PSZ 19:16 (Pind. 1/07)

UNIVERSITI TEKNOLOGI MALAYSIA

DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT Author’s full name : AZHARIE EFFENDDY BIN AZMI

Date of birth : 18 FEBRUARY 1978

Title : THE PROPERTIES AND FLEXURAL BEHAVIOUR

OF SELF COMPACTING CONCRETE USING

PALM OIL FUEL ASH AND ADMIXTURE

Academic Session : 2007/2008

I declare that this thesis is classified as: CONFIDENTIAL (Contains confidential information under the Official Secret Act 1972)* RESTRICTED (Contains restricted information as specified by the organization where research was done)* ���� OPEN ACCESS I agree that my thesis to be published as online open access (full text) I acknowledged that Universiti Teknologi Malaysia reserves the right as follows:

1. The thesis is the property of Universiti Teknologi Malaysia. 2. The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose

of research only. 3. The Library has the right to make copies of the thesis for academic exchange.

Certified by :

SIGNATURE

SIGNATURE OF SUPERVISOR

T3009211

(NEW IC NO. /PASSPORT NO.)

Assoc Prof Dr A.Aziz bin Saim

NAME OF SUPERVISOR

Date : 26 APRIL 2008 Date : 26 APRIL 2008

NOTES : * If the thesis is CONFIDENTIAL or RESTRICTED, please attach with the letter from the organization with period and reasons for confidentiality or restriction

“I/We* hereby declare that I/we* have read this project report and in my/our*

opinion this report is sufficient in terms of scope and quality for the

award of Master of Engineering (Civil – Structure)”

Signature : …………………………………………

Name of Supervisor : ...………………………………….........

Date : ...…………………………...……..........

ASSOC PROF DR A.AZIZ SAIM

26 APRIL 2008

THE PROPERTIES AND FLEXURAL BEHAVIOUR OF SELF COMPACTING CONCRETE USING PALM OIL FUEL ASH AND ADMIXTURE

AZHARIE EFFENDDY BIN AZMI

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Civil – Structure)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

APRIL, 2008

ii

I declare that this project report entitled “The Properties and Flexural Behaviour of

Self Compacting Concrete using Palm Oil Fuel Ash and Admixture” is the result of

my own research except as cited in the references. The report has not been accepted

for any degree and is not concurrently submitted in candidature of any other degree.

Signature : ………………………………………………

Name : ...………………………………….................

Date : ...…………………………...……..................

AZHARIE EFFENDDY BIN AZMI

26 APRIL 2008

iii

To my beloved Father & Mother

Azmi bin Hj Zaman & Zinab binti Mohd Tab

To my beloved Wife & Children

Tusiah binti Musa &

Amyra Haziera

Amir Haqimi

iv

ACKNOWLEDGEMENTS

In preparing this project report, I was in contact with many people, researchers, academicians, and practitioners. They have contributed towards my understanding and thoughts. In particular, I wish to express my sincere appreciation to my supervisor, Associate Professor Dr. A.Aziz Saim for his encouragement, guidance, critics, friendship and help during the development of this project report. I am especially grateful for his assistance in providing me with ample reference materials at the early stage of this study. I am also indebted and very thankful to the management of Sika Kimia Sdn Bhd, especially to Mr. Kathiravan Subramaniam, the Technical Manager for Admixtures Department, for his cooperation and assistance in supplying the one of the most important component in this research, the admixture of Sika ViscoCrete-15RM. I would also like to express my gratitude and thanks to my wife, Tusiah Musa, for her constant encouragement and advice. This project would not have been possible without her love and support. Lastly, my sincere appreciation also extends to all my colleagues and others who have provided assistance at various occasions. Their views and tips are useful indeed. Unfortunately, it is not possible to list all of them in this limited space. Thanks to all for helping me either directly or indirectly in the completion of this report project

v

ABSTRACT

This research was implemented to develop and to determine the properties

and flexural behaviour of Self Compacting Concrete (SCC) by using Palm Oil Fuel

Ash (POFA) and admixture (Sika ViscoCrete-15RM). Laboratory test was carried

out to investigate the properties of fresh SCC and the strength development

of hardened SCC. Six composition of design mix were prepared and tested. The

performance of the fresh SCC mixes was determined by testing the filling ability,

passing ability, and resistance to segregation characteristics. The properties of fresh

SCC mixes were examined through slump flow test, slump flow T50 test, L-box test

and sieve stability test. The compressive strength test was carried out at the ages

of 1, 7, 28 and 56 days to examine the strength development of hardened SCC mixes.

Two types of comparable reinforced concrete beams with similar reinforcement and

design strength were cast and tested for flexural behaviour comparison between the

optimum mix of SCC and normal concrete. The results indicate that POFA and

Sika ViscoCrete-15RM are suitable to be used together in producing SCC. The

properties and strength development of the produce SCC fulfilled the requirements to

be classified as SCC. The SCC also shows higher compressive strength as compared

to normal concrete. The flexural strength of the SCC beam indicates a comparable

behaviour to normal concrete beam at lower loads. However, the SCC beam achieves

higher ultimate strength and showed large ductile behaviour compared to normal

concrete beam.

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ABSTRAK

Kajian ini dilaksanakan bagi menghasilkan dan mengenalpasti sifat-sifat serta

kelakuan lenturan bagi konkrit tanpa mampatan (SCC) dengan menggunakan Abu

Pembakaran Kelapa Sawit (POFA) dan bahan tambah (Sika ViscoCrete-15RM).

Sifat-sifat serta perkembangan kekuatan bagi SCC ketika basah dan setelah mengeras

ditentukan melalui ujian makmal. Enam jenis campuran rekabentuk disediakan dan

diuji. Prestasi SCC ketika basah dikenalpasti dengan menguji sifat kebolehannya

mengisi ruang, melepasi halangan dan rintangan terhadap pengasingan. Sifat-sifat

campuran SCC ketika basah diuji melalui ujian serakan, ujian serakan pada T50,

ujian kotak-L dan ujian kestabilan ayakan. Kekuatan mampatan konkrit diuji pada

umur 1, 7, 28 dan 56 hari bagi menentukan perkembangan kekuatan bagi SCC

setelah mengeras. Dua jenis rasuk konkrit bertetulang yang sepadan, terdiri daripada

campuran SCC yang optimum dan konkrit biasa dengan besi tetulang serta

rekabentuk kekuatan mampatan yang sama, dihasilkan dan diuji untuk perbandingan

kelakuan lenturannya. Keputusan kajian menunjukkan penggunaan POFA dan

Sika ViscoCrete-15RM adalah bersesuaian bagi menghasilkan SCC. Sifat-sifat,

perkembangan kekuatan serta kelakuan lenturan bagi SCC yang terhasil memenuhi

keperluan untuk dikelaskan sebagai SCC. SCC yang terhasil juga menunjukkan

kekuatan dan prestasi yang tinggi berbanding dengan konkrit biasa. Kekuatan

lenturan bagi rasuk SCC menunjukkan perbandingan kelakuan yang hampir sama

dengan rasuk konkrit biasa di peringkat awal pembebanan. Walau bagaimanapun,

rasuk SCC telah mencapai kekuatan muktamad yang tinggi dan menunjukkan sifat

keanjalan yang besar berbanding dengan rasuk konkrit biasa.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF ABBREVIATIONS xv

LIST OF SYMBOLS xvi

LIST OF APPENDICES xvii

1 INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 2

1.3 Research Aim and Objectives 3

1.4 Research Scope 3

1.5 Research Significance 4

2 LITERATURE REVIEW 5

2.1 Introduction 5

2.2 Self Compacting Concrete 6

2.3 Cement Replacement Materials 9

2.4 Admixture 12

viii

2.5 Past Researches 14

2.6 Developing SCC Mixes 14

2.6.1 SCC Mixes Examples 15

2.6.2 SCC Production 17

2.6.3 SCC Delivery and Transportation 17

2.6.4 SCC Formwork System 18

2.6.5 SCC Casting 19

2.6.6 SCC Surface Finishing and Curing 19

2.6.7 SCC Cold Joint 19

2.7 Test Methods for SCC 20

2.7.1 Slump Flow Test and T50cm Test 21

2.7.1.1 Introduction 21

2.7.1.2 Assessment of Test 22

2.7.1.3 Interpretation of Result 22

2.7.2 J Ring Test 23

2.7.2.1 Introduction 23

2.7.2.2 Assessment of Test 24

2.7.2.3 Interpretation of Result 24

2.7.3 V-funnel Test and V-funnel Test at T5minutes 25

2.7.3.1 Introduction 25

2.7.3.2 Assessment of Test 26

2.7.3.3 Interpretation of Result 26

2.7.4 L Box Test 27

2.7.4.1 Introduction 27

2.7.4.2 Assessment of Test 28

2.7.4.3 Interpretation of Result 29

2.7.5 U Box Test 29

2.7.5.1 Introduction 29

2.7.5.2 Assessment of Test 30

2.7.5.3 Interpretation of Result 30

2.7.6 Fill Box Test 31

2.7.6.1 Introduction 31

2.7.6.2 Assessment of Test 32

ix

2.7.6.3 Interpretation of Result 32

2.7.7 Sieve Stability Test 32

2.7.7.1 Introduction 32

2.7.7.2 Assessment of Test 33

2.7.7.3 Interpretation of Result 33

2.7.8 Orimet Test 33

2.7.8.1 Introduction 33

2.7.8.2 Assessment of Test 34

2.7.8.3 Interpretation of Result 35

2.8 Properties of Fresh SCC 35

2.9 Properties of Hardened SCC 36

2.10 Advantages and Benefits of SCC 37

3 LABORATORY WORK 39

3.1 Introduction 39

3.2 Experimental Program 40

3.3 Materials Used 40

3.3.1 Cement 41

3.3.2 Sand 41

3.3.3 Coarse Aggregates 42

3.3.4 Water 43

3.3.5 Palm Oil Fuel Ash 43

3.3.6 Sika ViscoCrete-15RM 44

3.4 Specimens Preparation 46

3.4.1 Concrete Mixes 46

3.4.2 Specimens 49

3.4.3 Mixing Process 49

3.4.4 Placing Process 50

3.4.5 Curing Process 51

3.5 Test Instrumentation and Procedures 52

3.5.1 Slump Flow Test and Slump Flow T50 Test 52

3.5.2 Slump Test 54

3.5.3 L Box Test 55

x

3.5.4 Sieve Stability Test 57

3.5.5 Compression Test 59

3.5.6 Flexural Test 60

4 RESULTS AND DISCUSSION 62

4.1 Introduction 62

4.2 The Properties of Fresh SCC 62

4.3 The Strength Development of Hardened SCC 65

4.4 The Flexural Behaviour of SCC Beam 68

5 CONCLUSIONS AND RECOMMENDATIONS 73

5.1 Introduction 73

5.2 Conclusions 73

5.3 Recommendations 75

REFERENCES 76

Appendices A – J 78 - 89

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Percent composition of cement replacement materials

by mass. 10

2.2 Typical physical properties of cement replacement

materials. 11

2.3 Physical properties and chemical analysis of OPC and

POFA. 12

2.4(a) Examples of SCC mix in Japan. 15 2.4(b) Examples of SCC mix in Europe. 16 2.4(c) Examples of SCC mix in USA. 16 2.5 List of test methods for workability properties of

SCC. 20

2.6 Workability properties of SCC and alternative test

methods. 21

2.7 Acceptance criteria for fresh SCC. 35 2.8 Structural properties of SCC. 36 3.1 Details of samples. 47 3.2 Details of samples mix composition. 47 3.3 Percentage of samples mix composition. 48 3.4 Details of beam mix composition. 48 3.5 Description of workability and magnitude of slump. 55 4.1 Slump flow test, slump flow T50 test and slump test

results. 63

xii

4.2 L-box test results. 64 4.3 Sieve stability test results. 65 4.4 Compression test results. 66 4.5 Flexural strength test results. 68 4.6 Moment and shear capacity comparison. 69 5.1 Percentage of optimum SCC mix composition. 74

xiii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Comparison of mix proportioning between normal

concrete and SCC. 7

2.2 Basic principles for the production of SCC. 7 2.3 Equipment for slump flow test and T50cm test. 21 2.4 The J ring used in conjunction with the slump flow. 23 2.5(a) V-funnel test equipment (rectangular section). 25 2.5(b) O-shaped funnel test equipment (circular section). 26 2.6 L-box test equipment. 28 2.7 U box test equipment. 29 2.8 Fill box test equipment. 31 2.9 Orimet test equipment. 34 3.1 Flow chart of the research laboratory work. 39 3.2 Flow chart of the experimental program. 40 3.3 Cement. 41 3.4 Sand. 42 3.5 Coarse aggregates. 42 3.6 Water. 43 3.7 Palm oil fuel ash (POFA). 44 3.8 Sika ViscoCrete-15RM. 46

xiv

3.9 Cubes mould and beams formworks. 49 3.10 Mixing process. 50 3.11 Placing process. 51 3.12 Curing process. 52 3.13 Slump flow test and slump flow T50 test equipment. 53 3.14 Slump Cone (Mould). 54 3.15 L box test equipment. 56 3.16 L box test dimensioning. 56 3.17 Sieve stability test equipment. 58 3.18 Compression test machine. 59 3.19 Flexural test using Magnus frame. 60 3.20 Details of beam and flexural test setup. 61 4.1 Compressive strength development for various mixes. 67 4.2 Load - mid-span deflection curves of test beams. 70 4.3 Moment - mid-span deflection curves of test beams. 71 4.4 Beams after failure. 72

xv

LIST OF ABBREVIATIONS

SCC – Self Compacting Concrete NC Normal Concrete POFA – Palm Oil Fuel Ash OPC – Ordinary Portland Cement w/b – Water-binder pfa – Pulverized Fly Ash ggbs – Ground Granulated Blast-furnace Slag csf – Condensed Silica Fume VMA – Viscosity Modifying Admixture HRWR – High Range Water Reducing QC – Quality Control QA – Quality Assurance SF – Slump Flow HPC – High Performance Concrete

xvi

LIST OF SYMBOLS

E – Modulus of elasticity. fcu – Compressive strength. Ma – The difference between the weights full and empty. Mb – Mass of sample passing sieve. Wp – Pan weight. Ws – Sieve weight. Wr – Residual weight. Pcr – Load at 1st cracking. δcr – Deflection at 1st cracking. Py – Load at 1st yield of steel. δy – Deflection at 1st yield of steel. Pult Ultimate load. δmax Maximum deflection. Mc Calculated moment capacity. vc Calculated shear capacity. Mact Actual moment capacity. vact Actual shear capacity.

xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Details of Test Results for Concrete Mix

Sample S1. 78

B Details of Test Results for Concrete Mix

Sample S2. 79

C Details of Test Results for Concrete Mix

Sample S3. 80

D Details of Test Results for Concrete Mix

Sample S4. 81

E Details of Test Results for Concrete Mix

Sample S5. 82

F Details of Test Results for Concrete Mix

Sample S6. 83

G Details of Flexural Test Results for

Normal Concrete Beam. 84

H Details of Flexural Test Results for

SCC Beam. 85

I Detail Calculation of Moment and Shear

Capacity for Normal Concrete Beam. 86

J Detail Calculation of Moment and Shear

Capacity for SCC Beam. 88

1

CHAPTER 1

INTRODUCTION

1.1 Background

Concrete is the most widely consumed material in the world, after water.

Nowadays, most of the construction for buildings and infrastructures in Malaysia are

using concrete as construction material. Concrete is the only major building material

that can be delivered to the job site in a plastic state. This unique quality makes

concrete desirable as a building material because it can be molded to virtually any

form or shape and can be used to construct a wide variety of structures.

Self Compacting Concrete (SCC), a recent innovation in concrete technology,

has numerous advantages over normal concrete. Self-compacting concrete, as the

name indicates, is a type of concrete that does not require external or internal

compaction, because it becomes leveled and compacted under its self-weight. SCC

can spread and fill every corner of the formwork, purely by means of its self-weight,

thus eliminating the need of vibration or any type of compacting effort.

SCC has been in the market place for some time. This type of high-

performance concrete has been in use only since the late 1980s. Professor Hajime

Okamura (University of Tokyo, now Kochi Institute of Technology) advocated the

use of SCC in 1986 for the first time in the world and has been spread to all over the

world as the original of Japan. The first prototype was developed in 1988 as a

response to the growing problems associated with concrete durability and the high

demand for skilled workers.

2

Since the development of the prototype of SCC in 1988, the use of SCC in

actual structures all over the world has gradually increased. The main reasons for the

employment of SCC are to shorten construction period, to assure compaction in the

structure and to eliminate noise due to vibration. That means the current condition of

SCC is a “special concrete” rather than normal concrete.

By employing SCC, the cost of vibrating compaction can be saved and the

compaction of the concrete in the structure can be assured. SCC can greatly improve

construction systems which previously based on conventional concrete where

vibrating compaction is required. A new construction system, including formwork,

reinforcement, support and structural design also can be developed to suite the

advancement in this type of concrete.

Modern application of SCC is focused on high performance which better and

more reliable quality, dense and uniform surface texture, improved durability, high

strength and faster construction. The application of SCC in Malaysian construction

sector is still new and limited in precast concrete industry and geotechnical works.

Therefore, a lot of further research on this type of concrete technology needs to be

carried out to enhance our nation capability and quality in constructing building and

other infrastructures.

1.2 Problem Statement

The increasing demand for high performance concrete which use new

technique and new material have encouraged this research to be conducted. The

usage of POFA in this aspect of research is still new. The research implementation is

to study and determine the compatibility of Palm Oil Fuel Ash (POFA) as cement

replacement material and Sika ViscoCrete-15RM as an admixture to produce SCC.

Hopefully this research can contribute to the other findings in developing SCC and

can be applied in our local construction industry.

3

1.3 Research Aim and Objectives

The aim of this research is to produce a suitable concrete compound which

can be categorized as SCC that using POFA as cement replacement material together

with Sika ViscoCrete-15RM as admixture. The compatibility of both material bind

together also will be observed.

The objectives of this research being conduct are:

(i) To develop and produce SCC using Palm Oil Fuel Ash and

Sika ViscoCrete-15RM.

(ii) To investigate the properties and strength development of SCC.

(iii) To compare the flexural behavior of reinforced concrete beam of SCC

and normal concrete.

1.4 Research Scope

In executing the research, the scope boundary needs to be defined and a few

limitation factors to be drawn to avoid a very wide scope of research and unfocussed

study. The scope and limitation factors for this research are:

(i) The mixtures of SCC are only using POFA as cement replacement

material and Sika ViscoCrete-15RM as admixture.

(ii) The developments for the proposed SCC mix are only using Ordinary

Portland Cement (OPC).

(iii) The water- binder ratio (w/b) for all the mixes is fixed to 0.36.

(iv) The comparison in flexural behaviour aspect only involves the most

optimum design mix of SCC to be compared with normal concrete.

4

1.5 Research Significance

The advantages of SCC are already recognized by the concrete industry.

Design and construction specifications are urgently needed to give the designers

another option in meeting the demands of today and tomorrow for high performance

concrete in the construction.

From the research, clearer picture and differences between SCC and normal

concrete can be observed and understood. There will be high payoff in not requiring

vibration to achieve compaction and the low noise level to meet stringent

environmental requirements in urban and suburban construction. Less labour and

speedier construction will result in substantial cost savings, less traffic disruption and

risk reduction.

The use of POFA as cement replacement material in SCC will fully utilize

this natural resources instead of becoming an industrial waste material only. The

replacement can reduce the cost of concrete since the increasing in cement price and

at the same time to reduce the huge amount of palm oil industry waste material that

being produced.

SCC using POFA has good potential for greater acceptance and wider

applications in civil infrastructure works in Malaysia and other part of the world.

Hopefully, this research can guide the civil engineering community and the concrete

industry to take advantage of a new breed of SCC.

5

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

Self compacting concrete (SCC), also been described and known as concrete

without vibration, self consolidating concrete, self placing concrete and self leveling

concrete, is a highly flowable, non-segregating concrete that can spread into place,

fill the formwork and encapsulate the reinforcement without any mechanical

compaction. As a high-performance concrete, SCC delivers these attractive benefits

while maintaining all of concrete's customary mechanical properties and durability

characteristics.

SCC has been described as "the most revolutionary development in concrete

construction for several decades" [1]. Originally developed to offset a growing

shortage of skilled labour, it has proved beneficial economically because of a number

of factors, including:

(i) Faster construction.

(ii) Reduction in site manpower.

(iii) Better surface finishes.

(iv) Easier placing.

(v) Improved durability.

(vi) Greater freedom in design.

(vii) Thinner concrete sections.

(viii) Reduced noise levels, absence of vibration.

(ix) Safer working environment.

6

SCC's unique properties give it significant economic, constructability,

aesthetic and engineering advantages. SCC is an increasingly attractive choice for

optimizing site manpower through reduction of labor and possibly skill level,

lowering noise levels, and allowing for a safer working environment. SCC allows

easier pumping even from bottom up, flows into complex shapes, transitions through

inaccessible spots, and minimizes voids around embedded items to produce a high

degree of homogeneity and uniformity. That's why SCC allows for denser

reinforcement, optimized concrete sections and shapes, and greater freedom of

design while producing superior surface finishes and textures.

2.2 Self Compacting Concrete

Self Compacting Concrete (SCC) was first developed in Japan since the late

1980s in order to reach durable concrete structures. Since then, several investigations

have been carried out to achieve a rational mix design for a standard concrete, which

is comparable to normal concrete. SCC is defined so that no additional inner or outer

vibration is necessary for the compaction. SCC is compacting itself alone due to its

self-weight and is deaerated almost completely while flowing in the formwork. In

structural members with high percentage of reinforcement it fills also completely all

voids and gaps. SCC flows like “honey” and has nearly a horizontal concrete level

after placing.

With regard to its composition, SCC of the same components as

conventionally vibrated normal concrete which are cement, aggregates, water,

additives and admixtures. However, the high amount of superplasticizer for reduction

of the liquid limit and for better workability, the high powder content as “lubricant”

for the coarse aggregates, as well as the use of viscosity-agents to increase the

viscosity of the concrete have to be taken into account. Figure 2.1 shows the

comparison of mix proportioning between normal concrete and SCC [2].

7

Figure 2.1 : Comparison of mix proportioning between normal concrete and SCC.[2]

In principle, the properties of the fresh and hardened SCC, which depend on

the mix design, should not be different from normal concrete. One exception is only

the consistency. Figure 2.2 shows the basic principles for the production of SCC [3].

Figure 2.2 : Basic principles for the production of SCC.[3]

(Admixture)

8

SCC looks very different from conventional concrete while mixing. Concrete

producers must “retrain their eyes” for this very fluid mixture as it turns corners and

fills forms. Traditionally, concrete with the fluidity of SCC has had a very high

water-to-cement ratio, which would lower compressive strengths and compromise

durability. Properly designed SCC can save time and labour without sacrificing

performance. SCC mixes must meet three key properties as follows:

(i) Filling ability – the ability of the concrete to flow freely under its

own weight, both horizontally and vertically upwards if necessary,

and to completely fill formwork of any dimension and shape without

leaving voids.

(ii) Passing ability – the ability of concrete to flow freely in and around

dense reinforcement without blocking.

(iii) Resistance to segregation – during placement and while flowing, the

concrete should retain its homogeneity. There should be no separation

of aggregate from paste or water from solids, and no tendency for

coarse aggregate to sink downwards through the fresh concrete mass

under gravity.[4]

As an engineered concrete, SCC offers characteristics that engineer’s value.

Improved constructability to produce homogeneous and uniform concrete allows for

higher reliability in design assumptions. Engineering properties and their inter-

relationships remain unchanged from those of conventional concrete and any

differences are adequately addressed by conservatism in the design codes. The

principles of concrete durability with respect to reduced permeability, resistance to

freezing and thawing and sulfate attack, alkali-aggregate reactions, thermal stresses

and corrosion protection of reinforcement also apply similarly to SCC. SCC's

superior rheology allows for the design and construction of complex shapes with

congested reinforcement, and its non-segregating qualities are important for deep-

section or long-span applications. The fluidity of SCC can be engineered in terms of

its viscosity, both the rate and degree of flow, to allow for a wider variety of

placement and construction means and methods.

9

2.3 Cement Replacement Materials

Cement replacement materials are special types of naturally occurring

materials or industrial waste products that can be used in concrete mixes to partially

replace some of the Portland cement. Cement replacement materials are frequently

called fine minerals or pozzolans. Surprisingly, concrete with cement replacement

materials can actually be stronger and more durable than concrete with ordinary

Portland cement (OPC).

The three most-commonly used cement replacement materials are the

pulverized fly ash (pfa), ground granulated blast-furnace slag (ggbs) and condensed

silica fume (csf).

Fly ash is a fine, glass-like powder recovered from gases created by coal-fired

electric power generation. Power plants produce a huge amount of fly ash annually,

which is usually dumped in landfills. Fly ash is an inexpensive replacement for

Portland cement used in concrete, while it actually improves strength, segregation,

and ease of pumping of the concrete. Fly ash is also used as an ingredient in brick,

block, paving, and structural fills.

Fly ash concrete was found that it allowed for less total cement. Consisting

mostly of silica, alumina and iron [5] as shown in Table 2.1, fly ash is a pozzolan, a

substance containing aluminous and silicious material that forms cement in the

presence of water. When mixed with lime and water it forms a compound similar to

Portland cement. The spherical shape of the particles reduces internal friction thereby

increasing the concrete's fluidity, permitting longer pumping distances. Improved

workability means less water is needed, resulting in less segregation of the mixture.

Although fly ash cement itself is less dense than Portland cement, the produced

concrete is denser and results in a smoother surface with sharper detail.

10

Table 2.1 : Percent composition of cement replacement materials by mass.[5]

Ground granulated blast-furnace slag (ggbs) is the granular material formed

when molten iron blast furnace slag is quenched. It is a granular product with very

limited crystal formation is highly cementitious in nature and, when ground to

cement fineness, hydrates like Portland cement. Blast furnace slag cement is made by

intergrinding the granulated slag with Portland cement clinker (blended cement).

Condensed Silica Fume (csf) also known as microsilica, is a byproduct of the

reduction of high-purity quartz with coal in electric furnaces in the production of

silicon and ferrosilicon alloys. Silica fume is also collected as a byproduct in the

production of other silicon alloys such as ferrochromium, ferromanganese,

ferromagnesium, and calcium silicon.

Silica fume consists of very fine vitreous particles approximately 100 times

smaller than those of ordinary cement particles, and with a surface area of

20,000m2/kg [5] as shown in Table 2.2. Because of its extreme fineness and high

silica content, csf is a highly effective pozzolanic material. It has been found that csf:

improves compressive strength, bond strength, and abrasion resistance; reduces

permeability; and therefore helps in protecting reinforcing steel from corrosion.