Ijri cce 02 002

International Journal of Research and Innovation (IJRI)

International Journal of Research and Innovation (IJRI) INFLUENCE OF VISCOSCITY MODIFYING ADMIXTURES ON FRESH AND HARD1401-1402 ENED PROPERTIES OF SELF COMPACTING CONCRETE WITH VARYING DOSAGE OF FLYASH Shraddha1, M.V.Seshagiri rao2, K. Mythili3 1 Research Scholar, Department Of Civil Engineering, Aurora Scientific Technological and Research Academy, Hyderabad India.

2 Professor, Department Of Civil Engineering, JNTU Hyderabad, Hyderabad, India 3 Associate professor , Department Of Civil Engineering, Aurora Scientific Technological and Research Academy, Hyderabad India.

Abstract The use of self-compacting concrete (scc) in general building and civil engineering constructions is becoming popular over the years ever since it was invented and guide-lines have been formulated by the efnarc (european federation of national association representing concrete) in 2005. Although in india, we do not have any specific codal provisions for scc similar to normal concrete, considerable research has been done in both development of scc and its applications with various admixtures and fibers to enhance the properties of scc in hardened state. As scc is very sensitive to variations in moisture content and gradation of aggregates, construction sites face difficulties in free flow of scc.

In order to overcome this, viscosity modifying admixtures (vmas) have been introduced by the researchers apart from efnarc releasing guide-lines for vma for concrete in september-2006, as extensive studies have become imperative on the role of vma in scc.

The primary aim of this study is to explore the influence of vma on fresh and hardened properties of scc with varying dosage of mineral admixture namely fly ash and chemical admixture i.E. Super plasticizer for standard grade scc mixes of m30 grade. It is proposed to design m30 grade scc concrete mix and study in detail the fresh and hardened properties like 3-day, 7-day and 28-day compressive strengths for the mixes with the above variables. The test results of the specimens shall be compared for compressive strength of different mixes of scc and control mix and arrive at specific conclusions on the role of vma in the presence of admixtures. *Corresponding Author: Shraddha , Research Scholar, Department Of Civil Engineering, Aurora Scientific Technological and Research Academy, Hyderabad India.

Published: January 02, 2015 Review Type: peer reviewed Volume: II, Issue : I

Citation: Shraddha , Research Scholar (2014) "Influence Of Viscoscity Modifying Admixtures On Fresh And Hardened Properties Of Self Compacting Concrete With Varying Dosage Of Flyash"

INTRODUCTION GENERAL Present-day self-compacting concrete (scc) can be classified as an advanced construction material. As the name suggests, it does not require to be vibrated to achieve full compaction. This offers many benefits and advantages over conventional concrete.

These include an improved quality of concrete and reduction of on-site repairs, faster construction times, lower overall costs, facilitation of introduction of automation into concrete construction. An important improvement of health and safety is also achieved through elimination of handling of vibrators and a substantial reduction of environmental noise loading on and around a site. The composition of scc mixes includes substantial proportions of coarse and fine-grained inorganic materials and

this gives possibilities for utilization of mineral admixtures, which are currently waste products with no practical applications.

OBJECTIVES AND SCOPE GENERAL Despite its advantages and versatile nature, SCC has not gained much popularity in India, though it has been widely promoted in the Middle East for the last two decades. Awareness of SCC has spread across the world, prompted by concerns with poor consolidation and durability in case of conventionally vibrated normal concrete.

All the researchers have developed SCC taking the CA/FA ratio and also considered the limited content of coarse aggregate and more content of fines. But, there are very limited investigations reported considering the size effect of coarse aggregate content in the development of SCC. Keeping this in view, the present experimental investigation is taken up to study the effect of size of coarse aggregate in the development of M70 grade of Self Compacting Concrete. Powder content is the main aspect of a SCC mix design. In the present work, flyash is maximized in the SCC mixes as a filler material.

Keeping in view the idea explained above, a detailed and a systematic experimental program is laid down as explained in the next paragraphs. The main objective of the present investigation is:

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To study the effect of the viscosity modifying admixtures on fresh and hardened properties of M30 grade self compacting concrete with different dosage of fly ash by using Nansu mix design and rational mix design procedure.

With the above objectives in mind the experimental program is categorized as detailed below.

• Casting of cubes 3 for each type of mix say control mix, 20% replacement of fly ash,30% replacement of fly ash and with different dosage of VMA. • In this study, M30grade of SCC with different fly ash dosage and VMA dosage were designed based on Nan Su method and rational method, to determine the effect of VMA on SCC.The grade of concrete and age of curing were the parameters in the study.

A detailed experimental program was planned to achieve the objective of the study is explained in Chapter – 4.

EXPERIMENTAL INVESTIGATIONS ON SELF COMPACTING CONCRETE GENERAL In this chapter,wide spread applications of scc have been restricted due to lack of standard mix design procedure and testing methods. It is pertinent to mention that only features of scc have been included in indian standard code of practice for plain and reinforced concrete (fourth revision), [2000]. Slump flow test, l-box test, v-funnel test, u-box test, orimet test & gtm screen test are recommended by efnarc [european federation of producers and applicators of specialist products for structures, may 2005] for determining the properties of scc in fresh state.

MATERIALS Cement Coarse Aggregate Fine Aggregate Fly Ash Super Plasticizer Viscosity Modifying Admixture (VMA) Water

Mix Design and Trial Mix Proportions of Self Compacting Concrete An SCC mix of M30 standard grade was aimed and the initial mix proportion was obtained using the mix design methods as mentioned above. The mix proportion thus obtained was fine-tuned by incorporating different guidelines available and making various trial mixes to obtain the mix which satisfies the required fresh and hardened properties. The detailed mix design calculations are given in Appendix I. The final mass of ingredients for 1m3 of SCC is as follows: Mass of Cement = 330.0 kg Mass of filler (Fly Ash) = 150.0 kg Mass of water = 186.0 kg Mass of Coarse Aggregate (CA) = 795.5 kg Mass of Fine Aggregate (FA) = 870.4 kg Super plasticizer dosage = 1.8% by weight of cement VMA dosage = 0.1 to 0.6% by weight of cement (bwc) 2Mixing of Ingredients The mixing of ingredients was carried out in a power operated pan type concrete mixer. Initially coarse aggregate, fine aggregate, cement and fly ash were put in the pan mixer and mixed in the dry state for a few seconds. Then Super plasticizer (SP) was added to the water, thoroughly mixed and added to the material in the concrete mixer. The required amount of VMA was added and further mixed till a mix of required uniform consistency was achieved.

Methods of Evaluation of Workability of SCC Workability test methods available for conventional concrete mixes are not adequate for evaluation of workability of Self-Compacting Concrete mixes as they are not sensitive to ascertain all the requirements of Self-Compacting Concrete mixes. Different test methodologies were developed to characterize the fresh properties of

PHASE I: DEVELOPMENT OF PLAIN SCC AND INVESTIGATIONS ON ITS FRESH AND HARDENED PROPERTIES In this phase of investigations, M30 grade SCC mix is developed using mineral and chemical admixtures to study its fresh and hardened properties.

For developing SCC of M30 grade, the mix proportions were designed based on the method suggested

by Nan-Su et al (2001) and SV Rao et al(2010) using fly ash as mineral admixture and chemical admixtures like Super Plasticizers (SP) and Viscosity Modifying Agents (VMA). Finally, SCC mixes which have given required compressive strength with satisfactory fresh properties were taken for the next phase of investigations. This is explained in detail as given below.

SCC mixes. No single method was available till date, to assess relevant workability requirements. Hence, 123

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the SCC mixes have to be tested using more than one test for measuring different workability parameters. The following are the test methods available to characterize the desired workability requirements and for the finalization of fresh Self-Compacting Concrete mixes.

Slump Flow Test and T 50 cm Test The slump flow test is used to ascertain the free flow of Self Compacting Concrete without obstructions.

Interpretation of the results: Higher slump flow value indicates greater ability to fill the formwork under its own weight. A minimum value of 650mm is recommended for SCC. The T50 time is also an indication of SCC flow. A lower time means greater flowability. The research suggested a time range of 3-7 seconds for general civil engineering applications and 2-5 seconds for general housing applications (T.Suresh Babu,2008).

V-Funnel Test This test is performed to determine the filling ability (flowability) of the Self-Compacting Concrete.

Slump Flow Test Procedure: • About six litres of SCC is required to perform this test.

• First moisten the base plate and the inside surface 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 slump cone with SCC using a scoop. Do not tamp the concrete. Strike off the concrete surface with the top level of the cone with a trowel.

• Any surplus concrete in and around the base of the slump cone has to be removed.

• Lift the cone vertically and allow the SCC to flow freely.

• Start the stopwatch simultaneously, and record the time taken for concrete to spread upto the 500mm circle marked. (This is called T50 cm test).

• Afterwards, measure the final diameter of the concrete spread in two or more perpendicular directions.

• Then calculate the average of the measured diameters which is termed as the slump flow.

Procedure for V-Funnel Test : • Take about 12 litres of concrete to perform this test.

• Keep the V-funnel on level ground.

• Moist the inside surface of the V-funnel • Open the trap door to drain out any surplus water.

• Now close the trap door and keep a bucket underneath the V-funnel.

• Now fill the V-funnel apparatus completely with the SCC without any compaction or tamping. Then strike off the excess concrete and level the top with the help of a trowel.

• Open the trap door within 10 seconds after filling the funnel.

• Now allow the concrete to flow out of the funnel under gravity.

• Start a stopwatch immediately after the trap door of the funnel is opened. Record the flow time taken 124

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for the concrete to discharge completely from the funnel. This is recorded when light is seen from the top through the funnel.

• The test is to be completed within 5 minutes time.

Procedure: • Take about 14 litres of self-compacting concrete for performing this test.

• Place the apparatus on a level ground and ensure free opening and closing of sliding shutter. Moisten the inside surface of the L box apparatus.

• Fill the vertical section of the apparatus with the scc sample.

• Lift the sliding gate and allow the scc to flow out into the horizontal section.

• Start the stopwatch simultaneously, and the time taken for the scc to reach the 200mm and 400mm marks are to be recorded.

• The heights “h1” and “h2” are measured, when the scc stops flowing. Calculate the ratio h2/h1, which is the blocking ratio.

• The complete test is to be performed within a time of 5 minutes.

Procedure for flow time at T5 minutes • Take the same setup as above of v-funnel test and do not clean the inside of the funnel again.

• Close the trap door and fill the v-funnel apparatus completely with concrete, again without compaction. Strike off the excess concrete on top and level the top surface with a trowel.

• Place a tub underneath the funnel.

• Open the funnel door after 5 minutes after the filling of the funnel the second time and allow the concrete to flow freely under gravity.

• Start the stopwatch simultaneously when the door is opened, and record the time taken for the concrete to completely come out. This is the flow time at t5 minutes. This time is to be recorded when the light is seen from the top of the funnel.

Interpretation of results: The above test measures the ease of flow of the scc; shorter flow times indicate greater flow ability. For scc, 10 seconds flow time is considered appropriate.

Five minutes after settling, segregation of concrete indicates a lesser flow with an increase in the flow time.

L Box Test The test is for assessing the flow of the SCC and the blocking resistance.

Interpretation of results: If the concrete flows freely without any resistance, H2/H1 will be unity. Therefore the nearer the ‘blocking ratio’ to unity, the better the flow of the SCC. The European Guidelines [84] suggests a minimum value of 0.8.

Acceptance criteria for SCC S.No

Method

Unit

Minimum

Maximum

1

Slump flow by Abrams cone

mm

650

800

2

T 50 Slump flow

sec

2

5

3

J-ring

mm

0

10

4

V-Funnel

sec

6

12

5

V-Funnel @ T 5min

sec

0

+3

6

L-box

(h2/h1)

0.8

1

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

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Testing of scc in fresh state The scc mix in fresh state was tested to get fresh properties like filling ability, passing ability and segregation resistance by performing slump cone, v-funnel, and l-box tests as explained above.

Casting of specimens

S.No

Properties

Test results

1

Normal consistency

32%

2

Specific gravity

3.10

3

Initial setting time

50 min

Not less than 30 min

4

Final setting time

166 min

Not more than 600 min

After satisfying the requirements of scc in fresh state, the mix was placed in moulds and allowed to flow and settle by itself. Any excess scc on the top of the moulds was removed with a trowel.

Compressive strength

5

40 N/mm²

7 days 28 days

58 N/mm²

Curing of scc specimens The scc specimens were kept undisturbed at room temperature for 24 hours after casting. Then the specimens were removed from the moulds and transferred to curing ponds containing fresh potable water as shown below.

Compression test After the required curing period, the scc cubes were taken out of the curing tanks and the moisture was wiped off to make the surface dry. They were placed in the compression testing machine (ctm) in such a way that the face perpendicular to the direction of pouring of scc mix was on the bearing surfaces and the load was applied centrally at a uniform rate of 140 kg./Sq.Cm./Minute until the failure of the specimens, in accordance with is 516–1959. The testing was done on a 3000 kn capacity compression testing machine.

PROPERTIES OF MATERIALS The properties of materials used for developing SCC are shown in tables.

Should not be less than 53 N/mm²

Sieve analysis of Fine Aggregate S.No

IS Seive size

Weight retained in gm

Cumulative weight retained in gm

Cumulative % weight retained

Cumulative % passing

Grading limits IS 383-1970 zone II(%)

1

10 mm

0

0

0

100

100

2

4.75 mm

9

9

0.9

99.1

90-100

3

2.36 mm

25

34

3.4

96.6

75-100

4

1.18 mm

163

167

19.7

80.3

55-90

5

600 microns

408

605

60.5

39.5

35-59

6

300 microns

210

815

81.5

18.5

8-30

7

150 microns

165

980

98.0

2.0

0-10

8

<150 microns

20

--

--

--

--

9

total

1000

264

Fineness Modulus = Cumulative Percentage weight retained / 100 = 264/100= 2.64 Fine aggregate belongs to Zone II Sieve analysis of Coarse Aggregate s.no

IS Seive size

1

20 mm

0

0

2

12.5 mm

400

400

RESULTS OF EXPERIMENTAL INVESTIGATIONS ON FRSCC This chapter deals in detail with the results of experimental investigations carried out in different phases.

Should not be less than 37 N/mm²

Properties of Aggregate

Testing of hardened scc A proper time schedule for testing of hardened scc specimens was maintained in order to ensure proper testing on the due date. The specimens were tested using standard testing procedures as per is : 516 – 1959.

Requirements as per IS:12269-1987

Weight retained in gm

Cumulative weight retained in gm

Cumulative % weight retained

Cumulative % passing

Grading limits 12.5 mm graded aggregate IS 383-1970 zone II(%)

0

100

100

8

92

90-100

3

10 mm

2200

2600

52

48

40-85

4

4.75 mm

2100

4700

94

06

0-10

5

2.36 mm

300

5000

100

--

--

6

Total

5000

Coarse aggregate belongs to 12.5 mm Graded aggregate

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Properties of fine and coarse aggregate

Properties of viscosity modifying admixture (Source: BASF Chemical Company India Limited)GleniumStream 2

S.No

Property

Fine aggregate

Coarse aggregate

1

Specific gravity

2.6

2.6 S.NO

Parameter

Results

2

Loose density

1650 kg/m3

1440 kg/m3

1

Form or state

Liquid

3

Rodded density

1775 kg/m3

1695 kg/m3

2

colour

Colorless

3

Specific gravity

1.01+ 0.01 @25oc

4

Chloride content

Nil

5

pH

8+1

6

dosage

0.05 to 1.3% by weight of cement

Properties of fly ash S.No

Characteristics of fly ash

properties

1

Specific gravity

2.05

2

Surface area

410 m²/kg

Fresh propertiesof self compacting concrete mixes and control concrete

Chemical Composition of Fly ash (Source: Civil Aid Techno clinic Private Limited) S.NO

1

Characteristics

Test conducted

Required Percentage as per IS:38122003 (reaffirmed 2007)

Silicon dioxide(Sio2)+aluminum oxide(Al2o3)+iron oxide(Fe2o3),percent (minimum)

94.74

2

Silicon dioxide(Sio2),percent (minimum)

63.38

35%

3

Magnesium oxide(MgO), percent(maximum)

1.08

5.0%

4

Total sulphur as sulphur trioxide(So3),percent (maximum)

0.11

3.0%

Loss of ignition, percent (maximum)

0.10

5

70%

Fresh properties S.No

(Source: BASF Chemical Company India Limited)Master Glenium Sky8233 S.NO

Parameter

Specifications(as per IS:9103)

Results

1

Physical state

Reddish brown liquid

Reddish brown liquid

2

Chemical name of active ingredient

Poly carboxyl ate polymer

Poly carboxyl ate polymer

3

Relative density @250c

1.080(+/- 0.02)

1.081

4

pH

Minimum6

6.88

5

Chloride content (%)

Maximum 0.2

0.0056

6

Dosage

0.5 to 1.5 litres per 100 kg of cement

Slump flow(mm)

T50(sec)

V-Funnel (sec)

1

Control mix + SP

695

3.28

4.15

2

Control mix+SP+VMA0.1%

691

3.33

4.84

3

Control mix+SP+VMA0.2%

684

3.39

5.26

4

Control mix+SP+VMA0.3%

675

3.42

5.95

5

Control mix+SP+VMA0.4%

663

4.27

6.82

6

Control mix+SP+VMA0.5%

654

4.87

7.53

7

Control mix+SP+VMA0.6%

649

5.01

9.86

8

20% FA+SP

665

3.35

6.69

9

20% FA+SP+VMA0.1%

662

3.49

7.02

10

20% FA+SP+VMA0.2%

660

3.74

7.45

11

20% FA+SP+VMA0.3%

658

3.86

7.63

12

20% FA+SP+VMA0.4%

640

4.96

8.55

13

20% FA+SP+VMA0.5%

632

5.82

9.34

14

20% FA+SP+VMA0.6%

627

6.60

10.36

5.0%

Properties of Super Plasticizer

SCC Mix

15

30% FA+SP

657

4.76

7.13

16

30% FA+SP+VMA0.1%

653

4.82

7.43

17

30% FA+SP+VMA0.2%

650

5.05

8.25

18

30% FA+SP+VMA0.3%

648

5.10

8.53

19

30% FA+SP+VMA0.4%

595

6.88

10.88

20

30% FA+SP+VMA0.5%

553

7.76

12.33

21

30% FA+SP+VMA0.6%

498

8.01

14.42

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Hardened properties of self compacting concrete mixes and control concrete

S.No

SCC Mix

Graph showing Variation of 28 days Cube Compressive Strength for 20% Replacement of Fly ash

Hardened properties (compressive strength N/mm²) 3 days

7 days

28 days

1

Control mix + SP

37.17

43.28

45.21

2

Control mix+SP+VMA0.1%

37.53

44.18

46.22

3

Control mix+SP+VMA0.2%

38.46

46.10

48.38

4

Control mix+SP+VMA0.3%

35.26

42.86

50.96

5

Control mix+SP+VMA0.4%

35.08

40.33

46.30

6

Control mix+SP+VMA0.5%

32.01

37.43

42.96

7

Control mix+SP+VMA0.6%

30.36

33.89

39.42

8

20% FA+SP

33.19

36.34

40.73

9

20% FA+SP+VMA0.1%

33.98

37.88

42.50

10

20% FA+SP+VMA0.2%

35.62

39.46

43.62

11

20% FA+SP+VMA0.3%

36.37

39.93

46.24

12

20% FA+SP+VMA0.4%

30.13

34.17

39.75

13

20% FA+SP+VMA0.5%

29.56

32.80

38.22

14

20% FA+SP+VMA0.6%

27.13

31.99

37.12

15

30% FA+SP

31.94

35.37

35.84

16

30% FA+SP+VMA0.1%

32.17

35.85

36.87

17

30% FA+SP+VMA0.2%

33.55

36.22

37.22

18

30% FA+SP+VMA0.3%

33.90

36.98

38.23

19

30% FA+SP+VMA0.4%

27.11

33.75

37.32

20

30% FA+SP+VMA0.5%

25.68

29.22

36.52

21

30% FA+SP+VMA0.6%

23.76

27.35

35.39

Graph showing Variation of 28 days Cube Compressive Strength for Control Mix

Graph showing Variation of 28 days Cube Compressive Strength for 30% Replacement of Fly ash

CONCLUSIONSON TEST RESULTS OF SCC 1.Based on the present project work on influence of viscosity modifying admixtures on fresh and hardened properties of self compacting concrete with varying dosage of fly ash,Concrete mixes-study of compressive strength characteristics, the following conclusions are drawn.

2.The use of appropriate dosage of super plasticizer and viscosity modifying agent is essential to maintain the fresh properties of self-compacting concrete.

3.In this case, a VMA dosage of 0.3% is obtained as an optimum dosage by suitablyadjusting the dosage of admixtures.

FRESH PROPERTIES: 1.VMA has a substantial influence on fresh properties of SCC. A small change in VMA makes a substantial change in SCC properties i.e., flowing abilit y,passingability,stability,segregation resistance.

2.In this investigation, as the VMA dosage was increasing from 0 to 0.6% the flowing ability and passing ability of SCC decreased.

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HARDENED PROPERTIES: 1.The target mean strength has been attained in almost all the mixes.

2.With the increase in VMA content the compressive strength is varying i.e., the strength increased from 0.1 to 0.3% of VMA dosage and then decrease from 0.3 to 0.6%. hence the dosage of 0.3% VMA gives maximum strength.

APPENDIX SCC MIX DESIGN GENERAL GUIDE LINES FOR DESIGN OF SCC MIXES Scc mixes contain large quantity of powder (material whose particle size is smaller than 0.125Mm) to maintain plastic yield of the properties of fresh concrete. Further, it also requires super plasticizer to ensure sufficient fluidity for sufficient time without undergoing large slump loss. Viscosity modifying agents and other admixtures are also added to ensure fully cohesive and stable mixes. To achieve fluidity, cohesiveness and homogeneity, three different aspects were identified by okamura. They are : • Reduction in coarse aggregate fraction in order to reduce the frequency of collision of friction between the particles to increase the fluidity of concrete.

• Increase in the paste content for further improvement in fluidity.

• Managing the viscosity of the scc to reduce the risk of blocking of concrete when it flows through congested reinforcement. The typical ranges of proportions and quantities are given by efnarc(2005) in order to obtain self-compactability which are givenbelow. Further modifications of trial mixes are necessary in the laboratory to meet strength and other performance requirements of the actual mixes.

• Water/powder ratio (by volume) : 0.80 To 1.10 Of total powder content • Water :160 to 240 litres per cubic meter.

• Coarse aggregate content should be normally in the range of 28 to 35 per cent by volume of the scc mix.

• Generally, the mix has to be designed to ensure that the concrete is capable of maintaining its required fresh properties inspite of variations in the quality of raw materials. Viscosity-modifying admixtures are used for compensating the variations due to any fluctuations in the grading of fa and the moisture content in the aggregates.

gettu et al 3. Sedran et al method 4. Rational mix design proposed by svrao et.Al. 5. Nan-su et al method 6. Method proposed by jagadishvengala 7. The japanese method MIX DESIGN AND TRIAL MIX PROPORTIONS OF SELFCOMPACTING CONCRETE SCC mix with a compressive strength of 30 MPa with 85% control factor was aimed at. The initial design mix proportion is obtained by using Nan-Su et al(2001) method andrational mix design proposed

by SV Rao et. al(2010). This mix proportion was fine-tuned by incorporating various guidelines and laboratory trials to obtain SCC mix which satisfies the fresh and hardened properties.

MIX DESIGN 1.Target strength Target mean strength= fck+t*s =30+1.65*5 =38.25Mpa Calculation of Fine and Coarse Aggregate Contents Fine and coarse aggregate quantities are calculated considering unit volumes of loose saturated surface dry fa and ca, packing factor (pf) and volume ratio of fine and total aggregate.

Wca =pfx wcal (1-s/a) Wfa = pf x wfal (s/a) S/a = volume ratio of fine aggregate to total aggregate. It is generally taken between 50% to 57% Loose density ofca: 1455 kg/m3 Loose density of fa: 1635 kg/m3 Rodded density of ca: 1670 kg/m3 Rodded density of fa: 1710 kg/m3 The term “packing factor (pf) “is defined as the ratio of mass of aggregate of tight packed state to that of loose packed state(lower pf value is preferred ) Pf (for coarse aggregate): 1670/1455 = 1.147~1.15 Pf (for fine aggregate): 1710/1635 = 1.0458~1.05 W cal -unit volume mass of loose saturated surface dry ca: 1455 (kg/m³) W fal -unit volume mass of loose saturated surface dry fa: 1635 (kg/m³) WCA = Content of CA in SCC, kg/m3 WCA =PFX Wcal (1-S/a) 54 = 1.15 X 1455 (1-0.54) = 769.695g/m3 WFA = Content of FA in SCC, kg/m3 WFA = PF X Wfal X (S/a) = 1.05 X 1635 x 0.54 = 927.045kg/m3

VARIOUS METHODS OF MIX DESIGN

Calculation of Cement Content (C)

Even though there are no established scc mix design procedures by bis, certain methods were suggested for arriving at these quantities by different organizations and researchers. Various methods available for obtaining the trial mixes are: 1. European practice and specifications 2. Mix design method proposed by gomes, ravindra-

(As per the curves given in the rational mix design procedure by SV Rao et al(2010) C = 10.24 + 9.535 x strength of concrete i.e, C = 10.24 +9.535 x 38.25 = 374.95 kg/m3

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Calculation of Mixing Water Content Required

by Cement W wc = (w/c) C W wc = Mixing water required by cement, kg/m3 W/c = 0.55 = 0.55 X 374.95 = 206.2 liters Calculation of Filler (AS per the curves given in the rational mix design procedure) % Fly ash = 68.43 – 0.535 x grade of concrete = 68.43 – 0.535 X 38.25 = 47.96 Fly ash = 374.95 X 47.96 / 64.51 = 278.79 Kg

mixtures in Concrete, October 29-November 1, 2006, Sorrento, Italy pp253-261.

6.Collepardi. M “Mechanical Properties of Self-Compacting and Flowing Concretes”, Terence C. Holland Symposium on Advances in Concrete Technology – 2007, George C. Hoff, Editor. pp379384.

7.Frances Yang “Self – Consolidating Concrete”, CE 241: Concrete Technology, Spring 2004 ; Report # 1, March 9, 2004. 23.

8.Lachemi M and Hossain K. M. A. “Self-Consolidating Concrete incorporating New Viscosity Modifying Admixtures” Cement & Concrete Research 34(2004), pp185-193.

9.The European Guidelines for Self–Compacting Concrete” (Specification, Production and Use) May 2005.

AUTHOR

Calculation of Super plasticizer Dosage The dosage of super plasticizer can be obtained by experience or carrying marsh cone test on mortar.

Super plasticizer dosage determined in the present case is 1.8% by weight of cement.

Trial Mixes and Adjustment of Mix Proportion Trial mixes were carried out using the designed contents of different materials. Different trial mixes are tried in the laboratory to obtain an SCC mix, which satisfies the required fresh and hardened properties.

Finally small changes are made to the proportions of ingredients obtained by Nan Su et al method of mix design and based on the trail mixes, the final proportions of SCC mix are obtained for different filler materials and their combinations.

Final mass of ingredients used in the present investigations per 1 m3 of SCC are as follows: Mass of Cement = 330 kg Mass of filler (Fly Ash) = 150 kg Mass of water = 186 kg Mass of CA = 795.5 kg Mass of FA = 870.4 kg Super plasticizer dosage = 1.8% by weight of cement VMA dosage = 0.1 to 0.6% by weight of cement

Shraddha, Research Scholar, Department Of Civil Engineering, Aurora Scientific Technological and Research Academy, Hyderabad India.

M.V.Seshagiri rao, Professor, Department Of Civil Engineering, JNTU Hyderabad, Hyderabad, India

REFERENCES 1.Hajime Okamura and Masahiro Ouchi ; Invited Paper on “Self Compacting Concrete”-Journal of Advanced Concrete Technology Vol.1, No.1, pp5-15, April 2003 Japan Concrete Institute. 32.

2.Nan Su, Kung-Chung Hsu, His-Wen Chai “A Simple Mix Design Method for Self-Compacting Concrete” Journal of Cement and Concrete Research 31(2001) pp 1799-1807.

K. Mythili Associate professor , Department Of Civil Engineering, Aurora Scientific Technological and Research Academy, Hyderabad India.

3.Okamura H., et. al. “Mix-Design for Self-Compacting Concrete”, Concrete Library of JSCE, No.25, June 1995(ND), pp107-120.

4.Ouchi M. and Okamura H. “Effect of Superplasticizer on SelfCompactability of Fresh Concrete”, Journal of the Transportation Research Board, 1997, pp37-40.

5.Borsoi. A, Collepardi. M, Collepardi. S, Croce. E.N., Passuelo .A “Influence of Viscosity Modifying Admixture on the Composition of SCC”Supplementary volume of Eighth CANMET/ACI International Conference on Superplasticizers and other Chemical Ad-

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