Laboratory Studies on Bio-Enzyme Stabilized Lateritic Soil ... - pmgsy

<strong>Laboratory</strong> <strong>Studies</strong> on Bio-Enzyme Bio Enzyme Stabilized
Lateritic Soil as a Highway Material
Dr. I.R.Mithanthaya Dr. A.U.Ravishankar
Professor Professor & Head
Dept. of Civil Engineering Dept. of Civil Engineering
NMAMAIT, Nitte . NITK-Surathkal.
Lekha B.M
Research Scholar
Dept. of Civil Engineering
NITK-Surathkal.

Contents
• Introduction
• Objectives of the study
• Literature survey
• Experimental Investigations
• Fatigue Analysis
• Field Study
• Conclusions
• References

STABILIZATION MECHANISMS.
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 types
Standard 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 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 CBR values of
blended lateritic soil with different dosage of
enzyme.
• Study of fatigue behavior of enzyme stabilized
lateritic soil.

Objectives of the Investigation (Continued)
(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
• Field experimental investigation to study
the performance of road constructed using
stabilized soil.

Materials Used
• Lateritic soil
• And one commercially available enzyme

Lacuoture
et al. 1995
Hitam et al.
1998
Yusof et al.
1998
Brazetti et
al. 2000
Santoni et
al. 2001
Literature Review
Germany The reactions of the soils
treated with the enzyme
was observed and
recorded and compared to
the untreated samples
Malesiya Road constructed for a length
of 27 Km using enzyme
stabilized soil
Brigham
Young
University
<strong>Laboratory</strong> experiments with
two types of enzymes
Thailand Field experiment with six difft.
Types of soil mixture with
pieces of recycled pavement
USA Lab. experiments on two
types of soil with two types of
enzyme
The variation in properties
was observed over a period
six months
The sections were then
monitored for two rainy
seasons for erosion due to
rainwater and wear due to
usage.
Studied for variation in
strength and maintenance cost
The field stretches were
periodically tested with DCP to
evaluate variation in CBR
Variation in Unconfined
compressive strength was
observed

(Andrew et
al. 2002).
(Isaac et al.
2003).
Manoj et al.
2003).
Mihai et al.
2005
Literature Review
USA The objective was to
study the potential
applicability of tested
enzyme for unpaved
road in-situ
stabilization.
India 3 types of soil with
varying clay content
from Kerala were tested
India Six difft. Types of soil
with varying clay content
India Practical application for
roads
Evaluated on the basis of
statistical measurement of
change in CBR strength, soil
stiffness and soil modulus
Significant increase in CBR as
curing period increases
The field stretches were
periodically tested with DCP
(Dynamic Cone Penetrometer)
equipment.
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

• Effect of Bio-Enzyme use on soil
stabilization was conducted at Soil
Mechanics <strong>Laboratory</strong>, 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 2.45
2 Grain size distribution
a) Gravel, % 19
b) Sand, % 50
c) Silt, % 29
d) Clay,% 2
3 Consistency limits (%)
Liquid limit 35
Plastic limit 25
Plasticity index 10
4 IS Soil Classification SM-GM

Geotechnical properties of Soils
Sl No. Property Lateritic Soil
5 I.S standard Compaction
a) Max dry density, γ dmax
(kN/m 3 )
19.32
b) O.M.C 13.5%
I.S modified Compaction
a) Max dry density, γ dmax
(kN/m 3 )
19.95
b) O.M.C 11.4%
6 CBR Value (%)
I.S Standard Compaction
a) OMC condition 10.0 %
b) Soaked condition 4.0 %
I.S Modified Compaction
a) OMC condition 14.0 %
b) Soaked condition 8.0 %

Geotechnical properties of Soils
Sl No. Property Lateritic Soil
Un confined compression
7
test
I.S Standard Compaction
( kN/m2 )
I.S Modified Compaction
(kN/m2 )
8 Co-efficient of
permeability
I.S standard Compaction
(cm/sec)
I.S modified Compaction
(cm/sec)
108
142
4.78x10 -8
2.87x10 --8

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 m3 of soil
• Four dosages are selected
• The enzyme is to be mixed with
• 200 ml/3.5 m3 to 200 ml/2m3

Enzyme dosage for lateritic soil
Dosage Amount of
dosage
Amount required
/Kg of soil
1 200 ml/3.5m 3 0.029 ml
2 200 ml/3m 3 0.0338 ml
3 200 ml/2.5m 3 0.0406 ml
4 200 ml/2m 3 0.050 ml

UNCONFINED COMPRESSION TEST
CP ED1 ED2 ED3 ED4
Lateritic Soil -142 (kN/m 2 )
(Untreated)
1 205 272 343 447
2 262 324 398
3 330 434 532
4 428 513 607
513
716
782

CP
ED1 ED2 ED3 ED4
CBR values for treated soil
Untreated 08%
1 17 20 21 23
2 20 23 25
3 23 25 27
4 25 27 29
27
29
31

Variation of Coefficient of Permiability
CP ED1 ED2 ED3 ED4
k m/sec (10 -8)
1 2.87 2.87 2.63 2.63
2 2.63 2.39 2.39
3 1.91 1.91 1.91
4 1.91 1.67 1.67
2.39
1.67
1.67

Soilsand
(%) CP 1 CP 2 CP 3
CBR Values of blended soil with enzyme
CP 4
100-0 25 29 30 31
90-10 27 30 31
80-20 24 29 30
70-30 22 27 28
60-40 21` 24 27
32
31
30
28

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

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

Effect of curing period on Fatigue life

Effect of loading amplitude on fatigue life

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

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
• Soil properties have been improved with
dosage 4.
• CBR value increased by 400%
• UCC value increased by 450%
• Permeability decreased by 42%
• Improvement in soil properties by adding
sand ( 80-20).
• Effect of enzyme is less for cohesion less
soils
• CBR values of enzyme treated soil decreases
with increase in sand content

Conclusions
• 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
• 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
• Experimental field study
– The road constructed with enzyme stabilized
soil has monitored for its performance at
regular interval for 8-10 months. 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.

Concluding Remark
• Based on experimental analysis, study of
fatigue behavior and field study it can be
concluded that there is improvement in
geotechnical properties of lateritic soil and
can be effectively used in the design of
flexible pavement with the replacement of
WBM layer

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”,
32 nd 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.