fatigue behavior of lateritic soil stabilized with enzyme and effectiveness of flexible pavement...

Fatigue behavior of lateritic Soil stabilized with enzyme and effectiveness of flexible

pavement with stabilized soil as sub base

Dr. I.R.Mithanthaya Dr. A.U.Ravishankar Professor Professor & HeadDept. of Civil Engineering Dept. of Civil Engineering NMAMAIT, Nitte . NITK-Surathkal.

Dr. N.Bhavani Shankar Rao Professor Dept. of Civil Engineering NMAMAIT, Nitte .

Contents• Introduction• Objectives of the study• Literature survey• Experimental Investigations• Fatigue Analysis• Design of flexible pavement• Economical Analysis• Conclusions• References• Paper Publications

Concept of soil StabilizationSoil Improvement or Modification-A very

old conceptImportance of soil stabilization in highway

construction started after II World WarMainly two major concerns:

1. Shortage of conventional Aggregates

2. Energy Crisis

Why the Soil Stabilization

• When unsuitable site conditions exists :– Find a new Construction site– Redesign the structure to suit the poor soil– Replace the poor soil with good soil– Improve the engineering properties of the soil

• To improve the soil properties such as- Volume Stability-Strength & Durability- shear Strength- To prevent erosion &Dust generation

STABILIZATION MECHANISMS.

• Mechanical stabilization, whereby the stability of the soil is increased by blending the available soil with imported soil or aggregate, so as to obtain a desired particle-size distribution,

• Mixing or injecting additives such as lime, Cement, sodium silicate, calcium chloride, bituminous materials and resinous materials with or in the soil can increase stability of the soil. Chemicals stabilization is the general term implying the use of chemicals for bringing about stabilization.

CHEMICAL STABILZATION

• Mixing or injecting additives:

• Two typesStandard stabilizers :

lime, Cement, sodium silicate, calcium chloride, bituminous materials and resinous materials.

Non standard stabilizers:Sulfonated Oils, Ammonium Chloride, Enzymes,

Mineral Pitches and Acrylic Polymers.

Selection of stabilizer

• Selecting the stabilizer type depends on number of factors including:

• 1. gradation,• 2. plasticity index (PI),• 3. Availability and cost of the stabilizer and

appropriate construction equipment• 4. Its long term effect on strength etc.

Concept of Enzyme Soil Stabilization

• Demonstrated by the termites and white Ants – Build the shelter by Ant Saliva- which are rock hard and stand firm despite of heavy rainy seasons.

• Enzyme –Natural , Non toxic , non flammable, Non Corrosive liquid enzyme formulation fermented from vegetable extracts that improves the engineering properties of the soil.

Clay Particle –Water Relation• Behavior influenced by ability

to absorb exchangeable cat ions and the amount of water.– Negative charge on the

surface of clay particles attracts positive (Hydrogen) end of water molecule.

– Water molecules are arranged in a definite pattern-Adsorbed layer

Removal of absorbed water by enzyme

• Absorbed water in the structure of soil

• Elimination of absorbed water in he soil

Mechanism of Enzyme Stabilization• Enzyme catalyze the reaction between the clay and the organic cations

and accelerate the cat ion exchange process to reduce the adsorbed layer thickness.

Enzyme replaces adsorbed water with organic cations, thus neutralizing the negative charge on a clay particle.

Mechanism of Enzyme Stabilization

The organic cations also reduce the thickness of the electrical double layer. This allows enzyme treated soils to be compacted more tightly together.

Enzyme promotes the development of cementatious compounds using the following, general reaction:

H2o + clay Enzyme Calcium Silicate Hydrates

Net Effect of Enzyme

• Film of adsorbed water is greatly reduced.• The soil particles acquire a tendency to

agglomerate• As a result of relative movement , the soil

get condensed which in turn reduces the swelling capacity

Need for present Investigation

• Recently developed technique.• Produced by number of private agencies• More attention is given in foreign countries• Rigorous technical investigation is very

essential• Unclear how these product will work and

under what condition.• To better understand their potential value

for road construction

Objectives of the Investigation

• To study the change of geotechnical properties of the lateritic soil by stabilizing with enzyme.

• Study of quantitative changes in geotechnical properties this soil with different dosage of enzyme.

• Study of fatigue behavior of enzyme stabilized lateritic soil.

Objectives of the Investigation (Continued)

• To evaluate the influence of various parameters such as dosage of enzyme, curing period, on stress level and frequency of stabilized soil subjected to repeated loading

• To establish a relationship between fatigue life, enzyme dosage and curing period of stabilized soil.

Objectives of the Research (Continued)• Analysis of flexible pavements for low and

high volume roads with stabilized soil as sub base material.

• Economical Analysis: Initial Cost savings in the design of low and high volume roads using stabilized soil.

• Field experimental investigation to study the performance of road constructed using stabilized soil.

• To develop new design charts for low and high volume roads at par with IRC Codes.

Materials Used

• Lateritic soil • And one commercially available enzyme

Literature ReviewLacuoture et al. 1995

Germany The reactions of the soils treated with the enzyme was observed and recorded and compared to the untreated samples

The variation in properties was observed over a period six months

Hitam et al. 1998

Malesiya Road constructed for a length of 27 Km using enzyme stabilized soil

The sections were then monitored for two rainy seasons for erosion due to rainwater and wear due to usage.

Yusof et al. 1998

Brigham Young University

Laboratory experiments with two types of enzymes

Studied for variation in strength and maintenance cost

Brazetti et al. 2000

Thailand Field experiment with six difft. Types of soil mixture with pieces of recycled pavement

The field stretches were periodically tested with DCP to evaluate variation in CBR

Santoni et al. 2001

USA Lab. experiments on two types of soil with two types of enzyme

Variation in Unconfined compressive strength was observed

Literature Review(Andrew et al. 2002).

USA The objective was to study the potential applicability of tested enzyme for unpaved road in-situ stabilization.

Evaluated on the basis of statistical measurement of change in CBR strength, soil stiffness and soil modulus

(Isaac et al. 2003).

India 3 types of soil with varying clay content from Kerala were tested

Significant increase in CBR as curing period increases

Manoj et al. 2003).

India Six difft. Types of soil with varying clay content

The field stretches were periodically tested with DCP (Dynamic Cone Penetrometer) equipment.

Mihai et al. 2005

India Practical application for roads

Major district roads in Maharashtra are constructed with enzyme stabilized soil and are working very well.

• Variation of CBR with time for soil with very high Plasticity .

• Variation of CBR with time for soil with medium Plasticity .

• Increase in CBR values is of the range from 130 to 1800 times of the original value

• (Isaac et al. 2003). • I

Manoj Shukla et.al 2003

• Sharma (Scientist-IRRI New Delhi) has conducted laboratory studies on use of bio-enzyme stabilization of three types of soils

• 260% Increase in CBR value.-(After 4 weeks curing)

• 100% increase in UCS• Silt with medium plasticity soil showed 300%

increase in CBR value•

• Effect of Bio-Enzyme use on soil stabilization was conducted at Soil Mechanics Laboratory, Thailand (1996) to determine the effects on CBR

• Increase in CBR is more than 100% as compared to 28% -Untreated

• Investigators also reported reduction in gravel loss, road roughness, dust levels on the Enzyme treated road sections.

• Bio-Enzymatic soil stabilization in Road Construction

(Everyman’ Science VOL XLI No.6 March 06 Page No.60-69- Dr. C.Venkatasubramnyam School of Civil

Engineering SASTRA Tanjavur.)

• In this study 5 types of soil (From low to high clay content) are considered.

• Based on strength variation study has been done on cost saving by the use of enzyme stabilized sub base.

• The overall saving in the total cost of construction is 30-40%

• Field study : Prof. Hitam & Yusof-Palm oil research Institute Malaysia (1998)– 27 Kms of road was constructed with enzyme treated soil.– The section of the road was monitored for four monsoons.– No surface damage was observed

Geotechnical properties

Sl No. Property Lateritic Soil

1 Specific gravity 2.50

2 Grain size distributiona) Gravel, % 15.2

b) Sand, % 45.4

c) Silt, % 10.5d) Clay,% 28.9

3 Consistency limits (%)Liquid limit 51

Plastic limit 31

Plasticity index 20

4 IS Soil Classification MH

Geotechnical properties of SoilsSl No. Property Lateritic Soil

5 I.S standard Compactiona) Max dry density, γdmax (kN/m3)

17.8

b) O.M.C 14 %I.S modified Compactiona) Max dry density, γdmax (kN/m3)

18.6

b) O.M.C 13% 6 CBR Value (%)

I.S Standard Compaction

a) OMC condition 17.0 %

b) Soaked condition 6.0 %

I.S Modified Compaction

a) OMC condition 29.0 %

b) Soaked condition 14.0 %

Geotechnical properties of Soils

Sl No. Property Lateritic Soil

7 Un confined compression test

178

I.S Standard Compaction ( kN/m2) 210

I.S Modified Compaction (kN/m2) 178

8 Co-efficient of permeabilityI.S standard Compaction (cm/sec)

1.20x10-7

I.S modified Compaction (cm/sec) 0.94x10-7

Experiments on enzyme treated soil

• Enzyme is used for stabilization. (Nature Plus-USA).• Physical/Chemical Characteristics of Enzyme• Boiling Point: 212° F • Specific Gravity (H2O = 1): 1.000 - 1.090• Vapor Pressure (mmHg): As Water • Melting Point: Liquid• Vapor Density (Air = 1): 1 • Evaporation Rate : As Water• Solubility in Water: Infinite pH: 3.10 - 5.00• Appearance and Odor: Brown clear liquid

Enzyme Dosage

• Enzyme is to be added to water before mixing maintaining the OMC

• It is in terms of ml per kg of soil• Four dosages are selected• The enzyme is to be mixed with • 200 ml/3m3 to 200 ml/1m3

Enzyme dosage for lateritic soil

Dosage Amount of dosage

Amount required /Kg of soil

1 200 ml/3m3 0.033 ml

2 200 ml/2m3 0.050 ml

3 200 ml/1.5m3 0.067 ml

4 200 ml/1m3 0.10 ml

Variation of LL,PL&PI with dosage of enzymeED Lateritic soil

LL PL PI

0 51 31 20

1 46 34 12

2 42 36 6

3 40 35 5

4 41 35 6

0 0.5 1 1.5 2 2.5 3 3.5 4 4.50

10

20

30

40

50

60

Liquid limit Vs Enzyme dosage

Lateritic soil

Enzyme dosage

Liq

uid

limit

(%)

IS Modified Compaction ResultsED Lateritic soil

MDD (kN/m3) OMC (%)

0 18.6 13

1 19.3 12

2 20.6 11

3 20.1 14

4 19.7 15

0 0.5 1 1.5 2 2.5 3 3.5 4 4.514

16

18

20

22MDD Vs Enzyme dosage

Lateritic soil

Enzyme dosage

Max

. dry

den

sity

(kN

/m3

)

UNCONFINED COMPRESSION TEST

CP ED1 ED2 ED3 ED4

Lateritic Soil -UCS

(kN/m2)

0 267 298 242 246

1 383 467 378 365

2 523 684 474 464

3 654 775 648 636

4 754 876 730 720

6 802 1095 775 733

8 834 1120 802 796

0 1 2 3 4 5 6 7 8 90

200

400

600

800

1000

1200

UCS Vs Curing period

Dosage 1

Dosage 2

Dosage 3

Dosage 4

Curing period in weeks

Com

p. s

tress

KPa

Effect of curing period on UCS

0.5 1 1.5 2 2.5 3 3.5 4 4.50

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Enzyme Dosage Vs SGN(Lateritic soil)

Immediate1 week2 week3 week4 week6 week8 week

Enzyme dosage

Stre

ngth

Gai

n N

umbe

r

Variation of CBR with curing period

(for optimum dosage )

0 1 2 3 4 5 6 7 8 90

20

40

60

80

100

120

140

CBR Vs Curing period (Ltaeritic soil)

UnsoakedSoaked


CB

R (%

)

Permeability Test: soil treated with Enzyme

0 1 2 3 4 5 6 7 8 90.00E+00

2.00E-08

4.00E-08

6.00E-08

8.00E-08

1.00E-07

1.20E-07

Permiability Vs Curing period

Lateritic soil


Perm

iabi

lity

coef

feci

ent

cm

/ se

c

FATIGUE ANALYSIS

• CBR Test conducted for optimum dosage of enzyme shows the improvement in CBR with curing period.

• Since the increase in CBR value compared to untreated value is more than 500% , the pavement acts as semi rigid.

• Hence enzyme treated soil is tested for repeated load condition

Fatigue Behavior of materials• Term FATIGUE refers to premature failure

under the action of repeated loading.• Push-Pull type (Repeated) of loading

system is adopted in Lab.• Depends on :

• Nature of loading• Magnitude of max. load• No. of cycles to failure• Surface finish of test specimen• Temperature

Fatigue Analysis• Fatigue behavior of stabilized soil

under repeated loading.• Test has been performed using

fatigue testing machine.• A cylindrical specimen of length to

diameter ratio of 2 is used.• The Fatigue test equipment that is

capable of applying the repeated loads at a frequency 0 to 12 Hz is used in the present investigation.

Effect of Enzyme content on Fatigue life of Enzyme

treated soil specimens at different stress level Lateritic Soil

Effect of load repetitions on residual static UCS

•

0 1 2 3 4 6 80

100200300400500600700800900

Effect of load repetitions on residual( UCS (Dosage 1)

Ult. UCC (Kpa)Static UCC

Curing Period in weeks

Stre

sss

in K

Pa

0 1 2 3 4 6 80

200

400

600

800

1000

1200

Effect of load Repetitions on residual UCS (Dosage 2 )

Ult. UCCStatic UCC (Berore repetitions)

Period of curing in weeks

UCC

in K

Pa

0 1 2 3 4 6 80

200

400

600

800

1000

Effect of Repetitions on Residual UCS(Dosage 3)

Ult. UCCUCC (Before repeti-tions)

Curing Period in weeks

UCC

in K

Pa

1 2 3 4 5 6 70

100

200

300

400

500

600

700

800

Effect of load repetition on residual UCS(Dosage 4)

Ult. UCCUCC (Before repetitions)


Stre

ss in

KPa

Effect of load repetitions on Ultimate UCS strength(Lateritic soil)

0 1 2 3 4 5 6 7 8 90

200

400

600

800

1000

1200

f(x) = − 9.21675798476547 x² + 121.718695710277 x + 256.41854871041R² = 0.978499299434491

f(x) = − 6.65606485812286 x² + 105.927034611787 x + 305.862800124727R² = 0.98803515330285

f(x) = − 13.2038843601051 x² + 189.058666310303 x + 340.299567909483R² = 0.96228469629685

f(x) = − 12.4278364292396 x² + 162.969731391153 x + 281.049311773353R² = 0.99064905042452

Dosage 1Polynomial (Dosage 1)Dosage 2Polynomial (Dosage 2)Dosage 3Polynomial (Dosage 3)Dosage 4Curing period in weeks

Stre

ss in

KPa

Effect of curing period on Fatigue life

0 1 2 3 4 5 6 7 80

10000

20000

30000

40000

50000

60000

70000

80000

Enzyme Dosage 2 (Lateritic soil)

30 % stress level40 % stress level50 % stress level60 % stress level80 % stress level

Curing Period (weeks)

Fatig

ue L

ife (N

o. o

f cyc

les)

Effect of loading amplitude on fatigue life

1000 10000 100000-1.66533453693773E-16

0.2

0.4

0.6

0.8

1

1.2

Enzyme Dosage 2-LS 0 week

1 week

2 week

3 week

4 week

6 week

8 week

Log of cycles to faliure

Stre

ss ra

tio

1000 10000 100000-1.66533453693773E-16

0.2

0.4

0.6

0.8

1

1.2

Enzyme Dosage 1-SS 0 week1 week2 week3 week4 week6 week8 week


Stre

ss ra

tio

1000 10000 100000-1.66533453693773E-16

0.2

0.4

0.6

0.8

1

1.2

Enzyme dosage 2-BC 0 week1 week2 week3 week4 week6 week8 week


Stre

ss ra

tio

Fatigue life Vs UCS

Stress level Correlation equation of Lateritic soil for Enzyme dosage 2 R² value

30% Fatigue Life=272.2 UCS- 743.7 0.98

40% Fatigue Life =199.6 UCS- 1975 0.98

50% Fatigue Life =161.0 UCS - 5942 0.99

60% Fatigue Life =132.3 UCS- 7916 0.98

80% Fatigue Life =99.68 UCC - 10732 0.98

0 100 200 300 400 500 600 700 8000

10000

20000

30000

40000

50000

60000

70000

80000 Lateritic soil

For 30% stress level

Linear (For 30% stress level)

for 40% stress level

Linear (for 40% stress level)







UCC (kN/m2 )

Fatig

ue li

fe,N

o of

Cyc

les

Regression analysis

• Main Objective:To develop a statistical model that helps in predicting effect of ED,CP and SL on Unconfined compressive strength and fatigue life and to test the model adequacy.

SPSS software is used for the analysis.

Multiple linear regression analysis is adopted in this study

The fitness of model with the actual data is verified by Q-Q plot.

Effect of ED,CP on UCS:

• Variable : CP and ED• With 92% of accuracy the model test analysis gives

the relation as

UCS = 82.786 ED + 105.37 CP

Model Summary

RR

Square(a)Adjusted R

SquareStd. Error of the Estimate

.960(b) .922 .916 191.98454

Coefficients

Variable

s B Std. Error Beta tSignificance

value

EDCP

82.786105.37

19.27312.246

0.3420.683

4.2968.584

0.000.03

Effect of ED,CP and SL on FL: Regression analysis

• Variable : CP,SL and ED• With 96% of accuracy

the model test analysis gives the relation as

• FL = 3715.023 ED +8774 CP -767.529 SL

Model Summary

RR

Square(a)Adjusted R

SquareStd. Error of the Estimate

.960(b) .982(b) .960 10872.0734

20-2

Standardized Observed Value

2

1

0

-1

-2

Expected Norm

al Value

Normal Q-Q Plot of Fatigue Life

Basic Chemical analysis

• Chemical analysis for the enzyme solution to know the presence of dissolved metals

-By using mass spectrometry• Protein content and enzymatic activity (Measure of protein content)

Obtained from the manufacturer• Chemical analysis of soils to find the amount of

silicate clay minerals

Chemical Composition of the enzyme used Metal Concentration(ppm)

Al 80.5

Ca 335

Fe 5.15

K 2.55

Mg 4.55

Mn 0.98

Na 38,000

Si 9000

Zn 0.95

Cl- 16.5 (Inorganic ions)

SO42- 30.0 (Inorganic ions)

Type of soil % of clay content Amount of silicate in %

Lateritic soil 28.9 48.25

Silicate Clay Minerals in soils

Protein content and enzymatic activity

• The protein content is a measure of enzyme which also help the soil bacteria to release hydrogen ions, resulting in pH gradients at the surfaces of the clay particles, which assist in breaking up the structure of the clay.

• Probe compounds were used to analyze for the presence of active aminopeptidase (protein degrading), lipase (lipid degrading), or glucosidase (sugar degrading) enzymes.

• Enzymatic activity would be indicated by the ability to catalyze a reaction, such as the breakdown of glucose.

• The protein concentration in the undiluted enzyme solution was 9230 mg/L.

Flexible pavement analysis for low volume roads

• The analysis involves extensive use of KENPAVE, an FEM analysis and design software package for pavements.

• In the first stage, analysis using KENLAYER is performed on the standard cases based on IRC: SP: 72-2007.

• In second stage analysis is performed with the objective of introducing stabilized soil.

Traffic Parameter

Traffic CategoryCumulative ESAL

Applications

T1 10,000-30,000

T2 30,000-60,000

T3 60,000-100,000

T4 100,000-200,000

T5 200,000-300,000

T6 300,000-600,000

T7 600,000-1,000,000

Sub Grade StrengthQuality of

Sub-Grade Class Range (CBR%)

Very poor S1 2Poor S2 3-4

Fair S3 5-6

Good S4 7-9Very Good S5 10-15

Sub Grade Strength +Traffic Intensity

Type of combination

Sub grade Strength and traffic intensity

S1T1 to S1T7 CBR=2% with cumulative ESAL=30,000 -10,00,000

S2T1 to S2T7 CBR=3-4% with cumulative ESAL=30,000 -10,00,000




Modified design Charts with stabilized sub base

Lateritic soil (Optimum dosage : Dosage 2 ,8 weeks curing)

S1T1E28 S1T1E28 S1T1E28 S1T1E28 S1T1E28 S1T1E28 S1T7E28

S2T1 E28 S2T1 E28 S2T1 E28 S2T1 E28 S2T1 E28 S2T1 E28 S2T7E28


S4T1 E28 S4T1 E28 S4T1 E28 S4T1 E28 S4T1 E28 S4T1 E28 S4T7 E28


KENPAVE ANALYSIS• General Inputs:

– All layers are assumed to be linearly elastic with a constant elastic modulus.

– The number of layers varies among 2, 3 and 4.– The number of Z coordinates is calculated depending

upon the number of interfaces and the intermediate points for analysis.

– All layer interfaces are assumed to be bonded– SI units are used for calculations.– The number of responses is 3, which are

displacement, vertical stress,, Radial stress at interface layers and at bottom of sub grade.

– 3 Radial coordinates are considered from the centre of tyre

KENPAVE ANALYSIS• Material property Inputs:

Material CBR (%) Young's Modulus (kPa) Poisson's Ratio

Bitumen treated WBM (WBM 1) 100 1.035E+06 0.35

WBM (WBM 2) 100 1.035E+06 0.35

Gravel Base (GB) 100 1.035E+06 0.35

Granular Sub-Base (GSB) 20 2.070E+05 0.4

Improved subgrade 10 1.035E+05 0.4

Enzyme stabilized soil >100 2.00E+06 0.4

Subgrade (SG)

2 2.070E+04

0.4

3-4 4.140E+04

5-6 6.210E+04

7-9 9.315E+04

10-15 1.553E+05

Analysis for layer stresses

• By maintaining the same stress, vertical displacement and radial stress developed by WBM layer for different traffic intensities and sub grade strength, WBM layers are replaced by stabilized soil. By trial and error method by varying the thickness of the stabilized layer, minimum thickness of the pavement is established.

Stress Analysis: Layer concept• Analysis of stresses at

different interfaces and at the sub grade layer based on Burmster two and three layer system.

• KENPAVE software package can be used for multiple layers based on the same concept of Bermster theory.

• Vertical displacement at interfaces, Vertical and radial stresses at the sub grade layer are considered for the design.

z1 =Vertical stress at first interface z2 =Sub grade vertical stress r = Sub grade horizontal stress

DV = Vertical displacement at first interface

z1

z2

r

KENPAVE Analysis for low volume roads

Type

Std. Case

(IRC:SP:72-2007)

Modified case

( For optimum dosage)

Total thickness (mm)Stresses &

Vertical

displacement

Total thickness

in mm

Stresses & Vertical

displacement

S1T4E28425

Bitumen treated WBM 75mm +WBM 100 mm +GSB 100 mm +

Modified SG150 mm

z1 =142.18 KPaz2 =23.96 KPa

r = -157.15 KPaDV = 0.1022 cm

350

Stb. Soil 280 mm +

GSB 200 mm

z1 =69.6833 KPaz2 =19.09 KPa

r = -105.17 KPaDV = 0.093 cm

S2T7E28555

Bitumen treated WBM75mmWBM 150 mmGSB 150 mm

Modified SG150 mm

z1 =110.359 KPaz2 =20.56 KPar =-82.135 KPaDV =0.0722 cm

480

Stb. Soil 280 mm +

GSB 200 mm

z1 =47.342 KPaz2 =15.57 KPa

r = -37.457 KPaDV= 0.045 cm

Analysis for S1T4E28

425 mm (Std) 350 mm (Stb) 300 mm (stb)0

5

10

15

20

25

30

Depth Vs Vert. Stress (S1T4E28)

CR = 0

CR =15 cm

CR =30 cmDepth in mm

Ver

t. st

ress

in K

Pa

425mm (Std)

350 mm (Stb)

300 mm (stb)

0

0.02

0.04

0.06

0.08

0.1

0.12

Depth Vs Vert. Displacement (S1T4E28)

CR =0

CR =15 cm

CR =30 cmDepth in mm

Ver

t. di

spl.

in c

m

Analysis of S2T7E28

555 mm (Std. )

500 mm (Stb.

+GSB)

480 mm (Stb.

+GSB)

450 mm (Stb.

+GSB)

0

0.01

0.02

0.03

0.04

0.05

Depth Vs Vert. displacement (S2T7E28)

CR = 0

CR = 15 cm

CR = 30 cm

Depth in mm

Ver

t. di

spl.

in c

m

555 mm (Std. )

500 mm (Stb.

+GSB)

480 mm (Stb.

+GSB)

450 mm (Stb.

+GSB)

0

5

10

15

20

25

Depth Vs Vert. stress (S2T7E28)

CR = 0

CR = 15 cm

CR = 30 cm

Depth in mmV

ert.

stre

ss in

KPa

Modified design charts for High volume Roads (IRC:37-2001)

• IRC :37-2001( Guide lines for the design of flexible pavements)

• Given design charts based on• Sub Grade CBR ( 2% to 10 % )• Traffic Range (1-10 msa)• Total 40 design charts developed by IRC :37-

2001 are analyzed for stress variation and modified charts are established by introducing enzyme stabilized layer.

Modified design Charts with stabilized sub base(As per IRC:37:2001)

Lateritic soil (Optimum dosage : Dosage 2 ,8 weeks curing)

Case Sub grade CBR (%)

C2M10E22 %

(1-10 msa)

C3M10E2 3%

(1-10 msa)

C4M10E24%

(1-10 msa)

C5M10E25%

(1-10 msa)

C6M10E26%

(1-10 msa)

C7M10E27%

(1-10 msa)

C8M10E28%

(1-10 msa)

C9M10E29 & 10%

(1-10 msa)

KENPAVE analysis for high volume roads

TypeStd. Case

(IRC:37-2007)

Modified case

( For optimum dosage)

Total thickness (mm) Stresses & Vertical

displacement

Total thickness

in mm

Stresses & Vertical displacement

C2M10E28(CBR=2% & msa =10)

850Bituminous surfacing 140 +

GB 250 mm +GSB 460 mm +

z1 = 57.41 KPaz2 = 11.19 KPar = -23.32 KPaDV = 0.0920 cm

700 Stb. soil 300 mm +

GSB 400 mm

z1 =27.537KPa z2 = 7.487KPa r = -13.42KPa DV = 0.0709 cm

C3M10E28(CBR=3% & msa =10)

760 Bituminous surfacing 130 +

GB 250 mm +GSB 380 mm +

z1 = 40.186 KPaz2 = 13.77 KPar = -28.546 KPaDV = 0.09197cm

650 Stb. Soil 300 mm +

GSB 350 mm +

z1 = 26.63 KPaz2 = 8.04 KPa

r = -14.193 KPaDV = 0.06289 cm

C4M10E2

(CBR=4% & msa =10)


GB 250 mm +GSB 330 mm +

z1 = 38.12 KPaz2 = 12.46 KPar = -32.17 KPa

DV = 0.09123 cm


Stb. Soil 250 mm +GSB 230 mm +

z1 = 24.53 KPaz2 = 7.46 KPar = -12.42 KPaDV = 0.0596 cm

Analysis of C2M10E28

850 mm 700 mm 600 mm0

0.010.020.030.040.050.060.070.08

Depth Vs Vert. Displacement (C2M10E28)

RC=0RC =15 cmRC =15 cm

Thickness of pavement (mm)

Vert.

Dis

plac

emen

t (cm

)

850 mm 700 mm 600 mm0

2

4

6

8

10

12

Depth Vs Vertical Stress ( C2M10E28)

RC =0RC =15 cmRC =30 cm

Thickness of pavement

Verti

cal s

tress

(KPa

)

Design Chart for Heavy Volume roads(For CBR = 3 %, 1-10 msa)

1 2 3 5 100

100

200

300

400

500

600

700

Wearing Course Binder Course

Stabilzed soil Granular Base

Cummulative Traffic ( msa)

Thic

knes

s in

mm

Economical Analysis

• Initial cost of construction is considered in the economic analysis.

• Total cost of construction includes cost of the material, labour cost and transportation cost.

• Compared with the standard design as per IRC standards

Cost Analysis (Low volume roads)

CasesFor Standard Case For modified Case Saving in

cost

(%)Thickness of

pavement (mm)

Cost in Rupees (per m2)

Thickness ofpavement (mm)

Cost in Rupees

(per m2)

SIT6E28 550 576.00 480 336.00 40%

S3T4E28 300 450.00 280 226.00 49%

S4T6E28 325 472.50 300 230.00 51%

S5T7E28 350 520.00 320 234.00 55%

Cost Analysis (Heavy volume roads)

CasesFor Standard Case For modified Case Saving in

cost

(%)Thickness of

pavement (mm)

Cost in Rupees (per m2)

Thickness ofpavement (mm)

Cost in Rupees

(per m2)

C2M10E28(CBR=2% & msa =10)

850 1649.00 790 1320.00 20%

C3M10E28(CBR=3% & msa =10)

760 1512.00 630 1120.00 25%

C4M10E2

(CBR=4% &

msa =10)

700 1402 620 1055.00 24%

FIELD EXPERIMENTAL STUDY

• The road selected for the experimental investigation is at Nancharu-Kokkarne Road,Udupi District.

• The construction of road segment for a length of 1.35 Km was done under “Pradana Manthri Grameena Sadak Yojana” scheme.

Index properties of the soil at the site before the application of Enzyme

Dynamic Cone Penetration Test (Treated soil)

Long Term Effect of enzyme on soil

• Field CBR was conducted during the month of Feb. 2009 after allowing the road for one rainy season.

• The results were shown that the CBR value is more than 80%. This clearly indicates the long term durability of enzyme treated soil.

Conclusions• 1. CONSISTENCY LIMITS• Considerable decrease in Plasticity index as

dosage increases (to the range of 6-8). • 2. COMPACTION• Test results indicates change in MDD and OMC

as dosage increases. But shows little variation after enzyme dosage 3.

Conclusions• 3.UNCONFINED COMPRESSION TEST• From the test results it is observed that for Lateritic soil sample

the Unconfined Compressive Strength increases more than 300% when compared to untreated soil.

• 4. Permeability• Coefficient of permeability increases at the earlier

curing period and then decreases. Increase is because of flocculation caused by cation exchange and decrease is due to formulation of calcium and sodium silicates.

Conclusions

• 5. CALIFORNIA BEARING RATIO TEST

• The test results indicate that there is a continuous improvement in the CBR values with the higher curing period. After eight weeks of curing the increase in CBR value for the Lateritic soil samples is around 500%

Conclusions• 6. Fatigue Analysis

– Effect of Dosage :For different stress level (30-80 %) it is observed that the fatigue life of the stabilized soil increases with increase in dosage and beyond the dosage 2 the increase is marginal.

– Effect of Curing Period: Showing considerable increase in fatigue life up to 4 to 6 weeks of curing. Further it is marginal.

– Effect on residual UCS strength: Ultimate UCS strength (after repetitions) are higher than the original UCS strength for the specimen cured up to 4 weeks.

Conclusions• 7. Experimental field study

– The road constructed with enzyme stabilized soil has monitored for its performance at regular interval for 3 years. The road is performing well and field CBR test indicates that stabilized soil can be used as sub base material very effectively. But prior laboratory study is necessary to get the good result in the filed.

Conclusions8. From the stress analysis of different layer

it is found that stress variations are within the limit.

9.Based on analysis for low volume roads, the WBM layer can be replaced by soil layers. Initial cost saving is from 10 % to 70%.

10. For high volume roads the analysis indicates that the initial cost saving is 20 % to 30 %.

Concluding Remark

• Based on experimental analysis, study of fatigue behavior and field study the enzyme stabilized soil with clay content of the range 25% can be used in the design of flexible pavement with the replacement of WBM layer and the design charts may be considered for fixing the thickness depending upon sub grade strength.

Publications

• National Journal• Ravishankar, A.U., Mithanthaya I.R. and Harsha, K. Rai.

(2009): “Bio enzyme stabilized lateritic soil as Highway Material” , Sept. 2009.Journal of Indian Roads Congress, IRC Journal, Volume 7-2,paper no. 553.

• International Journal• Ravishankar, A.U., Mithanthaya I.R. N.Bhavanishankar Rao

and Ganesh C. “Fatigue Behaviour of lateritic soil stabilized with Enzyme” “International Journal of Civil Engineering –Research India Publications, ISSN 0973-4562, Volume 5, November 15,2010 , pp 2595-2608.

•

Publications

• Ravishankar, A.U. and Mithanthaya I.R.,.Bhavanishankar Rao N (2010): “Dynamic behavior of regional soils under repeated load condition”, (Code A-10-132-1), International Journal of Civil Engineering, Iran University & Science & Technology, Narmak, Tehran( Paper Status –Under Process).

• Ravishankar, A.U., Mithanthaya, I.R. and Ganesh, C.(2010) “ Effect of enzyme stabilizer on fatigue behavior of Black Cotton soil” , Journal of Indian Roads Congress, IRC Journal (Communicated).

Publications• International Conferences• Ravishankar, A.U. and Mithanthaya, I.R. (2008): “

Stabilization of soils using Enzyme-A case study” Proc. of International Conference on “ATEMA -08” ,Sept..2008 Bologna University, Cesena,Italy.

• Ravishankar, A.U. and Mithanthaya, I.R. (2009): “ Fatigue analysis of regional soil stabilized with enzyme”” Proc. of International Conference on “Advances in building sciences in 3rd millennium” December 14-19,2009, Vellure Institute of Technology, Vellure.

Publications

• International Conferences : Accepted• Ravishankar, A.U. and Mithanthaya, I.R. And

N. Bhavanishankar Rao(2011): “ Fatigue analysis of enzyme stabilized soil and effectiveness of use of stabilized soil in the design of flexible pavements “ International Conference on “ATEMA -11” will be held at Montrial Canada from August 1-5, 2011.

References• Andrew,R., Fadi,S.M., Nicholos, E. and Elahe, M.(2003): “An

Evaluation of Strength change on Subgrade soils stabilized with an Enzyme Catalyst solution using CBR and SSG comparisons”, Report submitted to University Transportation Cente South Carolina State University Orangeburg, SC, USA .

• Andromalos, K.B., Hegazy,Y.A. and Jasperse, B. H. (2000): ”Stabilization of Soils by Soil Mixing,” Proceedings, International Conference on Soft Ground Technology, ASCE, Noorwijkerhout, Netherlands, pp, 194-205.

• Beena, S.(2000): “Suitability of using CBR test to predict Resilient modulus” paper presented for the federal aviation administration airport technology transfer conference Rowan University,201 Mullica Hill Road, Glassboro, NJ 08028.

• Brazetti, R., and Murphy, S.R.(2000): “General usage of Bio-Enzyme stabilizers in Road Construction in Brazil”, 32nd annual meeting on paving, Brazil.

• Boateng P. Y. and Johnson, P. T. (1990): “Estimation of subgrade resilient modulus from standard tests” Journal of Geotechnical Engineering, Vol. 116, pp.68-78.

• Dhinakaran, C. and Prasanna K.R. (2007): “Bioenzyme soil stabilization in road construction”, Everyman’s Science, Vol.XLI No.6, pp.397-400

• Gidigasu, M.D. (1976): “Lateritic Soil Engineering Pedogenesis and Engineering Principles”, Elsevier Scientific Publishing Company, New York .

• Gireesh, B.G. (2008):“study on geotechnical properties of

laterite and black cotton soils with Bioenzyme as a stabilizer”, M.Tech. Thesis, National Institute of Technology, Srinivasanagar, Karantaka , India.

• Ganesh, C. (2008): “ Fatigue Behavior of enzyme stabilised

soil “,M.Tech. Thesis, National Institute of Technology, Srinivasanagar , Karantaka ,India.

• Hitam, A. and Yusof, A. (1998): “Soil stabilizers for plantation

road”, Proceedings, National seminar on Mechanisation in Oil Palm Plantation, , Selangor, Malaysia, pp.124-138.

E- for stabilized soil

200

400

600

800

1000

1200

0.00E+00

1.00E-04

2.00E-04

3.00E-04

4.00E-04

5.00E-04

6.00E-04

f(x) = 4.48938212199231E-07 x + 7.19112470112308E-05R² = 0.982729108137858

UCC Vs Strain(Dosage 2)

UCC Vs StrainLinear (UCC Vs Strain)

20 30 40 50 60 70 80 900

50000

100000

150000

200000

250000

300000

f(x) = 1805.38228479772 x + 75201.3901265372R² = 0.91902123341713

UCC Vs E(Drumn et.al 1990))

Axis Title

Stre

ss (K

Pa)

Stress Analysis: Layer concept

z1 =Vertical stress at first interface z2 =Sub grade vertical stress r = Sub grade horizontal stress

DV = Vertical displacement at first interface

z1

z2

r

Comparison between analytical method of analysis and analysis by KENPAVE SOFTWARE

• Case: 3 layer problem

• Material Data:

• E1 = 600,000 PSI (4.14E+06 KPa), h1= 3 inches (7.62 cm) PR = 0.5• E2 = 30,000 psi (2.07E+05 KPa), h1= 12 inches (30.48 cm) PR =

0.5• E3 = 15,000 psi (1.03E+05 KPa), h1= ∞ PR = 0.5

• As per 3 layer concept (Burmister’s 3 layer concept)

• z1 = (Vertical stress at first interface) = 37.6 psi (259 KPa)• r1 = (Radial stress at first interface) = - 315 psi (-2173 KPa)• z2 = (Vertical stress at top of sub grade ) = 8 psi (55 KPa)• r2 = (Radial stress at top of sub grade) = - 9 psi (62 KPa)

• From KENPAVE analysis• z1 = (Vertical stress at first interface) = 40 psi (276.611 KPa)

• r1 = (Radial stress at first interface) = - 331 psi (-2289 KPa)

• z2 = (Vertical stress at top of sub grade ) = 9.6 psi psi (66.901 Kpa )

• r2 = (Radial stress at top of sub grade) = - 7.5 psi (-51.95 Kpa )

Type of stress By Birmster’s 3 layer concept

By KENPAVE software

z1 (KPa) (Vertical stress at first

interface)

259 276

z2 (KPa)

(Vertical stress at top of sub grade )

55 66

r1 (Kpa)(Radial stress at first

interface)

-2173 -2289

r2 ( Kpa)(Radial stress at top of

sub grade)

-62 -51.95

KENPAVE ANALYSIS• Loading Inputs:• Type of loading is duel wheel system with

single axle.• The contact radius of circular loaded area

is 15 cm.• The contact pressure on circular loaded

area is 560 kPa

MDD Vs WC –for different enzyme dosage-LS

0 5 10 15 20 25 301.6

1.65

1.7

1.75

1.8

1.85

1.9

1.95

2

2.05

Enzyme Dosage 3

Water Content (%)

Dry

Den

sity

(gm

/cm

3)

4 6 8 10 12 14 16 18 20 22 241.65

1.71.75

1.81.85

1.91.95

22.05

2.1

Enzyme Dosage 2

Water Content (%)

Dry

Den

sity

(gm

/cm

3)

8 10 12 14 16 18 20 221.65

1.7

1.75

1.8

1.85

1.9

1.95

2

Enzyme Dosage -4

Water Content (%)

Dry

Den

sity

(gm

/cm

3)

6 8 10 12 14 16 18 20 22 241.7

1.75

1.8

1.85

1.9

1.95

Enzyme Dosage 1

Cost comparison for case:(S5T6E2)

Standard condition as per IRC :SP:72:2007

Sl.No Description QtyArea

(Sq. m)Thickness

( m) Qty (cum) Rate (Rs)Cost (Rs)

1.

Providing 75 mm Bituminous surface treated WBM CUM 1 0.075 0.075 1300.00 97.50

2.Providing 100 mm thick WBM, Grade II CUM 1 0.10 0.10 1400.00 140.00

3. Providing 125 mm thick GSBCUM 1 0.125 0.125 900.00 112.50

Rate in Rs /m2 350.00

Equivalent design with type 2 dosage, 8 week curing, enzyme stabilized S5T6E2


(Sq. m)Thickness

( m) Qty (cum)Rate (Rs)

Cost (Rs)

1.Providing 180 mm thick Stabilized soil CUM 1 0.180 0.180 200 36.00

2.

Providing & laying of granular sub base of 100 mm thickness CUM 1 0.10 0.10 900.00 90.00 Rate in Rs /m2 126.00

% savings in Initial cost

Case Layer As per(IRC:SP:72-2007) Modified case

S5T6E2

Material Thickness in mm

Bituminous surface(75 mm)

Stabilized soil(180 mm)

WBM(100 mm) GSB

(100 mm)GSB(125 mm)

% Saving in cost 64 %

Cost comparison for case:(C2M10E2)

Standard condition as per IRC :37:2001


(Sq. m)Thickness

( m) Qty (cum) Rate (Rs)Cost (Rs)

1.

Providing 40mm Bituminous BC wearing course CUM 1 0.040 0.040 6500.00 260.00

2.Providing 100 mm thickDBM, Grade II CUM 1 0.10 0.10 6500.00 650.00

3. Providing 250 mm thick GBCUM 1 0.250 0.250 1300.00 325.00

4 Providing 460 mm thick GSBCUM 1 0.460 0.460 900.00 414.00


Equivalent design with type 2 dosage, 8 week curing, enzyme stabilized S5T6E2


(Sq. m)Thickness

( m) Qty (cum)Rate (Rs)

Cost (Rs)

1. Providing 40mm Bituminous BC wearing course CUM 1 0.040 0.040 6500.00 260.00

2. Providing 100 mm thickDBM, Grade II CUM 1 0.10 0.10 6500.00 650.00

3250mm stb. soil CUM 1 0.250 0.250 200.00 50.00

4 Providing 400 mm thick GSBCUM 1 0.400 0.400 900.00 3604.00


Projects where Enzyme Stabilization Treatments were Used

Country Location Works Meter YearKenya Nairobi

LimuruLimuruThika

Trunk Access RoadsInfarm RoadsFeeder RoadIndustrial Road

5.0006002.4001.200

1995/6199519961996

U.S.A VirginiaTexas

Federal HighwayCity Council

6.0005.000

19991999

Canada Winnipeg Nat Park Authorities 12.000 1998/9

Mexico Colima Nueva Tierra Farm 9.000 1999

Holland VolkelPeelEindhovenVughtOtterloo

Patrol Roads AirforcePatrol Roads AirforcePatrol Roads AirforceMain Acces RoadAcces/Feeder Roads

13.0006.0003.0001.50024.000

2000/12000/120012000

2001

Poland Krakow Rural Main Roads 12.000 2009

Tanzania Neundorf Main Feeder Road 3.500 2001

India Perambadoor, ChennaiPanvel, Maharashtra

By pass road(NH66)

State Highway

6000

8000

2005

2006

Life Cycle Cost Analysis

• Evaluation of economical worth of a usable project segment by analyzing:

• Initial agency cost• Discounted future costs like – Maintenance cost,

user cost, reconstruction cost, rehabilitation cost, restoring cost, and surfacing cost over the life of

project segment.– User Costs are an aggregate of three component:

• V vehicle operating cost• Crash Costs• User Delay costs

LCCA Procedures

• Establishment of alternative design strategies for the analysis period.

• Determination of performance period and activity timing.• Estimate agency cost• Estimate user cost• Development of expenditure stream diagrams.• Computation of net present value• Analyze the results• Reevaluate the design strategies.

• Analysis period should be sufficiently long to reflect long term cost differences associated with reasonable design strategies.

• Performance period directly affects the frequency of agency cost and proper data with historical experience plays major role in analyzing performance period.

• Agency cost is includes material and construction cost, maintenance cost, operating cost. It also includes negative costs such as salvage value, residual value etc.– User Costs are an aggregate of three component:

• V vehicle operating cost• Crash Costs• User Delay costs

• Common economic indicators used for LCCA are: B/C Ratio, IRR, NPV, EUAC etc.

fatigue behavior of lateritic soil stabilized with enzyme and effectiveness of flexible pavement...

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