Dr. Raju Sarkar - WTERT

By

Dr. Raju SarkarDr. Raju Sarkar

Department of Civil & Environmental Engineering

Delhi Technological University(Formerly Delhi College of Engineering)

[email protected]

• Introduction

• Experimental Investigations and Material Properties

• Numerical Study on Pavements Constructed Using Stabilized Pond AshesStabilized Pond Ashes

• Conclusions

• One of the major challenges before manufacturing and production

industries is disposal of residual solid waste products.

• Present emphasis has been laid on residual solid products of thermal

power plants which utilize coal as a fuel for generation of power.

• In National Capital Region - Delhi alone, the production of ash is nearly

5000 tons by the three thermal power stations -Badarpur, Rajghat and

Dadri.

National Thermal Power Station (Badarpur)

Badarpur ash pond

National Thermal Power Station (Dadri)

Dadri ash pond

Pragati Thermal Power Station (Rajghat)

Rajghat ash pond

Few Definitions

Fly ash: fine fraction of ash collected through ESP (electrostatic precipitators) located inside Chimneys. Silt size.

Bottom ash: ash settled at the bottom of a furnace. Sand size.

Pond ash: fly ashes and bottom ashes sluiced in slurry form to ponds in the vicinity and gets collected in ponds is referred as pond ash. Heterogeneous material.Heterogeneous material.

Utilization of ashes

Fly ash: fine silt size, pozzolanic , used in cement manufacturing industry, in

concrete, brick making etc.

Bottom ash: sand size particles, alternative to fine aggregates in cement and

asphalt mixtures, and concrete. asphalt mixtures, and concrete.

Pond ash: with its heterogeneous character makes up for its subdued

chemical reactivity by its intergranular locking and is normally used

in the areas of bulk applications, such as structural fills, backfills,

embankments, road construction, etc.

Need of present study

The need of the present study arises from:

• Overall utilization of Industrial solid waste viz. pond ash needs be improved

i) to reduce the air pollution due to wind; to avoid mixing with surface runoff during flood; and to prevent leaching into the ground water.

Air pollutionFlooded ash pond near thermal power plant

Runoff mixed with pond ash in paddy field

Surface runoff mixed with pond ash

ii) to provide alternative material for road construction and raised embankments to reduce the pressure on conventional aggregates and local soil.

Road

Need of present study (contd.)

Raised embankmentRoad Raised embankment

• To remove confusion regarding cost benefit and provide technical inputs on utilization of several recently introduced materials (termed as admixtures or additives in this study) such as bentonite, fibers, lime, etc. in the stabilization of pond ash.

• Need to introduce better low cost additives, preferably, waste materials for better utilization of pond ash.

Objectives of the study

• Collection of pond ash samples from Badarpur, Dadri and Rajghat thermal power plants to determine physical and geotechnical properties of these pond ashes.

• Carry out Proctor compaction tests, triaxial shear tests and CBR tests on pond ash and its

Collection of pond ash sample from ash pond

Proctor compaction test Triaxial shear test CBR test

• Carry out finite element analysis of pavements having subbase layer made up of stabilized pond ash using PLAXIS.

Finite element analysis of pavements

CBR tests on pond ash and its mixes.

Materials used

Pond ash

Additives

Fiber(polypropylene, low

density, low softening temp. range, hydrophobic nature)

Lime(Calcium oxide – CaO, used to

stabilize soils)

Bentonite (montmorillonite, swelling property, highly absorbent)

New material introduced

(i) Gelatin

• A protein produced by partial hydrolysis of collagen extracted from the boiled bones, tissuesand organs of animals.

• Gelatin melts to a liquid when heated and solidifies when cooled again.

• Gelatin is used as a stabilizer and thickener.

Additives (contd.)

Gelatin

(ii) Starch

• Gelatin is used as a stabilizer and thickener.

• Carbohydrate found in all vegetable matters and in commercially recoverable quantities in Maize, Tapioca, Potato, Wheat and Rice.

• Maize starch used as binder, stabilizer, thickening and suspending agent in textile, paint, detergent and paper industry.

Gelatin

Starch

Waste material - Marble dust

• A by-product during cutting of marble.

• Waste is 20% of the total marble handled.

• Amount of marble dust generated in Rajasthan (from where the sample is collected) every year is 5-6 million tonnes.

Additives (contd.)

Marble industry of Rajasthan

Dry Marble dust Slurry Marble dust

Marble dust

Admixture Percentage

Bentonite 2, 5, 8, 10

Fiber0.5, 1.0, 1.5, 2.0, 2.5,

3.0, 3.5

Percentages of admixtures used for stabilizing pond ash

Details of experiments Materials Standard codes used

a) Specific gravity Pond ashes RILEM (1989)

b) Grain size distribution Pond ashes IS: 2720 ( Part 4) – 1985

c) Atterberg limit tests Pond ashes IS: 2720 ( Part 5) – 1985

d) Compaction tests:

Experimental programme

Lime 2, 5, 8, 10

Marble dust 2, 5, 8, 10

Gelatin-Starch

(1:2)0.5, 1.0, 1.5, 2.0, 2.5

d) Compaction tests:

i) Light compaction (standard Proctor) test

ii) Heavy compaction (modified Proctor)

test

Pond ashes

and mixes

IS: 2720 ( Part 7) – 1980

IS: 2720 ( Part 8) – 1983

e) Consolidated drained triaxial tests under

confining pressures of 100, 200, and 300 kPa

Pond ashes

and mixes

IS: 2720 ( Part 11) –

1981

f) California Bearing Ratio testPond ashes

and mixes

IS: 2720 ( Part 16) –

1987

Test results and discussions

Specific gravity (G)

• Specific gravity of Badarpur, Dadri and Rajghat pond ashes are 2.20, 1.96

and 2.10.

• Specific gravity of Indian coal ashes reported by Sridharan (2001) is 1.46• Specific gravity of Indian coal ashes reported by Sridharan (2001) is 1.46

to 2.66.

Grain size analysis

• Uniformity coefficient of Badarpur, Dadri and Rajghat pond ashes are 4.8,

5.96 and 5.11.

• McLaren and DiGioia (1987) have reported the mean value of uniformity

coefficient as 5.49 ±3.6.

Atterberg limit tests

• Liquid limits of Badarpur, Dadri and Rajghat pond ash are 38.5%, 46.6%

and 43.8%.

• Plastic limit test showed non-plastic behavior.

• Havanagi (1999) obtained the liquid limit of Rajghat fly ash as lying

between 38% to 51%.

Compaction characteristics

Type of Pond Ash Type of Proctor Compaction Test Value

Badarpur

StandardMDD (kN/m3) 12.0

OMC (%) 32.0

ModifiedMDD (kN/m3) 14.9

OMC (%) 24.0


OMC (%) 33.0

Table: Proctor compaction test results of pond ashes

Dadri

StandardOMC (%) 33.0


OMC (%) 22.1

Rajghat


OMC (%) 30.9


OMC (%) 25.2

15

20

Standard Proctor Test (Badarpur Pond Ash) Modified Proctor Test (Badarpur Pond Ash)

Standard Proctor Test (Dadri Pond Ash) Modified Proctor Test (Dadri Pond Ash)

Standard Proctor Test (Rajghat Pond Ash) Modified Proctor Tests (Rajghat Pond Ash)

Dry

Den

sity

(k

N/m

3 )

Fig.: Standard and modified Proctor test results for Badarpur, Dadri and Rajghat pond ashes

5

10

5 15 25 35 45Water Content (%)

Dry

Den

sity

(k

N/m

PropertiesSource of pond ash

Badarpur Dadri Rajghat

Fine sand size, 0.425-0.075 mm, % 72 56 66

Silt size, 0.075-0.002 mm, % 22 34 31

Uniformity coefficient, Cu 4.8 5.96 5.11

Coefficient of curvature, Cc 1.05 1.06 1.06

Effective sizeD10, mm 0.049 0.026 0.043

D30 size, mm 0.11 0.065 0.1

Table : Geotechnical properties of Badarpur, Dadri and Rajghat pond ashes

D30 size, mm 0.11 0.065 0.1

D60 size, mm 0.235 0.155 0.22

Specific gravity 2.2 1.96 2.1

Plastic Limit Non-plastic Non-plastic Non-plastic

Maximum dry density, kN/m3 12 11 11.9

Optimum moisture content, % 32 33 30.9

CBR value (%) 12.2 10.4 11.2

Triaxial (CD) Test

Cohesion intercept (c), kPa 0 0 0

Angle of shearing resistance φ, (°) 30.4 32.0 28.9

Table: Comparison of highest MDD and corresponding OMC of pond ashes mixed with admixture

Admixture Percentage Type of Proctor's testBadarpur

pond ash

Dadri

pond ash

Rajghat pond

ash

Bentonite 2

StandardMDD (kN/m3) 11.8 10.8 11.5

OMC (%) 31.4 32.4 30.1

ModifiedMDD (kN/m3) 14.4 13.3 13.9

OMC (%) 23.4 21.8 24.5

Fiber 3

Standard MDD (kN/m3) 13.4 12.3 13.0

OMC (%) 28.8 29.7 27.6


OMC (%) 21.3 19.7 22.3

MDD (kN/m3) 13.9 13.1 13.6

Lime 8


OMC (%) 34.8 36.3 34.0


OMC (%) 26.6 25.5 28.1

Marble dust 10


OMC (%) 29.6 30.6 28.6


OMC (%) 21.5 20.0 23.0

Gelatin-Starch

(1:2)2.5


OMC (%) 30.3 28.3 29.5


OMC (%) 25.2 22.9 24.3

Consolidated drained (CD) triaxial test

• On saturated compacted specimens of pond ashes and their combinations;

under confining stresses of 100, 200 and 300 kPa.

• Axial strain at failure increases with an increase in confining pressure for all

pond ashes and when mixed with admixtures.

• Deviator stress attained peak value at axial strains of 1.5-3.0% for all

specimens and thereafter remained constant.

0

250

500

750

0 1 2 3

100 kPa 200 kPa 300 kPa

Axial Strain (%)D

evia

tori

cS

tres

s (k

Pa)

0

250

500

750

0 1 2 3

100 kPa 200 kPa 300 kPa

Axial Strain (%)

Dev

iato

ric

Str

ess

(kP

a)

0

250

500

750

0 1 2 3

100 kPa 200 kPa 300 kPa

Axial Strain (%)

Dev

iato

ric

Str

ess

(kP

a)

y = 0.5059x

0

100

200

300

400

100 300 500 700p (kPa)

q (

kP

a)

y = 0.5306x

0

100

200

300

400

100 300 500 700p (kPa)

q (

kP

a)

y = 0.483x

0

100

200

300

400

100 300 500 700p (kPa)

q (kPa)

Fig.: Deviatoric Stress vs. Strain and p-q behavior of(a) Badarpur Pond Ash (b) Dadri Pond Ash (c) Rajghat Pond Ash

Table: Comparison of highest φ value of pond ashes mixed with admixture


Badarpur

Pond Ash

Dadri

Pond Ash

Rajghat

Pond Ash

c (kPa) φ (o) c (kPa) φ (o) c (kPa) φ (o)

Bentonite 2.0 13.0 30.0 15.2 31.6 12.2 28.5Bentonite 2.0 13.0 30.0 15.2 31.6 12.2 28.5

Fiber 3.0 14.6 34.1 12.4 33.8 14.9 33.6

Lime 8.0 0.00 33.0 0.00 33.1 0.00 32.4

Marble dust 10.0 0.00 32.5 0.00 32.4 0.00 31.3

Gelatin-Starch (1:2) 2.5 0.00 34.9 0.00 35.0 0.00 34.8

California Bearing Ratio (CBR) test

• Purpose of CBR test is to study the strength behavior of material when

used as a subbase material.

• CBR tests are carried out on pond ash and its mixes.

• Tests are carried out on the specimens compacted in accordance to

standard Proctor test.

Badarpur Pond ashRajghat Pond ashDadri Pond ash

(a) (b)

0

4

8

12

16

0 3 6 9 12

CB

R V

alu

e (%

)

Percentage Bentonite

5

15

25

35

45

0 1 2 3 4

CB

R V

alu

e (%

)

Percentage Fiber

Fig.: Variation of CBR value with percentage (a)Bentonite (b) Fiber (c) Lime (d) Marble dust

(a) (b)

0

10

20

30

40

0 3 6 9 12

CB

R V

alu

e (%

)

Percentage Lime

0

8

16

24

32

0 3 6 9 12

CB

R V

alu

e (%

)

Percentage Marble Dust(c) (d)

Badarpur Pond ash Rajghat Pond ashDadri Pond ash

0

12

24

36

48

0.6 1.2 1.8 2.4 3

CB

R V

alu

e (%

)

(e)

0.6 1.2 1.8 2.4 3

Percentage Gelatin-Starch

Fig.: Variation of CBR value with percentage (e) Gelatin-Starch

Table: Comparison of highest CBR value in percentage of pond ashes mixed with admixture


CBR Value (%)

Badarpur

Pond Ash

Dadri

Pond Ash

Rajghat Pond

Ash

Bentonite 2.0 11.9 10.1 10.8

Fiber 3.0 38.7 35.6 37.9

Lime 8.0 33.9 31.2 32.3

Marble dust 10.0 29.0 24.2 26.7

Gelatin-Starch (1:2) 2.5 42.7 36.9 40.2

• Finite Element Analysis (FEA) is most important numerical method to

solve complex geotechnical problems.

• Present study uses the PLAXIS computer program to predict the stress-

strain distribution within the different layers of pavement.

PLAXIS

PLAXIS has following features:

• Analyses such as static, modal, spectrum, transient and harmonic.

• Two-dimensional (plane stress, plane strain) and three-dimensional • Two-dimensional (plane stress, plane strain) and three-dimensional

analyses.

• Various constitutive models such as elastic, elasto-plastic (Mohr-

Coulomb), etc.

Pavement section

• A typical pavement structure is designed considering subgrade material

as Delhi silt with CBR equal to 9%.

• Traffic load of 100 million standard axles (msa) as per IRC: 37-2001.

Bituminous Concrete 50 mm

DBM Course 135 mm

3750 mm

Subgrade Course 300 mm

DBM Course 135 mm

WBM Course 250 mm

Sub-base Course 200 mm

935 mm

Fig.: Pavement structure (not in scale)

2

1

Ei = 1020 MPa, ν = 0.35Bituminous Concrete

(BC)

Dense Bituminous Macadam

(DBM)Ei = 750MPa, ν = 0.35

Water Bound Macadam

(WBM)

Ei = 167.6 MPa, ν = 0.35, c = 0, φ = 48o

50 mm

250 mm

135 mm

575 kPa

(BC and DBM)Linear elastic

response

Subbase

Ei = 34.5 MPa, ν = 0.35, c = 0, φ = 30.4o

Subgrade

Ei = 30 MPa, ν = 0.30, c = 0, φ = 32o

Fig.: Finite element discretization of pavement section

1100 mm150 mm

200 mm

300 mm

(WBM, Subbase and Subgrade)Elasto-plastic

(Mohr-Coulomb relationship)

Table: Values of modulus of elasticity and Poisson’s ratio and shear parameters for different pavement material

Pavement LayersConstitutive

Model

Modulus of

Elasticity

(Ei) (MPa)

Poisson’s

Ratio (ν)

Shear strength

parameters

c (kPa) ɸ (o)

Bituminous

Concrete (BC)Elastic 1020.0 0.35 - -

Dense Bituminous

Macadam (DBM)Elastic 750.0 0.35 - -

Macadam (DBM)Elastic 750.0 0.35 - -

Water Bound

Macadam (WBM)

Elasto-plastic

(Mohr-

Coulomb)

167.6 0.35 0 48

Subbase (range is

given for all

materials)

Elasto-plastic

(Mohr-

Coulomb)

30-140 0.35 0.0-14.9 26.9-43.0

Subgrade (Delhi silt)

Elasto-plastic

(Mohr-

Coulomb)

30.0 0.30 0 32

Table: Values of modulus of elasticity , density and shear parameters for different subbase materials

Material

Maximum Dry

Density (γd)

(kN/m3)

Modulus of

Elasticity (Ei)

(MPa)

Shear parameters

c (kPa) ɸ (o)

Pond ash

(Badarpur, Dadri, Rajghat)11.0-12.0 35.4-50.0 0 28.9-32.0

Pond ash mixed with bentonite

(2%, 5%, 8% and 10%)10.0-11.8 24.7-43.3 0 26.9-31.6

Pond ash mixed with fiber (0.5%, 1.0%,

1.5%, 2.0%, 2.5%, 3.0% and 3.5%)11.2-13.4 56.0-133.0 12.4-14.9 31.5-42.8

Pond ash mixed with lime

(2%, 5%, 8% and 10%)11.8-13.9 42.0-82.0 0 30.3-36.5

Pond ash mixed with marble dust

(2%, 5%, 8% and 10%)11.7-13.8 36.7-81.0 0 29.7-36.4

Pond ash mixed with gelatin-starch

(0.5%, 1.0%, 1.5%, 2.0% and 2.5%)11.8-17.3 40.0-140.0 0 31.3-43.0

Parametric study

• Detailed parametric study was carried out by considering the nominal

pavement as the standard structure and then varying the thickness of

each layer within practical limits.

LayerNominal pavement

thickness (mm)Variation in thickness (mm)

Table: Variation in thickness considered in pavement study

Layerthickness (mm)

Variation in thickness (mm)

Bituminous concrete (BC) 50 None

Dense Bituminous Macadam

(DBM)135 100, 135, 170, 205

Base Course (WBM) 250 150, 200, 250, 300, 350

Sub-base Course 200 200, 250, 300, 350, 400, 450, 500

Subgrade 300 None

0

200

0 500 1000 1500V

erti

cal

co

mp

ress

ive

stre

ss (

kP

a)Distance from centre of load (mm)

0

250

0 500 1000 1500

Distance from centre of load (mm)

Єv

(x1

0-3

%)

400

600

BC DBM WBM Subbase Subgrade

Ver

tica

l c

om

pre

ssiv

e

500

750

BC DBM WBM Subbase Subgrade

Fig.: Variation of (a) vertical compressive stress and (b) vertical compressive strain at the top of layers along the width of pavement (applied tyre pressure σv = 575 kPa)

(a) (b)

400

600

800

1000

0 200 400 600

Vertical compressive stress (kPa)D

epth

(m

m)

BC

DBM

WaterBound

Macadam

Subbase 400

600

800

1000

500 600 700 800ϵv (x10-3 %)

Dep

th (

mm

)

Fig.: Variation of (a) vertical compressive stress and (b) vertical compressive strain at the top of layers along the depth of pavement (applied tyre pressure σv = 575 kPa)

(a) (b)

0

200

400 Subbase

Subgrade

0

200

400

Design life of pavement

• IRC: 37-2001 : for design life against rutting failure alone:

NR = 4.1656 x 10-8 [1/ϵv]4.5337

NR = Cumulative standard axles to produce 20 mm rut depth

ϵv = Maximum vertical subgrade compressive strain

• Service life ratio (SLR) given below is used to compare the effect of subbase material type on service life of a pavement:

SLR = N1/N2

SLR = [ϵv2 / ϵv1]4.5337

where, N1, N2 = No. of traffic passes required to produce

allowable rutting for subbase materials 1 and 2

(a)

300

400

500

600

700

150 250 350 450 550

10% Bentonite 8% Bentonite 5% Bentonite 2% Bentonite 0% Bentonite

Sub-base thickness (mm)

Єv

(x10

-3 %

)

3.5% Fiber 3.0% Fiber 2.5% Fiber 2.0% Fiber1.5% Fiber 1.0% Fiber 0.5% Fiber

Fig. : Strain - Sub-base thickness behaviour of Badarpur pond ash mixed with (a) Bentonite (b) Fiber

(b)

200

280

360

440

520

150 250 350 450 550

1.5% Fiber 1.0% Fiber 0.5% Fiber

Sub-base thickness (mm)

Єv

(x10

-3 %

)

(c)

220

300

380

460

540

150 250 350 450 550Subbase thickness (mm)

2% Lime 5% Lime 8% Lime 10% Lime

Єv

(x10

-3 %

)

2% Marble Dust 5% Marble Dust 8% Marble Dust 10% Marble Dust

Fig. : Strain - Sub-base thickness behaviour of Badarpur pond ash mixed with (c) Lime (b) Marble dust

(d)

200

300

400

500

600

150 250 350 450 550Subbase thickness (mm)

2% Marble Dust 5% Marble Dust 8% Marble Dust 10% Marble Dust

Єv

(x10

-3 %

)

100

300

500

700

2% Bentonite 3.0% Fiber 8% Lime 10% Marble Dust

2.5% G-S CSM Pond ashЄ

v(x

10

-3 %

)

Fig.: Variation for different admixtures that gave the minimum vertical strain

100

150 250 350 450 550

Subbase thickness (mm)

200 300 380234 500

Table: Minimum vertical compressive strains at the top of subgrade in microns and service life ratio for different material

(subbase thickness = 200 mm)

Badarpur Dadri RajghatP

on

d a

sh a

lon

e

Fib

er (

3.0

%)

Lim

e (8

.0%

)

Mar

ble

Du

st (

8.0

%)

Gel

atin

-Sta

rch

(2

.5%

)

CS

M

Po

nd

ash

alo

ne

Fib

er (

3.0

%)

Lim

e (8

.0%

)

Mar

ble

Du

st (

8.0

%)

Gel

atin

-Sta

rch

(2

.5%

)

CS

M

Po

nd

ash

alo

ne

Fib

er (

3.0

%)

Lim

e (8

.0%

)

Mar

ble

Du

st (

8.0

%)

Gel

atin

-Sta

rch

(2

.5%

)

CS

M

Po

nd

ash

alo

ne

Fib

er (

Lim

e (

Mar

ble

Du

st (

Gel

atin

CS

M

Po

nd

ash

alo

ne

Fib

er (

Lim

e (

Mar

ble

Du

st (

Gel

atin

CS

M

Po

nd

ash

alo

ne

Fib

er (

Lim

e (

Mar

ble

Du

st (

Gel

atin

CS

M

VCS* 540 360 399 475 321 342 562 390 410 505 342 365 547 375 408 485 319 355

SLR** 0.13 0.79 0.42 0.23 1.33 1.00 0.14 0.74 0.37 0.23 1.34 1.00 0.14 0.78 0.38 0.24 1.62 1.00

*Vertical Compressive Strain**Service Life Ratio

Table: Variation in equivalent thicknesses due to different subbase materials for same life of pavement for Badarpur pond ash

Material

Subbase

thickness

(mm)

Increase in

subbase

thickness

(%)

WBM

thickness

(mm)

Increase in

WBM

thickness

(%)

DBM

thickness

(mm)

Increase

in DBM

thickness

(%)

CSM 200 0 250 0 135 0.0

Pond Ash + Fiber (3.0%) 234 17.0 278 11.2 151 11.9

Pond Ash + Lime (8.0%) 300 50.0 358 43.2 209 54.8

Pond Ash + Marble Dust

(10.0%)380 90.0 478 91.2 285 111.1

Pond Ash alone 500 150.0 542 116.8 345 155.6

Pond Ash + Gelatin-Starch

(2.5%)175 -12.5 215 -14.0 115 -14.8

Table: Thickness and cost of construction of various layers

Pav

emen

t C

om

po

nen

t

Su

bgr

ade

Sub-base Course

WB

M C

ou

rse

DB

M C

ou

rse

Bit

um

ino

us

Co

ncr

ete

Po

nd

ash

Po

nd

ash

+B

ento

nit

e (2

%)

Po

nd

ash

+F

iber

(3%

)

Po

nd

ash

+L

ime

(8%

)

Po

nd

ash

+M

arb

le d

ust

(10

%)

Po

nd

ash

+G

elat

in-s

tarc

h (

2.5%

)

Cost analysis

Pav

emen

t C

om

po

nen

t

Su

bgr

ade

WB

M C

ou

rse

DB

M C

ou

rse

Bit

um

ino

us

Co

ncr

ete

CS

M

Po

nd

ash

Po

nd

ash

+B

ento

nit

e (2

%)

Po

nd

ash

+F

iber

(3%

)

Po

nd

ash

+L

ime

(8%

)

Po

nd

ash

+M

arb

le d

ust

(10

%)

Po

nd

ash

+G

elat

in

Thickness

(mm)300 200 250 135 50

Cost per

m3 (Rs.)111.6 953.81 100.83 188.58 887.43 136.47 100.83 554.43 1371.14 5429.45 6402.75

Table: Percentage saving in cost for 1 km long pavement section with stabilized subbase layer for the same service life

Sl.

No.

Pavement

Component

Top width

(m)

Bottom

width (m)

Height*

(m)

Volume

(m3)

Rate per m3

(Rs.)

Total Rate

(Rs.)

Total Cost (Rs.)

(1+2+3+4+5)

Saving in

cost (%)

1Bituminous

Course3.750 3.950 0.050 192.5 6402.75 1232529

2 DBM Course 3.950 4.490 0.135 569.7 5429.45 3093158

3 WBM Course 4.490 5.490 0.250 1247.5 1371.14 1710497

4 Subgrade 6.290 7.490 0.300 2067 111.6 230677

5 Sub-base Course 5.490 6.290

(a) CSM 0.200 1178.0 953.81 1123588 7390450 -

(b) Pond Ash 0.500 2945.0 100.83 118778 6385639 13.6

Pond Ash + Bentonite (2%):

(c)

Pond Ash + Bentonite (2%):

(since this was the minimum

percentage used in tests)

0.570 3357.3 188.58 222147 6489009 12.2

(d)

Pond Ash + Fiber (3.0%):



0.234 1378.3 887.43 1045393 7312254 1.1

(e)

Pond Ash + Lime (8.0%):



0.300 1767.0 136.47 160762 6427623 13.0

(f)

Pond Ash + Marble Dust (10.0%):



0.380 2238.2 100.83 118778 6385639 13.6

(g)

Pond Ash + Gelatin-Starch (2.5%):



0.175 1030.8 554.43 653119 6919980 6.4

* Equivalent thickness for same SLR

• Pond ash samples of Badarpur, Dadri and Rajghat are sand size particles of 72%, 56% and 66% respectively.

• Of all the admixtures , bentonite gave CBR value less than 20. As per IRC: 2001, the CBR value of a subbase material should be at least 20 for low volume roads. So Bentonite mixed with the pond ash is not suitable.

• Vertical compressive strain at the top of subgrade is minimum in case of • Vertical compressive strain at the top of subgrade is minimum in case of pond ash stabilized with gelatin-starch.

• Comparing subbase, WBM and DBM, the variation in subbase thickness gives the maximum saving in the total cost of construction for the same service life ratio.

Thank You

Documents

Dr. Raju Sarkar - WTERT