MAHENDRA KUMAR 1.docx

8/10/2019 MAHENDRA KUMAR 1.docx

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SELF COMPACTING CONCRETE

MAHENDRA KUMAR

Page 1

A

MINOR PROJECT

REPORT

ON

PROJECT ON SELF

COMP CTION CONCRETE

Submitted in partial fulfillment for the award of the degree of

BACHELOR OF TECHNOLOGY

In

CIVIL Engineering

Guided by: Submitted by:

Mr. Mukesh Bugaliya Karan Kumar Meena

HOD of Civil Roll No: 11EROCE019

Department B.Tech.(C.E.)VII SEM.

REC, Dausa

DEPARTMENT OF CIVIL ENGINEERING

RAJASTHAN ENGINEERING COLLEGE DAUSA

RAJASTHAN


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MAHENDRA KUMAR Page 2

DEPARTMENT OF CIVIL ENGINEERING

RAJASTHAN ENGINEERING COLLEGE DAUSA JAIPUR

CERTIFIC TE

This is to certify that the Minor Project report is submitted by Karan Kumar

Meena (11EROCE019)in partial fulfillment for the award of degree of Bachelor

of Technology in Civil Engineering has been found satisfactory and is approved

for submission.

Guided By:

Mr. Mukesh Bugaliya

HOD

Deptt.of Civil Engineering

REC, Dausa

CKNOWLEDGEMENT


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This is to acknowledge my gratitude towards my guide Mr. MUKESH

BUGALIYA HOD dept. of civil engineering for his guidance and suggestionsin preparing this Minor Project report. His suggestion and way of summarizing

the things make me to go for independent studying and trying my best to get

the maximum in my topics this made my circle of knowledge very vast. I am

highly thankful for this Minor Project.

I also express my profound sense of gratitude to all Faculty Members for

giving encouragement and opportunity to complete my Minor Project

smoothly.

KARAN KUMAR MEENA

Roll No: 11EROCE019


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TABLE OF CONTENTS

TOPIC PAGE NO.

1.INTRODUCTION 6-9

2.MECHANISM INVOLVED IN S.C.C 10-11

3.VARIOUS METHOD OF PREPARATION OF S.C.C 12-14

4. VARIOUS TESTS PERFORMED ON S.C.C. 15-23

5.FACTORS OF SELF-COMPACTABILITY IN TERMS OF TESTING RESULTS 24-27

6.MIX DESIGN OF S.C.C. 28-33

7.APPLICATION OF SELF-COMPACTING CONCRETE AND ITS BENEFITS 34-37

8. FUTURE OF SELF COMPACTION CONCRETE 38-38

9.CONCLUSION 39-39

10.RECOMMENDATIONS 40-40

11.REFRENCES 41


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SELFCOMPACTING CONCRETE


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CHAPTER-1

1.INTRODUCTION

Selfcompacting concrete, Self placing concrete, or Self leveling concrete. These concretes are

highly flowable concretes that can spread into place under their own weight and achieve good

consolidation without internal or external vibration and without exhibiting defects due to

segregation and bleeding

Self-compacting concrete (SCC) can be defined as a fresh concrete which possesses

superior flow ability under maintained stability (i.e. no segregation), thus allowing self-

compaction that is, material consolidation without addition of energy. The three

properties that characteriseaconcrete as self-compacting are.....

Flowing abilitythe ability to completely fill all areas and corners of the formwork in

which it is placed

Passing abilitythe ability to pass through congested reinforcement without

separation of the constituents orblocking

Resistance to segregationthe ability to retain the coarse components of the mix in

suspension in order to maintain a homogeneous material

1.1 HISTORY OF SELF COMPACTION CONCRETE

The history and development of SCC can be divided into two key stages: its initial

development in Japan in the late 1980s and its subsequent introduction into Europe

through Sweden in the mid- to late-1990s.

1.1.1. Japan

SCC was first developed in Japan in 1988 in order to achieve more durable concrete

structures by improvingthe quality achieved in the construction process and theplaced

material.

The removal of the need for compaction of the concrete reduced the potential for

durability defects due to inadequate compaction (e.g. honeycombing). The use of SCC

was also found to offer economic, social and environmental benefits over traditional

vibrated concrete construction. These benefits included faster construction and the

elimination of noise due to vibration. One of the main drivers for the development of

the technology was the reduction in the number of skilled site operatives that the


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Japanese construction industry was experiencing in the 1980s. The use of SCC meant

that less skilled labour was required for the placing and finishing of the concrete

SCC was developed from the existing technology used for high workability and

underwater concretes, where additional cohesiveness is required. The first research

publications that looked into the principles required for SCC were from Japan around 1989

to 1991. These studies concentrated upon high- performance and super-workable

concretes and their fresh properties such as filling capacity, flowability and resistance to

segregation

Fig:1The quantity of a Self Compaction Concrete used in japan

1.1.2. Europe

In the second half of the 1990s, interest and use of SCC spread from Japan to other

countries, including Europe. Some of the first research work to be published from Europe

was atan International RILEM (International Union of Testing and Research Laboratories

of Materials and Structures) Conference

In London in 1996. Papers were presented on the design of SCC.by University College

London, and a mix-designmodel by the Swedish Cement and Concrete Research Institute

(CBI)

A Technical Committee (TC 174-SCC) was set up by RILEM in1997 with the objective of

gathering, analysing andpresenting a review of the technology of SCC, as well aslooking

for unified views on testing and evaluation. Seventeen full members and three


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corresponding members covering ten countries on four continents took part in the work

and a state-of-the-art report was published in 2000.

Sweden was the first country in Europe to begin development of SCC, and in 1993 the CBI

organised a seminar in Sweden for contractors and producers, leading to aproject aimedat studying SCC for housing.As part of this project, large numbers of half-scale house

walls were cast using SCCs whichwere made with different filler materials. The work from

this project contributed to the first European project onSCC which began in January 1997

and was completed in 2000. The main goal of this Brite-EuRam project (BRPR-CT96-

0366) was to develop a new vibration-free production system to lower the overall cost of

in-situ-cast concrete construction. The first part concerned the development of SCC with

or without steel fibres and the second part dealt with full-scale experiments in civil

engineering and housing. This project included partners from several European countries,

including the UK. For further details, includingproject summaries see Reference 17.During

this time, CBIalso developed a mix design model for thedesign and production of SCC.

Fig:2 NEED OF COMPACTION OF CONCRETE


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One solution for the achievement of durable concrete structures independent of the

quality of construction work is the employment of self-compacting concrete, which can

be compacted into every corner of a formwork, purely by means of its own weight and

without the need for vibrating compaction.The necessity of this type of concrete wasproposed by Okamura in 1986. Studies to develop self-compacting concrete, including a

fundamental study on the workability of concrete, were carried out by Ozawa and

Maekawa at the University of Tokyo.

Fig:3 Necessity of Self-Compacting Concrete

1.2WHAT ACYUALLY SELF COMPACTING CONCRETE (SCC)

SCCs are extremely workable concretes that can be placed without requiring vibration.

The high fluidity of these concretes is obtained by adding a superplasticiser. Calcareous

filler can be introduced into the concrete mix to reduce bleeding and segregation, and

improve the quality of concrete surface in terms of colour. The composition of the

concrete tested is given in.All particles of sand, cement and filler with a diameter of less

than 63 Am are referred to as fine particles or fines. The angular shape of these grains

can play an important role in the friction stress occurring at the concrete/wall interface.

Durable concrete structures

Skill of workers Self-Compacting Concrete

in the futuredecreasing

Durable concrete structures

Skill of workers Self-Compacting Concrete

in the futuredecreasing


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CHAPTER-2

2.1 MECHANISM INVOLVED IN S.C.C

Self-Compacting Concrete (SCC) was first developed in Japan about 10 years ago 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. Self-compacting concrete 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, self-compacting concrete consists 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. In principle, the properties of the fresh and hardened SCC, which depend on the

mix design, should not be different from NC. One exception is only the consistency. Self-

compacting concrete should have a slump flows of approx. s > 65 cm after pulling the flow

cone. Fig. 1 shows the basic principles for the production of SCC.

Fig:4 Basic principles for the production of Self-Compacting Concrete


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Fig:5 Mechanism for achieving self-compactability


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The mix Proportioning of self-compactig concrete is shown and compared which those of

normal concrete and RCD (Roller Compared Concrtet For Dams) concrete.The aggregate

content is smaller than convertional concrete that requires vibrating compaction.The Ratio of

the coarse aggregate to its solid volume (G/Glim) of each types of concrete.

Fig:7 Comparison of mix-proportioning of SCC with other types of conventional

concrete

Fig:8 Degree of aggregate compaction-coarse aggregate in concrete and fine aggregate

in motar

The degree of packing of coarse aggregate in SCC is approximately 50% to redusec the

interaction between coarse aggregate particles when the concrete deforms.IN addition,the


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ratio of fine aggergate volume to solid volume (S/Slim) in the mortar.The degree of packing

of fine aggergate in SCC mortar is approximately 60% so that shear deformability when the

concrete deforms may be limited.on the other hand,the viscosity of the paste in SCC is the

highest among the various types of concrete due to its lowest watre-powder ratio.

Fig:9 Degree of aggregates compaction-coarse

Fig:10 Relationship between paste volume and water-power ratio


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CHAPTER-4

4 VARIOUS TESTS PERFORMED ON S.C.C.

Following tests of achieve self compactability

4.1. PULL-OUT TESTS

4.2. SLUMP FLOW TEST

4.3 V-FUNNEL TEST

4.4 L-BOX TEST4.5 U-FLOW TEST

4.1. Pull-Out Tests

The bond behaviour for monotonic loading was tested with pull-out specimens,which

were modified RILEM specimens. The modification was necessary to get a reusable

specimen, which has also reasonable costs for production and maintenance. Another

advantage of the chosen specimens was to have an uniform concrete cover around the

whole reinforcing bar. The bar diameter for the whole test series was 10 mm.

Therefore, the specimens had a diameter of 10 cm and a length of also 10 cm. To avoid

an unplanned force transfer between the reinforcing bar and the concrete in the unbonded

area, the rebar were encased with a plastic tube and sealed with a highly elastic silicone

material. The rebars were placed concentrically and the concrete was cast parallel to the

loading direc- tion. The tests were carried out in an electro mechanic testing machine

(fig. 4b) where the specimens were loaded path-controlled. The loading rate was

0,0008 mm/sec. The applied force of the machine was measured corresponding to the slipdisplacement of the reinforcing bar on the non-loaded side. The increase of the slip path

was constantly monitored during the whole testing time.


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Fig:11 Pull-Out Specimen

Fig:12 Electro mechanic testing machine

4.2.SLUMP FLOW TEST

The slump flow test is the most often applied test method for SCC. Several parameters

are varied in order to study their effect on the test response. These parameters are


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presented in the following and their effect is compared with the standard method to

execute the slump flow test: dry plate, wet plate, plate in a slope, wooden base plate,

plastic cover on the base plate, fast lifting of the cone and turning the cone upside down.

The weighted effect is the averaged difference between the standard method and theadjusted method (Table S1) of all test results. The average standard deviation (STD) in

the acceptance range is 14 mm (slump flow), 0.30 s (T50) and 0.57 s (T60). Four

categories are defined to quantify the effect of a variation, the applied criteria are the

following (for slump flow): negligible (0-1STD = 0-14 mm), small (>1 and 2STD, 15-

28 mm), medium (> 2 and 3STD, 29-42 mm) and significant (> 3STD,> 43 mm). The

same characterisation is applied for the measurements of T50 and T60. T50 (T60) is

defined as the flow-time in the period when the cone leaves the plate and the moment

when the apparent maximum diameter of the concrete reaches the prescribed circle of

500 (600) mm.A minimum slump flow of 680-700 mm is recommended to obtain

meaningful T60 flow- times. The more flowable a SCC is the relatively better is the

passing ability (higher blocking ratio) for a given mixture composition. Passing and

filling abilities can be assessed with the L-box and the Orimet; it is not possible to

quantify or qualify segregation with these instruments for SCC of different mixture

compositions.

Fig:13 Determine of water/power ratio bp for zero slump flow


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3. V-Funnel test

Introduction

The test was developed in Japan and used by Ozawa et al (5). The equipment consists of a V-

shaped funnel, shown in Fig.D.4.1. An alternative type of V-funnel, the O funnel, with a

circular section is also used in Japan. The described V-funnel test is used to determine the

filling ability (flowability) of the concrete with a maximum aggregate size of 20mm. The

funnel is filled with about 12 litre of concrete and the time taken for it to flow through the

apparatus measured. After this the funnel can be refilled concrete and left for 5 minutes to

settle. If the concrete shows segregation then the flow time will increase significantly.

Assessment of test

Though the test is designed to measure flowability, the result is affected by concrete

properties other than flow. The inverted cone shape will cause any liability of the concrete to

block to be reflected in the resultif, for example there is too much coarse aggregate. High

flow time can also be associated with low deformability due to a high paste viscosity, and

with high inter-particle friction.While the apparatus is simple, the effect of the angle of the

funnel and the wall effect on the flow of concrete is not clear.

Equipment

V-funnel

bucket ( 12 litre ) trowel

scoop

Stopwatch

Fig:16 V-funnel test


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4..4 L-box test

4.4.1 Introduction

This test, based on a Japanese design for underwater concrete, has been described by

Petersson. The test assesses the flow of the concrete, and also the extent to which it is subject

to blocking by reinforcement. The apparatus is shown in figure D.6.1. The apparatus

consists of a rectangular-section box in the shape of an L, with a vertical and horizontal

section, separated by a moveable gate, in front of which vertical lengths of reinforcement bar

are fitted. The vertical section is filled with concrete, then the gate lifted to let the concrete

flow into the horizontal section. When the flow has stopped, the height of the concrete at the

end of the horizontal section is expressed as a proportion of that remaining in the vertical

section (H2/H1in the diagram). It indicates the slope of the concrete when at rest. This is an

indication passing ability, or the degree to which the passage of concrete through the bars is

restricted. The horizontal section of the box can be marked at 200mm and 400mm from the

gate and the times taken to reach these points measured. These are known as the T

20 and Ttimes and are an indication for the filling ability. The sections of bar can be of

different diameters and spaced at different intervals: in accordance with 40 normal

reinforcement considerations, 3x the maximum aggregate size might be appropriate.The bars

can principally be set at any spacing to impose a more or less severe test of the passing abilityof the concrete.

4.2 Equipment

L box of a stiff non absorbing material see figure D.6.1.

trowel

scoop

stopwatch


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Fig:17 Concrete fiowing through L-box test

Fig:18 L-box test

4.5. U-flow test

Introduction

The test was developed by the Technology Research Centre of the Taisei Corporation in

Japan Sometimes the apparatus is called a box-shaped test. The test is used to measure the

filling ability of self-compacting concrete. The apparatus consists of a vessel that is divided

by a middle wall into two compartments, shown by R1 and R2 in Fig.D.7.1 An opening with

a sliding gate is fitted between the two sections. Reinforcing bars with nominal diameters of


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13 mm are installed at the gate with centre-to-centre spacings of 50 mm. This creates a clear

spacing of 35 mm between the bars. The left hand section is filled with about 20 litre of

concrete then the gate lifted and concrete flows upwards into the other section. The height of

the concrete in both sections is measured.

Equipment

U box of a stiff non absorbing material see figure D.7.1.

trowel

scoop

stopwatch

Fig:19 U BOX TEST


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Experimental Procedure

The procedure adopted in the study is as follows

1) Using Japanese method of mix design, initial mix design was carried out at coarseaggregate content of 50 percent by volume of concrete and fine aggregate content of

40

2) percent by volume of mortar in concrete, the water/powder ratio was kept at 0.90.

These Trial mixes were designed with superplasticizer content of 0%, 0.76% and

3.80% for mixes TR1, TR2, TR3 respectively.

3) 2) To proceed towards achieving SCC, the coarse aggregate content was reduced to

45% by volume of concrete and thereby kept constant. Fine aggregate content waskept constant at 40% by volume of mortar in concrete and superplasticizer content at

1.14 percent of powder content i.e. cement and fly ash. The water-powder ratio was

varied from 1.06 to 1.19 for trial mixes TR4 to TR6.

4) 3) Coarse aggregate content was further reduced and fine aggregate content was

increased, until a slump flow of 500-700 mm is achieved by slump flow test. For each

trial, tests are carried out in order that the mix satisfies slump flow test, V-funnel test

and L-box passing ability test.

By reducing contents of coarse aggregate from 45% to 37% and increasing fine

aggregate contents from 40% to 47.5%, required results in all the tests i.e., slump flow,

Vfunnel and L-Box were obtained


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CLASS-5

FACTORS OF SELF-COMPACTABILITY IN TERMS OF TESTING

RESULTS

The factors making up self-compactability were described in terms of the result for fresh

concrete and mortar.

5.1. INFIUENCE OF COARSE AGGREGATE DEPENDING ON SPACING SIZE

It is not always possible to predict the degree of compaction into a structure by using the test

result on the degree of compaction of the concrete into another structure, since the maximum

size of coarse aggregate is close to the minimum spacing between the relationship between

coarse aggregate content in concrete and the filling height of the Box-type test, which the

standard index for self-compatibility on fresh concrete. The relationship between filing height

through obstacle R1 and that through R2 varied depending on the coarse aggregate content.

Fig:20 Influence of coarse aggregate content on self-compactability

5.2 ROLE OF MORTAR AS FLUID FLOWABILITY OF FRESH CONCRETE

Sufficient deformability of the mortar phase in concrete is required so that concrete can be

compacted into structures by its self-weight need for vibrating compaction. In addition,

moderate viscosity as well as deformability to the mortar phase is required so that the relative

displacement between coarse aggregate particles in front of obstacles can be reduced and

then segregation between coarse aggregate and mortar can be inhibition the necessity for

viscosity was confirmed by Hashimotos visualization test.

The indices for mortar deformability and viscosity proposed by using mortar flow and


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funnel test result. The relationship between mortar flow and funnel test result. The

relationship between mortar deformability and viscosity and the self-compctability of fresh

concrete. The existence of an optimum combination of deformability and viscosity of mortar

for achieving self-compactability of fresh concrete was demonstrated.

Fig:21 Relationship between mortars flow ability and self-compctability of fresh

concrete

5.3. Role of mortar as solid particles

In addition to its role as a liquid mentioned above, mortar also plays a role as particles. The

property is so-called pressure transferability, which can be apparent when the coarse

aggregate particles approach is subjected to normal stress.

Fig:22 Normal stress generated in mortar due to approaching coarse aggregate

particles

The degree of the decrease in the shear deformability of the mortar largely depends on the

physical characteristics of the solid particles in the mortar.


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Fig:23 Degree of increase in shear deform resistance due to depending on physical

characteristics of solid particles

The different in the relationships between the funnel speeds of mortar and concrete due to

different in the fine aggregate content in mortar. It was found that the relationships between

the flow ability of mortar and concrete cannot always be unique due to difference in the

characteristics of the solid particles in the mortar, even if the characteristics of the coarse

aggregate and its content in concrete are content.

Fig:24 Relationship between mortars and concretes flow ability

A simple evaluation method for the stress transferability of mortar was proposed by using

the ratio of the funnel speed of concrete with glass beads as the standard coarse aggregate

(Rcs) to the speed mortar (Rm) . The higher stress transferability corresponds to the smaller

value of Rcs/Rm. The relationships between fine aggregate content in mortar and Rcs/Rm.


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Fig:25 A simple Evaluation method for stress transferability of fresh mortar


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CLASS-6

6.1. MIX DESIGN OF S.C.C.

The principal consideration of the Chinese Method is that the voids of the aggregate are filled

with paste (cement, powder, water). The voids need to be filled with paste so that a workable

fresh concrete is attained. Upon the design of SCC it is usually more difficult to achieve

satisfactory workability than required strength. The Chinese Method starts with the content of

aggregate, which greatly influences the workability: the more aggregate, the less paste and

hence, less fluidity. Subsequently, the amount of cement is assessed. This quantity is

determined by the required compressive strength and durability of the hardened concrete.This approach corresponds to the Dutch Method of the design of normal medium strength

concrete. The amount of cement is also determined by the water/cement ratio and durability

requirements.As said, the main consideration of the Chinese Method is that voids present in

loose aggregate are filled with paste, and that the packing of the aggregates is minimized.

This is achieved by using more sand and less gravel (each about 50%). Here, it will be

investigated how this maximum packing can be achieved, and a relation is made with the

grading curve of the modified A&A model. The Chinese Method makes a distinction between

loose packing, and packing after compaction. As SCC is not vibrated, the densest packing

cannot be assumed right away.

Fig.:26 Determination of the mix components for SCC

The void part of loose aggregates generally amounts to about 4248%. Upon application in

SCC, mixing and resulting compaction, the void part is reduced to 3241%. In the Chinese

Method this void reduction is expressed with the help of a Packing Factor (PF). The PF


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represents the apparent density of aggregate in state of packing in SCC compared with the

apparent density of loosely packed aggregate:

PFSCC

=apparent density aggregate in SCC/apparent density loss aggregate

MIX DESIGN PROCEDURE

If the density of the loosely packed aggregate amounts to 1500 kg/m 3and the density of the

aggregate in SCC to 1750 kg/m3, then the PF has a value of 1.17. The PF that can be attained

in SCC (PF SCC) will be smaller than the value that can be achieved by vibrating the

aggregate. In the ChineseMethod the PF is assessed, and multiplied with the loose densities of coarse

(gravel) and fine (sand) aggregates.

Fig:27 mix design procedure


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Fig:28 Void fraction of sand (3 types)/gravel mixes, before and after compaction at

various sand contents (m/m) in sand/gravel mixes.

6.2. Materials Used

6.2.1 Cement

Ordinary Portland cement (Grade 43) was used. Its physical properties are as given in

Table 1.

Table 1. Physical Properties of Cement

6.2.2 Fly ash


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Class F Fly ash obtained from PanipatThermal Power Station, Haryana, India. The physical

and chemical properties of fly ash are given in the Table 2 and Table 3, respectively.

Table 2. Physical Properties of Fly Ash

Table 3. Chemical Properties of Fly Ash

6.2.3 Admixtures

A polycarboxylic ether based superplasticizer complying with ASTM C-494 type F,

was used.

6.2.4Aggregates

Locally available natural sand with 4.75 mm maximum size was used as fine

aggregate, having specific gravity, fineness modulus and unit weight as given in Table 4 and

crushed stone with 16mm maximum size having specific gravity, fineness modulus and unit

weight as given in Table 4 was used as coarse aggregate. Both fine aggregate and coarse

aggregate conformed to Indian Standard Specifications IS: 383-1970 [6]. Table 4 gives the

physical properties of the coarse and fine aggregates.


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Table 4. Physical Properties of Coarse and Fine Aggregates

6.3 Compressive Strengths and Correlations

The compressive strength results that mix-tures containing limestone powder developed

higher compressive strengths at both 7-day and 28-day compared to those mixtures with slag

+ silica fume or fly ash + silicafume. Similar observations have been made by Zhu et al[17].

The SCC1 had the highest 28-day compressive strength among all the mixtures with a value

of 61.8 MPa followedby SCC2 and SCC3 with values of 61.73 and 58 MPa, respectively.

Mixtures with higher quantities of CA 25 mmdeveloped higher compressive strength

compared to mixtures with lower CA 25 mm content for SCC with LP. Similar trends had

been observed for the mixtures containingSL+SF and FA+SF. High early strength values

were alsoobserved for the mixtures with LP which were in the rangeof 47~53 MPa. Whereas

the early strength of FA+SF ranged between 32 and 39 MPa and for SL+SF mixture the

rangewas between 28 to 32 MPa. It indicates that for given w/cmratio, the early development

of compressive strength wahighest for mixtures with LP followed by mixtures with FA+SF

and SL+SF.

Fig.29 W/p ratio vs. 7-day compressive strength.


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The material of size 125 or smaller were considered to be powder. As LP was a very fine

filler material and was included in the powder calculation, the w/p ratio for SCC with LP was

lowest and the value was 0.30, whereas w/p ratio for rest of the mixtures was around 0.39.

There is a definite trend between w/p ratio and compressive strength as evident from thefigures with a regression co-efficient of 0.89 and 0.82 respectively. However due to strong

influence of admixture on SCC, for a given w/p, different level of compressive strengths were

possible. Though the w/cm ratios of all the mixtures were kept approximately same, the range

of compressive strength varied greatly among the mixtures. This is due to the fact that the

paste volume and powder content have significant effect on the compressive strength for the

SCC.

Fig.30 W/p ratio vs. 28-day compressive strength.

Fig.31 7-day and 28-day compressive strength for 10 SCC mixtures.


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CLASS-7

7. APPLICATION OF SELF-COMPACTING CONCRETE AND ITS

BENEFITS

7.1. CURRENT CONDITION ON APPLICATION OF SELF-COMPACTING

CONCRETE

After the development of the prototype of self-compacting concrete at the University of

Tokyo, intensive research was begun in many places, especially in the research institutes of

large construction companies. As a result, self-compacting concrete has been used in many

practical structures. The first application of self-compacting concrete was in building in June

1990. Self-compacting concrete was then used in the towers of a prestressed concrete cable-

stayed bridge in 1990.Lightweight self-compacting concrete was used in the main girder of a

cable- stayed bridge in 1992.Since then, the use of self-compacting concrete in actual

structure has gradually increased. Currently, the main reasons for the employment of self-

compacting concrete can be summarized as follows.

To shorten construction period

To assure compaction in the structure: especially in confined zones where vibrating is

difficult

To eliminate noise due to vibration: effective especially at concrete products plants

Fig:33 Shin-kiba ohashi bridge


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The volume of self-compacting concrete in Japan. The production of self-compacting

concrete as a percentage of Japanese read-mixed concrete, Which account for 70% of total

concrete production in Japan, is only 0.1%. The current status of self-compacting concrete is

Special concrete rather than standard concrete

Other applications of self-compacting concrete are summarized below.

Bridge (anchorage, arch, beam, girder, tower, pier,joint between beam & girder)

Box culvert

Building

Concrete filled steel column

Tunnel (lining, immersed tunnel,)

Dam (concrete around structure)

Concrete products (blocks, culvert, wall, slab)

Fig:34 volume of s.c.c. cast

7.2 Large scale construction

Self-compacting concrete is currently being employed in various practical structures in order

to shorten the construction period of large-scale constructions. The anchorages of Akashi-

kaikyo (Akashi straits) bridge opened in April 1998, a Suspension bridge with the longest

span in world (1,991 meters). Self-compacting concrete was used in the construction of the


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two anchorages of the bridge. A new construction system that makes full use of the

performance of self-compacting concrete was introduced for this purpose. The concrete was

mixed at the batcher plant. It was transported 200 meters through pipes to the casting site,

where the pipes were arranged in row 3 to 5 meter apart.Self-compacting concrete was usedfor the wall of a large LNG tanks belonging to the Osaka gas company.

The adoption of self-compacting concrete in this particular project had the following

merits

The number of lots decreased from 14 to 10 as the height of one lot of concrete was

increased.

The number of concrete workers was reduced from 150 to 50.

The construction period of the structure decreased from 22 months to 18 months

7.3 Concrete products

Self-compacting concrete is often employed in concrete products to eliminate vibration noise.

This improves the working environment at plants and makes the location of concrete products

plants in urban areas possible. In addition, the use of Self-compacting concrete extends the

lifetime of mould for concrete products (Uno 1990). The production of concrete products

using Self-compacting concrete has been gradually increasing.

Fig:35 volume of SCC for concrete


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CLASS-8

FUTURE OF SELF COMPACTION CONCRETE

Since the development of the prototype of SCC in 1988, its use in actual structures hasgradually increased worldwide. SCC addresses many environmental issues; the main ones are

reduction in noise level in the factory as well as on site, reduction in personal injuries from

noise and manual handling, reduction in electricity usage and reduction in the overall

maintenance costs of vibration equipment. A typical application example of SCC is the two

anchorages of Akashi-Kaikyo (Straits) Bridge opened in April 1998, a suspension bridge

with the longest span (1991 m) in the world6. The SCC provides tangible opportunities to

both designer and contractor. It also has a future in the precast industry providing durableconcrete at a lower cost due to lower initial investments of vibrating facilities and lower

recurring costs due to faster reusage of moulds. It improves the working environment at

plants and sites by eliminating noise of vibration; it is possible for concrete product plants to

be located in the urban area.

Table:5 Potential opportunities from use of SCC


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CLASS-9

CONCLUSION

SCC that flows into formwork and through reinforcement under the influence of its own

weight can be made such that no external vibration is required. Although careful

proportioning and batching are needed, SCC can be produced with locally available

materials.

Concretes with a high slump flow are prone to segregation and bleeding. Tests should

be

conducted with the material used for a specific project to establish that the SCC flows

sufficiently but will not segregate, bleed, or require additional consolidation. To

minimize segregation, a large amount of fine material, a small NMA size, uniform

grading, and low water-cementitious material ratios are needed or conventional mixtures

with VMAs may be used.

SCC can have high compressive strength and low permeability for use in bridge

structures.

To mitigate high drying shrinkage, a large NMA size, a large amount of coarse

aggregate And a low water content are needed.

To avoid an improper air-void system that would reduce freeze-thaw resistance, either a

large air content or a conventional air content with the proper selection of admixtures

that will lead to a reduced void size and spacing is needed.

The use of SCC has the potential to provide initial savings because of the reduction in

labor required to place the concrete. Further savings can be obtained because

structures constructed with SCC should last longer.


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CLASS-10

RECOMMENDATIONS

Specific test procedures should be followed to determine if concretes are self-

consolidating or segregating. Specimens should be tested for strength and

permeability made with and without consolidation to determine if they are self-

consolidating. The slump flow test should be used to detect segregation based on

aggregate distribution and a mortar halo around the spread. The U-tube or a similar

test should be used to show that SCC can flow through the reinforcement and provide

high workability without segregation.

Rheometers should be used to provide data on yield stress and viscosity and to

describe the flow characteristics while the mixtures are being developed. Low

viscosity values indicate adequate flow characteristics. However, there is no

correlation between the viscosity number and segregation or equilibrium height or

spread in this limited study. Further work in this area is recommended.

SCC is recommended for use in transportation structures that can benefit from

concretes with high workability, particularly in thin sections and areas with dense

reinforcement.


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CLASS-11

REFRENCES

1. Japan Society of Civil Engineers, Recommendations for Design and Construction of

Antiwashout Underwater Concrete, Concrete library of JSCE, 19 (1992) 89 p.

2. Petersson, ., Billberg, P., Van, B.K., A model for self-compacting Concrete,

Proceedings of International RILEM Conference on Production Methods andWorkability of

Concrete, edited by P.J.M. Bartos, et al. (Chapman & Hall/E & FN Spon) (Paisley, 1996)

483-490.

3. Bartos, P.J.M., An appraisal of the Orimet Test as a Method for On-site Assessment of

Fresh SCC Concrete, Proceedings of International Workshop on Self-Compacting Concrete,

(Japan, August 1998) 121-135.

4. Haykawa, M., Development and Application of Super Workable Concrete, Proceedings

of International RILEM Workshop on Special Concretes - Workability and Mixing, edited

by Prof. P.J.M. Bartos, (Paisley, 1993) 183-190.

5. Ozawa, K., Sakata, N., Okamura, H., Evaluation of Self-Compactibility of Fresh

Concrete Using the Funnel Test, Concrete Library of JSCE, (25) (June 1995) 59-75.

6. Rooney, M., Bartos, P.M.J., Development of the settlement column segregation test for

fresh self-compacting concrete (SCC), to appear in the second international symposium on

SCC, Tokyo, Japan (2001).

7. Brite-EuRam programme: BE96-3801/BRPR-CT96-0366, Rational production and

improved working environment through using self-compacting concrete.

8. Henderson N A, Baldwin N J R, McKibbins L D, Winsor D S, & Shanghavi H B,

'Concrete technology for foundation applications', CIRIA Report C569: 2002

MAHENDRA KUMAR 1.docx

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