pond ash concrete

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INFLUENCE OF POND ASH AS FINE AGGREGATE ON STRENGTH AND DURABILITY OF CONCRETE

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POND ASH

Waste product from most of coal based thermal power plants.

The coarser material, which falls into furnace bottom in modern large thermal power plants and constitute about 20% of total ash content of the coal fed in the boilers.

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Introduction

Effective utilization of pond ash is essential to reduce the environmental pollution.

Pond ash is differ from fly ash mainly because of its physical properties.

It is found that it is possible to replace some percent of sand by pond ash as fine aggregate in concrete without compromising on strength and durability.

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Chemical composition of pond ash

Compounds Composition,%

Loss of ignition 1.83

SiO2 57.17

Al2O3 5.57

Fe2O3 29.24

CaO 1.96

MgO 2.01

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Mix Proportions and Experimental Factors

• M20 and M40 grades were chosen.• IS 10262:1982 and SP 23-1982.• Fine aggregates are replaced by pond ash

range from 0 to 50%.• Curing – 7,28,56,90 days.

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Casting and Testing

• 72 numbers of 100mm cubical specimens were cast.

• In addition to it 108 cubes are cast for durability test.

• Strength test was carried out using CTM with 140 Kg/Sq.cm/min loading.

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Cement

locally available sand

Pond ash

Coarse aggregate

Fine aggregate

Pond ash concrete

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Durability Test

• 10 cm concrete cubes were immersed in 3 different solutions namely 5% Magnesium Sulphate ,5% sodium chloride and 5% of HCl.

• Effect of chemicals on compressive strength and weight were observed for 28 and 56 days.

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Results and discussion

Effects on compressive strength: -Pond ash concrete gains strength at slower

rate at initial stages.

- porous structure of the pond ash could have caused increased permeation.

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Effects on Workability : - Workability measured in terms of compaction factor. - workability decreases with increase of replacement percentage of pond ash.

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Effect on flexural strength:

- The flexural strength is affected to more extent with the increase of pond ash.

- pond ash concrete gains flexural strength

with age that is comparable but less that of plain concrete.

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Effects on split tensile strength :

- Split tensile strength of concrete decrease with increase in the percentage of pond ash. - Increases with age of curing.

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Resistance against Sulphate attack

• Effect of sulphate attack is cracking and spalling of concrete.

• Less weight is observed as the percentage of the pond ash increases.

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Grade of concrete

Pond

ash,%

28 Days 56 days

Weight loss,% Compressive strength

( mpa)

Weight loss, %

Compressive strength

(mpa)

M20

0 0.53 25.9 0.44 26.5

10 0.36 24.8 0.28 23.9 20 0.28 23.6 0.24 24.2

30 0.2 22 0.16 21.6 40 0.12 19.8 0.12 20.8

50 0.08 18.6 0.04 19.2

M40

0 0.47 44 0.24 45.8

10 0.27 43.8 0.35 45.3

20 0.15 41.6 0.16 44.2

30 0.23 39.2 0.11 44.7

40 0.16 37.6 0.12 43.2

50 0.12 35.7 0.08 42.4

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Advantages

• By using pond ash in cement concrete, we can reduce the cost of concrete with out compromising the strength.

• This concrete is more useful in the areas were the cost of sand is expensive.

• By utilizing dumped pond ash we can protect the hectors of land from degradation.

• Compressive strength is high compared to the conventional mix

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Conclusion

• The workability of concrete decreased with the increase in pond ash content.

• Compressive strength of fine aggregates replaced pond ash concrete specimens were lower than control concrete specimens at all the ages.

• Pond ash used as fine aggregates replacement enables the large utilization of waste product.

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References

• Aggarwal, P. Aggarwal, Y. and Gupta, S.M., "Effect of pond ash s replacement of the fine aggregate in concrete", Asian journal of civil engin(Building housing),2007,vol.8,No.1,pp.49-62.

• Kandraivendhan. B.Velchuri sairam and k.Nandagopal. "Influence of pond ash on strength and durability of concrete", The Indian concrete journal , October 2011.

• Kalgal. M. R. Pranesh, R.N, and Ravi Shankar. s., "Strength and durability of concrete with pond ash as fine aggregate", , The Indian concrete journal, March 2007,vol.42.