fatigue behavior of lateritic soil stabilized with enzyme and effectiveness of flexible pavement...
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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
Curing period in weeks
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
Curing period in weeks
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)
Curing period in weeks
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
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 2-BC 0 week1 week2 week3 week4 week6 week8 week
Log of cycles to faliure
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)
for 50% stress level
Linear (for 50% stress level)
for 60% stress level
Linear (for 60% stress level)
for 80% stress level
Linear (for 80% 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
S3T1 to S3T7 CBR=5-6% with cumulative ESAL=30,000 -10,00,000
S4T1 to S4T7 CBR=7-9% with cumulative ESAL=30,000 -10,00,000
S5T1 to S5T7 CBR=10-15% 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
S3T1 E28 S3T1 E28 S3T1 E28 S3T1 E28 S3T1 E28 S3T1 E28 S3T7E28
S4T1 E28 S4T1 E28 S4T1 E28 S4T1 E28 S4T1 E28 S4T1 E28 S4T7 E28
S5T1 E28 S5T1 E28 S5T1 E28 S5T1 E28 S5T1 E28 S5T1 E28 S5T7E28
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)
700 Bituminous surfacing 120 +
GB 250 mm +GSB 330 mm +
z1 = 38.12 KPaz2 = 12.46 KPar = -32.17 KPa
DV = 0.09123 cm
600 Bituminous surfacing 120 +
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• 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
Sl.No Description QtyArea
(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
Sl.No Description QtyArea
(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
Rate in Rs /m2 1649.00
Equivalent design with type 2 dosage, 8 week curing, enzyme stabilized S5T6E2
Sl.No Description QtyArea
(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
Rate in Rs /m2 1320.00
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.
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