study on fluidity of flyash based on cement slurry for sifcon a report arumugam anna university,...
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Study on Fluidity of Flyash Based on Cement Slurry for Sifcon a Report arumugam Anna University, Chennai, IndiaTRANSCRIPT
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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