COMPRESSiVE 91RENCTffI OF HIGH SIRENGIH CONCREIF USING BRuSH STANDARD, EURO CODE AND NON- DESWUCHVE ThSI' APPROACHES

LFEJINAN

A thesis submitted in partial fulfillment of the requirements for the award of degree of Bachelor of Civil Engineering.

Faculty of Civil Engineering and Earth Resources

Universiti Malaysia Pahang

NOVEMBER 2010

ABSTRACT

High strength concrete has been widely used in civil engineering in recent

years. High strength concrete provides high compressive strength but lower the

ductility than normal strength concrete. In this study, the compressive strength of cube

and cylinder specimens was compared. Cube test is the common measurement of

concrete compressive strength. According to British Standard 8110, the design of

concrete structures is depend on the cube strength. In industries, the cube strength

test is conducted to obtain the grade of concrete before it is applied to the work. In

future, Eurocode 2 (EC2) will replace the existing British code 13S8 110 for the design of

concrete structure. EC2 have some benefits compared to British Standard. Concrete

strengths are referred to by cylinder strength, which are typically 10-20% less than the

corresponding cube strengths. In this investigation, the concrete cube and cylinder

were tested on 7 and 28 days of water curing. The result show that the value of

cylinder strength is about 18-21% less than the cube strength. Nondestructive test

which are Rebound Hammer test and Ultrasonic Pulse Velocity test was also used to test the concrete strength.

V

ABSTRAK

Konkrit kekuatan tinggi digunakan secara meluas dalam bidang kejuruteraan

awam pada kebelakangan mi. Konkrit kekuatan tinggi mernpunyai daya mampatan

yang tinggi tetapi kerapuhan yang rendah berbanding konkrit biasa. Dalam kajian mi,

daya mampatan antara konkrit kiub dan konkrit sunder dibandingkan. Ujian kiub

adalah ujian biasa digunakan untuk mengukur daya manpatan konkrit. Berdasarkan

kepada British Standard BS8 110 (BS8I 10), reka bentuk struktur bergantung kepada

kekuatan kiub. Dalam industri, ujian kekuatan kiub dijalankan untuk mendapatkan gred

konkrit sebelum diaplikasikan dalam keija pembinaan. Walaubagaimanapun Eurocode

(EC2) akan menggantikan Bs81 10 dalam merekabentuk struktur pada masa yang akan

datang. Eurocode rnempunyai kelebihan berbanding dengan British Standard.

Knkuatan konkrit silinder adalah antara 10 - 20 1/o kurang daripada kekuatan kiub.

Dalam kajian ml, kekuatan konkiit kiub dan silkier diukur pada hari ke 7 dan hari ke 28

selepas rendaman air dijalankan. Hasil ujikaji menunjukkan kekuatan sunder adalah

18-21% kurang daripada kekuatan Idub. Ujian nondestructive iaitu ujian Rebound

Hammer dan ujian Ultrasonic Pulse Velocity juga digunakan untuk mengiiji kekuatan

konkrit ]dub.

vi

TABLE OF CONTENT

CHAPTER

TITLE PAGE

TITLE i DECLARATION DEDICATION iii ACKNOWLEDGEMENT iv ABSTRACT v AI3STRAK vi TABLE OF CONTENTS vii LIST OF TABLES xi LIST OF FIGURES xiii LIST OF SYMBOLS xv

1 INTRODUCTION 1

1.1 Background of Study 1

1.2 Problem Statements 3 1.3 Objectives of Study 4

1.4 Scopes of Study 4

LIM

Mm

2 LITERATURE RIVIEW 5

2.1 Introduction 5

2.2 History of Concrete 6 2.2.1 Background of High-Strength Concrete 7 2.2.2 Advantages and Disadvantages of High- 8

Strength Concrete

2.3 Material 8 2.3.1 Fine Aggregate 8 2.3.2 Water 9 2.3.3 Portland Cement 9 2.3.4 Coarse Aggregate 10

2.4 European Standard 10 2.4.1 History of European Standards 11 2.4.2 Eurocode 2 11 2.4.3 Comparison between EC2 and BS8I 10 12

2.5 Strength of concrete 13 2.5.1 Compressive Strength of Concrete 13

2.6 Characteristic of Concrete i 2.6.1 Workability 15 2.6.2 Strength 16 2.6.3 Elasticity 17 2.6.5 Slenderness Ratio 17 2.6.6 Buckling 18

2.7 Mechanical Properties of Concrete 18 2.8 Factor Affecting Properties of Concrete 19

2.8.1 Water to Cement Ratio (W/C) 19 2.8.2 Concrete Material Factor 19 2.8.3 Temperature and Relative Humidity 20 2.8.4 Aggregate Properties 21

2 LITERATURE RIVIEW 5

2.1 Introduction 5

2.2 History of Concrete 6 2.2.1 Background of High-Strength Concrete 7 2.2.2 Advantages and Disadvantages of High- 8

Strength Concrete

2.3 Material 8 2.3.1 Fine Aggregate 8 2.3.2 Water 9 2.3.3 Portland Cement 9 2.3.4 Coarse Aggregate 10

2.4 European Standard 10 2.4.1 History of European Standards 11 2.4.2 Eurocode 2 11 2.4.3 Comparison between EC2 and BS81 10 12

2.5 Strength of concrete 13 2.5.1 Compressive Strength of Concrete 13

2.6 Characteristic of Concrete 15 2.6.1 Workability 15 2.6.2 Strength 16 2.6.3 Elasticity 17

2.6.5 Slenderness Ratio 17 2.6.6 Buckling 18

2.7 Mechanical Properties of Concrete 18

2.8 Factor Affecting Properties of Concrete 19 2.8.1 Water to Cement Ratio (W/C) 19

2.8.2 Concrete Material Factor 19

2.8.3 Temperature and Relative Humidity 20

2.8.4 Aggregate Properties 21

vJ-u

ix

2.9 Compressive strength test 21 2.9.1 Non Destructive Test (ND!) 23

2.9.1.1 Purpose ofNDF 24 2.9.1.2 Types ofNDF 25

3

METHODOLOGY 26

3.1 Introduction 26 3.2 Material 28

3.2.1 Fine Aggregate 28 3.2.2 Coarse Aggregate 29 3.2.3 Water 30 3.2.4 Ordinary Portland Cement 30

3.3 Preparation of Materials 31 3.4 Sieve Analysis 31 3.5 Mould of Specimen 33

3.5.2 Number of Specimens 34 3.6 Concrete Mix 35 3.7 Curing 35 3.8 Compressive Strength Test 36

3.8.1 Cylinder Test 37 3.8.2 Cube Test 38 3.8.3 Rebound Hammer Test 39 3.8.4 Ultrasonic Pulse Velocity Test 40

Iz-

x

4 RESULT AND DISCUSSION 42

4.1 Introduction 42 4.2 Comparison of concrete cube compression test 43

with concrete cylinder Compression test,

4.3 Comparison of concrete cube test 46 4.4 Result of Concrete Compression Test 49

4.4.1 Compressive Strength Test 49 4.4.1.1 Cube Test 49:. 4.4,1.2 Cylinder Test 51

4.4.2 Nondestructive Test 53

4.4.2.1 Rebound hammer Test 53

4.4.2.2 Ultrasonic Pulse Velocity Test 55

5 CONCLUSIONS AND RECOMMENDATIONS 58

5.1 Conclusion 58 5.2 Recommendation 59

REFERENCES 60

APPENDIX A 65 APPENDIX B 72

LIST OF TABLES

TABLE NO. TITLE PAGE

3.1 Volume of Sample 31 3.2 Quantity of Material for Concrete Grade 40 31 3.3 Quantity of Material for Concrete Grade 50 31 3.4 Quantity of Mould Used In Testing 34 4.1 Result of Concrete Cube Test and Concrete Cylinder 43

Test of Concrete Grade 40

4.2 Result of Concrete Cube Test and Concrete Cylinder 44 Test of Concrete Grade 50

4.3 Result of Concrete Cube Compression Test and 46 Nondestructive Test for Concrete Grade 40

4.4 Comparison between Concrete Cube Compression Test 47 and Nondestructive Test for Concrete Grade 50

4.5 Result of Cube Test for Concrete Cube Grade 40 49 4.6 Result of Cube Test for Concrete Cube Grade 50 50 4.7 The Result of Compressive Strength of Concrete 51

Cylinder Grade 40

4.8 The Result of Compressive Strength of Concrete 52 Cylinder Grade 50

4.9 Result of Rebound Hammer Test ofConcrete Grade 40 54 4.10 Result of Rebound Hammer Test of Concrete Grade 50 54 4.11 Result of Ultrasonic Pulse Velocity Test of Concrete 56

Grade 40

4.12 Result of Ultrasonic Pulse Velocity Test of Concrete 56

Grade 50

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Ratio of Compressive Strength to 28-Day 14 Cylinder Strength versus Time

2.2 Summary of Compressive Strength-Temperature By 20 Relationships for Normal Weight Concrete Obtained

Unstressed Test

2.3 The Effect of the Aggregate Type on Compressive

Strength 21 2.4 Compression Testing on Cube and Its Various Failure 22

Modes

2.5 Failure Mode of Cylindrical Specimen 23 3.1 Flowchart ofLaboratory Work 27 3.2 Fine Aggregate 28 3.3 Coarse Aggregate

3.4 Ordinary Portland Cement. 30 3.5 Sieve 32 3.6 Mechanical Sieve Shaker 33 3.7 Cube Mould of15Ommx15Omnxi5nn 33 3.8 Cylinder Mould of 150mm in Diameter and 300mm 34

Height.

3.9 Drum Mixer 35 3.10 Curing Tank 36

3.11 Compressive Test Machine 37 3.12 Cylinder Test 38 3.13 Rebound Hammer 40 3.14 Ultrasonic Pulse Velocity Test Equipment 41 4.1 Comparison of Concrete Cube Test with Concrete 43

Cylinder Test of Concrete Grade 40

4.2 Comparison of Concrete Compression Test with 45

Concrete Cylinder Compression Test of Concrete Grade

50

4.3 Comparison between Concrete Compression Test with 46

Nondestructive Test of Concrete Grade 40

4.4 Comparison of Concrete Compression Test with 48

Nondestructive Test of Concrete Grade 50

4.5 Comparison of Concrete Cube Compression Test 50

- between 7 and 28 Days Ages of Concrete

4.6 The Comparison of Concrete Cylinder Compression. 52

Test between 7 and 28 Days Ages of Concrete

4.7 Comparison of Rebound Hammer Test between 7 and 54

28 Days Ages of Concrete Grade 40 and 50

4.8 Comparison of Ultrasonic Pulse Velocity Test between 57

7 and 28 Days Ages of Concrete

MV

LIST OF SYMBOLS

fck - Characteristic cylinder strength

fYd - Design yield strength fc - Concrete strength

TM - Partial safety factor T - Time in second V - Velocity

cm - Centimeter mm - Millimeter km - Kilometer

UPV - Ultrasonic Pulse Velocity NSC - Normal Strength Concrete NDT - Non Destructive Test

ASTM - American Society of Testing Material

CHAPTER 1

INTRODUCTION

1.1 Background of Study

High strength concrete has been widely used in civil engineering in recent

years.This is because most of the rheological, mechanical and durability properties

of these materials are better than those of conventional concretes.

High strength is made possible by reducing porosity, inhornogeneity and

microcracks in concrete and the transition zone (Nawy, 1996). A definition of high

strength concrete in quantitative term which is acceptable to everyone is not

possible. In North American practice, high strength concrete is usually considered

to be a concrete with a 28-day compressive strength of at least 42 MPa. In a

recent CEB-FIP state-of-the-art report on high strength concrete, it is defined as

concrete having a minimum 28-day compressive strength of 60 MPa. In many

developed countries, the concrete producers arbitrarily defined the high

strength concrete as the concrete having the 28-day cube strength of above 45

MPa when the normal weight aggregate is used. Clearly then, the definition of high

strength concreteis relative; it depends upon both the period of time in question, and the location (Neville, 1997).

The use of high strength concrete results in many advantages, such as

reduction in beam and column sizes and increase in the building height with many

stories. In pre-stressed concrete construction, a greater span—depth ratio for

beams may be achieved with the use of high strength concrete. In marine

structures, the low permeability characteristics of high strength concrete reduce

the risk of corrosion of steel reinforcement and improve the durability of concrete

structures. In addition, high strength concrete can perform much better in

extreme and adverse climatic conditions, and can reduce maintenance and repair

costs (Mehta and Monteiro,1993).

The progress in the manufacturing of increasingly high strength concrete

and their successful use in high rise structures over the last 20 years is well known.

Most recently, concretes having the strength of around 138 MPa are being used in

columns of high rise buildings and in a few European bridges. Concretes having the

strength up to 800 MPa have been produced in France for special purposes (Gjorv, 1992).

By far, the most common test carried out on concrete is the compressive

strength test. The main reason to understand this fact is that this kind of test is

easy and relatively inexpensive to carry out Mindess et al, 2003). Testing standard

requirements use different geometries of specimens to determine the compressive

concrete strength, j. The most used geometries are cylinders with a

slenderness equal to two and cubes. Shape effect on compression strength has

been widely studied and different relationships between the compressive strength

obtained for these geometries have been proposed, mainly from a technological

standpoint. Such approach eludes the fact that there is a direct relation between

the nucleation and propagation of fracture processes and the failure of the

specimen, indeed, experimental observations confirm that a localized micro-

cracked area develops at peak stress (Mier, 1984) or just prior to the peak stress

(Torreti et al, 1993). For this reason compressive failure is suitable to be analyzed by means of Fracture Mechanics.

1.2 Problem Statement

Eurocode 2 (FC2) gives many benefits such as less restrictive than British

Standards, extensive and comprehensive, logic and organized to avoid repetition

and the new R2 are claimed to be the most technically advanced codes in the

world. In Europe, all public works must allow the Eurocodes to be used for

structural design. Use of the EC2 will provide more opportunity for United Kingdom

(UK) designers to work throughout Europe and for Europeans to work in the UK.

Other than that, EC2 also give the economic benefit. It is expected that there will be material cost saving of between 0 and 5% compared to using BS 8110 (Moss et. al,2004). In future the Malaysia will use Eurcode as a standard in construction and

British Standard will eliminate. The testing result in this study can be made as a

reference in our future study ofEurocode in Malaysia.

According to the grade of concrete, EC2 allows benefits to be derived from

using high strength concretes, which BS8I 10 does not. Concrete strengths are

referred to by cylinder strengths, which are typically 1020% less than the

corresponding cube strengths. The maximum characteristic cylinder strength, fk permitted is 90N/mm2, which corresponds to characteristic cube strength of 150N/mm 2 (Moss et.al, 2002). However, the data are obtained from Europe and the

strength of cylinder test less than the corresponding cube test for material from

Malaysia is unknown? This study will conducted to make a comparison of cylinder

strength with cube strength using material from Malaysia.

The non-destructive tests used are mainly focus on rebound hammer test and

Ultrasonic Pulse Velocity test in order to check the accuracy of these testing

ompared to the actual concrete grade by compressive strength test.

1.3 Objectives of Study

The objectives of this study are:

i. To determine the compressive strength of high strength concrete using

British Standard and Eurocode approaches. ii. To check the strength of concrete using non-destructive test. iii. To compare the compressive strength of concrete using difference method

of test.

1.4 Scope of Study

The scope is related to the materials and equipments that involved in this

study and fulfill the requirement according to standards below:

i. The concrete grades covered are G40 and G50.

ii. The non-destructive test is mainly focus on rebound hammer test and Ultrasonic Pulse Velocity test.

iii. Method to cure the concrete is water curing. iv. Testing will be carried out on 7 and 28 day age of concrete. V. The testing will be carried out according to:

• C 192/C 192M - 05 Standard Practice for Making and Curing Concrete Test

Specimen in the Laboratory.

• C 136-05 Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates.

• C 19/C 39 M - 04a Standard Test Method for Compressive Strength of

Cylindrical Concrete Specimens.

• BS 1881: Patti 16: 1983 Concrete Compressive Test.

BS 1881:Part2O2: 1986 Rebound Hammer Test.

• BS 1881 :Part2O3: 1986 Ultrasonic Pulse Velocity Test.

CHAPTER 2

LITERATURE REVIEW

21 Introduction

Construction achievement always associated with the availability of suitable

material and its design. The recent tendency has been develop more accurate and

elaborate method of design which effect saving material. Due to industrial demand

and the development of high strength concrete have improved rapidly because the

industrial demand of new features in concrete have improved rapidly because the

industrial demand of new features in concrete member stiffness. The benefit of

increased in compressive strength is lower volumes and produce smaller design in

term of design perspectives (Jefily, 2008)

In recent year, high strength concrete has rapidly used on the construction

industry especially for buildings and infrastructures. The utilization of high strength

concrete has been spurred on by the superior mechanical properties of the material

and it cost-effectiveness. However, high strength concrete tends to be more brittle

or less tough than normal strength concrete under compression load (Neville, 2002).

High strength concrete provides high compressive strength but lower the

ductility than normal strength concrete. The low ductility and compressive strength

can be increased by applied the confining reinforcement to the concrete under

compression. However, these confining effects are most determined by

experimental test. When the general view of studies is observed, many cases are

found in which experimental results were investigated analytically and give a

feedback between experiments and analyses.

In future, Eurocode 2 (EC2) will replace the existing British code BS8 110 for

the design of concrete structure. For example, EC2 allows benefits to derived from

using high strength concretes, which BS8I 10 does not. Concrete strengths are

referred to by cylinder strength, which are typically 1020% less than the

corresponding cube strengths (Moss et.al 2002).

2.2 History of Concrete

The word concrete comes from the Latin word "concretus" which mean "to

harden". In Serbia, remains of a hut dating from 5600 BC have been found, with a

floor made of red lime, sand, and gravel. The pyramids of Shaanxi in China, built

thousands of years ago, contain a mixture of lime and volcanic ash or clay. The

Assyrians and Babylonians used clay as cement in their concrete. The Egyptians used lime and gypsum cement.

According to-Rubin (2008), during the Roman Empire, Roman concrete made

from quicklime, pozolanic ash/pozzolana and an aggregate made from pumice was

very similar to modern Portland cement concrete. The secret of concrete was lost for 13 centuries until in 1756, the British engineer John Smeaton pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate.

Portland cement was first used in concrete in early 1840s.

In modern times, the use of recycled materials as concrete ingredients is

gaining popularity because of increasingly stringent environment legislation. The

most conspicuous of these is fly ash, a byproduct of coal fired power plants. This has

a significant impact by reducing the amount of quarrying and landfill space required,

and, as it acts as a cement replacement, reduces the amount of quarrying and

landfill space required, and, as it acts as a cement replacement, reduces the amount

of cement required to produce a solid concrete. As cement production creates

massive quantities of carbon dioxide, cement replacement technology such as this

will play a huge role in future attempts to cut CO2

The lightweight foam concrete has been discovered for a very long time ago.

Two thousand years ago the Romans were making a primitive concrete mix

consisting of small gravel and coarse sand mixed together with hot lime and water.

They soon discovered that by adding anima blood into the mix and agitating it, small

air bubbles were created making the mix more workable and durable (Aldridge, 2005).

2.2.1 Background of High-Strength Concrete

Although high-strength concrete is often considered a relatively new

material, its development has been gradual over many years. As the development

has continued, the definition of high strength concrete has changed. In the 1950s,

concrete with a compressive strength of 34 MPa was considered high strength. In

the 1960s, concrete with 41 and 52 MPa compressive strength were used

commercially. In the early 1970s, 62 MPa concrete was being produced.

More recently, compressive strength approaching 138 MPa have been used

in cast-in-place buildings. For many years, concrete with compressive strength in

excess of 41 MPa was available at only a few location. However, In recent years, the

applications of high-strength concrete have increased, and high-strength concrete

has now been used in many parts of world. The growth has been possible as a result

of recent developments in material technology and a demand for higher-strength concrete.

21.2 Advantages and Disadvantages of High-Strength Concrete

High strength concrete gives a lot of advantages in construction industry. It's

provides an economical benefits as it used in a primary member such as structural

members. Designer can design small size of structural member and ease the

construction method. With an increase in concrete strength, the engineers can

design a smaller member that carries the same amount of load. Hence, it's become

more economical advantage and gives a lot of aesthetical values.

However, high strength concrete is brittle and will crack when it is under

tension. Thus, it has lower ductility compare to normal strength concrete. Besides,

careful materials selection is necessary these materials may need more materials in

lower quality. Furthermore, allowable stress design stress design stress design

discourages the use of high strength concrete and load factor and resistance design

will be used. The used of load factor and resistance will increase the size of the high

strength concrete member. High strength concrete-has more issue relating to the

lack of performances standard because lack of control to maintained special properties required.

23 Material

The material that produced high strength concrete is fine aggregate, water,

Portland cement and course aggregate. The proportion of mix design should be

accurate to get the actual grade of high strength concrete designed.

2.3.1 Fine Aggregate

Natural materials such as river sand and crushed fine stone are generally

used in concrete as fine aggregates. Most of the aggregates used in our country are

river and sand as fine aggregates. Fine aggregate S used for concrete should conform to the requirements for the prescribed grading zone as per IS: 383 - 1970.

The stone particles comprising the sand should be hard and sound. The sand

particles should be near cubical or spherical in shape. They should not be covered

with deleterious materials like clay slumps and should be clean. They should not

contain organic or chemically reactive impurities.

Natural or river sand may not conform to all the above requirements and

may have to be improved in quality. Improvements by washing, grading and

blending may have to be done before use at consumer end. But, in the case of

crushed stone sand / manufactured sand all these processes can be done in the

plant itself and quality sand can be made available to the consumer directly by supplier.

23.2 Water

Water is the important factor to determine the strength of concrete. In

construction work, extra in utilizing water is not efficient. Pouring and mixing

concrete process will be and uncomplicated but the strength of concrete will

become low. This situation affects the durability of concrete in future. Sea sand is

totally cannot used because sea sand contain high value of salt. The kind of sand is

not suitable for masonry construction because affect reinforcement bar of structure.

The usage of sea sand also can expose a concrete structure to sulphate attack which can cause expansion, corrosion and cracking in concrete.

2.3.3 Portland Cement

The properties of concrete depend on the quantities and qualities of

Portland cement. Because cement is the most active component of concrete and

usually has the greatest unit cost, its selection and proper use are important in

obtaining most economically the balance of properties desired for any particular

concrete mixture.

Type I/LI portland cements, which can provide adequate levels of strength

and durability, are the most popular cements used by concrete producers. However,

some applications require the use of other cements to provide higher levels of

properties. The need for high-early strength cements in pavement repairs and the

use of blended cements with aggregates susceptible to alkali-aggregate reactions are examples of such applications.

It is essential that highway engineers select the type of cement that will

obtain the best performance from the concrete. This choice involves the correct

knowledge of the relationship between cement and performance and, in particular,

between type of cement and durability of concrete.

23.4 Coarse Aggregate

The grading and shape of coarse aggregates and maximum size of coarse

aggregates have important effects on workability. The maximum size of coarse

aggregate must be selected for each specific concrete condition. The choice will

usually involve consideration of such factors as spacing of reinforcing bars,

minimum width of form, and methods of placing and compacting the concrete mass.

2.4 European Standard

European Standard is containing common structural rules for the design of building and civil engineering structures.

2.4.1 History of European Standards

In 1975, the Commission of the European Community decided on an action

programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and

the harmonization of technical specifications. Within this action programme, the

Commision took the initiative to establish a set of harmonized technical rules for

the design of construction works which, in a first stage, would serve as an

alternative to the national rules in force in the Member State and ultimately, would

replace them (European Committee for Standardization, 2002).

European programme, led the first generation of European codes in the

1980s. The Structural European programme comprises the following standard

generally consisting of a number of Parts (European Committee for Standardization, 2002):

EN 1990 Eurocode 0: Basis of Structural Design

EN 1991 Eurocode 1: Actions on structures

EN 1992 Eurocode 2: Design of concrete structures

EN 1993 Eurocode 3: Design of steel structures

EN 1994 Eurocode 4: Design of composite steel and concrete structures

EN 1995 Eurocode 5: Design of timber structures

EN 1996 Eurocode 6: Design of mansory structures

EN 1997 Eurocode 7: Geotechnical design

2.4.2 Eurocode 2

Eurocode 2 (EC2) is a set often Eurocode programme in European Standards

that contain the design standard for concrete structures.

112 gives many benefits such as less restrictive than British Standards,

extensive and comprehensive, logic and organized to avoid repetition and the new

112 are claimed to be the most technically advanced codes in the world. In Europe,

all public works must allow the Eurocodes to be used for structural design. Use of

the EC2 will provide more opportunity for United Kingdom (UK) designers to work

throughout Europe and for Europeans to work in the UK. Other than that EC2 also

give the economic benefit. It is expected that there will be material cost saving of

between 0 and 5% compared to using BS 8110 (Moss et. al,2004).

2.4.3 Comparison between EC2 and BS81I0

According to the grade of concrete, EC2 allows benefits to be derived from

using high strength concretes, which BS8 110 does not. Concrete strengths are referred to by cylinder strengths, which are typically 10-20% less than the

corresponding cube strengths. The maximum characteristic cylinder strength, Ik permitted is 90N/mm2, which corresponds to characteristic cube strength of 150N/mm 2 (Moss et.al , 2002).

As with BS81 10, EC2 uses a basic material partial safety factor, yn for concrete of 1.5. Several years ago the material partial safety factor for reinforcing steel in BS81I0 was reduced from 1.15 to 1.05. 112 uses a value of 1.15 although this is subject to a National Annex. This is unlikely to have any practical impact however as steel intended to meet the existing yield strength of 460N/mm2 assumed by BS81 10 is likely to be able to meet the 50ON/mm2 assumption made by

so that the design yield strength, f'd will be virtually identical (Moss et.al , 2002).

In designing for fire and cover, 112 does not considered this topic and in

making comparisons between BS81 10 and EC2 assumes that covers and dimensions

of members are largely unaffected by the changed design process.