Effect of Activated Flyash in Metakaolin based cement

Hemant Chauhan#”# PG student, Department of Structural Engg., B.V.M. Engg.

College, V.V. Nagar, Gujarat1chauhan.hemant226@gmail.com

Smt. Bhavna K. Shah*

*Associate Professor. Department of Structural Engg., B.V.M. Engg. College, V.V.Nagar, Gujarat

2bks1954@yahoo.co.in

Abstract— Recent trend in engineering, especially in concrete structure is to develop economical, eco environmental and durable concrete with decreasing or reducing the use of natural material and increasing the use of industrial waste or by products from industries without affecting the higher strength of concrete. To achieve this higher strength, OPC as a cementitious material is not sufficient, so in this paper industrial waste like activated fly ash (class F), Iron Oxide and Metakaolin are used as supplementary cementitious materials in various proportions. By using this mineral admixtures with OPC cement, different five types of cement were prepared and same were used to find compressive strength of concrete cubes at 3,7,14,28 and 56 days.

Keywords— Compressive strength, Activated Flyash, Metakaolin, Iron Oxide, Workability

I. INTRODUCTION

Concrete has played important role in infrastructure development. Concrete has many advantages over other construction material including low cost, applicability under many conditions, adaptability, use and production of cement and concrete has increasingly become a major causes of global ecological problems with special reference to the over exploitation of non- renewable natural resources due to high-temperature production processes, fossil fuels combustion and extraction of raw material. Concrete is made up of cement, coarse aggregate, fine aggregate and water. When water is added in to cement, chemical reaction takes place and due to this hydration lime is generated. Out of that 25% of lime remains intact on surface and overtime it would be susceptible to the effect of weathering and loss of strength and durability. To overcome this effect, pozzolanic material i.e. siliceous material that develops any hydraulic cementitious properties in the presence of lime is added into OPC cement which reacts with free lime and convert in to calcium silicate hydrate (C-S-H) which gives strength to concrete and also make it durable.

Activated Fly ash (type F) and Iron Oxide is industrial waste and Metakaolin is easily available with low cost compared to silica fume used as a pozzolanic material to replace OPC in concrete which reduces the amount of cement used hence reducing the emission of CO2.

All these materials are finer, particles are glassy which help in reducing amount of water and help to increase workability. By using this mineral admixture, cost of concrete is reduced and eco friendly concrete is developed.

II. MATERIALS

A. CementOrdinary Portland Cement (53 grade) confirming to BIS

12269 -1987 was used. It’s chemical composition and physical properties are given in table -1.

TABLE ICOMPOSITION OF CEMENT, ACTIVATED FLYASH & METAKAOLIN

%age by massChemicalComposition Cement Fly ash MetakaolinSiO2 20.1 48.53 51.6Al2O3 4.51 24.61 41.3Fe2O3 2.5 7.59 0.64CaO 61.3 9.48 0.52MgO 1 2.28 0.16Loss onignition

2.41 0.93 0.72

B. Flyash Fly Ash comprises of the non- combustible mineral portion

of coal. Fly ash particles are glassy spherical shaped. It’s particles are finer than cement particles and have ball bearing effect which helps to reduce amount of water and improves workability of concrete. The chemical compositions of fly ash are given in table 1. And physical properties are given in table 2.

C. MetakaolinIt is highly pozzolanic material. It is obtained by

calcinations of Algerian kaolin at 700˚ C for 7 hours. The silica and alumina contained in the metakaolin are active and react with free lime to form C-S-H and alumina-silicates which greatly improve the strength.

D. Iron Oxide During the processing of steel in steel mills, iron oxide will

be formed on the surface of metal. This oxide is known as mill scale, occur during continuous casting, reheating and rolling operation. This is used as replacement for the fine aggregate.

E AggregateCrushed stones of 20 mm down size were used as coarse

aggregates and local river sand 1.18 mm down were used as fine aggregate listed in table 3.

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TABLE IIPHYSICAL PROPERTY OF FLYASH

Property ExperimentalValue

1 Fineness (passing 45μ IS: sieve) 78.9%

2 Specific Surface 4620 cm2/g

3 Unit weight 950 kg/m3

4 Specific gravity 2.13

TABLE III

PHYSICAL PROPERTIES OF FINE & COARSE AGGREGATE.

Aggregate FinenessModulus

Bulk Density(kg/m3)

SpecificGravity

Fine Agg. 3.64 1696 2.58

Coarse Agg. 7.07 1770 2.87

III. EXPERIMENTAL WORK

In this study, workability of fresh concrete and mechanical performance of hardened concrete were examined. Both tests were conducted using five sample group as shown in table 4.

Concrete were prepared at four water to cementitious material ratios – 0.40, 0.45, 0.50, 0.55. For each of above sample groups, concrete raw materials were batched and mixed for approximately 10 minutes in concrete mixer.

To find out workability of fresh concrete, compaction factor test was carried out for each mix.

TABLE IVCOMPOSITION OF DIFFERENT TYPES OF CEMENTS

Type Composition

A 100% OPC

B 88% OPC + 10% MK + 2% Iron Oxide.

C 78%OPC + 10% MK + 10% FA + 2% Iron Oxide

D 68%OPC + 10% MK + 20% FA + 2% Iron Oxide

E 58%OPC+ 10% MK + 30% FA + 2% Iron Oxide

For above all types of cement, four mix designs were prepared with w/c ratio 0.40, 0.45, 0.50, 0.55 and constituent of materials for different w/c ratio are summarized in table 5.

IV. RESULTS AND DISCUSSION

Five mixes of cement were prepared and for each type four w/c ratios were used. The result obtained for fresh concrete in form of compaction factor test is summarized in table 6.

TABLE VCONSTITUENT OF MATERIALS FOR DIFFERET CONCRETE MIX

w/cratio

Mixproportion

Mix Proportion / m3

Cement(kg)

Sand(kg)

Coarse Agg. (kg)

Water(kg)

0.40 1:1.72:2.28 450 772.58 1026 180

0.45 1:2.03:2.56 400 814.97 1026 180

0.50 1:2.35:2.85 360 847.73 1026 180

0.55 1:2.67:3.13 327 874.54 1026 180

TABLE VICOMPACTION FACTOR FOR DIFF. CONCRETE MIX

Type

W/C

A B C D E

0.40 0.78 0.8 0.827 0.835 0.842

0.45 0.8 0.812 0.819 0.825 0.834

0.50 0.815 0.84 0.852 0.857 0.863

0.55 0.87 0.88 0.912 0.92 0.915

Table VI shows that for type A cement, as w/c ratio increased, compaction factor increased due to decrease in amount of cement content, but for type B, C, D &E, for same w/c ratio and same amount of cement as per table 6, compaction factor increases due to addition of activated fly ash. Figure 1 shows various compaction factors for five types of cement. The result for harden concrete in form of compressive strength of concrete cubes at 3,7,14,28 & 56 days are summarized in table 7. Table 7 shows that when OPC is replaced by 42%, i.e. 30% with fly ash, 10% with metakaolin and 2% with iron oxide, although we get higher strength that is for w/c ratio of 0.4, 0.45, 0.5, & 0.55 which is higher than M-25 grade, which shows the effect of fly ash and metakaolin on strength of concrete. Result shows that compressive strength with addition of pozzolanic materials at 7 days and 14 days is lower than M25 grade OPC strength but equal at 28 days and higher at 56 days.

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Fig. 1 Compaction factor of different concrete mix

V. CONCLUSION

When OPC is replaced up to 42% in concrete, it gives strength up to 40.67 N/mm2 in 0.40 w/c, and in 0.55 w/c ratio it gives strength up to 25.47 N/mm2 at 56 days, so even in 0.55 w/c ratio we can get concrete of M25 grade level.

Increase in percentage of pozzolanic material, compaction factor is also increased which gives the improvement in workability of concrete due to ball bearing effect of activated flyash. By replacing OPC up to 42% with fly ash(30%), metakaolin(10%) and iron oxide (2%), cost of concrete is reduced which is helpful to make economic concrete. In general, we can conclude that addition of pozzolanic materials like (activated flyash, metakaolin, iron oxide) as replacement of OPC gives higher strength at 56 days and also improves the workability of concrete with lower w/c ratio.

Fig. 2 Compaction factor test apparatus

TABLE VIICUBE COMPRESSIVE STRENGTH OF CONCRETE MIX

Compressive strength (N /mm2)Mix

3days 7days 14days 28days 56days#A 36.17 38.22 45.03 51.25 62.74

#B 25.48 33.15 36.73 37.33 49.57

#C 22.32 28 33.43 40.42 47.29

#D 17.035 24.63 31.72 38.20 41.70

#E 17.55 23.37 30.29 36.32 40.67

!A 26.66 33.03 37.035 46.22 59.33

!B 26.36 27.18 34.33 47.70 45.55

!C 18.66 22.99 29.77 33.34 41.95

!D 15.04 20.78 26.96 32.29 39.53

!E 14.071 17.89 26.15 27.61 35.27

*A 20.29 30.51 38.07 41.92 46.66

*B 19.70 25.33 29.89 41.70 45.40

*C 13.62 15.25 20.88 23.93 32.80

*D 11.46 14.41 23.36 28.93 31.6

*E 9.53 12.11 20.85 23.05 25.78

!!A 14.81 25.33 26.36 29.15 43.22

!!B 13.77 22.10 23.55 32.29 34.96

!!C 14.36 18.81 24.63 29.34 33.68

!!D 11.64 16 25.91 29.15 32.35

!!E 10.02 14.51 15.95 20.15 25.47

Note:# Concrete mix with 0.40 w/c ratio! Concrete mix with 0.45 w/c ratio*Concrete mix with 0.50 w/c ratio!! Concrete mix with 0.55 w/c ratioA,B,C.... indicates types of cement used in concrete mix

Fig. 3 Compressive strength of concrete (0.40 w/c)

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Fig. 4 Compressive strength of concrete (0.45 w/c)

Fig. 5 Compressive strength of concrete (0.50 w/c)

Fig. 6. Compressive strength of concrete (0.55 w/c)

REFERENCES

[1] Shetty M.S., “Concrete Technology Theory and Practice”,

S.Chand & Company, New Delhi.

[2] ASTM C 33-93, Standard Specification for Aggregates

[3] A.M.Poppe, G. Baert and N.De Belie “Strength and Durability of

high-volume Flyash Concrete.”

[4] Chi sun poon, Lik Lam and Yuk Lung Wong, “Effect of Flysah and

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of materials in civil engineering/ August 1999, pp197-205.

[5] Jiping Bai, Albinas Gailus “Consistency of Flyash and Metakaolin

Concrete”.

[6] Justice J.M. et Al. “Comparison of Two Metakaolin and a Silica

Fume used as Supplementary Cementitious Materials” Article from

Proc. Seventh International Symposium on Utilization of High

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2005.

[7] Prabir C. Basu, “Flyash Base Concrete” Civil Engg. Department,

Atomic Energy Board, Mumbai, CE&CR, February 2009, pp – 78-

86.

[8] Shaikh Javed, “Processed Flyash For Superior Concrete”, CE&CR

February 2009, pp – 62 – 68.

[9] Tiwari A.K, Jha D.N. & Venkateshwaran D. “Property of High

Strength Concrete with High Volume Flyash” ICI journal, vol 6,

april – june 2005.

National Conference on Recent Trends in Engineering & Technology

13-14 May 2011 B.V.M. Engineering College, V.V.Nagar,Gujarat,India

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National Conference on Recent Trends in Engineering & Technology

13-14 May 2011 B.V.M. Engineering College, V.V.Nagar,Gujarat,India