STUDY ON FLUIDITY OF FLYASH BASED ON

CEMENT SLURRY FOR SIFCON

A REPORT 

 PRESENTED BY 

DR.E.ARUMUGAM AROONA ARUMUGAM

J. SHANTHARAM

      

DEPARTMENT OF CIVIL ENGINEERINGANNA UNIVERSITYCHENNAI - 600 025.

 

 

NNEED FOR THE STUDY

 

           SIFCON is a new and special type of

construction material, an attempt is made to

study the behaviour of SIFCON under flexure

and impact with various combinations of its

constituent materials.  

 

                 Flyash is available in plenty as a waste by-

product from thermal power plants.

Flyash possess pozzolonic property,

it can be used as a cement replacement

material. The study on the optimization of flyash content in SIFCON and

its structural behaviour is undertaken.

 

SSCOPE OF THE INVESTIGATION

 

                Marsh cone test method has been employed in this

study to optimize the dosage of superplasticizer for

cement slurry.  

REVIEW OF LITERATURE 

STUDIES ON FLUIDITY OF SLURRY

Agullo, et.al.,(1990) - Fluidity of cement pastes

with mineral admixture and superplasticizer

Francois De Larrard (1990) - a method of proportioning high strength concrete

mixtures

with superplasticizer

 

APPLICATIONS 

      i.      pavement overlay    ii.      precast slabs    iii.     refractory applications like furnace lintels, etc    iv.      security safe    v.      impact resistant panels    vi.      missile silo structural concepts   vii.      bridge deck renovation  viii.      bridge girder repair    ix.      fragment resistant walls     x.      explosive storage tanks    xi.      beam – column connections a repair

STUDY ON FLUIDITY OF CEMENT SLURRY 

 

Effect of superplasticizer dosage,

Water -cement ratio (w/c), mineral admixture

(flyash) dosage, fine aggregate of two different

grades on the flow characteristics and the strength

of cement based slurry are discussed. 

MATERIALS USED 

53 Grade OPC confirming to IS 12269-1987

River sand - fine aggregate passing through IS 1.18mm sieve and IS 600 microns sieve

confirming to IS 2386-1963

Mineral admixture - flyash collected from Thermal power plant, Neyveli

Chemical admixture - Naphthalene based superplasticizer

Potable water.

PROPERTIES OF MATERIALS  

The tests are carried out to study the basic properties:  Cement:                          i.      fineness of cement                       ii.      standard consistency                     iii.      setting time- initial and final setting time                    iv.      specific gravity                        v.      compressive strength

 Fine aggregate:

                         i.      fineness modulus of fine aggregate                       ii.      specific gravity

Table : Basic properties of Cement and Fine Aggregate 

Sl.No.

Description Observed As per BIS

1. Cement – fineness (IS 460 part I- 1985) 3% 10% (max)

2. Standard consistency (IS 3535-1986) 32% 25%

3. Initial setting time (IS 12269- 1987) 110minutes 30 minutes

4. Final setting time (IS 12269-1987) 210minutes 600 minutes

5. Specific gravity of cement (IS 4031- 1968) 3.23 3.15

6. Compressive strength at 28 days (IS 12269-1987) 57 N/mm2 53 N/mm2

7. Fine aggregate-fineness modulus (IS 2386- 1963) 2.46 2.2 – 2.6

8. Specific gravity of fine aggregate (IS 2386 – 1963) 2.67 2.6 – 2.7

Table: Composition of Flyash Used 

Sl.No. Properties Weight (%)

1. Silica as SiO2 48.50

2. Alumina as Al2O3 17.21

3. Calcium as CaO 10.46

4. Iron as Fe2O3 9.66

5. Magnesium as MgO 4.25

6. Sodium as Na2O 0.48

7. Potassium as K2O 0.12

8. Loss on ignition 1.59

9. Others 7.73

NECESSITY FOR FLOW TEST

 

        SIFCON is a cement based slurry with high volume

of fibre content. The incorporation of mineral

admixture (flyash) controls the flow of slurry. To

get the optimum dosage of chemical admixture, the

tests are carried out with Marsh cone apparatus.  

MIXING SEQUENCE

 

For a given proportion, cement, water and

1/3 volume of the superplasticizer were first mixed

for 2minutes.

The mineral admixture (flyash) was then added and

the paste was mixed for another 4 minutes.

In the next stage, 1/3 volume of the

superplasticizer was added and the paste was

mixed for further 2 minutes.

In the last stage, the remaining 1/3 volume of the

superplasticizer was added and mixed for

2 minutes.

Table : Combination of Matrices  

Set IngredientsProportions

Remarks

I Cement + water+ superplasticizer

w/c = 0.25, 0.30 & 0.35

 since paste with w/c=0.25 is highly dense and not feasible for practical purpose. Hence, w/c=0.25 is not considered for further tests.

II Cement + flyash +water + superplasticizer

w/b = 0.30, 0.35 Flyash=15%, 30%, 45% (by weight of cement)

Cement paste with flyash content of 45% has higher density and it requires more dosage of superplasticizer, which is uneconomical. Hence, cement paste with 45% of flyash content is not considered for further tests.

III (a) Cement + flyash +fine aggregate (passing through IS 1.18mm sieve) + water + superplasticizer

w/b= 0.30, 0.35 Flyash=0%,15%,20%, 25%& 30% (by weight of cement)

The fluidity of cement slurry with w/b=0.30 is very low and hence for further tests, slurry with w/b=0.35 alone is taken into consideration.

III (b) Cement + flyash + fine aggregate (passing thro’ IS 600 microns sieve) + water + superplasticizer

w/b=0.30,0.35 Flyash=0%,15%, 20%, 25%& 30% (by weight of cement)

The fluidity of cement slurry with w/b=0.30 is very low and hence for further tests, slurry with w/b=0.35 alone is taken into consideration.

Sl.No sp/c (%) Flow time in seconds

w / c

0.25 0.30 0.35

1. 0.50 ** 200 24

2. 0.75 ** 100 20

3. 1.00 ** 40 13

4. 1.25 ** 35 10

5. 1.50 ** 30 10

6. 1.75 ** 28 10

7. 2.00 ** 27 ***

8. 2.25 ** 27 ***

9. 2.50 ** *** ***

10. 2.75 395 *** ***

11. 3.00 265 *** ***

12. 3.25 135 *** ***

13. 3.50 65 *** ***

14. 3.75 46 *** ***

15. 4.00 40 *** ***

16. 4.25 37 *** ***

17. 4.50 35 *** ***

 Table : Standard Flow Time of Cement Paste

Table : Standard Flow Time of Cement Paste with Flyash 

Sl.No sp/c (%)

Flow time in seconds

w/b = 0.30 w/b = 0.35

% of Flyash (by weight) % of Flyash (by weight)

0 15 30 45 0 15 30 45

1. 0.5 200 275 300 350 27 29 32 33

2. 1.0 71 105 165 184 15 18 21 23

3. 1.5 35 40 56 68 10 12 14 17

4. 2.0 33 35 36 41 9 11 12 15

5. 2.5 32 33 35 39 8 10 11 14

6. 3.0 30 32 34 36 8 10 11 14

7. 3.5 *** 32 33 36 *** *** 10 13

0

5

10

15

20

25

30

35

40

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Superplasticizer dosage (%)

Flo

w t

ime

( s

ec

on

ds

)

FA=0%

FA=15%

FA=30%

FA=45%

w/b = 0.35

0

50

100

150

200

250

300

350

400

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Superplasticizer dosage (%)

Flo

w t

ime

( se

con

ds )

FA=0%

FA=15%

FA=30%

FA=45%

FIG.3.6: FLOW TEST ON CEMENT PASTE WITH FLYASH AND w/b=0.30

FIG.3.7 : FLOW TEST ON CEMENT PASTE WITH FLYASH AND w/b=0.35

Table: Standard Flow Time of Cement Mortar Slurry - SF

Sl.

No.

sp/c

(%)

Flow time in seconds

% of Flyash ( by weight)

w/b = 0.30 w/b = 0.35

0 15 0 15 20 25 30

1. 0.5 ** ** 174 240 ** ** **

2. 1.0 ** ** 67 105 ** ** **

3. 1.5 440 ** 48 73 255 271 290

4. 2.0 325 ** 37 59 97 132 183

5. 2.5 210 ** 33 48 62 85 104

6. 3.0 155 473 29 45 54 74 81

7. 3.5 120 280 *** 41 52 69 75

8. 4.0 100 172 *** 40 49 66 71

9. 4.5 83 140 *** *** *** 61 66

10. 5.0 75 128 *** *** *** *** 60

* * = Flow of paste is NIL *** = Flow time remains constant.

Table : Standard Flow Time of Cement Mortar Slurry – SVF

Sl.

No.

sp/c

(%)

Flow time in seconds

% of Flyash ( by weight)

w/b = 0.30 w/b = 0.35

0 15 0 15 20 25 30

1. 0.5 ** ** 315 392 ** ** **

2. 1.0 ** ** 140 244 ** ** **

3. 1.5 ** ** 104 120 ** ** **

4. 2.0 ** ** 73 81 412 ** **

5. 2.5 ** ** 61 64 264 ** **

6. 3.0 ** ** 57 58 177 341 **

7. 3.5 ** ** *** 56 123 211 **

8. 4.0 392 412 *** 53 88 107 **

9. 4.5 270 310 *** *** 65 83 313

10. 5.0 180 205 *** *** 57 78 252

 ** = Flow of paste is NIL *** = Flow time remains constant.

0

50

100

150

200

250

300

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Superplasticizer dosage (% )

Flow

tim

e (s

econ

ds)

FA=0%

FA=15%

FA=20%

FA=25%

FA=30%

w/b = 0.35

0

50

100

150

200

250

300

350

400

450

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0Superplasticizer dosage (%)

Flow

tim

e (s

econ

ds)

FA=0%

FA=15%

FA=20%

FA=25%

FIG. 3.9: FLOW TEST ON CEMENT SLURRY - SVF WITH w/b = 0.35

FIG. 3.8: FLOW TEST ON CEMENT SLURRY - SF WITH w/b = 0.35

 

RESULTS AND DISCUSSION

Effect of the water – cement ratio (w/c)

Effect of Mineral Admixture

Effect of Fine Aggregate in the Mix

TABLE : MARSH CONE FLOW TIME OF SUPERPLASTICIZED CEMENT SLURRY AND MORTAR WITH AND WITHOUT FLYASH AT SATURATION DOSAGE OF SUPERPLASTICIZER

SETS

INGREDIENTS

PROPORTION SATURATION

SP/C (%)FLOW TIME

(seconds)W/CFLYASH(%)

1. Cement + water + superplasticizer 0.250.300.35

000

4.252.001.50

372810

2. Cement + flyash + water + superplasticizer 0.30

0.35

0153045

0153045

2.002.502.503.00

1.502.002.503.00

28333536

10111213

3.a Cement + flyash + fine aggregate <1.18mm + water + superplasticizer

0.30

0.35

01520

015202530

4.505.00>5.00

2.003.003.504.004.50

83128>200

3745526666

3.b Cement + flyash + fine aggregate <600microns + water + superplasticizer

0.30

0.35

015

015202530

5.00>5.00

2.503.504.505.00>6.00

180>200

65667578>200

COMPRESSIVE STRENGTH OF SLURRY

STRENGTH OF SLURRY DETERMINED WITH UTM TESTING MACHINE

STRENGTH DETERMINED AT THE END OF

7 AND 28 DAYS

 Table : Compressive Strength of Cement Mortar Slurry with

w/b= 0.35

Sl.

No.

Mix Proportion sp/c

(%)

Compressive Strength (fcs)

(N/mm2)7 days 28 days

1. Cement : fine aggregate < 1.18mm 2.00 47 57

2. Cement : fine aggregate < 600microns 2.50 47 59

3. Cement + 15% flyash : fine aggregate < 1.18mm 3.00 45 54

4. Cement + 15% flyash : fine aggregate < 600microns 3.50 39 55

5. Cement + 20% flyash : fine aggregate < 1.18mm 3.50 36 48

6. Cement + 20% flyash : fine aggregate < 600microns 4.50 25 50

7. Cement + 25% flyash : fine aggregate < 1.18mm 4.00 28 44

8. Cement + 25% flyash : fine aggregate < 600microns 5.00 23 47

9. Cement + 30% flyash : fine aggregate < 1.18mm 4.50 28 41

10. Cement + 30% flyash : fine aggregate < 600microns 6.00 22 43

DISCUSSION FLUIDITY OF SLURRY

 

When the w/c ratio is 0.35, addition of superplasticizer

has insignificant effect on the fluidity whereas if the w/c

ratio is 0.3, the flow time decreases upto an addition of

1.0% of superplasticizer. Beyond this percentage, flow time

remains constant. Similarly, when the w/c ratio is

decreased to 0.25, there is a drastic decline in the flow time

upto an addition of 3.5% of superplasticizer. Beyond this

percentage, flow time remains constant.

If the w/b ratio is 0.30, addition of flyash has insignificant effect on the fluidity beyond 2.0% of

addition of superplasticizer.

If the w/b ratio is 0.35, higher the addition of flyash,

greater the flow time whereas if the flyash is

completely avoided, lower the flow time upto 1.5% of

addition of superplasticizer. However, the flow time

remains constant beyond 1.5% of addition of

superplasticizer irrespective of flyash content.

The flow time of slurry increases with increase

in the fineness of fine aggregate. The flow time

of slurry – SF remains constant irrespective of

flyash content beyond the addition of 3.0% of

superplasticizer whereas the flow time and the

optimum dosage of superplasticizer for

slurry – SVF increases with the addition of

flyash content

The fluidity of slurry – SVF with flyash upto 15%

by weight has insignificant effect beyond the

addition of 2.0% of superplasticizer whereas the

slurry with flyash beyond 15% requires 2.0% to

2.5% of superplasticizer as minimum dosage. As the

flyash content increases, the increase in dosage of

superplasticizer is upto 4.5%.

The higher the flyash content, the lower the

compressive strength of slurry. The addition of

flyash beyond 20% by weight reduces the

compressive strength upto 20% than the

conventional slurry. 

The addition of flyash strengthens the slurry only at

the later days. The increase in compressive strength

of slurry at the end of 28 days is upto 2.5 times

greater than the strength at the end of 7 days.

CONCLUSION 

Marsh Cone Test approach is very useful in

practical application to optimize the

superplasticizer dosage

The optimum superplasticizer dosage can be

defined in terms of the saturation dosage beyond

which there is no significant decrease in the flow

time.

Cement paste with w/c = 0.25 and below has very poor

flow quality despite addition of superplasticizer and

hence may not be of practical utility.

When cement is replaced partially by flyash, the

superplasticizer dosage increases to about 2 to 3 times

with the increase in flyash content. However, for w/b =

0.35 and above, the flyash content has little influence

on the fluidity of the mix.

Addition of fine aggregate in the cement paste

increases the superplasticizer dosage and the flow

time to about 1.5 to 2 times. Finer the

aggregate, lesser in the fluidity of the slurry

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