experimental investigation of use of ... · cementing material. ... l-box test and u-tube tests,...

Imperial Journal of Interdisciplinary Research (IJIR)

Vol-3, Issue-9, 2017

ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) 127

Experimental Investigation of Use of

Microsilica in Self Compacting Concrete

Mr. Rajvardhan M. Bhosale1 & Mrs. Shruti Wadalkar

2

1M.E. Construction & Management (Appeared), Department of Civil Engineering, Dr. D. Y.

Patil Institute of Technology Pimpri, Pune, India. 2

Assistant Professor, Department of Civil Engineering, Dr. D. Y. Patil Institute of

Technology, Pimpri, Pune, India.

Abstract— Self compacting concrete construction

and placing becomes faster and easier it eliminates

the need for vibration and reducing the noise

pollution; which consumes both time and labor. This

research is described in detail and presents

laboratory observation. Microsilica is used as a 10%

replacement of cement by weight. Various test were

conducted on microsilica, fly ash, cement,

superplasticizer, fine aggregate & coarse aggregate,

to determine specific gravity, bulk density, fineness

modulus of aggregate, concrete mix proportion

design using this parameter. For conventional

concrete water cement ratio of 0.4 and for

microsilica concrete is increased water contain

about 20liter/m3. Water demand increases in

proportion to the amount of microsilica added.

Mixing the concrete and various test are conducted

on fresh concrete i.e. Slump flow, V- Funnel, L-Box,

U-Box and result are obtained. Using this concrete

cube specimen are cast for testing different hardened

properties of concrete. i.e. 3 Days, 7 Days, 14 Days,

28 Days Compressive strength of concrete.

In this study the experimental investigation for M20

grade using addition of microsilica and different

percentage of fly ash has been done. The resultant

concrete can be used for building

substructures/superstructures where economical

mixes are required with lower strength.

Keywords- Self compacting concrete, Microsilica,

fly ash.;

1. INTRODUCTION

Self compacting concrete is firstly developed in

Japan in 1980; Self compacting concrete is a fluid

mixture suitable for placing in structures with

congested reinforcement without vibration. Self

compacting concrete development must make sure a

good poise between deformability and constancy

also, compatibility is affected by the characteristics

of materials and the mix proportions, self compacting

concrete is a concrete that exhibits high

deformability while maintaining resistance to

segregation.

Microsilica is a very fine pozzolanic material,

composed of amorphous silica or ferrosilican

produced by electric arc furnaces as a byproduct of

the production of elemental silicon or ferrosilicon.

When microsilica used in the concrete, it behaves as a

cementitious materials. The small microsilica particles

fill space between the cement past matrix and

aggregate particles. Microsilica also combines with

calcium hydroxide to form additional calcium

hydroxide through the pozzolonic reaction. Both are

these reaction results in a denser, and less permeable

materials. Microsilica is specifically used for Self-

compacting concrete (SCC) is a flowing concrete

mixture. The highly fluid nature of SCC makes it

suitable for placing in difficult condition & in

selections with congested reinforcement. Use of SCC

can help in hearing related damages on construction

site that are forced by vibration of concrete, another

advantages of SCC is that the time required to place

large section in consider ability reduced. It is recently

used at Mumbai for Bandra-Warli sea Link

Bridge.Microsilica as a fine pozzoanic material

produced as byproduct In production of elemental or

ferrosilicon,its used to increase concrete

properties,specially used for SCC for more

workability and high strength.As generally SCC has

been used for higher grade or higher strength

requirements the past work was majority focused on

SCC designs of higher grade using admixtures and

elements like silica fumes and fly ash.

1.1 BACKGROUND AND SCOPE OF WORK

The aim of the experimental program is to

compare the properties of Self-compacting concrete

(M20) made with and without silica fume and fly ash

at different percentage, used as supplementary

cementing material.

The M-20 Mix has been designed as SCC with

different percentage of replacement of cement by

microsilica and fly ash.The basic tests carried out on

concrete samples are- L box,U –box ,V –funnel test,to

investigate the properties of self compacting concrete

such as workability, viscosity,flow time etc and

results are compared with IS requirement of

http://www.onlinejournal.in/





Imperial Journal of Interdisciplinary Research (IJIR) Page 1128

SCC.Finally the cubes of designed mix has been

casted for different samples and compressive strength

of same is find out.Finally the results are tabulated in

format and compared with standard requirements as

per IS

1.2 OBJECTIVES

1. The main objective of this work is study and

experimental investigation of SCC for

finding out suitability of use of SCC in low

grade concrete.

2. To study the behavior of SCC mix design

at lower grade by replacing cement content

with cementitious materials such as

Microsilica and Fly ash at different

percentage.

3. Experimental investigation to check

suitability of SCC in low grade (M20)

Concrete

1.3 NEED OF PROJECT

As generally SCC has been used for higher grade or

higher strength requirements the past work was

majority focused on SCC designs of higher grade

using admixtures and elements like silica fumes and

fly ash. In this study experiments are carried out for

lower grade self compacting concrete with addition

of micro silica and fly ash in order to reduce costing

of SCC and same can be used for economical

construction at sub structure and super structures of

buildings.

1.4 ADVANTAGES AND LIMITATIONS

1.4.1 ADVANTAGES

SCC offers many advantages for the precast, pre-

stressed concrete industry and for cast-insitu

construction:

i. Low noise-level in the plants and

construction sites.

ii. Eliminated problems associated with

vibration.

iii. Less labour involved.

iv. Faster construction.

v. Improved quality and durability.

vi. Higher strength.

1.4.2 LIMITATIONS

i. Although the use of SCC has many

technical, social, and overall economical

advantages, its supply cost is two to three

times higher than that of normal concrete

depending upon the composition of the

mixture and quality control of concrete

producer. Such a high premium has

somehow limited SCC application to

general construction. SCC is specified only

to areas where it is most needed. These

include places where access to

conventional vibration is difficult, or

where there are congested reinforcements.

ii. The major difficulty which was faced in

development of SCC was on account of

contradictory factors that the concrete

should be fully flow able but without

bleeding or segregation. It is required that

the cement mortar of the SCC should have

higher viscosity to ensure flow ability while

maintaining non-sedimentation of bigger

aggregates..

2. LITERATURE REVIEW

The research work concerning to the various

application and methods used for testing of the Self-

compacting Concrete made by various cementitious

materials and admixtures and compressive review of

the work carried out by various researchers in the field

of Self-compacting Concrete is studied.

Shaik Khadar Jilani and Vanakuri Sainath (2017)- A Study On Self Compacting Concrete Made

With Partial Replacement Of Fine Aggergate With

Robo Sand And Ggbs As Admixture - Based on the

results obtained from the experiments

conducted the following conclusions are

drawn.

Robo sand is a suitable replacement for fine

aggregate in concrete

The optimum strength is obtained for 30% GGBS

and 100% Robo sand Compaction. But this

combination failed in workability point of view.

With Respective both strength and

workability,optimum mix is concluded as 30%

GGBS and 50%Robo sand Replacement

The optimum strength is obtained for 30% GGBS

and 100% Robo sand Compaction. But this

combination failed in workability point of view.

With Respective both strength and

workability,optimum mix is concluded as 30%

GGBS and 50% Robo sand Replacement.

Payal Painuly,Itika Uniyal (2016) - Making

concrete structure without compaction has been done

in the past. Like placement of concrete underwater

by the use of termie without compaction.

Inaccessible areas were concreted using such

techniques. The production of such mixes often used

expensive admixtures and very large quantity of

Cement. But such concrete was generally of lower

strength and difficult to obtain. This lead to the







development of Self Compacting Concrete (SCC)

The workability properties of SCC such as filling

ability, passing ability and segregation resistance are

evaluated using workability tests such as slump flow,

V-funnel and L-Box tests.

To increase the stability of fresh concrete

(cohesiveness) using increased amount o

f fine materials in the mixes. To development of self-

compacting concrete with reduced segregation

potential. The systematic experimental approach

showed that partial replacement of coarse and fine

aggregate with finer materials could produce self-

compacting concrete with low segregation potential

as assessed by the V-Funnel

test.The amount of aggregates, binders and mixing

water, as well as type and dosage of super plasticizer

to be used are the major factors influencing the

properties of SCC. Slump flow,V-funnel, L-flow, U-

box and compressive strength tests were carried out

to examine the performance of SCC. If we add the

mineral admixture replacement for we can have a

better workable concrete. It has been verified, by

using the slump flow, T50 cm slump flow J-ring test,

L-box test and U-tube tests, that self-compacting

concrete (SCC) achieved consistency and self-

compatibility under its own weight, without any

external vibration or compaction. SCC with mineral

admixture exhibited satisfactory results in

workability, because of small particle size and more

surface area

2.1 PROPERTIES FRESH SCC

2.1.1 Workability

EFNARC (2002), Investigated that the SCC

flows alone under its dead weight up to leveling, airs

out and consolidates itself thereby without any entry of

additional compaction energy and without a nameable

segregation. Due to the high content of powder, SCC

may show more plastic shrinkage or creep than

ordinary concrete mixes. These aspects should

therefore be considered during designing and

specifying SCC. Current knowledge of these

aspects is limited and this is an area requiring further

research.

A concrete mix can only be classified as Self-

compacting Concrete if the requirements for all three

characteristics are fulfilled.

Filling Ability: Ability of to fill a formwork

completely under its own weight.

Passing Ability: Ability to overcome

obstacles under its own weight without

hindrance. Obstacles are e.g. reinforcement

and small openings etc.

Segregation Resistance: Homogeneous

composition of concrete during and after the

process of transport and placing. They were

further elaborated as:

Table 2.1: List of test methods for workability

properties of SCC (EFNARC, 2002)

Sr.

No.

Method Property

1. Slump-flow by Abrams

cone

Filling ability

2. T50cm slump flow Filling ability

3. J-ring Passing ability

4. V-funnel Filling ability

5. V-funnel at T5minutes Segregation

resistance

6. L-box Passing ability

7. U-box Passing ability

8. Fill-box Passing ability

9. GTM screen stability test Segregation

resistance

10. Oriment Filling ability

For the initial mix design of SCC all three

workability parameters need to be assessed to

ensure that all aspects are fulfilled. These

requirements are to be fulfilled at the time of

placing. Likely changes in workability during

transport should be taken into account in

production. Typical acceptance criteria for Self-

compacting Concrete with a maximum aggregate

size up to 20 mm are shown in Table.

Table : 2.2 Acceptance criteria for Self-compacting

Concrete (EFNARC, 2002)

Sr.

No.

Method Unit Typical range of values

Minimum Maximum

1. Slump flow

by Abrams

cone

mm 650 800

2. T50cm slump

flow

Sec 2 5

3. J-ring Mm 0 10

4. V-funnel Sec 8 12

5. V-funnel at

T5minutes

Sec 0 +3

6. L-box (h2/h1) 0.8 1.0

7. U-box (h2-

h1)mm

0 30

8. Fill-box % 90 100

9. GTM screen

stability test

% 0 15

10. Orimet sec 0 5

If a certain test result is out of range it can

have different causes. The possible cause can be

found with more certainty by checking the value to







other test methods and subjectively checking the

workability characteristics. In this way the best

possible action for solving a problem can be found.

Table and Table provide a list of possible actions and

the effect that usually occurs in concrete. It is

obvious that the effect depends upon the size of

the action and on the actual workability and

composition of the concrete mix. Every action can

have both positive and negative effect on the different

concrete characteristics.

If the test results between different batches or loads

vary considerably, the cause can be the variation of:

Cement characteristics

Addition characteristics

Grading of aggregates

Moisture content of aggregates,

Temperature

2.1.2 TEST METHOD FOR FRESH SCC

2.1.2.1 SLUMP FLOW TEST (Ferraris, 1999), The basic equipment used is the

same as for the conventional Slump test. The test

method differs from the conventional one by the fact

that the concrete sample placed into the mould is not

ridded and when the slump cone is removed the

sample collapses. The diameter of the spread of the

sample is measured, i.e. a horizontal distance is

determined as opposed to the vertical distance in the

conventional Slump test. The Slump Flow test can give an Indication as to the

consistency, filling ability and workability of SCC.

The SCC is assumed of having a good filling ability

and consistency if the diameter of the spread reaches

values between 650mm to 800mm.

2.1.2.2 V-FUNNEL TEST

(Ferraris, 1999), Viscosity of the self-compacting

concrete is obtained by using a V-funnel maximum

aggregate diameter is 20 mm. The time for the amount

of concrete to flow through the orifice is being

measured. If the concrete starts moving through the

orifice, it means that the stress is higher than the yield

stress; therefore, this test measures a value that is

related to the viscosity. If the concrete does not

move, it shows that the yield stress is greater than the

weight of the volume used. An equivalent test using

smaller funnels is used for cement paste as an

empirical test to determine the effect of chemical

admixtures on the flow of cement pastes. Figure has

certain dimensions, in order for a given amount of

concrete to pass through an orifice. The amount of

concrete needed is 12 litters.

2.1.2.3 L-BOX TEST

(Ferraris, 1999), The L-box test evaluates the passing

ability of SCC in a confined space. The L-box is

composed of a vertical arm and a horizontal arm as

shown in Fig. The concrete flows from the vertical

arm, through reinforcing bars and into the horizontal

arm of the box.

Once the test is completed, the ratio of the heights of

the concrete at the two ends of the box, called the

blocking ratio (BR), is used to evaluate the passing

ability with obstructions as BR = H2/H1

If the SCC has perfect fresh properties, the blocking

ratio is then equal to 1. Conversely, the blocking ratio

is equal to zero. If the concrete is too stiff or

segregated. Blocking ratio is useful for SCC

applications involving complex shapes, and

congested reinforcement.

2.1.2.4 U-BOX TEST

(Ferraris, 1999), The many testing methods used for

evaluating self-compactability, the U-type test

proposed by the Taisei group is the most appropriate,

due to the small amount of concrete used, compared

to others. In this test, the degree of compact ability

can be indicated by the height that the concrete

reaches after flowing through obstacles. Concrete

with the filling height of over 300 mm can be judged as

self-compacting. Some companies consider the

concrete self-compacting if the filling height is more

than 85% of the maximum height possible.

2.2 HARDENED CONCRETE TEST

2.2.1 COMPRESSIVE STRENGTH

High strength concrete with a cube compressive

strength around 100MPa can be easily achieved by

incorporating microsilica with suitable water

reducing agent and suitable aggregates. With

constant W/C ratio, compressive strength of

microsilica concrete is normally higher than

conventional concrete. Researches indicate that the

shape of W/C to strength curve of microsilica

concrete is similar to conventional concrete but

shifted to a higher level. Optimum dosage of silica

depends on many factors including type of water

reducing agent and type of cement. It can be

determined using trial mixes and, 10% of SF by

weight of cement is a good starting point.

3 EXPERIMENTAL PROGRAMME

3.1 GENERAL

The aim of the experimental program is

to compare the properties of Self-compacting

concrete made with and without silica fume and fly

ash, used as supplementary cementing material.

The basic tests carried out on concrete samples

are discussed in this chapter, followed by a brief

description about mix deign and curing procedure

adopted. At the end, the various tests conducted on

the specimens are discussed.







3.2 MATERIAL USED

3.2.1 CEMENT Ordinary Portaland Cement (53 Grade) is

used Cement is a fine, grey powder. It is mixed with

water and materials such as sand, & aggregate to

make concrete. The cement and water form a

paste that binds the other

materials together as the concrete hardens. The

ordinary Portland cement contains two basic

ingredients namely argillaceous and calcareous. In

argillaceous materials clay predominates and in

calcareous materials calcium carbonate

predominates. Basic composition of cement is shown

in Table

Table:3.1. Composition limits of Ordinary Portland

cement.

INGREDIENT % CONTENT

CaO (Lime) 60-67

SiO2 (Silica) 17-25

Al2O3 (Alumina) 3-8

Fe2 O3 (Iron Oxide) 0.5-6

MgO (Magnesia) 0.1-4

Alkalies 0.4-1.3

Sulphur 1-3

Grade of 53 cement was used for casting cubes and

cylinders for all concrete mixes.

The cement was of uniform colour i.e. grey with a

light greenish shade and was free from any hard

lumps. Summary of the various tests conducted on

cement are as under given below in Table

Table:3.2. Physical Properties of Cement

S.

No. Characteristics

Values

Obtained Standard values

1. Normal

Consistency 33% -

2. Initial Setting

time 52 min

Not be less than

30 minutes

3. Final Setting

time 330 min

Not be greater

than 600

minutes.

4. Fineness 8 % <10

5 Specific

gravity 3.09 -

3.2.2 FINE AGGREGATES

The sand used for the experimental

program of sieve analysis. The sand was first

sieved through 4.75 mm sieve to remove any

particles greater than 4.75 mm and then was washed to

remove the dust. Properties of the fine aggregate used

in the experimental work are tabulated in Table. The

aggregates were sieved through a set of sieves to

obtain sieve analysis and the same is presented in

Table.

Table:3.3. Physical Properties of fine aggregates Sr.

No. Characteristics Value

1. Type Natural

2. Specific Gravity 2.2

3. Dry Loose Bulk Density 1.39 kg/m3

4. Fineness Modulus 3.18

5. Grading Zone (Based on

percentage passing 0.60

mm)

Zone I

Table:3.4. Sieve analysis of fine aggregates

Sieve

Retained on

Each Sieve

Cumulative

%

Retained

Passing

Through

% Wt(gms) %

40.00

mm

20.00

mm

10.00

mm

10 1.0 1.0 99

4.75

mm

35 3.5 4.5 95.5

2.36

mm

40 4.0 8.5 91.5

1.18

mm

250 23.0 31.5 68.5

600

micron

430 43.0 74.5 25.5

300

micron

240 24.0 98.5 1.5

150

micron

10 1.0 99.5 0.5

Pan 05 0.5 100 0

Wt of

Sample

Total

1000 100 318

Total weight taken = 1000gm

Fineness Modulus of sand = 3.18

3.2.3 COARSE AGGREGATE All types of aggregates are suitable. The normal

maximum size is generally 10-20 mm; however

particle size up to 30 mm or more have been used in

SSC. Consistency of grading is of vital importance.

Regarding the characteristics of different types of

aggregate, crushed aggregates tend to improve the

strength because of the interlocking of the angular

particles, whilst rounded aggregates improve the

flow because of lower internal friction.







Table:3.5. Physical Properties of Coarse Aggregates

(20 mm)

Sr.

No

Characteristics Value

1. Type Natural


3. Dry Loose Bulk

Density

1.45Kg/Lit

4. Fineness Modulus 6.1

Table:3.6. Sieve Analysis of Coarse Aggregates

(20mm)

Sieve

Retained on Each

Sieve

Cumul

ative

%

Retaine

d

Passi

ng

Thro

ugh

%

Wt(gm

s)

%

40.00 mm

20.00 mm 155 15.5 15.5 84.5

10.00 mm 790 79.0 94.5 5.5

4.75 mm 55 5.5 100 0

2.36 mm

1.18 mm

600 micron

300 micron

150 micron

Pan

Wt of Sample

Total

1000 100 110

Total weight taken = 1000gm

3.2.4 Water Generally, water that is suitable for drinking is

satisfactory for use in concrete. Water from lakes

and streams that contain marine life also usually is

suitable. When water is obtained from sources

mentioned above, no sampling is necessary. When it

is suspected that water may contain sewage, mine

water, or wastes from industrial plants or canneries, it

should not be used in concrete unless tests indicate

that it is satisfactory. Water from such sources should

be avoided since the quality of the water could change

due to low water or by intermittent tap water is used

for casting.

3.2.5 SUPPLEMENTARY CEMENT

MATERIALS

3.2.5.1 MICROSILICA Microsilica’s effectiveness as a pozzolonic

and filler depends largely on its composition and

particle size which in turn depend on the design of

the furnace and the composition of the raw materials

with which the furnace is charged. Dosages of

microsilica used in concrete have typically been in

the range of 10 percent by weight of cement. Used as

an microsilica can improve the properties of both

fresh and hardened concrete. Used as a partial

replacement for cement, microsilica can substitute

for energy-consuming cement without sacrifice of

quality.

Addition of silica fume enhanced the

resistance of cement mortar to chemical attack of

acid and sulphates resistance of silica fume cement

pastes to sulphate attack was comparable to sulphate

resisting cement. This has been attributed to fine

pore structure and reduction of lime content of silica

fume concrete. The ability of silica fume to hold

alkalis was found responsible for reducing alkali

silica expansion reaction.

Table: 3.7. Physical Properties of Microsilica

Sr.

No. Physical Properties Test Result

1. Particle Shape Spherical

2. Colour White Grey


4. Particle Size 0.1Micron

5. Specific Surface Area 20 m3/g

6. Dry Bulk Loose

Density

400-700 gm/ lit

Table:3.8. Chemical composition of Microsilica

Constituents Percent

SiO2 90-96

Al2O3 0.5-0.8

MgO 0.5-1.5

Fe2O3 0.2-0.8

CaO 0.1-0.5

Na2O 0.2-0.7

K2O 0.4-1.0

C 0.5-1.4

S 0.1-0.4

3.2.5.2 FLY ASH Fly ash is finely divided residue resulting

from the combustion of powdered coal and

transported by the fuel gases and collected by

electrostatic precipitator. In conclusion it may be

said that although fly ash is an industrial waste, it is

use in concrete significantly improve the long term

strength and durability and reduce heat of hydration.

In other words good fly ash will be an indispensable

mineral admixture for Self compacting concrete and

high performance concrete. It increase the

workability of concrete which permits fuller

compaction fly ash also maintain pH of concrete by

consumption of calcium hydroxide in some amount

which will be liberated by amount hydration and

avoided the corrosion of steel in concrete.







ASTM broadly classify Fly Ash into two classes

Class F Fly ash: Fly ash normally produced

from burning anthracite or bituminous coal

falls in this category. This class of fly ash

exhibits pozzolanic property but rarely if

any, self-hardening property.

Class C Fly ash: Fly ash normally produced

from lignite or sub- bituminous coal is the

only material included in this category. This

class of fly ash has both pozzolanic and

varying degree of self cementitious

properties. (Most class C fly ashes contain

more than 15 % CaO. But some class C fly

ashes may contain as little as 10 % CaO.

Class F Fly Ash obtain from Dahanu

Table:3.9. Physical Properties of Class F Fly Ash

Sr.No. Physical Properties Test Result

1 Colour Grey (Blackish)

2 Specific Gravity 2.13

Table:3.10. Chemical Properties of Class F Fly Ash

Sr. No Constituents Percent by

Weight

1 Loss on ignition 4.17

2 Silica (SiO2) 58.55

3 Iron Oxide (Fe2O3) 3.44

4 Alumina (Al2O3) 28.20

5 Calcium Oxide (CaO) 2.23

6 Magnesium Oxide (MgO) 0.32

7 Total Sulphur (SO3) 0.07

8 Insoluble residue -

9 Alkalies a) Sodium Oxide

(Na2O)

b) Potassium

Oxide (K2O)

0.58

1.26

3.2.5.3 ADMIXTURE

Superplasticizers are an essential component of SCC

to provide necessary workability. Superplasticizer has

been primarily developed for application in self

compacting concrete, ready mix concrete and precast

concrete industries where the highest durability and

performance is required. Field of Application / Used

It is higher range of super plasticizer and work as a

“Hyperplasticizer” It is intended of application where

high range is required and it is developed for:-

1) Self compacting concrete

2) Concrete with highest water reducer (upto

40%)

3) Concrete requiring long workability

retention

4) Precast concrete / Pumped concrete

Table :3.11. Physical Properties of super

plasticizer

Sr.No. Physical

Properties

Test Results

1 Name AC-VISCOCRETE-P

2 Colour Brown free flowing

liquid

3 Relative density 1.22

4 PH 7 To 8

5 Chloride content Nill

3.3 MIX DESIGN (FOR M20)

1 Concrete Specification

Strength: Characteristic Compressive Strength

(Fck)= 20N/mm2

Workability: = Medium

(Table:3.12. Workability (IS: 456 2000))

Durability: Exposure Condition = Mild

(Table:3.13. Environmental Exposure Condition (IS:

456 2000))

2. Materials Properties a) Fine Aggregates

Zone =Zone 1

Table:3.14. Grading limit for fine aggregate (IS:

383-1970)

IS

Sieve

Equivalent

BS Sieve

Zone-

1

Zone-

2

Zone-

3

Zone-

4

10-mm 3/8-in 100 100 100 100

4.75-

mm

3/16-in 90-

100

90-

100

90-

100

95-

100

2.36-

mm

No. 7 60-95 75-

100

85-

100

95-

100

1,18-

mm

No. 14 30-70 55-90 75-

100

90-

100

600-

micron

N0. 25 15-34 35-59 60-79 80-

100

300-

micron

No, 52 5-20 8-30 12-40 15-50

150-

micron

No. 100 0-10 0-10 0-10 0-15

Specific Gravity =2.18

Dry Loose Bulk Density (DLBD)

=1.29Kg/lit

b) Coarse Aggregates

Specific Gravity =2.48

Dry Loose Bulk Density (DLBD)

=1.40Kg/lit

Maximum Aggregate Size = 20mm

c) Cement

Type of Cement (Fm) =OPC 53 Grade

Standard Deviation (s) =20.1Kg/cm3

Characteristic Strength of cement (Fc)=49.58N/mm2

(Fc = Fm – 1.65 s)

Cement Grade = Grade “D”

Table:3.15. 28 – Day Strength of Cement tested

according to (IS : 4031-1968)







28 – Day Strength of Cement tested according to

IS : 4031-1968 A 31.9 – 36.8 N/mm

2 E 51.5

– 56.4 N/mm2

B 36.8 – 41.7 N/mm2 F 56.4 –

61.3 N/mm2

C 41.7 – 46.6 N/mm2

G* 61.3

– 66.2 N/mm2

D 46.6 – 51.5 N/mm2

2 Maximum W/C ratio =0.5

(Table:3.16. Maximum water-cement ratio (IS:456

2000))

3 Minimum Cement Content

=290Kg/m3

4 Slump – in mm

=75mm.

5 Slump – Degree in workability

=Medium

6 Target Strength

Standard Deviation‘s =5N/mm2

Value of ‘t’ =1.65

(Table:3.17. Assumed Standard Deviation (IS: 456

2000)

Table:3.18. Value of “t” (IS: 10262-1982)

Acceptance proportion

of low result

“t”

1 in 5 0,84

1 in 10 1.28

1 in 15 1.50

1 in 20 1,65

1 in 40 1,96

1 in 100 2.33

Target Mean Strength Fm =28.25 N/mm2

(Fm = Fck + t x s)

(Relation between free water/cement ratio and

concrete strength at 28 days for different Cement

curves (IS: 10262-1982)) 8. Water - Cement ratio [W/C] (from Graph) =0.48

9. Final W/C =0.48

C FA CA Water

1 2.20 2.5 0.48

Table:3.19. Mix Proportion

Mix

ture

Ce

me

nt

(Kg

/m3)

SF

(Kg

/m3)

FA

(Kg

/m3)

San

d

(Kg

/m3)

CA

(Kg

/m3)

W

ate

r

SP

(Kg

/m3)

CC 410 915 990 19

4

SC 369 41 915 990 21

C-1 4

SC

C-A

287 41 82 915 990 21

4

6.5

SC

C-B

246 41 123 915 990 21

4

6.5

SC

C-C

205 41 164 915 990 21

4

6.5

Table: mix proportion for 1 cubic meter of

concrete.

Where,

CC= Conventional Concrete

SCC-1= Self Compacting Concrete with 10%

Microsilica.

SCC-A= Self Compacting Concrete wite 10%

Microsilica,

20% Fly Ash, & 2.4% Superplasticizer.

SCC-B= Self Compacting Concrete wite 10%

Microsilica,

30% Fly Ash, & 2.4% Superplasticizer

SCC-C= Self Compacting Concrete wite 10%

Microsilica,


SF= Silica Fume or Microsilica.

FA= Fly Ash.

CA= Coarse Aggregate.

SP= Superplasticizer.

3.4 TEST CONDUCTED

3.4.1 FRESH CONCRETE TESTS.

SCC differs from conventional concrete in

that its fresh properties are vital in determining

whether or not it can be placed satisfactorily.

It is important to appreciate that none of the test

methods for SCC has yet been standardized, and the

tests described are not yet perfected or definitive.

The methods presented here are descriptions rather

than fully detailed procedures. They are mainly ad-

hoc methods, which have been devised specifically

for SCC.

3.4.1.1 SLUMP FLOW TEST

Introduction

The slump flow is used to assess the horizontal

free flow of SCC in the absence of obstructions.

It was first developed in Japan for use in

assessment of underwater concrete. The test method

is based on the test method for determining the

slump. The diameter of the concrete circle is a

measure for the filling ability of the concrete.

Assessment of test

This is a simple, rapid test procedure, though two

people are needed if the T50 time is to be measured.

It can be used on site, though the size of the base

plate is somewhat unwieldy and level ground is

essential. It is the most commonly used test, and

gives a good assessment of filling ability. It gives







no indication of the ability of the concrete to

pass between reinforcement without blocking, but

may give some indication of resistance to

segregation. It can be argued that the completely

free flow, unrestrained by any boundaries, is

not representative of what happens in practice in

concrete construction, but the test can be

profitably be used to assess the consistency of

supply of ready-mixed concrete to a site from load

to load.

Equipment

The apparatus is shown in Fig.

Mould in the shape of a truncated cone with

the internal dimensions 200 mm diameter at

the base, 100 mm diameter at the top and a

height of 300 mm.

Base plate of a stiff non absorbing material,

at least 700mm square, marked with a circle

marking the central location for the slump

cone, and a further concentric circle of

500mm diameter.

Trowel

Scoop

Measuring Tape

Procedure

About 6 liter of concrete is needed to

perform the test, sampled normally.

Moisten the base plate and inside of slump

cone, Place base plate on level stable ground

and the slump cone centrally on the base plate

and hold down firmly.

Fill the cone with the scoop. Do not tamp,

simply strike off the concrete level with the

top of the cone with the trowel.

Remove any surplus concrete from around the

base of the cone.

\Raise the cone vertically and allow the

concrete to flow out freely.

Measure the final diameter of the concrete in

two perpendicular directions.

Calculate the average of the two measured

diameters. (This is the slump flow in mm).

Note any border of mortar or cement paste

without coarse aggregate at the edge of the

pool of concrete.

Interpretation of result

The higher the slump flow (SF) value, the greater its

ability to fill formwork under its own weight. A value

of at least 650mm is required for SCC. There is no

generally accepted advice on what are reasonable

tolerances about a specified value, though ±

50mm, as with the related flow Table test, might be

appropriate.

3.4.1.2 V-FUNNEL TEST

Introduction

The equipment consists of a V-shaped funnel,

shown in Fig. 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 liters of concrete

and the time taken for it to flow through the

apparatus measured.

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 result - if, 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 are not clear.

Equipment

V-funnel

Bucket ( ±12 liter )

Trowel

Scoop

Stopwatch

Procedure for flow time



Set the V-funnel on firm ground.

Moisten the inside surfaces of the funnel.

Keep the trap door open to allow any surplus

water to drain.

Close the trap door and place a bucket

underneath.

Fill the apparatus completely with concrete

without compacting or tamping, simply

strike off the concrete level with the top with

the trowel.

Open within 10 sec after filling the trap

door and allow the concrete to flow out







under gravity.

Start the stopwatch when the trap door is

opened, and record the time for the

discharge to complete (the flow time).

This is taken to be when light is seen

from above through the funnel.


This test measures the ease of flow of the

concrete; shorter flow times indicate greater

flowability. For SCC a flow time of 8 to 12 seconds

is considered appropriate.

3.4.1.3 L-BOX TEST

Introduction

This test is based on a Japanese design for underwater

concrete. 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 Fig.

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,

and 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 T20 and T40 times 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 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 ability of the concrete.

Assessment of test

This is a widely used test, suitable for laboratory, and

perhaps site use. It assesses filling and passing ability

of SCC, and serious lack of stability (segregation)

can be detected visually Segregation may also be

detected by subsequently sawing and inspecting

sections of the concrete in the horizontal section.

Unfortunately there is no agreement on materials,

dimensions, or reinforcing bar arrangement, so it is

difficult to compare test results. There is no evidence

of what effect the wall of the apparatus and the

consequent wall effect‘ might have on the concrete

flow, but this arrangement does, to some extent,

replicate what happens to concrete on site when it is

confined within formwork. Two operators are required

if times are measured, and a degree of operator error

is inevitable.

Equipment

L box of a stiff non absorbing material see

Fig

Trowel

Scoop

Stopwatch

Procedure



Set the apparatus level on firm ground,

ensure that the sliding gate can open freely

and then close it.

Moisten the inside surfaces of the apparatus,

remove any surplus water.

Fill the vertical section of the apparatus with

the concrete sample.

Leave it to stand for 1 minute.

Lift the sliding gate and allow the concrete to

flow out into the horizontal section.

Simultaneously, start the stopwatch and

record the times taken for the concrete to

reach the 200 and 400 mm marks.

When the concrete stops flowing, the distances

H1 and H2are measured.

Calculate H2/H1, the blocking ratio.

The whole test has to be performed within 5

minutes.


If the concrete flows as freely as water, at rest it will

be horizontal, so H2/H1 = 1. Therefore the nearer this

test value, the ‗blocking ratio‘, is to unity, the better

the flow of the concrete. The European Union research

team suggested a minimum acceptable value of 0.8.

T20 and T40 times an give some indication of ease

of flow, but no suitable values have been generally

agreed. Obvious blocking of coarse aggregate behind

the reinforcing bars can be detected visually.

3.4.1.4 U- BOX TEST

Introduction

The test was developed by the Technology

Research Centre of the Taisei Corporation in Japan.

Sometimes the apparatus is called a U-Box 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. An

opening with a sliding gate is fitted between the

two sections. Reinforcing bars with nominal

diameters of 13 mm are installed at the gate with

centre-to-centre spacing of 50 mm. This creates a

clear spacing of 35 mm between the bars. The left






Imperial Journal of Interdisciplinary Research (IJIR) 37

hand section is filled with about 20 liter of

concrete then the gate lifted and concrete flows

upwards into the other section. The height of the

concrete in both sections is measured.

Assessment of test

This is a simple test to conduct, but the equipment

may be difficult to construct. It provides a good direct

assessment of filling ability, this is literally what the

concrete has to do, modified by an unmeasured

requirement for passing ability. The 35mm gap

between the sections of reinforcement may be

considered too close. The question remains open of

what filling height less than 30 cm. is still acceptable.

Equipment

U box of a stiff non absorbing material see

Fig

Trowel

Scoop

Stopwatch

Procedure



Set the apparatus level on firm ground,

ensure that the sliding gate can open freely

and then close it.

Moisten the inside surfaces of the apparatus,

remove any surplus water. Fill the one

compartment of the apparatus with the

concrete sample. Leave it to stand for 1

minute.

Lift the sliding gate and allow the concrete to

flow out into the other compartment.

After the concrete has come to rest,

measure the height of the concrete in the

compartment that has been filled, in two

places and calculate the mean (H1). Measure

also the height in the other compartment

(H2)

Calculate H1 - H2, the filling height.

The whole test has to be performed within 5

minutes


If the concrete flows as freely as water, at rest it will be

horizontal, so H1 - H2 = 0. Therefore the nearer this

test value, the ‗filling height‘, is to zero, the better the

flow and passing ability of the concrete.

3.4.2 HARDNESS CONCRETE TEST

3.4.2.1 CASTING OF CUBE

At a time 12 cubes were cast in the

laboratory of size 15 cm x l5 cm x 15 cm. The

casting of cubes was done as follows.

First of all the moulds used for casting

purpose were oiled from inside so that the concrete

will not stick to the surface. Then nuts and bolts were

checked, whether well tightened or not. Immediately

after mixing the concrete was field in mould. This

concrete as SCC compaction was not required. Like

this 12 moulds cubes were filled

3.4.2.2 CURING OF CUBE The prepared cubes are kept as such as a temperature

27°±2°C in an atmosphere of at least 90% relative

humidity for 24 hrs. From the time of addition of

water to dry ingredients. At the end of this period

concrete cubes are taken out of mould for curing

purpose. The method of curing by pounding in this

method after taking out cubes from the mould they

are immediately submerged in clean and fresh water

for curing and kept for specific period till they are

taken out for testing purpose.

3.4.2.3 COMPRESSIVE STRENGTH

Objective: Determination of compressive strength of

concrete.

Apparatus: Testing Machine: The testing machine

may be of any reliable type of sufficient capacity for

the tests and capable of applying the load at the

specified rate. The permissible error shall not be

greater than 2 percent of the maximum load. The

testing machine shall be equipped with two steel

bearing platens with hardened faces. One of the

platens shall be fitted with a ball seating in the form

the portion of the sphere, the centre of which

coincides with the central point of the face of the

platen. The other compression platen shall be plain

rigid bearing block. The bearing faces of both platens

shall be at least as larger as, and preferably larger than

the normal size of the specimen to which the load is

applied.

Age at test: Tests shall be made at recognized ages of

the test specimens, the most usual being 3, 7, 14 & 28

days. The ages shall be calculated from the time of the

addition of water of the dry ingredients.

Number of Specimens: At least three specimens,

preferably from different batches, shall be made for

testing at each selected age of 3, 7, 14, 28 days.

Procedure: Specimens stored in water shall be tested

immediately on removal from the water and while

they are still in the wet condition. Surface water

and grit shall be wiped off the specimens and any

projecting find removed specimens when received

dry shall be kept in water for 24 hours before they

are taken for testing. The dimensions of the

specimens to the nearest 0.2mm and their weight

shall be noted before testing. Placing the specimen

in the testing machine the bearing surface of the

testing machine shall be wiped clean and any loose

sand or other material removed from the surface of

the specimen, which are to be in contact with the

compression platens. In the case of cubes, the







specimen shall be placed in the

machine in such a manner that the load shall be

applied to opposite sides of the cubes as cast, that is,

not to the top and bottom. The axis of the specimen

shall be carefully aligned with the centre of thrust of

the spherically seated platen. No packing shall be

used between the faces of the test specimen and steel

platen of the testing machine. As the spherically

seated block is brought to bear on the specimen, the

movable portion shall be rotated gently by hand so

that uniform seating may be obtained. Until the

resistance of the specimen to the increasing load

breaks down and any unusual features in the type

of failure shall be noted.

Calculation: The measured compressive strength

of the specimen shall be calculated by dividing

the maximum load applied to the specimen during

the test by the cross sectional area, calculated from

the mean dimensions of the section and shall be

expressed to the nearest Kg/cm2. Average of three

values shall be taken for calculation

3.5 RESULTS AND DISCUSSIONS

4.1 GENERAL

In this experimental programs studied on

the conventional concrete & with replacement of

fly ash and Microsilica with cement in self-

compacting concrete are discussed. The

parameters such as Compressive strength and

comparisons between the various mixes are

represented.

4.2 FRESH CONCRETE TEST In order to study the effect on fresh concrete

properties when Microsilica and Fly Ash is added

into the concrete as cement replacement, the SCC

containing different proportion of microsilica and fly

ash were tested for Slump flow, V- Funnel, L-Box,

U-Box.

The result of fresh properties of Self compacting

microsilica and fly ash concrete are included in

table. Table shows the properties such as Slump

flow, V- Funnel, L-Box, U-Box. In terms of slump

flow, all SCC exhibited satisfactory slump flows in

rang of 550-800 mm, which is an indication of a

good deformability.

Table: 4.1. Fresh concrete properties

Mixture Slump

Cone

(mm)

Slump

Flow

(mm)

V-

Funnel

(sec)

L-Box

(H1/H2)

U-

Box

(H1-

H2)

CC 95

SCC-1 160 550 14 0.67 55

SCC-A 660 & 12 0.83 30

690

SCC-B 700 &

700

11 0.89 10

SCC-C 720 &

690

11 0.96 5

As per EFNARC, Time ranging for V-Funnel from 6

to 12 seconds is considered adequate for a SCC. The

V-funnel flow times were in the range of 4-10

seconds. Test results of this investigation indicated

that all SCC mixes meet the requirements of

allowable flow time. Maximum size of coarse

aggregate was kept as 20 mm in order to avoid

blocking effect in the L-box. The gap between re-

bars in L-box test was 35 mm. The L-box ratio

H2/H1 for the mixes was above 0.8 which is as per

EFNARC standards. U-box difference in height

of concrete in two compartments was in the range

of 5-40 mm. All the Fresh properties of concrete

values were in good agreement to that of the values

given by European guidelines.

Fig:4.1. Slump flow test at various mixes

Fig Fig: 4.2. V-Funnel test at various mixes







3.1: Fig: 4.3. L-Box test at various mixes

Fig: 4.4. U-Box test at various mixes

4.3 HARDENED CONCRETE TEST

In order to study the effect on compressive

strength when microsilica and fly ash is added into

self compacting concrete as cement replacement, the

cube containing different proportion of microsilica

and fly ash are prepared and kept for curing for 3,

7,14 and 28 days. The test are conducted on

compressive testing machine of capacity 2000 KN.

Table: 4.2. CC= Conventional Concrete

Compressive strength of cubes

Mix Curing

Period

Number

Of Cube

Compressive

strength(MPa)

Average

Compressive

strength(MPa)

M20 3 Days 1 12.21

2 9.8 10.25

3 8.72

7 Days 1 16.13

2 13.08 13.95

3 12.64

14 Days 1 19.18

2 17 18.18

3 18.3

28 Days 1 21.36

2 23.54 24.3

3 27.9

Table:4.3. SCC-1= Self Compacting Concrete with

10% Microsilica.


Mix Curing

Period

Number

Of Cube

Compressive

strength(MPa)

Average

Compressive

strength(MPa)

M20 3 Days 1 13.95

2 10.9 12.5

3 12.64

7 Days 1 17.44

2 18.3 17.29

3 16.13

14 Days 1 23.54

2 19.18 21.5

3 21.8

28 Days 1 30.52

2 27.9 27.9

3 25.28

Table:4.4. SCC-A= Self Compacting

Concrete with 10% Microsilica,



Mix Curing

Period

Number

Of Cube

Compressive

strength(MPa)

Average

Compressive

strength(MPa)

M20 3 Days 1 10.7

2 13.2 12.2

3 12.6

7 Days 1 18.6

2 19.0 18.3

3 17.3

14 Days 1 20.5

2 19.6 20.6

3 21.8

28 Days 1 27.3

2 26.7 27.16

3 27.5

Table: 4.5. SCC-B= Self Compacting

Concrete with 10% Microsilica,









Mi

x

Curi

ng

Perio

d

Numb

er Of

Cube

Compressiv

e

strength(M

Pa)

Average

Compressiv

e

strength(M

Pa)

M2

0

3

Days 1 11.9

2 12.6 11.6

3 10.3

7

Days 1 16.1

2 18.5 17.1

3 16.7

14

Days 1 20.1

2 18.2 19.43

3 20.0

28

Days 1 25.7

2 26.6 26.06

3 25.9

Table: 4.6. SCC-C= Self Compacting Concrete with

10% Microsilica, 40% Fly Ash, &

2.4% Superplasticizer


Mix Curing

Period

Number

Of

Cube

Compressive

strength(MPa)

Average

Compressive

strength(MPa)

M20 3 Days 1 9.3

2 10.5 10.3

3 11.2

7 Days 1 13.2

2 14.6 14.1

3 14.4

14

Days 1 16.5

2 18.7 17.7

3 17.8

28

Days 1 21.9

2 22.5 22.2

3 22.2

Fig: 4.5. Compressive strength of SCC mixes at

various ages

Where,

CC= Conventional Concrete

SCC-1= Self Compacting Concrete with 10%

Microsilica.

SCC-A= Self Compacting Concrete wite 10%

Microsilica,


SCC-B= Self Compacting Concrete wite 10%

Microsilica,


SCC-C= Self Compacting Concrete wite 10%

Microsilica,


3.6 CONCLUSION CONCLUSION On the basis of experimentation work carried out, the

following conclusions are drawn:

1. As per the observed workability and high

flow ability of SCC, it can be used in highly

congested reinforcement structure as

compare to conventional concrete.

2. 10% replacement of microsilica for cement

makes a good strength of concrete.

3. The compressive strength for design mixes

3 Days, 7 Days, 14 Days, 28 Days are

obtained 11.6MPa, 17.1MPa, 19.4MPa,

24.3MPa respectively using 10% of

Microsilica and 30% 0f Fly Ash for 53

grade of cement.

4. Compressive strength of conventional

concrete is obtained nearly equal to the

compressive strength of Self Compacting

Concrete using 10% Microsilica, 30% fly

ash and 2.4% super plasticizer.

5. SCC with 10% of Microsilica & 30% of Fly

Ash replacement the fresh properties &







compressive strength were good, after

increase the % of Fly Ash above 30% the

compressive strength of a concrete is

decrease.

6. On a basis of total cost, including the labors

charges, formwork and making good

finished surfaces, SCC can be more

advantageous.

7. Fly ash is very cheap, it can be used

successfully in place of cement, it gives

good results at very low content.

8. At this water/cement ratio, the Slump flow

test, V-funnel test, L-Box test, U-Box test

results were found to be satisfactory.

3.7 References

1. Friede Bernd - “Microsilica

Charecterization Of An Unique

Additive” , Sao Paulo, Brazil. October

15 - 18, 2006.

2. Md Safiuddin, S. N. Raman and

M.F.M. Zain - “Effect of Different

Curing Methods of the Properties of

Microsilica Concrete”, Australian

Journal of Basic andApplied Sciences,

1(2): 87-95, 2007.

3. Paramita Mondal, Surendra P. Shah,

Laurence D. Marks, and Juan J. Gaitero

- “Comparative Study of the Effects of

Microsilica and Nanosilica in

Concrete”, Transportation Research

Board of the National Academies,

Washington,2010, pp.6–9.

4. EFNARC, (2002). Specifications and

Guidelines for Self-Compacting

Concrete, EFNARC, UK

(www.efnarc.org), pp. 1-32.

5. IS: 456-2000



http://www.efnarc.org/

experimental investigation of use of ... · cementing material. ... l-box test and u-tube tests,...

Documents