphous structure is being transformed into a skeletal structure that exhibits

cementations properties.

2) Properties of fresh concrete: Concrete remains in its fresh state from the time it is mixed

until it sets. During this time the concrete is handled, transported, placed and compacted.

Properties of concrete in its fresh state are very important because the influence the quality of

the hardened concrete. Properties of concrete are divided into two major groups

 Properties of Fresh Concrete

 Properties of Hardened Concrete

Fresh concrete is that stage of concrete in which concrete can be moulded and it is in plastic

state. This is also called "Green Concrete". Another term used to describe the state of fresh

concrete is consistence, which is the ease with which concrete will flow.

 Consistency

 Workability

 Settlement, Bleeding and Segregation

 Plastic shrinkage

 Loss of consistency

 Setting of Concrete

 Concrete Hydration

 Air entrainment

12
4a) Consistency: Consistency of a concrete mix is a measure of the stiffness or sloppiness or

fluidity of the mix. For effective handling, placing and compacting concrete, consistency

must be the same for each batch. It is therefore necessary to measure consistency of concrete

at regular intervals. Slump test is commonly used to measure consistency of concrete.

4b) Workability: The workability of a concrete mix is the relative ease with which concrete

can be placed, compacted and finished without separation or segregation of the individual

materials. Workability is not the same thing as consistency. Mixes with the same consistency

can have different workabilities, if they are made with different sizes of stone – the smaller

the stone the more workable the concrete. It is not possible to measure workability but the

slump test, together with an assessment of properties like stone content, cohesiveness and

plasticity, gives a useful indication.

4c) Settlement, bleeding and segregation: Cement and aggregate particles have densities

about three times that of water. In fresh concrete they consequently tend to settle and displace

mixing water which migrates upward and may collect on the top surface of the concrete. This

upward movement of mixing water is known as bleeding; water that separates from the rest

of the concrete is called bleed water.

Concrete Bleeding: Bleeding in concrete is sometimes referred as water gain. It is a

particular form of segregation, in which some of the water from the concrete comes out to the

surface of the concrete, being of the lowest specific gravity among all the ingredients of

concrete. Bleeding is predominantly observed in a highly wet mix, badly proportioned and

insufficiently mixed concrete. In thin members like roof slab or road slabs and when concrete

is placed in sunny weather show excessive bleeding.

13
Due to bleeding, water comes up and accumulates at the surface. Sometimes, along with this

water, certain quantity of cement also comes to the surface. When the surface is worked up

with the trowel, the aggregate goes down and the cement and water come up to the top

surface. This formation of cement paste at the surface is known as “Laitance”. In such a case,

the top surface of slabs and pavements will not have good wearing quality. This laitance

formed on roads produces dust in summer and mud in rainy season.

Water while traversing from bottom to top, makes continuous channels. If the water cement

ratio used is more than 0.7, the bleeding channels will remain continuous and un-segmented.

These continuous bleeding channels are often responsible for causing permeability of the

concrete structures. While the mixing water is in the process of coming up, it may be

intercepted by aggregates. The bleeding water is likely to accumulate below the aggregate.

This accumulation of water creates water voids and reduces the bond between the aggregates

and the paste.

The above aspect is more pronounced in the case of flaky aggregate. Similarly, the water that

accumulates below the reinforcing bars reduces the bond between the reinforcement and the

concrete. The poor bond between the aggregate and the paste or the reinforcement and the

paste due to bleeding can be remedied by re vibration of concrete. The formation of laitance

and the consequent bad effect can be reduced by delayed finishing operations.

Bleeding rate increases with time up to about one hour or so and thereafter the rate decreases

but continues more or less till the final setting time of cement.

Prevention of Bleeding in concrete

 Bleeding can be reduced by proper proportioning and uniform and complete mixing.

14
  Use of finely divided pozzolanic materials reduces bleeding by creating a longer path

for the water to traverse.

 Air-entraining agent is very effective in reducing the bleeding.

 Bleeding can be reduced by the use of finer cement or cement with low alkali content.

Rich mixes are less susceptible to bleeding than lean mixes.

The bleeding is not completely harmful if the rate of evaporation of water from the surface is

equal to the rate of bleeding. Removal of water, after it had played its role in providing

workability, from the body of concrete by way of bleeding will do good to the concrete Early

bleeding, when the concrete mass is fully plastic, may not cause much harm, because

concrete being in a fully plastic condition at that stage, will get subsided and compacted. It is

the delayed bleeding, when the concrete has lost its plasticity, which causes undue harm to

the concrete. Controlled re vibration may be adopted to overcome the bad effect of bleeding.

Segregation in concrete: Segregation can be defined as the separation of the constituent

materials of concrete. A good concrete is one in which all the ingredients are properly

distributed to make a homogeneous mixture. There are considerable differences in the sizes

and specific gravities of the constituent ingredients of concrete. Therefore, it is natural that

the materials show a tendency to fall apart. Segregation may be of three types

1. Coarse aggregate separating out or settling down from the rest of the matrix.

2. Paste separating away from coarse aggregate.

3. Water separating out from the rest of the material being a material of lowest specific
gravity.

A well-made concrete, taking into consideration various parameters such as grading, size,

shape and surface texture of aggregate with optimum quantity of waters makes a cohesive

15
mix. Such concrete will not exhibit any tendency for segregation. The cohesive and fatty

characteristics of matrix do not allow the aggregate to fall apart, at the same time; the matrix

itself is sufficiently contained by the aggregate. Similarly, water also does not find it easy to

move out freely from the rest of the ingredients

Vibration of concrete is one of the important methods of compaction. It should be

remembered, that only comparatively dry mix should be vibrated. If too wet a mix is

excessively vibrated; it is likely that the concrete gets segregated. It should also be

remembered that vibration is continued just for required time for optimum results. If the

vibration is continued for a long time, particularly, in too wet a mix, it is likely to result in

segregation of concrete due to settlement of coarse aggregate in matrix.

4d) Plastic shrinkage: If water is removed from the compacted concrete before it sets, the

volume of the concrete is reduced by the amount of water removed. This volume reduction is

called plastic shrinkage. Water may be removed from the plastic concrete by evaporation or

by being absorbed by dry surfaces such as soil or old concrete or by the dry wooden form

work.

4e) Slump loss/ Loss of Consistency: From the time of mixing, fresh concrete gradually

loses consistency. This gives rise to the problems only if the concrete becomes too stiff to

handle, place and compact properly. Slump loss in concrete is caused due to the following

reasons.

 Hydration of cement (generating more heat)

 Loss of water by evaporation

 Absorption of water by dry aggregates

 Absorption of water by surfaces in contact with the concrete.

16
4f) Setting of Concrete: The hardening of concrete before its hydration is known as setting

of concrete or, the hardening of concrete before it gains strength or, the transition process of

changing of concrete from plastic state to hardened state. Setting of concrete is based or

related to the setting of cement paste. Thus cement properties greatly affect the setting time.

Following are the factors that affect the setting of concrete.

-Water Cement ratio 

-Suitable Temperature 

-Cement content 

- Type of Cement 

-Fineness of Cement 

-Relative Humidity 

4g) Hydration in concrete: Concrete derives its strength by the hydration of cement

particles. The hydration of cement is not a momentary action but a process continuing for

long time. Of course, the rate of hydration is fast to start with, but continues over a very long

time at a decreasing rate In the field and in actual work, even a higher water/cement ratio is

used, since the concrete is open to atmosphere, the water used in the concrete evaporates and

the water available in the concrete will not be sufficient for effective hydration to take place

particularly in the top layer.

If the hydration is to continue, extra water must be added to refill the loss of water on account

of absorption and evaporation. Therefore, the curing can be considered as creation of a

favourable environment during the early period for uninterrupted hydration. The desirable

conditions are a suitable temperature and ample moisture.

17
Concrete, while hydrating, releases high heat of hydration. This heat is harmful from the

point of view of volume stability. Heat of hydration of concrete may also shrinkage in

concrete, thus producing cracks. If the heat generated is removed by some means, the adverse

effect due to the generation of heat can be reduced. This can be done by a thorough water

curing.

4h) Air Entrainment: Air entrainment reduces the density of concrete and consequently

reduces the strength. Air entrainment is used to produce a number of effects in both the

plastic and the hardened concrete. These include:

1. Resistance to freeze–thaw action in the hardened concrete.

2. Increased cohesion, reducing the tendency to bleed and segregation in the plastic concrete.

3. Compaction of low workability mixes including semi-dry concrete.

4. Stability of extruded concrete.

5. Cohesion and handling properties in bedding mortars.

1) Properties of hardened concrete

Following are the properties of hardened concrete:

 Strength of concrete
 Concrete Creep
 Shrinkage
 Modulus Of Elasticity
 Water tightness (Impermeability)
 Rate of Strength gain of Concrete
 Tensile Strength
 Durability

18
5a) Strength: The strength of concrete is basically referred to compressive strength and it

depends upon three factors.

 Paste strength: It is mainly due to the binding properties of cement that the

ingredients are compacted together. If the paste has higher binding strength, higher

will be strength of concrete.

 Interfacial bonding: Interfacial bonding is very necessary regarding the strength. Clay

hampers the bonding between paste and aggregate. The aggregate should be washed

for a better bonding between paste and aggregate.

 Aggregate strength: It is mainly the aggregate that provide strength to concrete

especially coarse aggregates which act just like bones in the body. Rough and angular

aggregate provides better bonding and high strength.

Following are the factors that affect the strength of concrete:

 Water-Cement ratio  Type of aggregate

 Type of cementing material  Air content

 Amount of cementing material

 Admixtures

5b) Creep in concrete: Concrete creep is defined as: deformation of structure under

sustained load. Basically, long term pressure or stress on concrete can make it change shape.

This deformation usually occurs in the direction the force is being applied. Like a concrete

column getting more compressed, or a beam bending. Creep does not necessarily cause

concrete to fail or break apart. Creep is factored in when concrete structures are designed.

19
5c) Shrinkage in Concrete: Concrete is subjected to changes in volume either autogenous or

induced. Volume change is one of the most detrimental properties of concrete, which affects

the long-term strength and durability. To the practical engineer, the aspect of volume change

in concrete is important from the point of view that it causes unsightly cracks in concrete.

We have discussed elsewhere the effect of volume change due to thermal properties of

aggregate and concrete, due to alkali/aggregate reaction, due to sulphate action etc. Presently

we shall discuss the volume change on account of inherent properties of concrete

“shrinkage”.

One of the most objectionable defects in concrete is the presence of cracks, particularly in

floors and pavements. One of the important factors that contribute to the cracks in floors and

pavements is that due to shrinkage. It is difficult to make concrete which does not shrink and

crack. It is only a question of magnitude.

Now the question is how to reduce the shrinkage and shrinkage cracks in concrete structures.

The term shrinkage is loosely used to describe the various aspects of volume changes in

concrete due to loss of moisture at different stages due to different reasons.

5d) Rate of Strength Gain of Concrete: Strength can be defined as ability to resist change.

One of the most valuable properties of the concrete is its strength. Strength is most important

parameter that gives the picture of overall quality of concrete. Strength of concrete usually

directly related to cement paste.

 Hardening is the process of growth of strength. This is often confused with 'setting'

but setting and hardening are not same.

 Setting is the stiffening of the concrete after it has been placed. Hardening may

continue for weeks or months after the concrete has been mixed and placed.

20
5e) Tensile Modulus - Young's Modulus or Modulus of Elasticity - is a measure of

stiffness of an elastic material. It is used to describe the elastic properties of objects like

wires, rods or columns when they are stretched or compressed.

Tensile Modulus is defined as the "ratio of stress (force per unit area) along an axis

to strain (ratio of deformation over initial length) along that axis"

It can be used to predict the elongation or compression of an object as long as the stress is

less than the yield strength of the material.

5f) Permeability: is the ease with which liquids or gases can travel through concrete. This

property is of relation to the water tightness of liquid retaining structures and to chemical

attack. It is necessary for concrete to be reliable and to withstand the conditions it has been

designed for, to have trouble free service life. Thus it has to be durable. Durability is

achieved through resistance of adverse external environmental conditions as well as adverse

internal conditions of concrete. In both cases, the permeability of concrete is important to

avoid deterioration of concrete.

The penetration of solutions into concrete depends on its permeability and as this result many

adverse effects that are not desired. Concrete which are permeable may have cracks during

freezing and thawing. Through time, these cracks may increase in size to affect the strength

of concrete. Also, the penetration of chlorides, water, water etc., through these cracks water

may lead to corrosion of the reinforcement to cause loss of strength. Another cause of

permeability of concrete is the pores within the cement matrix. The causes of these voids are

mainly: non-optimum water-cement ratio, incomplete compaction, bleeding, adverse curing

techniques and temperatures, rate of hydration and material size distribution. Due to these

21
adverse effects, preventive measures must be taken to avoid these problems such as optimum

water-cement ratio value, optimum compaction time, or / and adding mineral admixtures.

5g) Tensile strength of concrete: The estimate of flexural tensile strength or the modulus of

rupture or the cracking strength of concrete from cube compressive strength is obtained by

the relations

fcr = 0.7 fck N/mm2

The tensile strength of concrete in direct tension is obtained experimentally by split cylinder.

It varies between,1/8 to 1/12 of cube compressive strength.

5h) Durability of concrete: Durability of concrete is its ability to resist its disintegration and

decay. One of the chief characteristics influencing durability of concrete is its permeability to

increase of water and other potentially deleterious materials.

The desired low permeability in concrete is achieved by having adequate cement, sufficient

low water/cement ratio, by ensuring full compaction of concrete and by adequate curing.

22
 CHAPTER TWO LITERATURE REVIEW

LITERATURE REVIEW
2.0 PREAMBLE

The high cost of construction materials like cement and reinforcement bars, has led to

increased cost of construction, especially at a time where the local currency is being devalued

daily. This coupled with the pollution associated with cement production, has necessitated a

search for an alternative binder (which must be economical) which can be used sorely or in

partial replacement of cement in concrete production. More so, disposal of agricultural waste

(also known as Agro-waste) materials such as rice husk, groundnut husk, corn cob and

coconut shell have constituted an environmental challenge, hence the need to convert them

into useful materials to minimize their negative effect on the environment. Research indicates

that most materials that are rich in amorphous silica can be used in partial replacement of

cement (Pozzolans). It has also been established that amorphous silica found in some

pozzolanic materials reacts with lime more readily than those in crystalline form. Use of such

23
Pozzolans can lead to increased compressive and flexural strength. In order to produce

environmental friendly concrete, reduced use of natural resources, technology consuming less

amount of energy and producing lower carbon dioxide emissions is suggested. McCaffrey

suggested that the amount of CO2 emissions by the cement industries can be reduced by

decreasing the amount of calcinated materials in cement, by decreasing the amount of cement

in concrete, and by decreasing the number of building elements using cement.

The present study attempts to explore the possibility of using coconut shell ash in the

development of binding material with alkalis, that is, sodium hydroxide + sodium silicate in

the manufacture of concrete. The cementing material shall act as an alternative to cement

(partial replacement). This will address the issues of reducing the emission of greenhouse

gases, reduction in energy requirement and also the disposal of the by-products in an

environment- friendly way.

This work is aimed at evaluating the characteristic of locally available coconut shell ash in

the vicinity of Lagos/Nigeria to check its use in the development of cementing material.

2.1 POZZOLANS

The term pozzolan (or pozzolana), in general sense of it, is employed to designate any

material irrespective of origin which possessed similar properties as the pozzolana

(consolidated volcanic ash or turf) found near Pozzuoli in Italy (Shetty, 2005). Pozzolans are

siliceous or siliceous and aluminous materials, which in themselves possess little or no

cementitious value, but will, in finely divided form and in the presence of moisture,

chemically react with calcium hydroxide released from the hydration of Portland cement, at

ordinary temperature, to form compounds of low solubility, possessing cementitious

properties. This action is termed pozzolanic action. These materials are often added to

concrete to make concrete mixtures more economical, reduce permeability, increase strength,

24
or influence other concrete properties, which can be used individually or in combination with

Portland or blended cement or as partial replacement of Portland cement (Gambhir, 2013).

Figure 2.1a: Volcanic ash (natural pozzolan) Figure 2.1b: Hot volcanic ash from a volcano

(Source: earthobservatory.nasa.gov)

2.1.1 History

Evidences exist to confirm that Pozzolans were used at the time of the ancient Greeks,

Egyptians and Romans because X-ray diffraction shows the presence of a zeolitic material

called "analcime" which ranges from 10 to 40% by weight in the lime mortars; this zeolite is

often found in tuffs and other pozzolanic materials of Europe (Davidovits, 1987).

The term "pozzolan" came from a U.S. simplification of "pozzolana" which evolved from the

location "Pozzuoli, Italy" where the Romans found a reactive silica-based material of

volcanic origin which they called "pulvis puteolanus” (Davis, 1950) (Spence & Cook,

1983).Today both the terms "pozzolan" and "pozzolana" are used (Day, 1990).

The Roman practice for using pozzolan was to mix it with lime and rubble, add as little water

as necessary and ram the mix into a compacted mass (Mielenz, 1948). The Romans used the

red or purple tuff found near Naples (Pozzuoli) after it was finely ground and mixed with

lime or hydraulic lime and sand. If pozzolanic earth was not available they used powdered

25
tiles or pottery (Anon, 1988) (Miles, 1974). The 42m-span dome in the Pantheon, Rome, is

one of several examples of Roman structures, many including pozzolans, that has survived

nearly 2000 years and is made from lime-pozzolan (Spence, 1980).

During technological developments in Greece and Rome, mortars and renderings of many of

India's ancient buildings were being manufactured from lime-surkhi (a mixture of lime and

crushed clay brick). From the 19th century to the present lime-surkhi is still used for canals

and damworks because (a) it is less liable to shrink, (b) it produces a more impermeable

structure, and (c) the material can better accommodate internal stresses (Spencer, 1984).

In Northern Europe, Rhenish trass has been known for 2000 years; mortars containing trass

have been found in Roman buildings along the Rhine. Such materials were even in use in the

U.K. at one time - in 1909 "Potters' red cement" was manufactured consisting of ground burnt

clay and Portland cement. The presence of bauxite has also been reported in some ancient

mortars - e.g. the ruins at Baux in the Rhone valley; some French mortars have been made

from pulverized bauxite and lime (Lea, 1970).

After the Roman era there does not appear to be many developments in construction practices

until the Industrial revolution when cements were required to ensure progress and later, when

Portland cement was discovered. In England it was not until the 17th century that imported

Dutch trass-lime mixtures were used. Such mixtures were also extensively used in Holland

for construction of harbours and sea defence (Miles, 1974). A common theme during this

period appears to be the realization that pozzolans produced construction materials that had

high durability to an aggressive marine environment.

Contemporary use of natural pozzolans was, and still is, widespread in Europe. In the United

States considerable investigations and uses of natural pozzolans occurred after their first

substantial use for the Los Angeles aqueduct in 1912. In this structure, 1x108kg of 11

26
OPC/pozzolan cement, (50% OPC and 50% "deeply altered" rhyolite tuff) was used. The

savings due to the use of the pozzolan amounted to $700,000 and was one of the principal

reasons why the pozzolan was used in the first place (Drury, 1954).

Early construction under the control of the U.S. Bureau of Reclamation used pozzolans

which, today, would be thought very poor. Nevertheless, good performance resulted. In 1915

the Arrowrock dam in the U.S. was constructed using a "granite" pozzolan. Although this

dam had to be refaced in 1937 due to surface weathering, there was no problem with the

interior concrete and it was reported to have given 60 years of distress-free service (Elfert,

1973). Other dams built at the time were the Lahontan Dam, 1915, using siliceous silt and the

Elephant Butte dam, 1916, which used ground sandstone. Typically, 55% OPC was

interground with 45% of a pozzolan found near the site of the dam.

Early U.S. investigations of American pozzolans showed that Portland-cement concretes

made with pozzolans had desirable properties such as improved permeability and resistance

to action by aggressive waters. As a result, in 1935 pozzolan was used in the Bonneville

Dam, in the Friant Dam in 1942. The Friant Dam marked the first use of a pumicite or first

"real" pozzolan, while for the Davis Dam in 1950 a calcined opaline shale was used. Use of

pozzolan on the Friant Dam resulted in a savings of $301,000 (Drury, 1954).

From 1940-1973 the Bureau of Reclamation has used 360,000 tonnes of natural pozzolans in

7.1 million cubic metres of concrete; over the same period they have used 275,000 tonnes of

fly ash in 5.4 million cubic metres of concrete (Drury, 1954).

It should be noted that the principal reason for the use of Pozzolans by U.S. authorities was

cost. On all of the projects involving large quantities of Pozzolans were discovered close to

the construction site; transportation costs were very small for applications in which high

strengths were not required. For example, local Monterey shale was used for the San

27
Francisco and Golden Gate bridges. In the anchorage of the Bay bridge 53,000 m 3 of shale

was used and the material was also used for the pier and fender of the Golden Gate Bridge.

Economy was of prime concern, but the pozzolan was also used because of its proven

resistance to alkali soils and sulphates and its favourable heat generation (Price, 1975)

(Meissner, 1950).

Early applications of pozzolan in ancient civilizations and contemporary uses in Europe, Asia

and America have shown pozzolans to be useful materials. This potential has caused a surge

of research about many types of pozzolanic materials for use in a multitude of applications

(Day, 1990).

It has been noted that natural pozzolans, either in a pulverized state or in compacted form,

can be found in 6 countries in Africa: Burundi, Cameroon, Cape Verde, Ethiopia, Rwanda

and Tanzania (HABITAT, 1985). However, examination of the literature has also revealed

that research exists on:

a. Trachytic ashes found in the Canary Islands (Robertson, 1984);

b. Volcanic ashes from Madagascar (Alsac & Nadeau, 1965);

c. Fine grained gluconitic sandstones in Egypt (Suzanic &Hraste, 1978) and

d. Rhyolitic volcanic ashes in Morocco (Hilali et al., 1981).

The Moroccan Volcanic rocks are centered on Casablanca. Compression tests on a 80:20

OPC: Rhyolite glass pozzolan gave strengths at 180 days in the region 40 - 50Nmm-2. In

Egypt, "Karnak" cement is being used as blended cement with 25% OPC replaced by finely

ground siliceous sand. The strength of concrete at 28 days is about 50% of an OPC control

concrete (Eldarwish & Shehata, 1983). Nevertheless, this is perhaps recognition that modern

cements produce too strong a concrete for many practical applications.

28
Tanzania has been the site of fairly extensive scientific evaluations of this pozzolan (Stulz,

1983) (Allen, 1983) (Makange & Massawe, 1986). Tests indicate good strengths, even up to a

60% replacement level of OPC. Other test results are reported in more detail in subsequent

sections.

Another possible pozzolanic source in Africa is bauxite waste. Bauxite is mined in Ghana

and approximately 25% of this is washed away as "red mud" (Day, 1990).

There are clays everywhere in Africa that could be used as pozzolans; there are also oil-spent

shales in Nigeria, Gabon and the Ivory Coast that could also be used (Hammond, 1983).

Finally, in Africa alone there are about 40 countries where rice is grown, thus making the

development of a rice husk ash industry attractive (Day, 1990).

2.1.2 Classification of Pozzolans

Day (1990) noted that several classification systems have been proposed for pozzolans. These

systems can be placed into two categories based upon the:

1. Chemistry and mineralogy of the material, and

2. Reactivity or performance characteristics of the pozzolan.

The most common classification system used today is one which the primary division of

pozzolans is into two classes, namely:

Artificial Pozzolans

These include materials such as fly ash, blast furnace slag, surkhi, siliceous and opaline

shales, spent oil shale (used in Sweden to make "gas concrete"), rice husk ash, burnt banana

leaves, burnt sugar cane stalks and bauxite waste (Grane, 1980) (Lea, 1970). Other potential

materials, such as bagasse ash, laterite soils and red tropical soils which require firing to

29
induce pozzolanicity would also presumably be classified as artificial pozzolans, but if

calcination was not required then they would be natural pozzolan.

Natural Pozzolans

Among the natural pozzolans are tuff, Santorin earth (volcanic ashes), trass, rhyolitic

pumicite, diatomite, gaize and tripoli (Grane; 1980).

One other classification system worthy of mention is that of Sersale (1980), who

characterized pozzolans into five categories:

a) natural sialic - unaltered pozzolans;

b) natural, siliceous mixed - digenetic lithoid tuffs, clay;

c) artificial, traditional - burnt clay, shales;

d) artificial, non-traditional - fly ash, plant ash

Plant ash or agricultural wastes-ash is numerous, and some of them include:

a) bone ash, f) Sugar cane bagasse,

b) rice husk ash, g) groundnut husk ash,

c) corn husk ash, h) cassava peel ash

d) periwinkle ash, i) Palm kernel shell ash, etc.

e) coconut shell ash,

2.1.3 The Pozzolanic Reaction

There are several steps involved in the pozzolanic reaction in concrete. As Portland cement

reacts with water, the tri-calcium silicate (C3S) and di-calcium silicates (C2S) react to form

calcium silicate hydrates (C-S-H), largely responsible for strength development, together with

calcium hydroxide, Ca(OH)2 (often referred to as “lime”). At the same time, the alkalinity of

the water (now referred to as pore fluid) increases to pH 13 or higher. This combination of

30
events provides ideal conditions under which the pozzolan can react. The high pH first causes

the silicate network structure of the pozzolan to break down to smaller units, which then react

with the calcium hydroxide to form more calcium silicate hydrate binder. The net effect is

that the calcium hydroxide in the concrete — which itself has no strength-forming properties

and is also a potential site of weakness for certain forms of chemical degradation — is

converted by the pozzolan to additional C-S-H binder which is deposited in pore spaces. This

leads to a general densification of the cement matrix, which contributes to increased strength,

reduced permeability, and increased long-term durability (Vitro, 2006).

Figure 2.6: Pozzolanic reaction. (Source: Nazir et al., 2016)

Portland cement requires only about 25% water to completely react to form concrete.

However, many concrete mixes employ larger percentages of water content to allow the mix

to flow properly into the formwork or to achieve proper workability. This excess water

inevitably introduces void spaces in the concrete that make the concrete porous and provide

conduits for the passage of water and aggressive solutions. It is therefore easy to understand

that the water-to-cement (w/c) ratio is a major controlling factor in the strength potential of a

given concrete mix design: low w/c ratios are associated with higher strengths; whereas high

31
w/c ratios are associated with lower strengths. The conversion of the calcium hydroxide to C-

S-H by the pozzolanic reaction and the filling of the void spaces both contribute to improved

concrete quality, compressive and flexural strength, and long-term durability [Vitro, 2006].

2.1.4 Reactivity of Ash Pozzolans

Ash pozzolans have relatively slow and variable reaction rates depending on the following:

 Type of ash (e.g. coal combustion fly ash, agricultural waste ash)

 Production process (e.g. burning temperature & cooling rate)

 Physical and chemical characteristics (e.g. morphology, fineness)

 Silicates and/or aluminates content in the ash

Methods To Improve The Reactivity Of Ash Pozzolans

 Controlled burning/rapid cooling to form amorphous compounds

 Grinding to increase surface area

 Use of chemical activators (CaCl2, NaOH, and other alkali-based activators)

 Heat curing of ash based cement products

Advantages of Adding Pozzolan to Concrete Mixes

It has been demonstrated that the best pozzolan in optimum proportions mixed with Portland

cement improves many qualities of concrete, such as:

 Improved workability with lesser amount of water.

 Lower heat of hydration and thermal shrinkage.

 Improved resistance to attack from salts and sulphates from soil and sea water.

 Reduced permeability.

 Reduced Alkali-aggregate reaction.

 Reduced susceptibility to dissolution and leaching of calcium hydroxide.

32
  Lower costs of concrete production.

2.2 COCONUT

2.2.1 History, Spread and Cultivation

Coconut palm (Cocos nucifera) is one of the most essential and valuable palms in the world,

it is an important crop in the agricultural economy of many countries of the world providing

food, drink, housing and raw materials for industries (Nair et al., 2003). The coconut palm,

Cocos nucifera is the only accepted species in the genus Cocos. The term coconut refers to

the entire palm and the seed or the fruit. There are two natural sub-groups, simply referred to

as “Tall” and “Dwarf” cultivars. The Tall cultivar group is sometimes given the name Cocos

nucifera var typica and the dwarf cultivar group Cocos nucifera var nana (Perera et al.,

2009).The tall cultivars are grown for commercial purpose because they live longer and are

higher yielding than the dwarf cultivars (Chan et al., 2006). The origin of the plant is the

subject of debate (Grimwood et al., 1975). Several authorities submit an Indo-Pacific origin

either around Melanesia and Malesia or the Indian Ocean, while others see the origin in

northwestern South America (Perera et al., 2009). The coconut palm is now widely

distributed throughout Asia, Africa, Latin America, the Caribbean and the Pacific region

(FAO, 2011). In Africa, the northern limits are located on the West Coast in Cape Verde

(15oN) and on the east, Djibouti (11.5oN) with isolated coconut palms found in the far north

on the Red Sea and up to 24 oN. The Southern limits in Africa is located at 15 oS on the West

Coast and the Zambezi River (19oS), on the east and also found farther south in Port Dauphin

in Madagascar at 25oS.

33
 Coconut fronds

Whole coconut fruit

Coconut shell

Edible nut

Coconut husk

Stem

Root

Figure 2.1c: Components of a coconut palm and makeup of its drupe. (Source: Wikipedia)

In Nigeria, the coconut palm is found mostly in the Southern states and in some marginal

areas up to 10oN. Though coconut palms are known to grow under diverse types of climate

and are highly adaptable, they are usually grown along sea coasts and in plain ground. They

can be cultivated up to 1000m above sea level, and tends to grow best in places with a mean

annual temperature of 25°C - 28°C and an annual rainfall of 200mm. More than 90% of

Nigeria’s coconut belt is a continuation of the plantations or grooves along the West African

coast running from Cote d’evoire and southeast towards Ghana, Togo and Benin to Lagos

state in Nigeria. This belt continues in a 1km wide strip of grooves along some 200km of

coastline in Lagos state. The largest coconut palm plantation is found in the Badagry local

government area of Lagos State located in the South West of Nigeria. The first coconut

plantation in Nigeria was established in 1876 by the Roman Catholic Mission in Badagry,

Lagos State, and a good number of palms are found along the beach while most are found as

34
home stead palms. It can also be found along banks of small streams and stagnant pools of

water in some northern states. The farthest distance from the sea shore with yielding coconut

in Nigeria is about 1,400 kilometres which are to be found in the palace of the Emir of Dutse

and other places in Jigawa State of Northern Nigeria (NIFOR, 2008).

Figure 2.2: A map of Nigeria showing the states where coconut can be cultivated (in red thick
marks), with Lagos (in yellow) accounting for most of the cultivated coconut trees.
The cultivation of coconut is in scattered holdings and mostly in groves in the rainforest zone

of Nigeria, so it is difficult to estimate the number of farmers that grow the crop. An

estimated 36,000ha is presently under cultivation mostly in Lagos and Rivers states and an

estimated 1.2million hectare of land is suitable for coconut cultivation (NIFOR, 2008). The

West African tall (WAT) is the most extensively grown tall variety both as a plantation and

compound crop. Traditionally, tall varieties are commercially cultivated are usually known

by the places where they are cultivated. They grow to a height of 15-18metres and their life

span extends up to 60 to 75 years. They come to flowering 6 to 7 years after planting and

produces large-sized nut with good quality copra and oil content of 67% (Nair et al., 2003).

Coconut is the main cash crop in Lagos State where 30,000 families who are farmers use it as

source of livelihood. Lagos’ coconut belt stretches about 180km length from Seme Border

35
through Badagry, Ojo, AmuwoOdofin, EtiOsa and IbejuLekki. The belt continues through

Ogun, Edo, Delta, AkwaIbom and Cross River States (LASMAC, 2010).

2.2.2 Production

On very fertile land, a tall coconut palm can yield up to 75 fruits per annum. The bulk of the

coconut produced in Nigeria is mainly for home consumption and local trading. As at 2004

Nigeria’s annual coconut production in value was 195,000MT, then Nigeria was in the 20th

position among the world’s major coconut producing countries. By 2005, there was an

increase in the production of coconut in Nigeria to 209,000MT. In 2006 Nigeria moved to the

19th position in the world with an annual production of 225,000MT, 16000MT higher than the

previous year. In 2007 the country produced 225,500MT. 2008 saw the national coconut

production rise to 234,000MT. Nigeria became the 5th major producer of coconut in Africa,

producing a total of 1,088,500MT of coconut between 2004 and 2008 (Uwubanmwen et al.,

2011). With reference to the information available on FAOSTAT website, Nigeria’s coconut

production from 2000 to 2014 is given in the table below.

Table 2.1: Coconut production in Nigeria between 2000 and 2016

YEAR PROD.(TONNE) YEAR PROD.(TONNE)

2000 160000 2009 242949

2001 161000 2010 263815

2002 171000 2011 265000

2003 182000 2012 264814

2004 195000 2013 266045

36
 2005 209000 2014 267520

2006 225000 2015 Not Available

2007 225500 2016 Not Available

2008 234000 2017 Not Available

(Source: Food and Agriculture Organization of the United Nations)

It should be noted that, it is very difficult to capture all coconut production in the country,

because a reasonable amount of the crop are being cultivated as home stead crops. However,

the figures quoted above are reasonable representation of Nigeria’s coconut production since

it covers the commercial production figures of the country.

300000
250000
200000
150000
100000
50000
0

Figure 2.3: A line chart showing Nigeria’s coconut production from 2000 to 2014
(Chart data is from Table 2.1)

2.2.3 Parts of Coconut and Their Respective Uses

The different uses of the different parts and components of a coconut tree and its nut are

shown in table 2.2.

Table 2.2: Uses of the different components of a coconut tree/nut.

S/N Component Uses
1 Coconut Fronds  Used for making brooms, mats, basket, roof, sheds
 Dried coconut fronds can be burnt to ash and harvested for lime.

37
2 Trunk  Coconut trunks are used for building small bridges and huts;
 Trunks are preferred for their straightness, strength, and salt
resistance.
 The trunk of coconut may be used as wood logs processed for
use as furniture;
 Dried logs may further be broken into pieces for use as firewood
3 Roots  Used as a dye, a mouthwash, and a medicine for diarrhea
and dysentery.
 A frayed piece of root can also be used as a toothbrush
5 Husk  The smoke from burning husk may be used to repel mosquitos.
 Husks are used for fuel and are a source of charcoal;
 A dried half coconut shell with husk can be used to buff floors
 Fresh husk of a brown coconut may serve as a dish sponge or
body sponge
 Fiber from the husk of the coconut is used in ropes, mats, door
mats, brushes, sacks, caulking for boats, and as stuffing fiber
for mattresses
 Husks are used as a potting medium to produce healthy forest
tree saplings.
6 Shell  Pulverized coconut shell may be used as partial replacement for
fine aggregate in concrete production
 Coconut shell ash may be used as pozzolana in concrete and
sancrete blocks.
 Activated carbon manufactured from coconut shell is considered
extremely effective for the removal of impurities in treatment of
water
 May be used as carvings and artifacts for decorations.
7 Seed (Edible nut)  Primarily serves as food
 provides oil for frying, cooking, and making margarine
 used fresh or dried in cooking, especially in confections
 Coconut flour has been developed for use in baking
 Oil, butter, chips, milk, etc., may be produced from fresh or
processed coconut seed.
8 Water  Taken as sport drinks
 Coconut water can be fermented to produce coconut vinegar
Summarized from an article on coconut in Wikipedia

2.3 WASTE PRODUCTS

2.3.1 Definition

People have to know the real definition of waste. Waste is anything that is unusable and

unwanted. Around the world there are billions of waste materials that are continuously being

produced by man. That is why there is a great need for human to understand the types and

how they can manage this waste properly:

38
According to the Basel convention on the control of trans-boundary movements of hazardous

wastes and their disposal of 1989, Art. 2(1), "'Wastes' are substance or objects, which are

disposed of or are intended to be disposed of or are required to be disposed of by the

provisions of national law".

The UNSD Glossary of Environment Statistics[2] describes waste as "materials that are not

prime products (that is, products produced for the market) for which the generator has no

further use in terms of his/her own purposes of production, transformation or consumption,

and of which he/she wants to dispose. Wastes may be generated during the extraction of raw

materials, the processing of raw materials into intermediate and final products, the

consumption of final products, and other human activities. Residuals recycled or reused at the

place of generation are excluded."

Under the Waste Framework Directive 2008/98/EC, Art. 3(1), the European Union defines

waste as "an object the holder discards, intends to discard or is required to discard."[3] For a

more structural description of the Waste Directive, see the European Commission's summary.

There is a need today for an effective waste management since inaccurate waste disposal is a

huge threat to the health of people and also to the environment. A lot of experts have been

proven over the years that inappropriate waste disposal has a lot of detrimental effect to the

lives of the people all over the world. These effects can cause diseases to spread because of

rodents, insects, and other pests that can cause gastrointestinal problems.

These gastrointestinal problems are also caused by poor disposal of garbage that leads to the

multiplication of mosquitoes and cockroaches. These pests can spread a lot of bacteria that

can cause illness to people. Improper waste disposal can contaminate the resources around

the world. It can greatly contaminate water, soil, and the air. If this thing happens, it can lead

to traumatic natural disaster or a pandemic/epidemic.

39
2.3.2 Classification of Waste Products

Waste comes in many different forms and may be categorized in a variety of ways.

Wastes can be classified into:

 Biodegradable Wastes - The biodegradable wastes are those that can be decomposed

by the natural processes and converted into the elemental form. For example, kitchen

garbage, animal dung, etc.

 Non-biodegradable Wastes - The non-biodegradable wastes are those that cannot be

decomposed and remain as such in the environment. They are persistent and can cause

various problems. For example, plastics, nuclear wastes, glass, etc.

2.3.3 Types of Waste Products

The types listed here are not necessarily exclusive and there may be considerable overlap so

that one waste entity may fall into one to many types

 Animal by-products  Consumable waste

 Biodegradable waste  Controlled waste

 Biomedical waste  Demolition waste

 Bulky waste  Dog waste

 Business waste  Domestic waste

 Chemical waste  Electronic waste (e-waste)

 Clinical waste  Food waste

 Coffee wastewater  Gaseous wastes

 Commercial waste  Green waste

 Composite waste  Grey water

 Construction and Agricultural waste  Hazardous waste

 demolition waste (C&D waste)  Household waste

40
 Household hazardous waste  Packaging waste

 Human waste  Post-consumer waste

 Sewage sludge  Radioactive waste

 Industrial waste  Low level waste

 Slag  High level waste

 Fly ash  Mixed waste

(radioactive/hazardous)
 Sludge
 Spent nuclear fuel

 Inert waste  Recyclable waste

 Inorganic waste  Residual waste

 Kitchen waste  Retail hazardous waste

 Litter  Sewage

 Liquid waste  Sharps waste

 Marine debris  Ship disposal

 Medical waste  Slaughterhouse waste

 Metabolic waste  Special waste - see hazardous

 Mineral waste waste

 Mixed waste  Toxic waste

 Municipal solid waste  Uncontrolled waste

 Nuclear waste (see Radioactive  Waste heat

waste)  Wastewater

 Organic waste  Winery wastewater

2.4 MECHANISM OF ACTIVATION

Calcium hydroxide is one of the soluble hydrates that formed from the reaction between

Ordinary Portland Cement and water. It exists in the interfacial zone which promotes micro-

cracks. The Ca(OH)2 product can be reduced and the production of C-S-H which contributes

41
to the strength can be further increased with the addition of pozzolanic materials. This is due

to the reaction between pozzolans and the Ca(OH) 2 formed (Lee et al., 2003). It has been

reported that the use of chemical activators namely sulphate activation and alkali activation

may be utilized to accelerate fly ash reactivity. It was stated that sulphate activation can be

studied by using several chemicals such as gypsum, CaSO4·2H2O and sodium sulphate,

Na2SO4, whereas NaOH and Ca(OH)2 are used for alkali activation studies. The effect of

using other types of chemical to accelerate pozzolanic reactivity such as CaCl 2·2H2O and

NaCl was also reported by previous researchers.

2.4.1 Alkali Activation

Martinez-Ramirez and Palomo (2001) defined alkali activation as a chemical process where

the amorphous structure is being transformed into a skeletal structure that exhibits

cementitious properties. Polymeric gel with variable composition is formed in the media of

high alkalinity. The gel is produced when the solution of high alkalinity reacts with the

starting materials. The main behaviour of the products formed via these conditions is having

great mechanical properties at the early period of hydration.

Palomo et al. (1999b) investigated the way to activate fly ash by alkali activation method.

They reported that the Si-O-Si and Al-O-Al covalent bonds collapsed and the (Si and Al) ions

travel into the liquid phase. Condensation of structure occurred, then, forming a cementitious

material with a disordered structure and it possesses a good strength properties.

According to Alonso and Palomo (2001), as the metakaolin is activated in the media of high

alkalinity in the presence of Ca(OH)2, it will produce sodium aluminosilicate that have

amorphous structure with similar features to geopolymeric gel. The product formed is similar

to the product obtained once metakaolin is activated in the absence of Ca(OH)2 and it was

found that the secondary product which is also known as C-S-H is formed. Subjecting

42
metakaolin to alkali activation is a way of producing cementitious materials with high

strength (Palomo et al., 1990). However, the quantity of additives used must be limited. The

addition of alkali in excess also results in cement paste degradation (Wu et al., 1990).

Wu et al. (1990) studied the activation of ground granulated blast furnace slag (GGBS) and

reported that the activation of slag can be done by reaction with high alkalinity solution. This

is because the bonds in the slag network structure are easily broken and enhances the slag

hydration process. When the pH value of the solution reaches 12, the hydration of slag is

most accelerated and the ettringite is formed stably. Sufficient hydroxyl should be provided

in order to create an environment of high alkalinity in order to break the bonds in the glass

structure and stabilizing the ettringite formed.

Palomo et al. (1999b) concluded that there are two alkali activation models which are based

on the conditions of the starting situation. The first model is the activation of blast furnace

slag (Si + Ca) with a mild alkaline solution and the second model is the activation of

metakaolin (Si + Al) with a medium to high alkaline solutions. The content of reactive silica,

amorphous phase and calcium are some of the most important reactivity parameters

(Fernandez-Jimenez and Palomo, 2003).

Granizo and Blanco (1997) stated that a solid having an aluminosilicate network structure are

possible to be produced. Mixing metakaolin with certain quantities of sodium hydroxide,

NaOH solution (the concentration ranging from 7 to 12 M) and then cured at temperatures

below 100°C have been suggested by them. Data obtained shows that this solid possesses

interesting mechanical properties. This is due to the network structure formed, where it

consists of a series of SiO4 and AlO4 tetrahedral linked by their corner and sharing all

oxygen ions. The negative charge of the tetra-coordinated aluminium ions is balanced by the

alkali ions from the activating solution present in the structure (Palomo et al., 1999a).

Ma et al. (1995) found that an additional material is required to enhance the hydration

43
process of the lime-fly ash system. They reported that when the lime is mixed together with

fly ash, the mechanical strength obtained at the early age is reduced. The way to activate the

reactivity of this system is by adding a certain amount of Ca(OH) 2 or CaSO4·2H2O. It has

been previously reported that in the presence of Ca(OH)2, the amorphous SiO2 in fly ash

tends to dissociate much more easier (Lokken et al., 1990; Brown, 1986). The bonds are

broken down and dissolution of the three dimensional network structure of the glass

noticeably increases (Fraay et al., 1989; Roy and Silsbee, 1992). Puertas et al. (2000) have

studied the effect of introducing specific amount of NaOH solution into pastes made from a

combination of fly ash and slag. They found that fly ash is partially dissolved and participates

in the reactive process with the most important product which is C-S-H gel containing high

quantities of tetra coordinated Al in its structure are formed.

Martinez-Ramirez and Palomo (2001) disclosed the results of Portland cement hydration in

the high alkalinity medium. In their findings, the Portland cement hydration process tends to

be retarded due to the effect of common ion: the increasing of hydroxide ion, OH-

concentration in the system causes the equilibrium to shift towards the left side in the

hydration process of C3S and C2S. This phenomenon impeding the common evolution of the

hydration process:

C3S +2H2O ------- CSH + Ca(OH)2 (1)

Therefore, they concluded that as the alkaline concentration of the hydrating solution

increases, this reduces the degree of hydration of anhydrous silicates, for this reason, the

compressive strength also reduced. Martinez-Ramirez and Palomo (2001) investigated the

mechanical properties of pastes using NaOH solution in the hydration process. They

concluded that mechanical strength of the pastes hydrated with NaOH solution drastically

decreases compared to the one that is hydrated with waterglass, Na 2CO3 and deionized water.

Figure 1a) shows the SEM image of C-S-H gel produced when the sample hydrated with

44
deionized water and Figure 1b) shows the formation of the hexagonal-like shape of Ca(OH) 2

when 10 M NaOH solution is used in the hydration process.

Neville (1995) also agreed with that reported by Martinez-Ramirez and Palomo (2001). He

also found that when the hydration of cement is carried out in the media of high alkalinity

and subjected to curing processes of less than 28 days, the strength is affected and he

concluded that the strength reduces with increasing alkali concentration.

2.4.2 Sulphate Activation

The principle of sulphate activation also involves the dissolution of the network structure of

the glass (Xu and Sarkar, 1991). This can be monitored by the addition of CaSO4·2H2O into

45
pozzolan materials where the sulphate ions, SO42- react with aluminate which comes from

fly ash. Based on Li et al. (2003) cited by different researchers, previous studies have

measured the mechanism of sulphate activation and can be summarized into the following

points:

C3S + 2H2O  CSH + Ca(OH)2

i. Introduction of sulphate activators speed up the reduction of Ca(OH)2 in the fly ash-cement

system at the early stage of hydration (Shi and Day, 1995).

ii. At early ages, the ettringite (AFt) generated in the fly ash-cement system are much more in

the presence of activators and the network structure of the glass is broken down in an alkaline

environment (Poon et al., 2001).

iii. Pore distribution in fly ash-cement pastes is affected by the presence of sulphate activators

where the pore size becomes smaller and also reduced the porosity (Ma et al., 1995).

iv. The strength of fly ash mortar at an early age is enhanced with the presence of activators

but at later ages the strength is almost similar to that fly ash mortar without activators (Xu

and Sarkar, 1991).

The ettringite formed at the early stage of hydration in fly ash–cement pastes is increased

with the addition of Na2SO4 and K2SO4 since the SO42- ions will react with tri-calcium

aluminate, C3A. At 7 days of hydration, ettringite is mostly formed and is later converted to

46
mono-sulphates, C4AH13 and C2ASH8. This shows that, the production of ettringite is

influenced by the addition of Na2SO4 and K2SO4 which contributes to early strength

development of mortars consisting of fly ash and cement. Lee et al. (2003) used Na 2SO4 and

K2SO4 as activators in the fly ash-cement paste system. According to XRD patterns, it was

found that a small ettringite peak was observed when no activator is added to the fly ash-

cement pastes. For the fly ash-cement pastes with the presence of chemical activators, a peak

was observed at early stage of hydration (up to 7 days) resulting from the formation of

ettringites. These hydration products were created by the reaction between SO 32- ions which

come from the activators and the aluminates.

As the time increased, the ettringite is converted to mono-sulphate and other products, but, a

small amount of ettringite still remains at 28 days. On the other hand, the major product

generated from the hydration process is Ca(OH) 2 and its peak shows the highest intensity at 3

days of hydration, but decreases thereafter due to the pozzolanic reaction. These results tally

with the research done by Poon et al., (2001) and Shi (1998). They point out that the

production of ettringite is helpful for early strength development of the fly ash–cement pastes

system consisting of a specific amount of sulphate activators with a reduction of Ca(OH) 2

content. Figure 2 shows the XRD patterns at different ages of hydration for fly ash-cement

pastes.

Figure 3 shows SEM images of C-S-H, Ca(OH)2 and ettringite produced from the pozzolanic

reaction at 3 days of hydration. C–S–H and mono-sulphate products are mainly formed in the

fly ash-cement pastes in the absence of a chemical activator; however, for the fly ash-cement

pastes in the presence of sulphate activator, a needle-shape hydration product which is

ettringite was formed. These hydration products were created by the reaction between SO 32-

ions which come from the activators and the aluminates (Lee et al., 2003).

Qian et al. (2001) investigated the mechanism of fly ashes by Na2SO4. Amorphous

47
aluminosilicate is the major component in the fly ash. Ca(OH)2 is hydrolysed first when water

without an activator is mixed with lime-fly ash cement, and the pH value of the solution

reaches almost 12.5 at 20°C very rapidly:

Ca(OH)2 ------- Ca2+ + 2OH- (2)

In the solution with high alkalinity, various ions that are present in the fly ash are quickly

dissolved into the liquid phase. Examples of the ions are Ca 2+, K+ and Na+. This condition also

causes the silicate or aluminosilicate structure to dissociate and dissolve into the solution. As

the dissolved mono-silicate and aluminate react with Ca2+ ions, the formation of C-S-H and

calcium aluminate hydrate, C4AH13 are promoted. As Na2SO4 is added to the system, there is

a reaction between Na2SO4 and Ca(OH)2 and this can be expressed in the equation:

Na2SO3 + Ca(OH)2 + 2H2O ------- Ca2SO4.H2O + 2NaOH (3)

The pH value of the liquid phase is increased by this reaction hence the resulting fly ash

dissociates and the Ca(OH)2 tends to react much more with the fly ash. Simultaneously, the

SO42- ion concentration increases with the presence of Na2SO4 thus producing additional

ettringite (AFt). For this reason, the structure becomes denser and results in the increase of

the early strength of pastes (Qian et al., 2001).

2.4.3 Other Types of Activation

The addition of chemical activators in concretes with various natural and artificial pozzolans

has been examined by previous researchers. Many types of activators can be used to

accelerate the reactivity of pozzolan materials. Shi and Day (1993) found that there are

significant effects on the pozzolanic activity over a period of time with the presence of CaCl 2

in the pozzolanic materials. Referring to Shi and Day (2000b) which is from Guo (1986), the

Ca(OH)2 dissociates very slowly. The introduction of CaCl 2 reduced the Ca(OH)2 solubility,

however, the dissolution rate of Ca(OH)2 was increased significantly.

48
Shi and Day (2000b) used CaCl2 to study its consequence on the lime-pozzolan blend system.

The presence of 4% CaCl2.2H2O caused a decrease in alkalinity of the liquid phase from pH

value of 12.5 to 11.75. However, the detailed mechanism of the hydration process of cement

with the addition of CaCl2 is still unclear. For the lime-pozzolan system with the presence of

CaCl2, the reaction can be summarized according to the following mechanisms:

When the CaCl2 solution was added into the lime-pozzolan blend, the resulting Ca(OH) 2

dissolves and reduces the solution alkalinity. A reduction of the alkaline environment shows

the negative effect where the pozzolan dissolution process tends to be retarded. The addition

of CaCl2 leads to a greater Ca2+ content but the amount of dissolved mono-silicate and

aluminium species are much less in the activated pastes solution as compared to the control

paste. This causes the production of C3A·CaCl2·10H2O to form very rapidly.

2[Al(OH)4]- + 2Cl- + 3Ca2+ + 4OH- + 4H2O  C3A·CaCl2·10H2O (4)

The solid solution of C3A·CaCl2·10H2O-C3A·Ca(OH)2·12H2O was formed easily as both

products C3A·CaCl2·10H2O and C3A·Ca(OH)2·12H2O comprised of an identical structure.

Through this solid solution formation, the reaction increases the consumption of the dissolved

mono-silicate and aluminate. The product produced is precipitated away from the pozzolan

particles so that a further reaction can take place. The solid volume increased greatly with the

49
formation of C3A·CaCl2·10H2O. The solid volume produced by this product is higher than

those of the C-S-H and C3A·Ca(OH)2·12H2O formation. Therefore, the paste structure

become denser and high in strength compared to the control pastes at certain periods of time.

2.5 STRENGTH DEVELOPMENT USING VARIOUS CHEMICAL ACTIVATORS

Strength development of mortars containing various chemical activators has been reviewed

for the evaluation of the pozzolanic activity of each sample studied by previous researchers

2.5.1 Alkali Activators

Alkali activation is also known as a method that transforms a glassy network of structures

into a very compact well-cemented composite (Palomo et al., 1999b). The addition of

alkaline activators breaking the Si-O and Al-O bonds in the slag glass structure and thus

accelerates the rate of dissolution of Si and Al ions into the liquid phase. Some of the

chemicals that are commonly used by previous researchers for alkaline activation are

Ca(OH)2, NaOH and KOH solutions (Wu et al., 1990).

Sodium Hydroxide (NaOH)

Puertas et al. (2000) used NaOH solutions as an activator in the fly ash/slag pastes system.

50
They found that the addition of 10 M NaOH solution into the mixture consisting of 50% fly

ash/ 50% slag and subjected to curing temperatures of 25°C produce a compressive strength

of about 50 MPa at 28 days of hydration. Paya et al. (2000) studied the rice husk ash (RHA)

activation using the NaOH solution and it was noticed that the presence of NaOH caused the

compressive strength to increases slightly at 1 day of hydration. However, between the 2 to 7

days period, the compressive strength values were lower than those for mortars without this

addition, indicating the negative role of the addition and the non-activation of RHA. This

shows that NaOH did not act as an effective pozzolanic activator for crystallized RHA. The

compressive strength developments for mortars with and without the NaOH additions were

presented in Figure 4.

Calcium Hydroxide Ca(OH)2

Ma et al. (1995) noticed that the SiO 2 solubility in the fly ash increased with the presence of

Ca(OH)2. As the Ca(OH)2 activator was added into the fly ash, this resulted in a reaction

between the most part of Ca(OH)2 and the silicate, forming a C-S-H gel and ettringite (Li et

al., 2000). At 7 days of hydration, he found out that a lot of needle-like shaped ettringite were

formed hence improving the properties and mechanical strength of cement at an early age.

Paya et al. (2000) carried out research on the activation of the rice husk ash (RHA)/ cement

system by replacing 5% of the cement by powdered Ca(OH)2 in order to investigate the

strength development of mortars containing RHA with a 15% cement replacement. However,

they found that the compressive strength increased slightly at 1 day and was lower than those

mortars without the chemical addition at 2 to 7 days.

Quicklime (CaO)

Antiohos and Trismas, (2004) studied the activation of fly ash/ cement (FC) systems by

quicklime. Fly ash from class C which consists of high calcium content was used. The fly ash

mortars were used to determine the mechanical strength and any changes in the fly ash during

51
the hydration process was measured. It showed that the compressive strength of mortars

containing a replacement of 3 and 6% by quicklime was slightly accelerated as compared to

fly ash mortar without quicklime at the early testing period.

2.5.2 Sulphate Activators

Alkaline-slag cement has been widely used for a long time and possesses significant

properties of high strength. Other behaviours such as porosity, permeability and heat

evolution is markedly low instead of having a high resistance to chemical attack (Wu et al.,

1990). However, alkali such as NaOH is expensive and potentially harmful to the operators

while handling it, therefore, neutral salts such as Na2SO4 and others that provide similar

consequences can be used to substitute the alkali activators since it is less harmful in addition

of less expensive.

Sodium Sulphate (Na2SO4)

The activation of lime-pozzolan cements (LPC) using a chemical activator was reported by

Shi and Day (1993). The addition of 4% Na 2SO4 activator considerably enhanced the strength

of LPC at early age. The LPC is a mixture of 20% hydrated lime and 80% natural pozzolan

and chemical activators added based on the mass of LPC. They also found that the strength of

52
hardened LPC pastes were also enhanced at later age with the Na2SO4 addition, however, the

effect is more apparent at early ages as compared to the later ages.

Lee et al. (2003) investigated the use of Na 2SO4 to accelerate the strength of mortar

containing fly ash at an early age. 40% of the fly ash used in the mortar mix consisted of 1%

Na2SO4 addition based on the weight of the cementations materials. The compressive strength

increased noticeably for mortars containing 1% and more Na2SO4 at 1 day but the strength

was similar to that mortar containing 40% fly ash without the presence of Na2SO4 at 28 days.

Shi and Day (1995) also studied the effect of using Na 2SO4 as an activator on the strength

development using two different kinds of fly ash (low calcium content, LFA and high

calcium content, HFA) on lime/ fly-ash pastes system. The reactivity of ashes was studied

based on the strength development of the mixtures consisting of 80% fly ash and 20%

hydrated lime. The results obtained show that the pozzolanic reactivity of pozzolans for both

forms of ash increased with the addition of Na 2SO4. This was shown by significant

improvement in strength. Na2S04 mainly influences the strength development during early

age of hydration whereas the effect on later ages differed depending on the type of fly ash

used. The results are shown in Figure 5.

An experiment on the strength of lime-fly ash mortars was carried by Qian et al. (2001). They

reported that the lime-ungrounded fly ash mortars without an activator did not show any

strength development (Figure 6). However, the strength of lime-fly ash mortar increased

considerably when the fly ash used was subjected to the grinding process. On the other hand,

they found that grinding is an energy intensive process and requires a complex instrument.

The strength of the lime-fly ash mortars containing Na2SO4 also increased significantly and

was greater than of grinding effect. By comparing the different activation techniques

according to the price for one unit strength, Shi and Day (2001) concluded that the most

helpful technique is the chemical activation.

53
Gypsum (CaSO4·2H2O)

Xu and Sarkar (1991) mentioned that when an activator such as gypsum is being used, it

produces sulphate ions which are able to react with aluminate causing the dissolution of the

glass structure. The increase of compressive strength for pastes containing fly ash (Class F:

low calcium content) is around 30 to 60% which is caused by the presence of 3 to 6%

gypsum as compared to pastes without the addition of gypsum that produces a lower

compressive strength.

Calcium sulphate anhydrite (CaSO4)

Poon et al. (2001) investigated the use of an anhydrite to activate the fly ash cement system.

The mortar was subjected to steam curing at a temperature of 65°C for 6 hours before normal

curing at room temperature. He made a comparison between the mixture with the absence of

an activator and the mixtures containing various anhydrite contents. A 10% anhydrite was

found to be the maximum addition for mortars containing fly ash with a replacement of up to

35%.

An evaluation was done between gypsum and anhydrite to compare their roles in activating

the fly ash reactivity. It shows that the compressive strength resulting from the fly ash mortar

with a 35% cement replacement containing 10% anhydrite is greater than 10% gypsum (Poon

54
et al., 2001).

Hemihydrate gypsum (CaSO4·0.5H2O)

Shi and Day (1993) used various dosages of CaSO 4·0.5H2O as an activator to study its effect

on the development of strength of lime-pozzolan cement (LPC) pastes. They discovered that

the strength was highest with the addition of 6% CaSO 4·0.5H2O. Although at later ages of

hydration, the strength of pastes increased with an addition of 6% CaSO 4·0.5H2O, however,

its effect is lower than those activated pastes with the addition of 4% CaCl2·2H2O.

2.5.3 Other Types of Activator

According to Shi and Day (1995), the addition of other chemicals which do not belong to the

alkali or sulphate group such as CaCl2 has a considerable influence on the strength at an early

age and at the intermediate ages. It was discovered that the strength of pastes containing a 3

to 5% CaCl2 activator were noticeably enhanced at 90 and 180 days of hydration.

Flake Calcium Chloride (CaCl2·2H2O)

Shi and Day (1993) also utilized various dosages of CaCl2.2H2O activator in the LPC system

in order to study its effect on the compressive strength development. An insignificant effect

on the development of compressive strength of LPC pastes containing CaCl 2 was found at 3

days of hydration. At all ages, the strength of the LPC pastes was reduced with the addition

of 1% CaC12.2H2O, however, the strength increased when increasing the amount of dosage

used. The strength was enhanced with the addition of CaCl2.2H2O above 3%. Their results led

them to conclude that the addition of a CaCl2 activator is not effective on the early strength

development; however, the later strength is much more accelerated using this chemical

activator. The pastes containing a 4% CaCl2 activator resulted in a greater strength at later

ages as compared to pastes containing a 4% Na2SO4 (Shi and Day, 1993).

The effect of using a CaCl2 activator on the strength development of fly ash (low calcium

content) LFA and (high calcium content) HFA pastes (Figure 7) was investigated by Shi and

55
Day (1995). An insignificant effect had been observed with the addition of CaCl2 on 1 day

strength for both types of the pastes and this effect is found to be the same to that strength

resulting from the lime-pozzolan pastes without an activator. However, after 1 day and

thereafter, the improvement on strength of LFA pastes was observed with the addition of

CaCl2 from 1 to 5% dosage. However, the improvement of strength for HFA pastes is only

helpful with the addition of 3 to 5% CaCl 2 dosage. Therefore, they concluded that, CaCl2

activators are much more activate in the LFA pastes than in the HFA pastes.

Sodium Chloride (NaCl)

The strength development of LPC pastes containing certain amounts of NaCl was studied by

Shi and Day (1993). It was found that as NaCl was added into the system, it does not

contribute to the strength development of the pastes with an addition of up to 5 % and at 180

days of hydration.

Shi and Day (1995) also studied the influence of 0 to 5% NaCl addition on the development

of the strength of HFA pastes. They also found that the addition of a NaCl activator had an

insignificant effect on the development of strength of HFA pastes. A similar observation was

obtained when pastes consisting of lime-natural pozzolan blends were tested in 1993. Even

56
though the tests using NaCl as an activator on LFA pastes were not performed, it can be

concluded that the same observation would be obtained since there is a similarity between the

chemical composition of LFA and natural pozzolans which had been tested before.

2.6 CALCIUM HYDROXIDE (Ca(OH)2) CONTENT

Ca(OH)2 is not a desirable product in the concrete structure. It is soluble in water, hence,

may be leached out making concrete porous and is harmful for the concrete strength (Shetty,

2008; Yang et al., 2000). The use of pozzolan materials such as fly ash, silica fume and other

pozzolanic materials are the steps to reduce the amount of Ca(OH)2 in order to improve the

microstructure and quality of concrete.

The amounts of Ca(OH)2 present in the samples can be determined by thermo gravimetric

analysis, TGA ( Bhatty and Reid, 1985; Vessalas et al., 2009). Degree of reaction of Ca(OH) 2

in lime-pozzolan pastes was studied by Shi and Day (2000a). They found that the remaining

Ca(OH)2 in Na2SO4-activated pastes was less than that of the control pastes. Similar

observations were also made by Lee et al. (2000). Lee et al. (2000) determined the amount of

Ca(OH)2 produced with and without the presence of chemical activators for the fly ash-

cement pastes system (Figure 8). They showed that the amount of Ca(OH) 2 in the cement

paste containing 40% fly ash was nearly 50% less compared to the cement paste without fly

ash. The addition of chemical activators resulted in similar trends to cement pastes containing

40% fly ash. However, it was found that Na2SO4 was the most effective in decreasing the

level of Ca(OH)2 at early age.

Antiohos and Trismas (2004) have shown that cement paste without fly ash is constantly

producing Ca(OH)2 throughout the hydration period. On the contrary, the specimens with fly

ash were explained by the simultaneous production and consumption of Ca(OH) 2. However,

small replacement of fly ash by 3% lime accelerated the Ca(OH) 2 depletion from the early

period of hydration. The Ca(OH)2 contents of the high-calcium (class C) fly ash designated as

57
Td with 3 and 6% fly ash replacement by quicklime with hydration age are shown in Fig. 9.

2.7 CONCLUSIONS

Numerous species serve as activators and accelerators. By reviewing previously published

work, it can be concluded that for maximum benefits, choosing a suitable activator and the

type of material to be activated is very important. The rate of pozzolanic reaction, mainly the

58
early strength development, together with the pozzolanic reactivity can be improved using

suitable chemical activators instead of using other techniques such as the thermal and

mechanical methods. The reaction of pozzolanic materials with a solution in high alkaline

environments was found to be one of the principal ways in which the pozzolanic materials

can be activated. This involves breaking down the bonds in the network structure of glass and

hence, accelerating the rate of hydration of the pozzolan. However, many aspects should be

considered in selecting proper activators especially those including the financial and practical

processes of handling the chemicals.

59
 CHAPTER THREE METHODOLOGY

METHODOLOGY
3.0 PREAMBLE

The aim of this research study is to determine the behaviour of alkaline activated coconut

shell ash as partial replacement of ordinary Portland cement in reinforced concrete slabs.

To achieve this, certain preliminary tests were carried out on the parent materials in the

laboratory. They are the determination of the physical properties of aggregates (coarse, fine)

and cement used, tensile and compressive tests on the hardened concrete after curing,

moment of resistance, workability and setting time test on green concrete. Density and

Specific gravity are the other tests to be carried out.

3.1 PARENT MATERIALS

Materials considered are

 Cement  Sodium Hydroxide

 Sharp sand  Sodium Silicate

 Granite  Potable Water

 Coconut shell ash

3.1.1 Cement

Cement is a hydraulic binder and is defined as a finely ground inorganic material which,

when mixed with water, forms a paste which sets and hardens by means of hydration

reactions and processes which, after hardening retains its strength and stability even under

60
water. The cement used was Ordinary Portland cement (Lafarge Elephant Portland Cement

32.5R). This cement satisfies international standards on cement (BS 12 Portland Cement).

This ensures that the cement passes the test (soundness) for which its properties being

determined.

3.1.2 Fine Aggregate (Sharp Sand)

The fine aggregate used in this research study was River sand obtained from Ogun River bed

located at Ibafo town in Ogun state. The sand particles were confirmed free from clay, loam,

dirt and organic impurities of any form. The particles passed through BS sieve No 4 (aperture

2.36mm) but retained on sieve No 220 (aperture 0.06mm) ensuring that the dust particles

were removed from the sand.

3.1.3 Coarse Aggregate (Granite)

The coarse aggregate used in this research study were crushed granite of igneous origin. They

come in different sizes but the recommended size is 12.5mm to 19mm. It helps to improve

the strength of the concrete. The granites were sieved off dust particles and dirt to ensure it is

free of noticeable impurities.

3.1.4 Potable Water

The water used was from the University of Lagos concrete laboratory. Being the same source

of water that have been used severally to produce concrete cubes specimens over the years, it

has been proven to be suitable for concrete production as the 28th day strength of cubes

produced using this water fall within the acceptable range of not less than 90% of a

comparable cube obtained from distilled water. Care was taken during collection of water

from this source to avoid the introduction of external impurities by using clean containers or

bowls (or buckets) every time the water is collected from the source.

61
3.1.5 Coconut Shell Ash

Coconut shell sourced from Badagry town in Badagry local council was burnt in open air for

5hours and allowed to cool. The resulting material was ground to very fine particles in a

milling machine, and then sieved through 75µm sieve to obtain CSA needed for this project.

3.1.6 Sodium Hydroxide (NaoH)

The Sodium Hydroxide gotten is in flakes and was sourced from Ojota, Lagos. Sodium

Hydroxide, commonly known as caustic soda, lye, or sodium hydrate, is a caustic compound

which attacks organic matter. (Caustic soda is sodium hydroxide, caustic potash is potassium

hydroxide and silver nitrate is lunar caustic.) It is hygroscopic and readily absorbs water from

the air, and so it was stored in an airtight container.

3.1.7 Sodium Silicates (Na3SiO2)

A well-known member of this series is sodium metasilicate, Na 2SiO3. Also known as water

glass or liquid glass, these materials are available in aqueous solution and in solid form. The

pure compositions are colourless or white, but commercial samples are often greenish or blue

owing to the presence of iron-containing impurities. The sodium silicate gotten was in liquid

form and was sourced from Ojota, Lagos.

3.2 PREPARATION OF ALKALINE ACTIVATOR

The solution of sodium hydroxide and sodium silicate are used as alkaline solutions in the

present study. Commercial sodium hydroxide in pellets form and sodium silicate solution are

used.

In this work, concrete is activated with different concentration of alkaline solution and their

physical and mechanical properties are tested and observed. The molecular weight of sodium

hydroxide is 40g/mol. To prepare 12 Molarity of solution, 480g (40x12= 480g/dm 3) of

sodium hydroxide flakes are weighed and dissolved in distilled water to form 1 litre solution.

62
Volumetric flask of 1 litre capacity is taken, sodium hydroxide flakes are then added solely to

distilled water to prepare 1 litre solution.

As there are no code provisions for the mix design of geo-polymer concrete, the density of

geo-polymer concrete is assumed as 2400Kg/m3. The alkaline solution to the binder ratio is

kept at 0.4. The ratio of sodium hydroxide to sodium silicate is kept as 2.5. The convention

method used in making of normal concrete is adopted to prepare geo-polymer concrete. Prof.

Davidovits (Geopolymer Institute, France) has recommended that the sodium silicate solution

and the sodium hydroxide solution be mixed a day prior to preparing the geo-polymer

concrete.

3.3 MIXING/CASTING OF CONCRETE

Mixing of concrete was carried out in the concrete workshop. Mixing of concrete was done with

the use of concrete mixer. All the materials were weighted accurately before mixing. The

machine mixer was turned on and the materials poured into the tilting drum in the order of,

granite, sharp sand, coconut shell ash, cement, water and alkaline activator. The mixture was

thoroughly mixed for about a minute and poured on to a flat metal container where the mixing is

completed via hand mixing with the aid of shovel. The surface of the flat metal container was

wetted before putting the materials to reduce the water loss. The alkaline activator was added into

the water before poured into the dry mixture. Then the mixture of water alkaline activator was

added slowly to the dry mixture and mixed consistently to form fresh concrete. After the fresh

concrete was formed, slump and compaction factor tests were performed to check its workability.

The fresh concrete was then poured into the steel cylindrical moulds and cube moulds. The inner

surface of the steel mould was lubricated with oil for the ease of demoulding/striking. The

concrete was demoulded after 24 hours, cured in a tank of fresh water or lagoon water (different

media). The concrete samples were tested at the concrete age of 7, 14 and 28 days after curing.

63
3.4 CURING OF CONCRETE

A total of fifty four concrete cubes, thirty six concrete cylinders were cured (for 7, 14 and 28

days) in the laboratory with normal water, while another fifty four concrete cubes were cured

(for 7, 14 and 28 days) in lagoon water.

3.5 APPARATUS, TOOLS AND EQUIPMENTS

The apparatus, tools and equipment used for the tests and observations in the laboratory are

briefly outlined below:

3.5.1 Avery Weighing Machine

This is comprised of a metal platform where the material to be measured is placed, a standing

rod that holds the reading meter and a reading meter on which the value of the mass

measured is displayed. The capacity of this weighing machine is 150kg. The Avery weighing

machine was used to measure the mass of concrete materials such as water, cement, CSA,

sand and granite used in this work.

3.5.2 Cube Moulds

These were made of cast iron with inner dimensions of 150x150x150mm.They have a sheet

metal base and they were well tightened and greased to prevent excessive slurry escape and

facilitate easy de-moulding of hardened concrete cubes.

3.5.3 Slump Mould

The slump mould is a metal hollow frustum of a cone having the following dimensions;

Diameter of top = 100mm

Diameter of base = 200mm

Height of mould = 300mm

64
It is used to determine the workability of a mix by measuring the slump height. It also

comprises of a tamping rod and a base plate to facilitate compaction and prevent moisture

escape respectively.

3.5.4 Concrete Mixer

This is a diesel engine powered tilting drum mixer. It has a single cylinder engine as well as a

mobile rotating drum which rotates in order to ensure proper mixing of constituent materials

thereby creating a homogeneous concrete mix.

3.5.5 Vicats Apparatus

This is used to determine initial and final setting times of the Lafarge cement used for this

work. It is comprised of a circular metal base, a stem that holds the base and the measuring

scale on to which the piercing needle compartment is held in position.

65
3.5.6 Avery Dennison Compression Testing Machine (Capacity: 1500kN)

This is hydraulically – operated equipment. It consists of a measuring gauge with two

indicators or pointers (black and red). The indicators must be set to zero marks before testing.

The load is applied to a test specimen through two steel loading platforms; a fixed upper

platform and an up warding moving the lower platform. The lower platform has markings

which help in centralizing a test specimen to receive the concentric load. At failure, the black

pointer drops back while the red pointer stays fixed at the failure value.

3.5.7 Wheel Barrow

This was used to transfer large masses of aggregates and tested specimens

3.5.8 Tamping Rod

The tamping rod is a straight steel bar or circular cross-section of 16mm diameter and

600mm long. It was used to compact the concrete in the cube moulds.

3.5.9 Set of Sieves

These are of different aperture sizes used to obtain the grain size classification of aggregates.

3.5.10 Other Equipment

The other equipment used in this project includes trowel, shovel, head pan, greasing oil and

curing tanks.

3.6 EXPERIMENTAL TEST PROCEDURES

The experimental procedure began with the preliminary investigation on the CSA, granite,

sand and cement and ended with the compressive strength determination of 180N0s of

150mm x 150mm x 150mm concrete cubes. A prescribed mix ratio of 1:2:4 by weight of

cement, sand and granite was used throughout for all batches of concrete mixes with constant

water/cement ratio of 0.55. The ratio of CSA to OPC was kept constant at the optimum value

66
of 10%, while the molality of alkaline activator (NaoH+Na 3SiO2 ) was varied in step of 5 (i.e

0moldm-3, 4moldm-3, 8moldm-3, 12moldm-3, 16moldm-3).

3.6.1 Preliminary Investigation

The preliminary investigation carried out is to determine the properties of each material. The

tests include:

 Sieve analysis

 Specific gravity

 Bulk density

 Dry density

 Moisture content

 Aggregate crushing value and impact value

3.6.1.1 Sieve Analysis/Gradation of Aggregates

Sieve analysis is the name given to the simple operation of dividing a sample of aggregates

into the fraction, each consisting of particles of approximately the size. Before this

experiment, the aggregates (sand, granite, polyvinyl waste and steel slag) were dried

sufficiently to avoid lumps of fine particles being classified as the large particle (in the case

of sand and to prevent clogging of finer sieves).

Apparatus:

1. Mechanical Sieve Shaker

2. Sieve brush

3. Weighing Balance

4. Various Sizes of Sieve Ranging From 2.36mm - 65µm

5. Drying oven

6. Evaporating pans.

Procedure:

67
Fine Aggregate (Sand)

• Some quantity of sand was air dried for 24hrs

• 1000g of sand was measured out from the dried sand

• A set of sieves with aperture sizes ranging from 10mm to 75µm was arranged in order

• A clean measuring tray was placed under the 10mm sieve and the measured sand poured

into the sieve, and shaken over the tray and jarred until not more than a trace passes for a

period of not less than 2minutes

• The sand retained on this sieve was poured into a separate clean tray and weighed.

• The sand passing the sieve in the first clean tray is then poured into the next sieve size and

the process repeated.

• This continued until after the least sieve size of 75microns for which the remaining particles

passing is considered dust.

Coarse Aggregate (Granite)

• Some quantity of granite was air dried for 24hrs

• 1000g of granite was measured out from the dry granite

• A set of sieves with aperture sizes ranging from 25mm to 2.36µm was arranged in order

• A clean measuring tray was placed under the 25mm sieve and the measured granite poured

into the sieve, and shaken over the tray and jarred until not more than a trace passes for a

period of not less than 2minutes

• The granite retained on this sieve was poured into a separate clean tray and weighed.

• The granite passing the sieve in the first clean tray is then poured into the next sieve size

and the process repeated.

• This continued until after the least sieve size of 2.36µm.

68
3.6.1.2 Specific Gravity

Specific gravity is the ratio of the density of a substance to the density (mass of the same unit

volume) of a reference substance. Apparent specific gravity is the ratio of the weight of a

volume of the substance to the weight of an equal volume of the reference substance.

The specific gravity of a soil is often used to describe the relationship between the weight of

soil and its volume. As soil contains different particles with different specific gravities; the

term Gs represents an average value for all the particles.

Apparatus

1. Density bottle

2. Glass rod

3. Wash bottle containing distilled water

4. Drying Oven

Procedure

• The dried density bottle is weighed, (W1).

• About 25.0g of the oven dried material was measured and transferred into a density

bottle. The stopper is replaced and the bottle and contents weighed, (W2).

• Tap water from the concrete laboratory was added so that the soil in the bottle is just

covered. The mixture was then stirred thoroughly with a glass rod and shaken to remove air

trapped in the soil.

• The bottle is filled with tap water and the stopper replaced. The density bottle and its

contents were shaken carefully to remove any remaining air and weighed, (W3)

• The content of the bottle was emptied, washed and the bottle filled with distilled

water only and weighed, (W4).

W 2 −W 1
Gs=
( W 4−W 1 )−( W 3−W 2 )

69
Where;

W1 = Weight of bottle

W2 = Weight of bottle and dry

W3 = Weight of bottle, soil and water

W4 = Weight of bottle filled with water only.

The specific gravity is used in the laboratory to help with the calculation of the void ratios of

soil specimens, in the determination of the moisture content of a soil, and in the particle-size

analysis, also known as the sedimentation test.

3.6.1.3 Bulk Density

The apparatus includes a cylindrical metal container of approximately 15 or 30-litre capacity.

The volume of the metal container is first obtained by determining the weight of water

required to fill it. The container is then filled to overflowing with aggregate being discharged

from a height of not more than 50mm above the top of the container. The aggregate in the

container is then weighed and divided by the volume of the container to give the bulk density

in kg/m3.

Apparatus:

1. A 6” (150mm) diameter open-ended steel cylinder with plunger and base plate.

2. A standard metal tamping rod

3. Weigh balance

4. B.S. test sieves 1/2” (12.5mm) and 3/8”(9.8mm)

5. A compression testing machine

3.6.1.4 Moisture Content

Water content or moisture content is the quantity of water contained in a material. It is the

ratio of water present in the soil mass to the weight of the soil solids. . The moisture content

70
of the sand and granite used for this work was determined by the oven-drying method.

The aggregate specimen of sand was weighed and placed in the oven for 24 hours, then

weighed when removed from the oven. The decrease in weight of the specimen shows the

corresponding loss of moisture content and it is expressed in percentage.

Apparatus:

 Temperature controlled oven

 Cylindrical aluminium cans (in place of crucibles)

 Spatula

 Digital weighing machine

Procedure

 3 empty cylindrical cans were cleaned, dried, labelled (A,B,C) and weighed to get

M1A, M1B, M1C

 A quantity of test sample was placed in the three cans

 Each can and its content was weighed to get M2A, M2B, M2C

 The cans and contents were then placed in the oven and turned on, with the heating

temperature set at 110oC

 After 24hours, the cans and their content were removed from the oven and allowed to

cool; the cans and their content were weighed to obtain M3A, M3B, M3C

M 2 −M 3
w= ❑ M 2−M
 The water content is obtained using the relation M 3 −M 1 w=
M 3−M
3

71
3.6.1.5 Dry Density Test

The moisture content of the sample was first determined. Then, the sample was placed in a

mould and weighed. The volume and weight of the mould were also determined. The bulk

density (ᵞ) was calculated by dividing the mass of sample by the volume of the mould.

Dry density = ᵞ/ (1+w)

3.6.1.6 Aggregate Crushing Value and Impact Value

Aggregate Crushing Value:

The material for this test consists of aggregate passing the 14mm B.S. test sieve and retained

on the 10mm B.S. test sieve and tested in a surface-dry condition. The apparatus required for

this test consists of an open-ended steel cylinder of normal size 150 mm internal diameters

with plunger and base plate. The approximate quantity may be found conveniently by filling

the cylindrical measure in three layers, each layer being tamped 25 times from a height of

about 50mm above the surface of the aggregate with the rounded end of the rod and finally

levelled off. Record the mass (weight) of the sample (W1). Insert the plunger so that it rests

horizontally on this surface.

Place the apparatus between the platens of the testing machine and applied a load of

399.5KN. (40ton) Release the load and remove the crushed material into a clean tray. Sieve

the whole of the sample on the No. 7 (2.36mm) B.S. test sieve. Weigh the fraction passing the

sieve (W2). The ratio of the mass of fines formed to the total mass of the sample expressed as

the percentage is the aggregate crushing value.

Percentage fines = (W1-W2)/W2 × 100.

This value is usually not greater than 30%.

Aggregate Impact Value:

The aggregate impact value gives a relative measure of the resistance of an aggregate to

sudden shock or impact, which usually differs from its resistance to a slowly applied

72
compressive load. The aggregate impact value is usually not more than 30.

The standard aggregate impact test is made on aggregate passing a 14mm B.S. sieve and

retained on a 10mm sieve. The impact test machine is a circular metal base weighing between

22kg and 30kg with a plane lower surface of not less than 300mm diameter. A cylindrical

steel cup having an internal diameter of 102mm and an internal depth of 50mm. A metal

hammer weighing 13.5kg to14kg and 100mm diameter with 50mm long. Means for raising

the hammer and allowing it to fall freely between the vertical guides from a height of 380mm

on to the test sample in the cup. Also, means for automatically recording the number of blows

is desirable.

The aggregate in a surface dry condition is filled into the cup of the machine and tamped

evenly with 25 blows of the tamping rod. The net mass of aggregate are measured and

recorded (W1). Fix the cup firmly in position on the base of the machine. Subject the test

sample to a total of 15 blows.

Then remove the crushed aggregate and sieve the whole of the sample in the tray on the

2.36mm sieve. Weigh the fractions passing the 2.36mm sieve (W2). The ratio of the mass of

finely formed to the total sample is expressed as a percentage.

W1/W2 ×100

Where

W1 is the mass of fraction passing the sieve for separating the fine (g).

W2 is the mass of surface dry sample (g).

3.6.2 Secondary Investigation

The secondary investigations carried out in the course of this research study are:

 Consistency/Setting time of cement

 Workability (Slump test, compaction factor test)

 Split Cylinder test

 Compressive strength test

73
3.6.2.1 Consistency/Setting Time of Cement

The aim is to get the consistence of standard cement paste and to determine the initial and

final setting time of fresh Lafarge cement paste of standard consistence; to determine as well

the setting times of alkaline activated coconut shell ash partially replacing ordinary Portland

cement.

Initial setting time is the time from mixing dry cement with water till the beginning of

interlocking of the gel. Final setting time is the time from mixing dry cement with water till

the end of interlocking of the gel.

It is very important to know the setting times. Knowing the initial setting time is important in

estimating free time for transporting, placing, compaction and shaping of cement paste.

Apparatus:

1. VICAT Apparatus.

2. Digital weighing scale, used to measure the weight of dry cement.

3. Glass graduates used to measure the volume of water.

4. Trowel.

5. Mixing bowl.

6. Stop-watch.

7. Portland Pozzolan Cement.

8. Water.

Procedure:

•Once we determine the normal consistency, we can use the taken specification of that paste

to measure the initial and final setting times. So we make a fresh cement paste using the

amount of water and cement to the standard consistency. The stop-watch shall start at this

step.

•We use the 1 mm diameter needle, and penetrate the sample with this needle by leaving it to

free fall, and then we read the VICAT ruler scale. We do a trial each 15 minutes until the

depth of penetration is 5 mm. The elapsed time from mixing the water with dry cement till

this moment is called initial setting time.

74
•We replace the needle with another angular one (Final setting needle), and penetrate the

sample by it every 15 minutes till only the needle makes an impression on the paste surface

but the cutting edge fails to.

3.6.2.2 Workability

Slump Test

The concrete slump test is an empirical test that measures the workability of fresh concrete. It

measures the consistency of the concrete in that specific batch.

Apparatus

1. Mould : (in form of the frustum of a cone) the mould is provided with suitable foot pieces

as well as handles to facilitate placing the concrete and lifting the moulded concrete test

specimen in a vertical position.

2. Tamping rod: (16mm diameter, 600mm long and rounded at one end)

3. Steel rule

4. Stopwatch

5. Hand trowel.

6. Head pan

Procedure:
• The surface of the mould was first cleaned and the mould placed on a smooth,

horizontal, rigid and non-absorbent surface.

• Some quantity of freshly mixed concrete from each batch mix was collected and placed

in the slump mould in four layers, each approximately ¼ of the height of the mould;

each layer is tamped 25 strokes using the tamping rod.

• The strokes were distributed evenly over the entire cross-section of the mould; the

concrete was then struck off level after the top layer is rammed.

• The mould was removed immediately by raising it slowly and carefully in a vertical

direction to allow the concrete subside (or slump).

75
• The difference in level between the height of the mould and that of the highest point of

the subsided concrete was measured using a steel rule.

• This procedure was repeated for the concrete mix of all four batches

3.6.2.3 Split Cylinder Test

The split cylinder test is to determine the split tensile strength of concrete.

Apparatus

 Compression testing machine,

 Tamping bar,  Two packing strips of plywood 30

 Moulds, cm long and 12mm wide.

Procedure

1. Take the wet specimen from water after 7 days of curing

2. Wipe out water from the surface of specimen

3. Draw diametrical lines on the two ends of the specimen to ensure that they are on the same

axial place.

4. Note the weight and dimension of the specimen.

5. Set the compression testing machine for the required range.

6. Keep the plywood strip on the lower plate and place the specimen.

7. Align the specimen so that the lines marked on the ends are vertical and centred over the

bottom plate.

8. Place the other plywood strip above the specimen.

9. Bring down the upper plate to touch the plywood strip.

10. Apply the load continuously without shock at a rate of approximately

14-21kg/cm2/minute (Which corresponds to a total load of 9900kg/minute to

14850kg/minute)

11. Note down the breaking load (P)

76
3.6.2.4 Compressive Strength Test

To determine the compressive strength of concrete using concrete cubes.

Apparatus

 Compression testing machine  Curing tank

 Tamping bar,  Trowel

 Cube moulds,  Shovel

 Weighing machine  Scoop.

 Vibrator

77
Procedure

1. A set of 3No.s concrete cubes from each of the batches were removed from the curing

tanks (plastic drums) at the maturity age of 7, 14, 28, 90, and 120days.

2. The water on each cube was allowed to drain off for just about 2minutes, immediately

placed on the platform of the weighing machine to measure its mass

3. Each concrete cube was then placed and set properly in the Avery Dennison machine

4. The machine is turned on operated to apply load on the cube until the cube fails

5. The value of load at failure is recorded from the meter reading of the machine

6. The recorded failure load is divided by the area of a face of the cube to obtain the

compressive strength of the cube in N/mm2

3.7 MATERIAL QUANTITIES

3.7.1 Casting Schedule for Concrete Cubes

A total of 180 cubes (90cubes to be cured in normal water and another 90 cubes to be cured

in lagoon water) were cast with 3 cubes for each sample category (Table 3.2).

The total material quantities required are itemized below;

1. Density of concrete: 2400Kg/m3

2. Volume of single cube (for concrete) = 150x150x150= 0.003375m3.

3. No of cubes required= 180

4. Concrete cube mix ratio = 1:2:4.

Total volume required for 180 cubes = 180 x 0.003375= 0.6075m3.

 Weight of components = ratio of component x total volume x density of concrete.

Total ratio

 Weight of Binder = 1/7x0.6075x2400= 208.29kg

 Weight of Fine aggregates = 2/7x0.6075x2400= 416.572kg

 Weight of coarse aggregates = 4/7x 0.243x2400=833.143kg

93
Since the binder (cement) is to be partially replaced with coconut shell ash; a sample

calculation of the partial replacement weights of wastes materials and cement is shown

below;

For 10% replacement;

Total weight of cement required == 208.29kg

No of cubes required for 10% replacement = 150 cubes (refer to table 3.1)

Total weight of binder (cement) reqd. for 0% replacement (30 cubes) = (208.29/180) x 30 =

34.715kg.

Total weight of coarse aggregate reqd for X% replacement = X x total wt. of binder reqd for X %
replacement 100

The weight of Coconut shell ash required for 10% replacement = (10/100) x 34.715 = 3.4715kg.

CONCRETE AGE ( IN DAYS)

28 DAYS 90 DAYS
7 DAYS 14 DAYS 120 DAYS
SAMPLES SUM
NW LW NW LW NW LW NW LW NW LW

Normal 3 3 3 3 3 3 3 3 3 3 30

Normal + 3 3 3 3 3 3 3 3 3 3 30
10%CSA

Normal +
10%CSA+ 3 3 3 3 3 3 3 3 3 3 30
4moldm-3
Normal +
10%CSA+ 3 3 3 3 3 3 3 3 3 3 30
8moldm-3
Normal +
10%CSA+ 3 3 3 3 3 3 3 3 3 3 30
12moldm-3
Normal +
10%CSA+ 3 3 3 3 3 3 3 3 3 3 30
16moldm-3

94
 SUMMATION 180
*NW---- Normal water for curing, *LW----Lagoon Water for curing
Table 3.1: Showing Numbers of concrete cubes cast, age and method of curing in their respective
categories
Concrete Cubes
WT. OF
TOTAL WT. WT OF FINE
W/C CSA CSA WT. CEMENT COARSE
OF AGGREGATE
SAMPLES RATIO % (Kg) WT. (Kg) AGGREGATE
BINDER(Kg) WASTE (Kg)
REQD. (Kg)

Normal 0 0 34.715 34.715 13.886 27.77

Normal +
10%CSA 10 3.4715 31.2435 34.715 13.886 27.77
Water/cement ratio= 0.55

Normal+
10%CSA+ 10 3.4715 31.2435 34.715 13.886 27.77
4moldm-3
Normal +
10%CSA+ 10 3.4715 31.2435 34.715 13.886 27.77
8moldm-3
Normal +
10%CSA+ 10 3.4715 31.2435 34.715 13.886 27.77
12moldm-3
Normal +
10%CSA+ 10 3.4715 31.2435 34.715 13.886 27.77
16moldm-3

TOTAL 17.3575 190.9325 208.29 416.572 833.143

Table 3.2: Material quantification of constituents for casting concrete cubes

3.7.2 Casting Schedule for Concrete Cylinders

A total of 60 cylinders were cast with 2 cylinders for each sample category (Table 3.4).

The total material quantities required are itemized below;

1. Density of concrete: 2400Kg/m3

2. Volume of single cylinder (concrete) 150mm (dia) and 300mm (height) = 3.142 x 1502 x
0.25 x 300 = 0.0053m3.

3. No of cylinders required= 60

4. Concrete mix ratio = 1:2:4.

95
Total volume required for 60 cylinders = 60 x 0.0053= 0.318m3.

 Weight of components = ratio of component x total volume x density of concrete.

Total ratio

 Weight of Binder = 1/7x0.318x2400= 109.03kg

 Weight of Fine aggregates = 2/7x 0.265x2400= 218.06 kg

 Weight of coarse aggregates = 4/7x 0.265x2400= 436.12 kg

Since the binder (cement) used is to be partially or totally replaced with coconut shell ash a

sample calculation of the partial replacement weights of wastes materials and cement is

shown below;

For 10% replacement;

Total weight of binder required = 109.03kg

No of cylinders required for 10% replacement = 50 cylinders (refer to table 3.4)

Total wt. of cement reqd. for 0 %replacement (10 cylinders) = (109.03/60) x 10 = 18.172kg.

Total weight of coarse aggregate reqd for X% replacement = X x total wt. of binder reqd for X %
replacement 100

The weight of CSA required for 10% replacement= (10/100) x 18.172kg = 1.8172kg.
Concrete Cylinders

CSA TOTAL WT. WT OF FINE WT. OF COARSE

W/C CSA CEMENT AGGREGATE AGGREGATE
WT. OF
SAMPLES RATIO % WT. (Kg)
(Kg) BINDER(Kg) REQD. (Kg) REQD. (Kg)

Normal 0 0 18.172 18.172 36.343 72.687

Normal +
Water/cement ratio= 0.55

10%CSA 10 1.8172 16.3548 18.172 36.343 72.687

Normal+
10%CSA+ 10 1.8172 16.3548 18.172 36.343 72.687
4moldm-3
Normal +
10%CSA+ 10 1.8172 16.3548 18.172 36.343 72.687
8moldm-3
Normal + 10 16.3548 18.172 36.343 72.687
10%CSA+ 1.8172
12moldm-3

96
Normal +
10%CSA+ 10 1.8172 16.3548 18.172 36.343 72.687
16moldm-3

TOTAL 9.086 99.946 109.03 218.06 436.12

Table 3.3: Material quantification of constituents for casting concrete cylinders

CONCRETE AGE ( IN DAYS)

SAMPLES SUM
28 DAYS 90 DAYS
7 DAYS 14 DAYS 120 DAYS

Normal 2 2 2 2 2 10

10
Normal +
2 2 2 2 2
10%CSA
Normal +
10%CSA+ 10
4moldm-3 2 2 2 2 2

Normal +
10%CSA+ 10
2 2 2 2 2
8moldm-3
Normal +
10%CSA+ 10
2 2 2 2 2
12moldm-3

Normal + 10
10%CSA+
2 2 2 2 2
16moldm-3

SUM 10 10 10 10 10 60

Table 3.4: Showing Numbers of concrete cylinders cast, and age in their respective categories all
cured in normal water

97
 MATERIAL ESTIMATIONS AND COSTING

Unit Quantity
Items 10% Total Cost (Naira)
(Kg) Purchased. (Kg)

Cement 536.0245 kg 53.60245 kg 589.62695 600kg 33600

Sharp
1169.492 kg 116.9492 kg 1286.4412 1.5 tons 15000
Sand
Granite 2338.983 kg 233.8983 kg 2572.8813 3 tons 25000

CSA 48.7295 kg 4.87295 kg 53.60245 55kg 30000

Sodium
Hydroxide 50 kg 50 kg 20000
(NaOH)
Sodium
silicate 20 lt 20 litres 10000
(Na2SiO3)
Haulage 10000

Workmanship 30000
Marine
boards and 40000
labour cost
TOTAL 242900
Table 3.7: Total material quantification and total costing of project

98
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