MECHANICAL PROPERTIES OF CONCRETE CONTAINING 15% AND 20% OF

TEXTILE WASTEWATER.

MUHAMAD AIZAT BIN LENGAH

A thesis submitted in partial fulfillment of the

requirement for the award of the degree of

Bachelor of Civil Engineering

Faculty of Civil Engineering and Earth Resources

University Malaysia Pahang

DECEMBER 2010

ABSTRACT

Textile industry is one of the most important and rapidly developing industrial

sectors in Malaysia. It has a high effect in terms of its environmental impact in

producing highly polluted discharge water in large amounts. Textile mills in Malaysia

are required to control their discharge and therefore have started installing treatment

plants in the name of environmental protection. Besides that, concrete are the most

widely used man-made construction material and playing important part in all building.

It can be defined as a composite material composed of a coarse granular material

embedded in a hard matrix of material (cement or binder) that fills the space between

the particles and bond together. Many researchers have been done to produce concrete

which is economic as possible. The environmental regulation have initiated in

increasing interest in using wastewater as a construction materials partially replacing

the tap water in concrete structures. In this study, the idea is replacing tap water with

textile wastewater (WWC) as concrete material. The objective of this study concentrates

on mechanical properties that are compressive and flexural strength of concrete with

WWC. There are two different percentages of WWC which is 15% and 20% were used

to replaced the tap water and were tested at 7 and 28 days. The strength of normal

concrete as a control mix has been compared with the concrete with WWC. The result

revealed that the normal concrete presented the highest compressive and flexural

strength and the followed by concrete with 15% and 20% WWC but have the potential

to increase from 15% to 20% WWC. As a conclusion, WWC will increases the

compressive and flexural strength of concrete but still need suitable percentage to be

targeted for concrete used in construction.

v

ABSTRAK

Industri tekstil merupakan salah satu sektor industri yang paling penting dan

berkembang pesat di Malaysia. Ia mempunyai pengaruh yang cukup besar dari segi

kesan persekitaran dalam menghasilkan keluaran air tercemar dalam jumlah yang sangat

besar. Kilang tekstil di Malaysia hendaklah mengawal pengeluaran mereka. Justeru itu

mula memasang loji rawatan untuk perlindungan alam sekitar. Selain itu, konkrit adalah

buatan manusia yang paling banyak digunakan sebagai bahan bangunan dan memainkan

bahagian penting dalam pembangunan. Hal ini dapat ditakrifkan sebagai bahan

komposit terdiri dari bahan granular kasar dan keras yang tertanam dalam matriks bahan

(simen atau pengikat) yang mengisi ruang antara zarah dan mengikat bersama-sama.

Banyak penyelidikan telah dilakukan untuk menghasilkan konkrit yang sangat ekonomi.

Keadaan persekitaran telah memulakan dalam meningkatkan minat dalam

menggunakan air sisa sebagai bahan pembinaan seterusnya mengantikan air paip

didalam struktur konkrit. Dalam kajian ini, idea adalah menggantikan air paip dengan

air sisa tekstil (WWC) sebagai bahan konkrit. Tujuan kajian ini tertumpu kepada sifat

mekanik iaitu kekuatan mampatan dan lenturan konkrit yang mengandungi WWC.

Terdapat dua peratusan WWC yang berbeza iaitu 15% dan 20% digunakan untuk

menggantikan air paip dan diuji pada 7 dan 28 hari umur konkrit. Kekuatan konkrit

biasa dijadikan sebagai bancuhan kawalan untuk dibandingkan dengan kekuatan konkrit

dengan WWC. Keputusan kajian menunjukkan bahawa konkrit biasa menghasilkan

kekuatan mampatan yang tertinggi dan diikuti dengan konkrit dengan 15% dan 20%

WWC namun mempunyai potensi meningkat dari 15% kepada 20% WWC. Sebagai

kesimpulan, WWC akan meningkatkan kekuatan mampatan dan lenturan konkrit tetapi

masih memerlukan peratusan yang sesuai untuk digunakan dalam pembinaan konkrit.

vi

TABLE OF CONTENT

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF ABBREVITIONS xiv

LIST OF APPENDIX xv

1 INTRODUCTION 1

1.1 Background of Study 1

1.2 Problem Statement 3

1.3 Objectives of Study 4

1.4 Scopes of Study 4

1.5 Significant of Study 5

2 LITERATURE REVIEW 6

2.1 Introduction 6

vii

2.2 Concrete 6

2.2.1 Properties of Concrete 7

2.2.1.1 Workability 7

2.2.1.2 Strength 8

2.2.1.3 Curing 9

2.3 Concrete Mixture 10

2.3.1 Cement 11

2.3.2 Aggregates 11

2.3.3 Water 12

2.4 Textile Wastewater 12

2.4.1 Definition of Textile Wastewater 12

2.4.2 Characteristic of Wastewater 13

2.4.2.1 Physical 13

2.4.2.2 Chemical 15

2.4.2.3 Biological 17

2.5 Water Quality Parameter 18

2.5.1 Biochemical Oxigen Demand (BOD) 18

2.5.2 Chemical Oxygen Demand (COD) 19

2.5.3 Total Suspended Solids 19

2.5.4 pH Value 19

2.5.5 Chloride 19

2.5.6 Sulphates 20

2.6 Workability 20

2.6.1 Slump Test 20

3 RESEARCH METHODOLOGY 22

3.1 Introduction 22

3.2 Research Characteristic 25

3.3 Laboratory work Methodology 25

3.4 Material selection and preparation 28

3.4.1 Cement (Ordinary Portland cement) 28

viii

3.4.2 Aggregate 29

3.4.2.1 Coarse Aggregate 29

3.4.2.2 Fine Aggregate 29

3.4.3 Tap Water and Wastewater 29

3.4.3.1 Tap Water 29

3.4.3.2 Industrial Wastewater 29

3.4.3.3 Biochemical Oxygen Demand 30

3.4.3.4 Chemical Oxygen Demand 31

3.4.3.5 pH value 32

3.4.3.6 Chloride 33

3.4.3.7 Sulphates 33

3.5 Concrete Mix Design 34

3.6 Preparation of Specimen 35

3.6.1 Cube Specimen 35

3.6.1.1 Moulds for Specimen 35

3.6.1.2 Proportion of Cubes 35

3.6.1.3 Preparation of Cubes 36

3.6.1.4 Mixing Procedures for Cubes 36

3.6.2 Beam Specimen 37

3.6.2.1 Mould for Specimen 37

3.6.2.2 Proportion of Beams 37

3.6.2.3 Preparation of Beams 37

3.6.2.4 Mixing Procedures for Beams 38

3.7 Curing 39

3.8 Laboratory Testing 40

3.8.1 Workability Test 40

3.8.1.1 Slump Test 40

3.8.2 Destructive Test 41

3.8.2.1 Compressive Strength Test 41

3.8.2.2 Calculation of Compressive Strength

Test 42

ix

3.8.2.3 Flexural Strength Test 43

3.8.2.4 Calculation of Flexural Strength

Test 45

4 RESULT AND DISCUSSION 47

4.1 Introduction 47

4.2 Textile Wastewater Quality Test 47

4.2.1 Biochemical Oxygen Demand (BOD) 48

4.2.2 Chemical Oxygen Demand (COD) 50

4.2.3 pH Value 51

4.2.4 Chloride 52

4.2.5 Sulphate 53

4.3 Concrete Testing 54

4.3.1 Workability Test 54

4.3.1.1 Slump Test 54

4.3.2 Compressive Strength Test 56

4.3.3 Flexural Strength Test 58

4.3.4 Comparison between Compressive Strength

with Flexural Strength 61

5 CONCLUSIONS AND RECOMMENDATIONS 65

5.1 Introduction 65

5.2 Conclusion 65

5.2.1 Textile Wastewater Parameter 65

5.2.2 Compressive Strength 66

5.2.3 Flexural Strength 67

5.3 Recommendations 67

REFERENCES 68

APPENDIX 71

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LIST OF TABLES

TABLE NO TITLE PAGE

2.1 Composite Textile Industry Wastewater Characteristics 15

2.2 Description of Workability and Magnitude of Slump 21

3.1 Major Constituents of Typical Domestic Wastewater 30

3.2 Describe of Command for Figure 3.16 44

4.1 Parameter Limit of the Effluent of Standard A and

Standard B 48

4.2 Compressive Strength Result 56

4.3 Flexural Strength Result. 59

4.4 Comparison between Compressive Strength with

Flexural Strength. 62

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LIST OF FIGURES

FIGURES NO TITLE PAGE

2.1 Type of Slump 21

3.1 Flowchart of Research 24

3.2 Flowchart of Laboratory Work 27

3.3 Ordinary Portland Cement 28

3.4 Sieve Analysis Apparatus 29

3.5 BOD Testing 31

3.6 COD Testing 32

3.7 pH Measurement using pH Meter. 32

3.8 Chlorine Testing 33

3.9 Sulfate Testing 34

3.10 Mould for cubes specimens 35

3.11 Mould for rectangular beam. 37

3.12 Covering the specimen with sack 39

3.13 Curing process 40

3.14 Slump test apparatus 41

3.15 Compression Testing Machine 42

3.16 Diagrammatic View of a Flexural Test by Center-Point

Loading Method. 44

3.17 Flexural Test of Concrete by Center-Point Loading Method 45

4.1 Analysis of BOD5 for Textile Wastewater 49

4.2 Analysis COD Value for Textile Wastewater 50

xii

4.3 Analysis of pH Value for Textile Wastewater 52

4.4 Analysis of Chloride Value for Textile Wastewater 52

4.5 Analysis of Sulfate Data for Textile Wastewater 53

4.6 Slump Test Result 55

4.7 Shear Slump 56

4.8 Compressive Strength with Different Type of Concrete 57

4.9 Satisfactory Failure for cube 57

4.10 Flexural Strength with Different Type of Concrete 59

4.11 Satisfactory Failure for beam 61

4.12 Comparisons Compressive Strength with Flexural Strength 64

xiii

LIST OF ABBREVIATIONS

ASTM - American Standard of Testing and Materials

APHA - American Public Health Association

BOD - Biochemical Oxygen Demand

BS - British Standard

CMD - Concrete Mix Design

COD - Chemical Oxygen Demand

C25 - Concrete Grade 25

C30 - Concrete Grade 30

OPC - Ordinary Portland cement

DOE - Department of Environment

MOR - Modulus of Rupture

Mpa - Mega Pascal

N/mm2 - Newton per Millimeter square

Psi - Pound per Square Inch.

MS - Malaysia Standard

TSS - Total Suspended Solids

UMP - Universiti Malaysia Pahang

W/C - Water Cement Ratio

WWC - Wastewater Concrete

WWC15 - Wastewater Concrete at 15%

WWC20 - Wastewater Concrete at 20%

xiv

LIST OF APPENDICES

APPENDIX NO. TITLE PAGE

A Concrete Mix Design 71

B Quantity of material in concrete at each percentages of waste water. 73

C Water Quality Result. 74

D Compressive Strength Test Result. 76

E Flexural Strength Test Result 78

F Parameter Limits of Effluents of Standard A and B. 80

G Composite Textile industry wastewater characteristic. 80

xv

CHAPTER 1

INTRODUCTION

1.1 Background of Study

The availability of water supply adequate in terms of both quality and quantity is

essential to human existence. Early people recognized the importance of water from a

quantity viewpoint. Civilization developed around water bodies that could support

agriculture and transportation as well as provide drinking water. Recognition of the

importance of water quality developed more slowly. Early humans could judge water

quality only through the physical senses of sight, taste, and smell (Florio, 2003).

Generally, the most widely used construction material is concrete, commonly

made by mixing Portland cement with sand, crushed rock, and water. Today, the rate at

which concrete is used is much higher than 40 years ago. Concrete are the most widely

used man-made construction material and playing part in all building structures.

Concrete can be defined as a mixture of cement, water, aggregate (fine and coarse), and

admixture. Too many researchers have been done to produce concrete which is

economic as possible (Gambhir, 2004).

The strength, durability, and other characteristic of concrete depend upon the

properties of its ingredients, the proportions of mix, the method of transporting, placing,

compacting, and curing. Concrete grade is defined as that number, which indicates the

characteristic compressive strength of concrete in N/mm2, determined by cube tests

made at 28 days. Thus, a grade 30 concrete has a characteristic strength of 30 N/mm2.

According to BS-5337, 93 the grade 25(C25) is the lowest grade that may be used as

reinforced concrete, but in practice, a C30 mix invariably necessary because of

durability considerations and almost all concrete production that using the grade 30

concrete (Gambhir, 2004).

Normally, the composition in concrete consists of cement, water, and aggregate

are 7-15%, 14-21%, and 60-80% respectively. The water/cement ratio (w/c) of the

mixture has the most control over the final properties of the concrete. The water/cement

ratio is the relative weight of the water to the cement in the mixture. The water/cement

ratio can control over two opposing, yet desirable properties which are strength and

workability (Neville, 2005).

In general the waste water contains dissolved solids which include sulfates and

hydroxides from cement, chlorides from the use of calcium chloride as an admixture, oil

and grease from the equipment, and small quantities of other chemicals associated with

hydration of Portland cement and derivatives from chemical admixtures (Sivakumar,

2008).

The composition of wastewater varies widely such as pathogens, bacteria,

organic and inorganic materials, microorganism, gases, emulsion and toxins. The

quality of wastewater can be determined by using the wastewater quality indicator such

as the Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD)

to obtain the relative oxygen-depletion effect of a waste contaminant. Both have been

widely adopted as a measure of pollution effect. The BOD test measures the oxygen

demand of biodegradable pollutants whereas the COD test measures the oxygen

demand of biogradable pollutants plus the oxygen demand of non-biodegradable

2

oxidizable pollutant. The suitable wastewater which is fulfill the requirement needed

can replace the potable water function as the concrete mixing water. In this situation the

clean water source can be reserved for the other important usage (Hassan, 2005).

1.2 Problem Statement

Water scarcity and water pollution are some of the crucial issues in the world.

One of the ways to reduce the impact of water scarcity and pollution is to expand water

and wastewater reuse. It is a common practice to discharge untreated sewage directly

into bodies of water or put onto agricultural land, causing significant health and

economic risks. Nowadays, batik industries will be grown following the market request.

Because of that, the waste water from that batik industry will increase then can give a

bad effect to environment impact such as water pollution. As an alternative to solve this

problem sewage water (water waste textiles) is use as water replacement in concrete and

behavior of concrete will be investigated

Therefore, Malaysia as a developing country should be aware about this issue

from now on and start to consider the alternative of wastewater reuse to avoid any

possible effect to human health and the environment in the future besides to preserve

the clean water supply. So industries should be encouraged to invest in better water

efficiency, more recycling and management for clean water conservation. Industrial

water reuse has the following specific benefits, in addition to reduction in water

consumption and pollution load to the environment (Florio, 2003). The reasons for

establishing a waste water reuse program is to identify new water sources for increasing

water demand and economical ways to meet increasingly more stringent discharge

standards. Textile wastewater includes a large variety of dyes and chemicals additions

that make the environmental challenge for textile industry not only as liquid waste but

also in its chemical composition

3

Major pollutants in textile wastewaters are high suspended solids, chemical

oxygen demand, heat, colour, acidity, and other soluble substances (Dae-Hee et al.,

1999). The removal of colour from textile industry and dyestuff manufacturing industry

wastewaters represents a major environmental concern. In addition, only 47% of 87 of

dyestuff are biodegradable. It has been documented that residual colour is usually due to

insoluble dyes which have low biodegradability as reactive blue 21, direct blue 80 and

vat violet with COD/BOD ratio of 59.0, 17.7, and 10.8, respectively (Hassan, 2005).

Nowadays, the clean water supplies are still available, however in the future the

scarcity of the clean water supplies will become the world’s crisis if the possible

alternatives are not taken into consideration. This is the main reason why the potential

of textile wastewater reuse should be explored and be applied wisely in every aspect

that possible.

1.3 The Objective of Study

The study is carried out to achieve the following objectives:

I. To determine the quality of wastewater sample.

II. To determine the value of compressive strength and flexural strength of concrete

with different percentage of waste water replacement.

III. To investigate the effect of waste water to the strength and durability of

concrete.

1.4 The Scope of Study

The concrete samples which will be mixed with the domestic wastewater (textile

waste) will be prepared at the Concrete Laboratory. The test to the concrete samples

4

will also be carried out at the laboratory to determine the quality of the concrete with

the domestic wastewater as the concrete mixing water. Before that, the wastewater

samples will be tested to determine the composition and the quality whether they are

fulfill the requirement of concrete mixing water or not.

The concrete samples of grades C30 with partially water replacement the textile

of waste water will be prepared. The percentage of textile waste water 0%,15% and

20%. The sizes of specimen are 150mm × 150mm × 150mm cube for compressive

strength test and 100mm × 100mm × 500mm prism for flexural strength test. The

testing will be carried out at the age of 7 and 28 day for all batches. The scope is related

to the material and equipments that involved in this study and fulfill the requirement

according to standard BS 1881: Part 116:1983: Concrete Compression Test and ASTM

C 78 - 08: Concrete Flexural Test and BS 3148:1980: Water for making concrete

(including notes on the suitability of the water).

1.5 Significant of Study

Although the industrial batik in this country is grown following the market

required but textile wastewater reuse is not be used for to commercial. The application

in construction area especially in Malaysia is still cannot be determined. Therefore, by

conducting this study the potential of the wastewater reuse can be further investigated

and contribute to expand the application of the wastewater reuse. Besides, the study can

help to promote the new alternatives to use the wastewater in the industrial sector thus;

will probably lead to water pollution diminution. Therefore wastewater reuse has a big

potential to bring about environmental, economic and financial benefits. Finally, the

data obtained during the research can be applied or used as a reference in future

research to improve the outcome obtained.

5

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

This chapter will discuss more about the textile wastewater, the textile

wastewater reuse, the strength and weakness of concrete and also the concrete mixing

water requirements.

2.2 Concrete

Concrete is the most widely used man-made construction material in the world,

and is second only to water as the most utilized substance on the planet. It is obtained

by mixing cementitious materials, water and aggregates (and sometimes admixtures) in

required proportions. The mixture when placed in forms and allowed to cure hardens

into rock-like mass known as concrete (Gambhir, 2004).

The hardening is caused by chemical reaction between water and cement and it

continues for a long time, and consequently the concrete grows stronger with age. The

hardened concrete may also be considered as an artificial stone in which the voids of

larger particles (coarse aggregate) are filled by the smaller particles (fine aggregate) and

the voids of fine aggregate s are filled with cement. In a concrete mix the cementitious

material and water form a paste called cement-water paste which in addition to filling

the voids of fine aggregate, coats the surface of fine and coarse aggregates and bind

them together as it cures, thereby cementing the particles of the aggregates together in a

compact mass (Gambhir, 2004).

The major factors responsible for wide usage of cement-concrete are

mouldability, early hardening, and high early compressive strength, development of

desired properties with admixture to be used in adverse situations, pumpability and

durability. These are simple reasons for its extensive use in the construction within a

wide range by using appropriate ingredients and by special mechanical, physical and

chemical processing techniques.

2.2.1 Properties of Concrete

During hydration and hardening, concrete needs to develop certain physical and

chemical properties. Among other qualities, mechanical strength, low moisture

permeability, and chemical and volumetric stability are necessary.

2.2.1.1 Workability

Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold

properly with the desired work (vibration) and without reducing the concrete's quality.

Workability depends on water content, aggregate (shape and size distribution),

cementations content and age (level of hydration), and can be modified by adding

chemical admixtures. Raising the water content or adding chemical admixtures will

increase concrete workability. Excessive water will lead to increased bleeding (surface

7

water) and/or segregation of aggregates (when the cement and aggregates start to

separate), with the resulting concrete having reduced quality. The use of an aggregate

with an undesirable gradation can result in a very harsh mix design with a very low

slump, which cannot be readily made more workable by addition of reasonable amounts

of water.

Workability can be measured by the slump test, a simplistic measure of the

plasticity of a fresh batch of concrete following the ASTM C 143 or EN 12350-2 test

standards. Slump is normally measured by filling an "Abrams cone" with a sample from

a fresh batch of concrete. The cone is placed with the wide end down onto a level, non-

absorptive surface. It is then filled in three layers of equal volume, with each layer

being tamped with a steel rod in order to consolidate the layer. When the cone is

carefully lifted off, the enclosed material will slump a certain amount due to gravity. A

relatively dry sample will slump very little, having a slump value of one or two inches

(25 or 50 mm). A relatively wet concrete sample may slump as much as six or seven

inches (150 to 175 mm).

2.2.1.2 Strength

Concrete has relatively high compressive strength, but significantly lower tensile

strength. It is fair to assume that a concrete sample’s tensile strength is about 15%- 20%

of its compressive strength. As a result, without compensating, concrete would almost

always fail from tensile stresses even when loaded in compression. The practical

implication of this is that concrete elements subjected to tensile stresses must be

reinforced with materials that are strong in tension (Neville, 2005).

The ultimate strength of concrete is influenced by the water-cement ratio (w/c)

the design constituents, and the mixing, placement and curing methods employed. All

things being equal, concrete with a lower water-cement (cementations) ratio makes a

stronger concrete than that with a higher ratio. The total quantity of cementations

materials can affect strength, water demand, shrinkage, abrasion resistance and density.

8

All concrete will crack independent of whether or not it has sufficient compressive

strength (Neville, 2005).

In fact, high Portland cement content mixtures actually crack earlier due to

increased hydration rate. As concrete transforms from its plastic state, hydrating to a

solid, the material undergoes shrinkage. Plastic shrinkage cracks can occur soon after

placement; but if the evaporation rate is high, they often can actually occur during

finishing operations for example in hot weather or a breezy day. In very high strength

concrete mixtures greater than 10,000 psi, the crushing strength of the aggregate can be

a limiting factor to the ultimate compressive strength. In lean concretes with a high

water-cement ratio the crushing strength of the aggregates is not so significant.

Experimentation with various mix designs begins by specifying desired

workability as defined by a given slump, durability requirements taking into

consideration the weather exposure conditions (freeze-thaw) to which the concrete will

be exposed in service, and finally the required 28 day compressive strength, as

determined by properly molded standard-cured cylinder samples. The characteristics of

the cementations content, coarse and fine aggregates, and chemical admixtures

determine the water demand of the mix in order to achieve the desired workability. The

28 day compressive strength is obtained by determination of the correct amount of

cementations (and often chemical admixtures) to achieve the target water-cementations

ratio. Compressive strength is widely used for specification requirement and quality

control of concrete (Neville, 2005).

2.2.1.3 Curing

As the cement requires time to fully hydrate before it acquires strength and

hardness, concrete must be cured once it has been placed and achieved initial setting.

Curing is the process of keeping concrete under a specific environmental condition until

9

hydration is relatively complete. Good curing is typically considered to provide a moist

environment and control temperature.

A moist environment promotes hydration, since increased hydration lowers

permeability and increases strength resulting in a higher quality material. Allowing the

concrete surface to dry out excessively can result in tensile stresses, which the still-

hydrating interior cannot withstand, causing the concrete to crack. Also, the amount of

heat generated by the exothermic chemical process of hydration can be problematic for

very large placements. Allowing the concrete to freeze in cold climates before the

curing is complete will interrupt the hydration process, reducing the concrete strength

and leading to scaling and other damage or failure.

The effects of curing are primarily a function of geometry (the relation between

exposed surface area and volume), the permeability of the concrete, curing time, and

curing history. Improper curing can lead to several serviceability problems including

cracking, increased scaling, and reduced abrasion resistance. (Pierce, 2000).

2.3 Concrete Mixture

Thorough mixing is essential for the production of uniform, high quality

concrete. Therefore, equipment and methods should be capable of effectively mixing

concrete materials containing the largest specified aggregate to produce uniform

mixtures of the lowest slump practical for the work (Gambhir, 2004).

10

2.3.1 Cement

Portland cement is the most common type of cement in general usage. It is a

basic ingredient of concrete, mortar and plaster. English engineer Joseph Aspin patented

Portland cement in 1824; it was named because of its similarity in color to Portland

limestone, quarried from the English Isle of Portland and used extensively in London

architecture. It consists of a mixture of oxides of calcium, silicon and aluminums.

Portland cement and similar materials are made by heating limestone (a source of

calcium) with clay, and grinding this product (called clinker) with a source of sulfate

(most commonly gypsum). When mixed with water, the resulting powder will become a

hydrated solid over time (Blackledge, 1999).

High temperature applications, such as masonry ovens and the like, generally

require the use of refractory cement; concretes based on Portland cement can be

damaged or destroyed by elevated temperatures, but refractory concretes are better able

to withstand such conditions (Blackledge, 1999).

2.3.2 Aggregates

The water and cement paste hardens and develops strength over time. Both fine

and coarse aggregates are used to make up the bulk of a concrete mixture. Sand, natural

gravel and crushed stone are mainly used for this purpose. However, it is increasingly

common for recycled aggregates (from construction, demolition and excavation waste)

to be used as partial replacements of natural aggregates, while a number of

manufactured aggregates, including air-cooled blast furnace slag and bottom ash are

also permitted. Decorative stones such as quartzite, small river stones or crushed glass

are sometimes added to the surface of concrete for a decorative "exposed aggregate"

finish, popular among landscape designers (Gambhir, 2004).

11

2.3.3 Water

Potable water can be used for manufacturing concrete. The water/cement ratio is

the key factor that determines the strength of concrete. A lower w/c ratio will yield a

concrete which is stronger and more durable, while a higher w/c ratio yields a concrete

with a larger slump, so it may be placed more easily. Cement paste is the material

formed by combination of water and cementations materials; that part of the concrete

which is not aggregate or reinforcing. The workability or consistency is affected by the

water content, the amount of cement paste in the overall mix and the physical

characteristics such as maximum size, shape, and grading of the aggregates (Seeley,

1995).

2.4 Textile Wastewater

Generally, the textile industry is very water intensive. Treatment of wastewater

is one of the biggest problems faced by textile manufacturers. Textile industry is one of

the most important and rapidly developing industrial sectors in Malaysia. It has a high

importance in terms of its environmental impact, since it consumes considerably high

amounts of processed water and produces highly polluted discharge water in large

amounts. The textile wastewater from batik manufacturing is so much and can give

more effect to human health and for our environment (Florio, 2003)

2.4.1 Definition of Textile Wastewater

Water is used for cleaning the raw material and for many flushing steps during

the whole production. Produced waste water has to be cleaned from, wax, oil, colour

and other chemicals, which are used during the several production steps. That also can

12