Paper on Addition of Flyash[1]

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ADDITION OF FLY-ASH BEYOND BIS LIMIT ( AS MENTIONED IN IS 1489 : 1991 ),

IN PORTLAND POZZOLANA CEMENT

A R&D WORK FOR CLEANER ENVIRONMENT

S.B.ROONGTA , T.S.DEWANGAN , DR. USHA SINGH

Introduction : Fly ash is a artificial pozzolanic material, which is a inorganic residue

obtained from the burning of pulverized coal. A finely divided Pozzolana form compounds

which have cementitious properties, when mixed with hydrated lime and alkalies. As such,

the generation/ consumption ratio of fly ash is very high in India, hence every year a huge

stock of fly ash is increasing. As it comes under hazardous waste material, the disposal is

also a major problem. But now a days in the many field the fly ash is used either as a

ingredient of raw material or as a filler. The cement and concrete are the examples, where it

is used as a pozzolanic material. The fly ash should conform the parameters laid down in IS

3812 : 2003 Part I and II for its different usage.

Earlier , when IS 1489 :1969 for PPC was introduced in India , the addition of fly ash was

limited from 10 – 25 % only. From 1980 onwards there is revolutionary change in cement

technology and the production of high strength giving clinker started. Based on the

production of high strength clinker , Bureau of Indian Standard revised its limit and was

increased and now the limit of fly ash addition in PPC is 15 – 35 %.

In India and other part of the world , the scientist are involved to increase the addition of fly

ash in PPC manufacturing, to make the environment more cleaner. This is not only for

“Waste to best” conversion but also for “ash to cash”, keeping environment friendly

approaches for better to-morrow.

Keeping the clean and green environment in mind, this research and development work was

carried out in Quality Control Department of Cement Manufacturing Company Limited

Meghalaya India in the laboratory scale, to know the impact of higher addition of fly ash

beyond BIS limit, with respect to clinker quality, fineness and Indian Specification IS 1489

:1991 for Portland Pozzolana Cement. Presently OPC 43 Grade , OPC 53 Grade and PPC

Part I ( Fly Ash based ) cements are being manufactured and marketed with “STAR” Brand,

which become the most popular and leading brand of cement in North – East States of India

within a year of commencing production. The Company is also selling clinker to various

small and mid sized customers for its premium quality as low alkali, low C3A and low

Chloride are the requirement for mass construction , which are easily met by clinker / cement

manufactured in CMCL.

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The cement grinding in Cement Manufacturing Company Limited, started in February 2005 .

From June 2005 production of Portland Pozzolana Cement ( Fly ash based ) started. Initially

the addition of fly ash was kept lower side and than gradually increased upto 33 % without

compromising on any parameter During the process of more addition of fly ash we have

conducted trial in laboratory for various parameters of cement and fly ash both. We are

taking fly ash from Kahalgaon. The details of Quality Parameters of fly ash as per Indian

Specification are as under :-

Table 3 : Specification of pulverized fuel ash (IS : 3812 – 2003)

Requirement

Test Characteristics Part 1 Part 2

Siliceous Calcareous Siliceous Calcareous

A. Chemical

Fly ash used in

CMCL for PPC

production (Avg)

1. SiO2 + Al2O3 + Fe2O3 % min 70 50 70 50 90.23

2. SiO2 % min 35 25 35 25 61.25

3. Reactive silica** % min 20 20 20 20 -

4. MgO % max 5 5 5 5 0.48

5. SO3 % max 3 3 5 5 0.31

6. Alkalies as Na2O % max 1.5 1.5 1.5 1.5 0.74

7. Chloride % max 0.05 0.05 0.05 0.05 0.019

8. LOI % max 5.0 5.0 5.0 5.0 1.98

B. Physical

1. Fineness, m2/kg min 320 320 200 200 356

2. Wet 45micron sieve** % max 34 34 50 50 17.2

3. Lime reactivity, MPa min 4.5 4.5 4.5 4.5 6.8

4. Autoclave % % max 0.8 0.8 0.8 0.8 0.01

5. Compressive strength

at 28 days, MPa

Not less than 80% of the strength of

corresponding plain cement mortar cube

59.88* =87.28% of OPC

* Compressive strength of fly ash-cement mortar cube 59.88 Mpa and corresponding test on plain

cement-sand mortar cube 68.61 Mpa. Compressive strength of fly ash at 28 days 87.28 % strength

observed against corresponding plain cement mortar cube. Testing carried out as per IS – 1727 :

1967.

** Optional test

We have carried out the test in two parts. In first part we have taken trial up to 35 % addition

of fly ash in laboratory scale and than commercial production also started up to 33 %

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addition of fly ash . Both the data are given below for taking out the co-relation in between

them.

Portland Pozzolana Cement with higher additions of fly ash

Quality product of PPC with higher addition of fly ash; depends on the quality of clinker and

fly ash. Particle size and fineness is also important factor for strength development in cement.

Trial conducted at laboratory scale replacement of OPC by consumption of fly ash at

different quantities. Test results are as under-

Table 7 : Laboratory Ball Mill Physical Test Result

(CMCL clinker with different percentage of fly ash)

Fly ash consumption

Physical Test 0% 20% 25% 30% 35%

Normal consistency % 24.5 27.00 26.50 25.75 26.25

Fineness M2/Kg 310 375 347 368 375

Le-Chatelier Expansion mm Nil Nil Nil Nil Nil

Autoclave Expansion % Nil Nil Nil Nil Nil

Initial setting time Minutes 95 110 140 135 140

Final setting time Minutes 130 145 175 170 175

1- Day c/strength MPa 28.0 18.0 16.0 18.0 16.0

3 Days c/strength MPa 43.0 36.5 28.5 28.5 26.0



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The Quality Parameters of Commercial Production are given below with fly ash addition

from 20 - 33 %.

Physical Test Results of PPC

(Commercial production with different percentage of fly ash)

Fly Ash

Physical Test

Requirement

as per

IS : 1489-1991

(Part 1)

20% 25% 30% 33%

Normal consistency % - 29.2 28.5 28.5 28.8

Fineness M2/Kg 300 (Min) 367 330 338 355

Le-Chatelier Expansion mm. 10 (Max.) Nil Nil Nil Nil

Autoclave Expansion % 0.8 (Max.) Nil Nil Nil Nil

Initial setting time Minutes 30 (Min) 110 120 140 135

Final setting time Minutes 600 (Max.) 160 160 170 175

1- Day c/strength MPa - 16 15 13 13

3 Days c/strength MPa 16 (Min) 27 25 22 21



.

In the second part of the trial we have conducted tests with 40 to 50 % of fly ash addition, the

results are not only encouraging, but we would like to draw the attention of the concerned

governing bodies, scientists of cement and environmental field to join their hands in the

interest of the nation and the world to make more clean and green environment , the

permissible range of addition of fly ash is to be reconsidered

The Quality Parameters of cement with 40 – 50 % fly ash addition is given below to compare

the data with different % of addition as per the requirement of Indian Standards IS 1489

:1991 (Part I )

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Chemical TEST 40%

Fly Ash

42%

Fly Ash

45%

Fly Ash 47%

Fly Ash

50%

Fly Ash

0 %

Fly Ash

LOI % 1.07 1.17 1.32 1.40 1.55 0.46

IR% 35.16 36.68 40.31 41.89 43.68 0.07

SO3% 1.49 1.40 1.38 1.30 1.20 2.46

SiO2% 13.01 12.45 10.81 10.61 11.36 20.61

Al2O3% 5.54 5.25 5.14 5.09 5.05 6.31

Fe2O3% 2.50 2.60 2.70 2.75 2.85 3.80

CaO% 39.53 38.79 36.31 34.52 32.70 64.49

MgO% 1.21 1.20 1.21 1.15 1.01 1.21

Physical Test 40%

Fly Ash

42%

Fly Ash

45%

Fly Ash 47%

Fly sh

50%

Fly Ash

0 %

Fly Ash

N. C . % 26.25 26.50 26.50 26.50

26.75 24.0

Blain M2/Kg 350 360 360 370

370 299

Lechatelier Exp.

mm.

Nil 1.0 Nil Nil

Nil Nil

Autoclave Exp.

%

Nil Nil Nil Nil

Nil Nil

IST (Minutes) 105 110 110 105

100 90

FST (Minutes) 135 140 140 135

130 125

Compressive

Strength ( MPa)

1- Day 13 12 10 9

8 26

3- Days 24 22 20 20

16 40

7-Days 38 34 32 32

24 52

28-Days 58 58 52 52

48 69

You may please observe from the above data that with 370M2/Kg fineness the cement with

50 %fly ash addition is also conforming the relevant specification. If the fineness is increased

to more than 380 ,than it will cross boundary line for 3 days strength and on better side for 7

days also.

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Here it will be better to mention that the most important factor for higher addition of fly ash

is the compatibility of clinker , which is used for the manufacture of PPC . We would like to

inform you that in the process of Ordinary Portland Cement grinding and above mentioned

PPC , the gypsum was not used as setting retarder. However with the use of 1.5 % Mineral

Gypsum as setting retarder the chemical and physical parameters were observed as under in

the next set of testing with another set of clinker. All the samples were prepared in laboratory

ball mill. In this series of test Bhutan Gypsum was also used as setting retarder. :

Chemical TEST Cement

With 30%

Flyash,

1.3%

Gypsum

Cement

With

35%

Flyash,

1.3%

Gypsum

Cement

With

40%

Flyash,

1.4%

Gypsum

Cement

With

45%

Flyash,

1.4%

Gypsum

Cement

With

50%

Flyash

1.5%

Gypsum

0 %

Fly Ash

& O%

Gypsum

LOI % 1.21 1.35 1.45 1.76 1.92 0.36

IR% 22.30 26.13 36.87 38.54 45.29 0.17

SO3% 2.23 1.93 2.20 1.83 1.86 2.36

SiO2% 16.82 15.39 10.38 9.89 9.79 20.55

Al2O3% 4.52 4.42 4.89 4.62 4.36 5.80

Fe2O3% 3.80 3.40 3.20 3.00 2.80 4.20

CaO% 46.74 45.42 39.23 37.57 32.27 64.56

MgO% 1.20 1.20 0.60 1.20 1.01 1.41

Physical Test Cement

With 30%

Flyash,

1.3%

Gypsum

Cement

With

35%

Flyash,

1.3%

Gypsum

Cement

With

40%

Flyash,

1.4%

Gypsum

Cement

With

45%

Flyash,

1.4%

Gypsum

Cement

With

50%

Flyash

1.5%

Gypsum

0 %

Fly Ash

& O%

Gypsum

N. C . % 28.00 28.50 28.75 29.00 29.50 26.00

Blain M2/Kg 351 350 350 360 370 300

Lechatelier Exp.

mm.

Nil Nil Nil Nil Nil Nil

Autoclave Exp.

%

0.00 0.04 0.06 0.02 0.02 0.00

IST (Minutes) 120 120 125 120 155 100

FST (Minutes) 150 155 165 150 185 130

Compressive

Strength ( MPa)

1- Day 20 18 16 14 08 29

3- Days 30 32 24 24 16 41

7-Days 46 44 38 36 27 50

28-Days 63 63 56 54 44 64

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The important characteristics of clinker quality are as under :-

THE HIGH-LIGHTS OF CMCL CLINKER

1. Above 52 % C3S content.

2. High SO3 content ( > 2 % ) in clinker.

3. Remarkably low Alkali content (< 0.6 % in terms of Na2O ).

4. Lower C3A content clinker ( < 6.5 % ).

5. Lower free lime content clinker.

6. Better strength with lower fineness.

7. Lower Heat of Hydration.

8. Lower alkali- aggregates reaction.

9. Darker clinker ( C4AF > 11 % )

10. Most ideal to manufacture OPC, PPC, and PSC.

11. More resistant for aggressive environmental attack.

12. More sound cement.

13. Most ideal for Project-work, Mass construction, Bridge pier, Dam, Tunnels,

Hydro-electric power stations, General purpose construction, and Specially high

strength requirements.

14. Lower/No Gypsum requirements means higher contribution of clinker to

produce cement ( more strength developing material )

15. Low Chloride content clinker.

16. Scientifically designed composition, resulting more durable constructions.

Since the beginning , plant is using Meghalaya Coal , which is having 5 – 6 % sulphur

content. The Plant is supplied by Walchand Ind. Ltd. Pune, which is equipped with 5 stage

preheater with RSP pre-calciner. Presently plant is producing 1700 – 1800 MT clinker per

day, without any jamming problem in pre-heater as it does not have any volatiles by-pass

system. There is a lot of scope to work on the quality parameter of clinker, related to higher

addition of fly ash and which is going on in Cement Manufacturing Company Limited. The

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plant performance can be quoted as an example in cement world, as no-body believes upon

the plant operation parameters, for the volatiles “Q” factor, as it is far away from the

acceptable limit for the cement plant operation , and that too, without by-pass system.

For any more information /clarifications on above , concerned plant personnels and

authorities can be contacted.

References

1. Taylor H. F. W (1998) Cement Chemistry, Thomas Telford Publishing, London.

2. Perry Robert H & Green Don H. (1997) Perry’s Chemical Engineer’s Handbook,

Mc Graw-Hills New York.

3. Labahn Otto & Kohlhaas B. (1983) Cement Engineer’s Handbook, Bauverlag

GmbH, Wiesbaden and Berlin.

4. Sarkar S. L. & Ghosh S. N. (1993) Progress in cement and concrete, Mineral

admixtures in cement and concrete, Volume – 4, ABI Books Pvt. Ltd. New Delhi

100 019 INDIA

5. IS – 1760 (Part 3) : 1992 Chemical analysis of limestone, dolomite and allied

materials (Part – 3 determination of iron oxide, alumina, calcium oxide and

magnesia, Bureau of Indian Standards New Delhi 110 002

6. IS – 3812 (Part-1) : 2003 Pulverised fuel ash- Specification, Part- 1 for use as

pozzolana in cement, cement mortar and concrete, Bureau of Indian Standards

New Delhi 110 002

7. IS – 3812 (Part - 2) : 2003 Pulverised fuel ash- Specification, Part- 2 for use as

admixture in cement mortar and concrete, Bureau of Indian Standards New Delhi

110 002

8. IS – 1489 (Part - 1) : 1991 Portland Pozzolana Cement - Specification, Part- 1

flyash based, Bureau of Indian Standards New Delhi 110 002

9. IS – 4031 (Part 1 - 15) Methods of physical test for hydraulic cement, Bureau of

Indian Standards New Delhi 110 002

10. IS – 4032 : 1985 Methods of chemical analysis of hydraulic cement, Bureau of

Indian Standards New Delhi 110 002

11. IS – 1727 : 1967 Methods of test for pozzolanic materials, Bureau of Indian

Standards New Delhi 110 002

12. Use of high sulphur content Meghalaya coal in Cement Manufacturing Company

Limited by Mr. S.B. Roongta & T.S.Dewangan ( Paper published in 9th

International seminar NCCBM 2005 ) 13. Blended Cement with higher addition of fly ash and fineness as a tool with

respect to clinker quality by Mr. S. B. Roongta, T. S. Dewangan, Dr. Hemant Sahu

( A paper accepted for Indian Cement Industry Desk - Book.)

*****

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Details of Authors

1. Mr. S.B. Roongta is having B.Sc. in Mechanical Engg. Degree from Birla Institute of

Technology . Ranchi ( Bihar ) , having 47 years experience in cement industry. He

joined Satna Cement Works as Trainee Mechanical Engineer and Retired as

President of Birla Corps, presently working as a Managing Director in CMCL.

2. T.S.Dewangan is a merit scholar & M.Sc. in Inorganic Chemistry from Pt.

Ravishankar University Raipur He started his carrier as Prof. in Deptt. Of Chemistry,

Govt. Post –Graduate College of Science Raipur.He was the top ranked student of

this institution, among all the subjects of post – graduation available therein. After

two years in education,joined cement industry as trainee in Production & Q.C. in

Century Cement. He has worked in Birla, Sanghi , Tata , and Lafarge Group.

Presently working as Head of Department Quality Control in CMCL.

3. Dr. Usha Singh is having M.Sc. in Inorganic Chemistry from Saugar University M.P.

She did Ph.D from Pt. Ravishankar University Raipur. Presently working as Prof. in

Deptt. of Chemistry, Govt Post Graduate College Balaghat ( M.P. )

Paper on Addition of Flyash[1]

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