permeability characteristics of coarse pond ash

7/27/2019 permeability characteristics of coarse pond ash

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INTRODUCTION

LITERATURE REVIEW

SCOPE OF THE PRESENT WORK

EXPERIMENTAL WORK AND METHODOLOGY RESULTS AND DISCUSSIONS

CONCLUSIONS

REFERENCES


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Thermal power plants using coal is chief source of energy in

our country.

The total production of ash was found to be 131 million tonnes

during 2010-11

Wet disposal method is most widely used by the thermal

power plant.

At present around 265 km2 of area is covered by ash ponds

and by 2015 it would require 1,000 km2 for its disposal

Scarcity of land the power plants raise the height of dykes to

increase the ponding capacity.


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Filters and drains are two most important criteria for stability

and reliability of ash pond.

Purpose of filter

1. to protect the fly ash against being carried away with

seepage.

2. to take out the seepage water in order to keep the fly ash

in dry condition avoiding liquefaction .


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TITTLE OF

PAPER

AUTHOR

(YEAR)

DETAILS NAME OF THE

JOURNAL

Seismic failures

of Chilean

dams.

Dobry and Alvarez

(1967)

Studied seismic failures of

some tailings dams in Chilie

and found that the reason

being inadequate drainage.

Journal of

Geotechnical

Engineering,ASCE

Flow failures of

some mine

tailings dams

K. J. Jeyapalan,

(1981)

Reviewed failures of 16

tailings dams and ash dykes

which were caused due to

the instability of dams

constructed using theupstream method due to

excessive pore pressures

and absence of internal

drainage

Journal of

Geotechnical

Engineering,

ASCE


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TITTLE OF

PAPER

AUTHOR

(YEAR)

DETAILS NAME OF THE

JOURNAL

Granular Filterfor Ash Dykes S.R.Gandhi andV. Gima

Mathew(1996)

Conducted tests onamount of penetration,

amount of bypassing and

amount of clogging of fly

ash through different size

sand filter

IndianGeotechnical

Conference held at

Madras during

December 11-14,1996

Design And

Maintenance Of

Ash Pond For

Fly Ash

Disposal

S.R.Gandhi

(2005)

Described the design and

maintenance of ash pond

for fly ash disposal

Indian

Geotechnical

Conference,

Warangal. 2005

Use of Bottom

ash in lieu of

sand as filter in

ash dyke

embankment

J. Kumar and

D.N.Naresh

(2012)

Conducted a case study on

the use of bottom ash as

filter in lieu of sand as

internal drainage for

exiting the hydraulic

gradient

Geo Congress

2012,ASCE .


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MOTIVATION:

Non-availability of good sand as a filter material during monsoon

and just after monsoon creates a problem in construction of ash

dyke. Coarse pond ash and bottom ash which are the waste

products and non-plastic in nature and available abundantly may

replace the conventional sand as a filtering material.SCOPE

To study the crushability and permeability properties of samples

subjected to different loading intensities (dynamic compacting

energies of 0 to 4278 kJ/m3

) To find out the filter criteria and check whether these materials

are suitable as a filter media after being subjected to loading.


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Bottom ash and coarse pond ash samples were collected from

NTPC, Kaniha, Odisha


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Determination of index properties

Grain size distribution curve, specific gravity, plasticity index of

both the samples were determined as per the Indian Standard Code

of practice IS-2720 part (VI), IS-2720 part (III) and IS-2720 part

(VI) respectively.


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Physical parameter Pond Ash Bottom Ash

Colour Light grey Grey colour with

unburned coal

Shape Rounded/ sub rounded Rounded/ sub rounded

Mean diameter, D50 0.3 mm 0.28 mm

Uniformity coefficient,Cu

3.33 3.52

Coefficient of

curvature, Cc

1.2 1.028

Specific gravity, G 2.18 2.12

Plasticity index, Ip Non-plastic Non-plastic

Loss on ignition 0.347 4.0265


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Sample preparation

Subjected to dynamic compactions in a Proctor mould at drystate either in using Standard Proctor rammer or Modified

Proctor rammer

The number of blows and layers are so adjusted that the

resulting compactive effort (E) on the sample are either 149,595, 1070, 2674 or 4278 kJ/m3


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Grain size distributions for all twelve samples were conducted

as per IS: 2720 part (IV)

0

10

20

30

40

50

60

70

80

90

100

110

0.01 0.1 1 10 100

%f

iner

particle size in mm

E=0

E=149kJ/m3

E=595kJ/m3

E=1070kJ/m3

E=2674kJ/m3

E=4278KJ/m3

Fig 1 Grain size distribution curve of pond ash


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0

10

20

30

40

50

60

70

80

90

100

110

0.01 0.1 1 10 100

%f

iner

particle size in mm

E=0

E=149kJ/m3

E=595kJ/m3

E=1070kJ/m3

E=2674kJ/m3

E=4278kJ/m3

Fig 2 Grain size distribution curve of bottom ash


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Coefficient of uniformity, coefficient of curvature and mean

diameter of the samples

Compaction energy

in kJ/m3

Pond Ash Bottom ash

D50

Cu

Cc

D50

Cu

Cc

0 0.35 3.33 1.2 0.29 3.52 1.028

149 0.29 3.88 1.4 0.267 3.69 1.154

595 0.26 4.91 1.77 0.26 3.79 1.219

1070 0.258 5.08 1.8 0.25 4.20 1.279

2674 0.24 5.185 1.85 0.24 4.37 1.366

4278 0.23 5.192 1.9 0.23 5.79 1.392


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Determined as per IS-2720 part (14) for samples that have

been subjected to different compactive energies

Minimum dry density was determined by filling the standard

mould in sand raining method to their loosest state

Maximum dry density was determined with respect to their

densest state using vibrating table and putting a surcharged

weight over it


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Compaction

Energy in

kJ/m3

Pond ash Bottom ash

minimum

density in

gm/cc

maximum

dry density

in gm/cc

minimum

density in

gm/cc

maximum

dry density

in gm/cc

0 0.8025 1.009 0.862 1.038

149 0.858 1.081 0.901 1.087

595 0.8795 1.11 0.938 1.138

1070 0.9245 1.161 0.946 1.144

2674 1.0135 1.223 0.994 1.203

4278 1.0369 1.254 1.036 1.246


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Coefficient of permeability of both pond ash and bottom ashsamples were determined per IS: 2720 (part 36 )1987


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Compaction

Energy in

kJ/m3

Pond ash Bottom ash

Coefficient of

permeability

at minimum

density in 10-3cm/sec

Coefficient of

permeability

at maximum

dry density in10 -3 cm/sec

Coefficient of

permeability at

minimum

density in 10 -3cm/sec

Coefficient of

permeability

at maximum

dry density in10 -3 cm/sec

0 11.54 8.40 8.5478 5.388

149 10.06 7.193 7.264 4.493

595 9.070 5.147 5.611 2.656

1070 8.204 4.162 4.669 1.4158

2674 6.327 2.246 2.288 0.791

4278 4.256 1.354 1.123 0.551


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Cu increases from 3.33 to 5.192 for pond ash and for bottomash it increases from 3.52 to 5.79 with increase in compactive

energy from 0 to 4278 kJ/m3

Cc increases from1.2 to1.9 for pond ash sample and for

bottom ash sample 1.028 to1.392 with increase in compactiveenergy from 0 to 4278 kJ/m3

This indicates that with increase in compactive effort the size

of grains reduced and the samples tend to be well graded.


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0

1

2

3

4

5

6

7

0 500 1000 1500 2000 2500 3000 3500 4000 4500

C

cocuvueauomity

compaction energy in kJ/m3

Cu of pond ash

Cc of pond ash

Cu of bottom ash

Cc of bottom ash

Fig. 3 Coefficient of curvature and uniformity of samples subjected to different

compactive energies


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Fig. 4 Minimum and maximum density of samples subjected to different

compactive energies

0.7

0.8

0.9

1

1.1

1.2

1.3

0 500 1000 1500 2000 2500 3000 3500 4000 4500

dydtyngm/


minimum dry density of pond ash

maximum dry density of pond ash

minimum dry density of bottom ash

maximum dry density of bottom ash


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0

2

4

6

8

10

12

0 500 1000 1500 2000 2500 3000 3500 4000 4500

pmety1cm/


at minimum dry density condition of PA

at maximum dry density condition of PA

at minimum dry density condition of BA

at maximum dry density condition of BA

Fig 5 Graph between compaction energy and permeability


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D15 (F) > 5 D15 (B) or 0.1mm

D15 (F)=0.15mmTest result is found to be 5D15(B) = 0.88 mm but

After crushing D15 (F) = 0.07 and 5D15 (B) = 0.025mm

Partially Satisfying IS criteria

As it is a silty sand and for percentage finer than 15%- 39%

D15 (F) < (40-A)/(40-15) *(4D85(B)-0.7)+0.7 m m

where A = % passing 75 micron

Test result is found to be (40-A)/(40-15) *(4D85(B)-0.7)+0.7

= 9.716 mm

After crushing at maximum compaction energy is found to be

D15 (F) = 0.07< 2.708

Satisfying IS criteria


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Filter materials are non-cohesive

Maximum size of the filter materials are less than 75mm.

Filter material passing 75 micron is less than 5%


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Specific gravity for both pond ash and bottom ash are found to

be 2.18 and 2.12 respectively which are lower than theconventional earth material of similar gradation

As the compaction energy increases, particles crushed but their

gradation changes from uniformly graded to well grade

Particles after crushing (subjected to compaction energiesfrom 0 to 4278 kJ/m3 ) however it also satisfies the IS filter

criteria

After crushing permeability of both pond ash and bottom ash

decreases but lies within the range of sand Use of bottom ash as a filter material also reduces the cost of

construction of ash dyke.

It is also an effective means of utilisation of thermal power

plant waste.


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Dobry. R and Alvarez, L. (1967), Seismic Failures of Chilean

dams. Journal of Geotechnical Engineering, ASCE,Vol.93.No.SM6,pp.237-260

Jeyapalan, K.J. (1981). Flow Failures of some mine Tailings

Dams, Geotechnical Engineering. Vol. 12, pp. 153-166.

Gandhi, S.R., and Gima V. Mathew, (1996) Granular Filterfor Ash Dykes, Proceedings of Indian Geotechnical

Conference held at Madras during December 11-14, 1996.

pp.532-535.

Gandhi, S.R., Raju, V.S., and Vimal Kumar, (1997)Densification of Deposited Ash Slurry, Proceedings of 13th

International Conference on Solid Waste Management,

Philadelphia.


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Gandhi S. R.,(2005) Design And Maintenance Of Ash PondFor Fly Ash Disposal. Indian Geotechnical Conference,

Warangal.

Pedro J Amaya, Andrew J Amaya, (2007) The use of Bottom

Ash in the Design of Dams World of coal ash (WOCA),

Northen Kentucky , USA

Indian Standard (IS): 9429Drainage System for Earth and

Rockfill DamsCode of Practice.

Kumar, J. and Naresh, D.N (2012)Use of Bottom ash in lieu

of sand as filter in ash dyke embankment GeoCongress2012,ASCE


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permeability characteristics of coarse pond ash

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