Experimental Case Study On Pond Ash Replacement Engineering Essay

Abstract

This research studies the potential of using Pond ash from Deepnagar Thermal Power Plant, Bhusawal, Dist. Jalgaon, as a part replacement with sand in plaster mortar. Pond ash is rarely used in concrete due to its inactive pozzolanic reaction may be used as a fine aggregate in mortar mix used for plastering purpose, improves the quality of plastered surface in terms of strength and durability. When pond ash was used at a 20% replacement of sand to make mortar mix, produced higher percentage compressive strength as well as a higher development rate than those of the traditional cement – sand mortar mix. As a result of the compressive strengths, it was concluded that pond ash could be used as a good replacement material in mortar. It is proposed to perform some field and laboratory experiments on different mix proportions of pond ash and plaster sand and to compare the results with traditional plaster mortar. The cubical specimens were tested to determine compressive strength. The Soundness test is performed to know the amount of expansion after the setting time. With the help of Davel abrasion test, it is possible to relatively compare the abrasion values of the different proportions of the plaster mortar cubes. In the investigation some field and laboratory experiments on different mix proportions of pond ash and plaster sand are done and the results are compared with traditional cement-sand plaster mortar.

Due to Pond Ash replacement, the initial strength gaining process is quite slow but in later stages it gains very good strength as compare to traditional mortar mixes. Workability of mortar mix is increased due to addition of pond ash, which will result in the reduced w/c ratio. Change in the volume of hardened mortar is very less due to addition of pond ash, which results less occurrence of surface cracks.

Keywords- Mortar, Pond Ash, Pozzolonic.

1. INTRODUCTION

1.1 General

Pond ash is the waste product from most of the thermal power plants in India. The fly ash gets mixed with bottom ash and disposed off in large pond dykes as slurry. Pond ash contains relatively coarse particles. The huge amount of pond ash accumulated around the thermal power stations is still posing threat to environment. The utilization of pond ash as a building material is one of the possible way of its sustainable management. In the present study, an attempt is made to ascertain the possibility of using the pond ash as a replacement of sand in plaster mortar.

Origin of Pond Ash

Pond ash is the waste product from most of thermal power plants in India. The fly ash gets mixed with bottom ash and disposed off in large pond or dykes as slurry. Pond ash contains relatively coarse particles. As Pond ash is being produced at an alarming rate, efforts are required to safely dispose it and if possible find ways of utilizing it.

Necessity of Pond Ash Management

It is estimated that by the end of tenth planned period an additional 124000 Mega Watt (MW) of power sector expansion will require in India to meet the raising demands of energy. So the quantum of Pond ash generation will increase in future. It has warranted the scientific as well as industrial community to initiates research and development work for finding innovative use and safe disposal of Pond ash so that instead of a waste product, the pond ash can be utilized in large quantities in various engineering works. The ash produced in thermal power plants can cause all three environmental risks – air, surface water and ground water pollution. Air pollution is caused by direct emissions of toxic gases from the power plants as well as wind blown ash dust from ash ponds. The air borne dust can fall in surface water system or soil and may contaminate the water/soil system. The wet system of disposal in most power plants causes discharge of particulate of ash directly into the nearby surface water system. [2]

Sources of Pond Ash in India

In India as coal based Thermal Power Plant has contributes to 75% to the total power generation. The coal reserves of the country is predominately of lower grade of non-cooking and as a result the quantity of ash produced will also increase. The Indian coal on an average has 35% ash and this is one of the prime factors which lead to increase ash production. Hence, ash utilization is a problem for the country. The Indian Thermal power plant uses high ash and inferior quality non-cooking coal. Present India’s Thermal installed capacity to an estimate is 1, 00,000 MW and coal consumption for Thermal power generation required is 300 million MT every year. Use of coal brings many problems, primarily due to huge amount of ash, which is produced by-product of the process of power generation. Out of total ash produced, fly ash contributes to small percentage, majority being pond ash and bottom ash.

Environmental Consideration

The ash produced in thermal power plants can cause all three environmental risks – air, surface water and ground water pollution. Air pollution is caused by direct emissions of toxic gases from the power plants as well as wind blown ash dust from ash ponds. The air borne dust can fall in surface water system or soil and may contaminate the water/soil system. The wet system of disposal in most power plants causes discharge of particulate of ash directly into the nearby surface water system. The long storage of ash in the ponds under wet condition and humid climate can cause leaching of toxic metals from ash and contaminate the underlying soil and ultimately the ground water system. Kumar [2]

1.6 Existing Use of Pond Ash

The literature available specifically on the use of pond ash is scarce. However in general the fly ash has lot of potential for its sustainable use. The use of fly ash in the construction of road and embankment has been successfully demonstrated in the country. The Ministry of Surface Transport (MOST) and Central Public Works Department (CPWD) have accepted the use of fly ash and have executed many projects. The fly ash can be utilized in cement concrete and mortar as an ingredient / partial replacement of cement and sand. The replacement of OPC may vary from 15 to 35 % or even higher percentage in mass concrete. BIS: 456 [5] The pond ash is also utilized in manufacturing of Light Weight Aerated Concrete (LWAC) products such as blocks, panels, reinforced slab, etc, which are much lighter than conventional materials. The bulk density of product ranges from 500kg/cum to 1800kg/cum, depending upon reinforcement. The use of block in housing construction can results nearly40 % reduction in dead weight, 50 % saving in construction time and about 80 % saving in consumption of mortar in comparison to conventional brick work. The fly ash (90-95%) mixed with OPC (5-10%), along with the water make the flow able fill material termed as Controlled Low Strength Material (CLSM), which can use in the restricted areas where placing and compaction is very difficult such as narrow trenches, utilities structure like mines, tunnels, tanks and trenches in road pavement cut. The use of pond ash in mine fill material is one of the possible alternatives to be considered by various agencies. The optimum utilization of pond ash through mine void filling by High Concentrated Slurry Disposal (HSDS) system may prove a plausible solution of pond ash management. The use of fly ash in agriculture applications has been well demonstrated and is gaining momentum in the agriculture sector of country. This is picking up in Karnataka, West Bengal and Madhya Pradesh and for wasteland reclamation in Uttar Pradesh. [5]

Overview of the Project

In this investigation partial replacement of sand by pond ash in plaster mortar is attempted. It is possible to use pond ash as fine aggregate without compromising on strength and durability. This study opens up a major avenue for the utilization of pond ash. Studies are done on pond ash sample from Deep Nagar Thermal Power Plant, Bhusawal, Dist. Jalgaon. The large scale utilization of Pond Ash would be possible and this will become major contributing factor for reducing pollution. Sand, precious natural resources, is becoming scarce and quarrying of this has been restricted in many states in India, this has made to look for the possibility for partial replacement of sand by Pond ash. It is proposed to perform some field and laboratory experiments on different mix proportions of pond ash and plaster sand and to compare the results with traditional plaster mortar. The flow diagram in figure-1, shows the detail procedure.

Figure 1: Overview of Experimental Programme

2. POND ASH IN PLASTER MORTAR

2.1 Proportioning of Mortar

The experimental programme utilizes the ponded ash from DeepNagar Thermal Power Plant and tests were conducted in field as well as in laboratory. The mortar mixes were considered at pond ash replacement percentage of 0, 20, 25, and 30 and with mix proportions of cement: pond ash: sand and additional proportion of cement: fly ash: sand. Hand mixing, with volume batching was done. [1], [9]

Proportion

% Replace

ment

Cement

Pond ash Replacement

sand

W/C Ratio

P-1

5

1

0.25

4.75

1.10

P-2

10

1

0.50

4.50

1.10

P-3

15

1

0.75

4.25

1.10

P-4

20

1

1.00

4

1.10

P-5

25

1

1.25

3.75

1.10

P-6

30

1

1.50

3.50

1.10

P-7

1

5

1.10Table 1: Different Proportion of Mortar Mixes

2.2 Plastering Process

The surface to be plastered was cleaned and freed from dust, loose material, oil, grease, mortar dropping, sticking of foreign matter, trace of algae, etc. Raking of joint was carried out along with masonry and checked out thoroughly so as to receive good key. The plaster was provided in two coats. Thickness of undercoat was 15mm and balanced in the second finishing coat. The second coat was of 10 mm. The under coat was allowed to dry and shrink before applying the second coat of plaster. After a suitable time interval (After 2 days) the second coat was applied. [7], [8]. Figure -2 show different patches of plaster.

Figure 2: Plastering Process on Brick Wall

2.3 Compression Test

The compression test has been carried out on specimens cubical in shape. The cube specimen is of the size 7.07 x 7.07 x 7.07 cm. Three specimen samples for all proportions are prepared. Universal testing machine (UTM) of 400 kN capacity was used in testing the mixes.

Figure 3: Compression Test Sample-Before and After Deformation

The mortar was filled into the mould in three layers approximately. Each layer was compacted by hand. After the top layer compacted, the surface of the mortar was finished with the top mould, using a trowel. The test specimens were submerged in the water for 7 and 28 days.

Universal testing machine (UTM) of 400 Kilo Newton (kN) capacity was used in testing the mixes. Compression test was carried out for 7 day and 28days strength for the different proposed proportions are shown in the Table 2.

SN

Propor

tion

P.A.

Replacement

7 day Comp. Strength

28day Comp. Strength

1

P-1

5%

3.31

7.68

2

P-2

10%

4.11

8.79

3

P-3

15%

4.91

9.89

4

P-4

20%

5.27

11.00

5

P-5

25%

5.87

10.92

6

P-6

30%

5.04

10.23

7

P-7

0%

2.51

6.57Table 2. Compression Test Results of Pond Ash Mortar Specimens

Figure given below shows the graph of Percentage Pond Ash Replacement v/s 7 and 28 Days Compressive Strength.

Figure 4: Percentage Pond Ash Replacement v/s 7 and 28 Days Compressive Strength.

2.4 Soundness Test Using Le-Chatelier’s Apparatus

The mortar after preparation is liable to expand after the setting action is complete. It is one of the causes of cracking of plaster mortar. The Soundness test is, therefore, performed to know the amount of expansion after the setting time. [6] Table 3 shows Expansion of the mortar for different proportions.

2.5 Davel Abrasion Test

This research work does not deal with the coarse aggregate as the coarse aggregate is not the constituent material for the mortar. But with the help of this test, the abrasion values of the different proportions of the plaster mortar cubes can be relatively compared. The abrasion value determined should not be more than 16 % for the concrete aggregates. Table 4 gives Davel Abrasion Test Results for different mortar mixes.

SN

Propor

tions

% Repl’t

Final Exp.

(mm)

Initial

Exp.

(mm)

Total

Exp.

(mm)

1

P-1

5

13

11

2

2

P-2

10

14

11

3

3

P-3

15

13

10

3

4

P-4

20

14

11

3

5

P-5

25

15

12

3

6

P-6

30

13

11

2

7

P-7

15

11

4Figure 5: Soundness Test Using Le-Chatelier’s Apparatus

Table 3: Expansion for different Mortar Mixes.

SN

Proportions

% Repl’t

Initial Wt. of Cube

(kg)

Crush passing thr. sieve

Abr’n Value

1

1

5

0.786

0.11

13.75

2

2

10

0.786

0.10

12.75

3

3

15

0.796

0.10

12.5

4

4

20

0.786

0.094

12

5

5

25

0.786

0.098

12.5

6

6

30

0.796

0.10

12

7

7

0.785

0.12

15

Table 4: Davel Abrasion Test Results

3. CONCLUSION

From the experimental results on the replacement of Pond Ash as Replacement with Sand in Plaster Mortar, the conclusions can be drawn as, the use of Pond Ash as part replacement for sand in plaster mortar gives higher compressive strength than traditional mortar mixes. Part replacement with 20 % Pond Ash in mortar, gives higher compressive strength then the other percentage replacements (0%,5%, 10%, 15%, 25% & 30%), when tested for 28 days compressive strength. Due to Pond Ash replacement, the initial strength gaining process is quite slow but in later stages it gains very good strength as compare to traditional mortar mixes.

The problem of disposing pond ash can is reduced by utilizing it in large quantity in various engineering work. In the present study, the possibility of using a locally available fine grained pond ash as a replacement of sand in plaster mortar has been tested and analyzed. This study opens up a major avenue for the utilization of pond ash. The large scale utilization of Pond Ash would be possible and this will become major contributing factor for reducing pollution.

4. REFRENCES

[1] A.M. Pandey, L.M. Gupta, “Proportions of concrete ingredients and their significance in compressive strength “Indian Concrete Journal, Vol.81, June 2007, pp.15-27

[2] Kumar (2004), Dr Virender Kumar “Compaction and Permeability Study of Pond Ash Amended with Locally Available Soil and Hardening Agent”. Journal of ‘The Institution of Engineers (India)’, Vol.85, May2004, pp 31-35.

[3] Chai & Cheerarot (2003), Chai Jaturapitakkul and Raungrut Cheerarot. “Development of Bottom Ash as Pozzolanic Material”. Journal of Material in Civil Engineering, Vol. 15, No. 1, January/February 2003, pp.48-53

[4] S.K.Sekar, P.Devdas, U.John, “Performance of Fly ash Concrete”, New Building Material and Construction World, Volume-81, No.06, July-2003, pp.46.

[5] FAUP (2005), Fly Ash Utilization Programme”Fly Ash Management in India: An Integrated Approach “, Proceeding of “Fly Ash, India-2005”, International Congress, Dec. 2005, Convention Hall, Hotel Ashok, New Delhi, India.

[6] BIS 383 (1970), Specification for Coarse and Fine Aggregate from natural Sources for Concrete (Second Revision), Bureau of Indian Standards. Manak Bhavan, 9, Bahadur Shah Zafar Marg IN-New Delhi 110002.

[7] BIS 1661 (1972), Code of Practice for Application of Cement and Cement Plaster Finishes, Bureau of Indian Standards. Manak Bhavan, 9, Bahadur Shah Zafar Marg IN-New Delhi 110002.

[8] BIS 2402 (1963), Code of Practice for External Rendered Finishes, Bureau of Indian Standards. Manak Bhavan, 9, Bahadur Shah Zafar Marg IN-New Delhi 110002.

[9] BS 5390:1976, Code of Practice for Stone Masonry, BSI British Standards, Customer Services, 389, Chiswick High Road, London, W4 4AL, United Kingdom.