BIO-ENZYME STABILIZED LATERITIC AND SHEDI SOILSThesis Submitted
in partial fulfillment of the requirements for the degree of MASTER
OF TECHNOLOGY in TRANSPORTATION SYSTEMS ENGINEERING by GANESHA
CHATRADA (07TS06F)
DEPARTMENT OF CIVIL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY
KARNATAKA SURATHKAL, MANGALORE -575 025 JULY, 2009
BIOENZYME STABILIZED LATERITIC AND SHEDI SOILSThesis submitted
in partial fulfillment of the requirements for the degree of
MASTER OF TECHNOLOGY in TRANSPORTATION SYSTEMS ENGINEERINGby
GANESHA CHATRADA (07TS06F)
DEPARTMENT OF CIVIL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY
KARNATAKA SURATHKAL, MANGALORE-575 025 July, 2009
DECLARATION
I hereby declare that the report of the Post Graduate Project
Work entitled BIOENZYME STABILIZED LATERITIC AND SHEDI SOILS which
is being submitted to The National Institute of Technology
Karnataka, Surathkal in partial fulfillment of the requirements for
the award of the Degree of Master of Technology in Transportation
Systems Engineering in the Department of Civil Engineering, is a
bonafide report of the work carried out by me. The material
contained in this report has not been submitted to any University
or Institution for the award of any Degree.
07TS06F, GANESHA CHATRADA
-----------------------------------------------------------------------------Department
of Civil Engineering
Place: NITK, SURATHKAL Date: June 2009
CERTIFICATE
This is to certify that the P.G. Project Work Report entitled
BIOENZYME STABILIZED LATERITIC AND SHEDI SOILS submitted by GANESHA
CHATRADA, (Registration Number: O7TS06F), as the record of the work
carried out by him, is accepted as the P.G. Project Work Report
submission in partial fulfillment of the requirements for the award
of the degree of Master of Technology in Transportation Systems
Engineering in the Department of Civil Engineering.
Dr. A.U.Ravi Shankar Professor Department of Civil Engineering
NITK, Surathkal
Chairman- DPGC
ACKNOWLEDGEMENTI would like to express my sincere thanks and
gratitude to my esteemed guide Dr. A. U. Ravi Shankar, Professor,
Department of Civil Engineering, for his guidance, valuable
suggestions, continuous encouragement and the facilities extended
during the course of my thesis work. I am extremely thankful to Dr.
N. Bhavanishankar Rao, Professor and Mr. I. Ramesh Mithanthaya
Research Associate, Department of Civil Engineering for their help,
valuable suggestions and guidance throughout my thesis work. I
acknowledge my sincere gratitude to Dr. M.C. Narasimhan, Professor
and Head of the Department of Civil Engineering for his guidance,
for his suggestions and cooperation during my thesis work. I
express my thanks to geotechnical laboratory staff Sri. Sadanand
Kadri for his cooperation and providing the necessary assistance
during the experimental investigation of this project work. I am
thankful to all my friends and classmates for their help and
support throughout my stay in this college. I am greatly indebted
to my parents who are responsible for successful completion of my
M.Tech course. At the end I thank one and all who have supported me
directly or indirectly.
GANESHA.CHATRADA
DEDICATED MY FAMILY AND FRIENDS
ABSTRACTEngineers are responsible for selecting or specifying
the correct stabilizing method, technique, and quantity of material
required. Soils vary throughout the world and the engineering
properties of soils are equally variable. The key to success in
soil stabilization is soil testing. The method of soil
stabilization selected should be verified in the laboratory before
construction and preferably before specifying or ordering
materials. Various techniques are being used for stabilization of
soil. Stabilization of soil with BioEnzyme is a very new method to
improve the geotechnical properties of the soil. The Bio-Enzyme
when added to water and mixed with soil alters the engineering
properties depending upon the type of the soil and dosage of
enzyme. These enzymes are liquid additives, which act on the soil
to reduce the voids between soil particles and minimize absorbed
water in the soil for maximum compaction. The enzymes react with
the organic matter (humid matter) in the soil to form cementatious
material. This reaction commences almost immediately and it is
verified that under the right environmental conditions about 90% of
the reaction may be complete within the first 96 hours. Initial
reaction product is a formation of a gel, which crystallizes to
form bonds, which hold together particles. Loss of moisture by
evaporation is essential for the crystallization of gels. The
reaction is at micron level and the presence of finely divided
humid matter and clay-sized particles is essential. Presence of
clay is essential as the bonds formed bind this size of particles.
In this present study, the effectiveness of bio enzyme in
stabilizing the different types of soils of Udupi and South Kanara
districts are investigated through laboratory experiments as well
as field study. The locally available lateritic and shedi soils are
procured from the field is used for the investigation. Bio-Enzyme
namely TerraZyme has been used as stabilizer. The pavements in
Udupi and Dakshina kannada districts are damaged due to improper
drainage system and Heavy rainfall (>3000 mm) added problems
(about 6 month in a year) and another reason is the failure of the
sub base due to improper material usage. The type of soils
available in this region are Lateritic and shedi. The plasticity
index is much more due to the high percentage of silt and clay
content in these types of soil. In
this study, lateritic and shedi soil samples were collected from
various sites to investigate the geotechnical properties. All the
soil samples were tested for geotechnical properties and treated
with variable enzyme dosages. The strength parameter of the
stabilized soil has been evaluated after for a curing periods of 0,
1,2,3,4, and 8 weeks. The tests were carried out to determine the
consistency limits, unconfined compressive strength and CBR. Since
the CBR tests results on Bio-Enzyme treated soil indicate
insignificant results and hence fatigue behavior of soil has been
examined. These tests have been conducted with different curing
period and with different dosages of enzyme. The laboratory tests
have shown much improvement in its fatigue behavior. To verify the
laboratory results, field study has been done by construction a
stretch of flexible pavement with enzyme stabilized soil as sub
base. Its long term effect on CBR strength is also evaluated by
conducting the field test at regular interval after the road is
open to the traffic. The field results have shown promising results
in terms of strength of the stabilized soil. The road stabilized
with Bio-Enzyme after one year clearly indicates the effectiveness
of Bio-Enzyme as a stabilizing agent. Justify the use of enzyme as
a stabilizer to stabilize the sub base soil in the road
construction, analysis has been done by KENPAVE software. Keywords:
Fatigue, TerraZyme, Stress level and KENPAVE.
CONTENTS
CERTIFICATE ACKNOWLEDGEMENT ABSTRACT CONTENTS LIST OF TABLES
LIST OF FIGURES 11.0 1.1 1.2 1.3 1.4 1.5
i v vi 1-51 2 2 4 4 4
INTRODUCTIONGENERAL BRIEF HISTORY OF THE AREA UNDER
INVESTIGATION USE OF ENZYME STABILISATION OBJECTIVES OF THE STUDY
SCOPE OF THE WORK ORGANIZATION OF THE THESIS
22.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.7.1 2.7.2
LITERATURE REVIEWSOIL STABILIZATION APPLICATIONS OF SOIL
STABILIZATION STABILIZATION OF LATERITIC SOILS TYPES OF
STABILIZATION TECHNIQUES BIO-ENZYMES AS SOIL STABILIZERS IN ROAD
CONSTRUCTION T THE ENZYMES CHEMICAL STRENGTHENING FUNCTION
MECHANISM OF SOIL STABILIZATION BY BIO-ENZYME TERRAZYME, A
BIO-ENZYMATIC SOIL STABILIZER TerraZyme uses for construction
Features of TerraZyme
6-246 6 6 7 7 9 10 11 11 11
i
2.7.3 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17
Environmental benefits of TerraZyme TYPES OF SOIL AND TERRAZYME
EFFECTS COST SAVING FEATURE OF TERRAZYME WORKING MECHANISM OF
TERRAZYME FAILURES IN SUBBASE LITERATURE REVIEW ON USE OF
BIO-ENZYMES IN SOIL STABILIZATION GENERAL CONCLUSIONS ON THE
BEHAVIOR OF TERRAZYME STABILIZED SOILS UNDER STATIC LOADING
BEHAVIOUR OF SOILS UNDER REPEATED LOADING GENERAL CONCLUSIONS FOR
SOILS UNDER REPEATED LOADING CONSTRUCTION METHODOLOGY TERRAZYME ON
INDIAN ROADS
12 12 12 13 14 15 18 18 21 22 24 25-35 25 25 25 25 26 29 30 30
31 33 35
33.0 3.1 3.2 3.2.1 3.2.2 3.3 3.4 3.5 3.6 3.7 3.8
METHODOLOGY AND EXPERIMENTAL INVESTIGATIONSGENERAL DOSAGE OF
ENZYME TESTING PROGRAMME Testing Programme for Basic Properties
Testing Programme for Fatigue Experiments GRAIN SIZE ANALYSIS TEST
ATTERBERGS LIMIT COMPACTION TEST UNCONFINED COMPRESSION TEST
CALIFORNIA BEARING RATIO TEST PERMEABILITY TEST
44.0 4.1
FATIGUE ANALYSIS OF LATERITC AND SHEDI SOILSINTRODUCTION
LABORATORY FATIGUE TESTING ii
36-5236 36
4.2 4.3 4.4 4.5 4.6
EFFECT OF ENZYME ON FATIGUE CHARACTERISTICS OF STABILIZED SOILS
EFFECT OF ENZYME CONTENT ON FATIGUE LIFE EFFECT OF CURING PERIOD ON
FATIGUE LIFE EFFECT OF LOADING AMPLITUDE (STRESS LEVEL) ON THE
FATIGUE LIFE CORRELATION BETWEEN FATIGUE LIFE AND UNCONFINED
COMPRESSIVE STRENGTH
38 40 44 47 51
55.0 5.1 5.2 5.3
PAVEMENT ANALYSIS AND DESIGNGENERAL KENPAVE - SOFTWARE PAVEMENT
DESIGN USING -IRC 37-2001 ANALYSIS OF PAVEMENT SECTION
53-5853 53 53 54
66.0 6.0.1 6.0.2 6.1 6.1.1 6.1.1.1 6.1.1.2 6.1.2 6.1.2.1 6.1.2.2
6.1.3 6.1.3.1 6.1.3.2
ANALYSIS OF TEST RESULTS AND DISCUSSIONSGENERAL Lateritic Soil
Shedi soil TESTS ON ENZYME TREATED SOIL
59-6359 59 59 60
Effect on Consistency Limits of Enzyme Treated Lateritic and
Shedi 60 soils Effect of Enzyme on Lateritic Soil Effect of Enzyme
on Shedi soil 60 60
Effect on Heavy Compaction of Enzyme Treated Lateritic and Shedi
61 soils Effect of Enzyme on Lateritic Soil Effect of Enzyme on
Shedi soil Effect on Unconfined compression test results of Enzyme
Treated Lateritic and Shedi soils Effect of Enzyme on Lateritic
Soil Effect of Enzyme on Shedi soil 61 61 61 61 62
iii
6.1.4 6.1.4.1 6.1.4.2 6.1.5 6.1.6
Effect on CBR results of Enzyme Treated Lateritic and Shedi
soils Effect of Enzyme on Lateritic Soil Effect of Enzyme on Shedi
Soil Effect on Permeability of Enzyme Treated Lateritic and Shedi
soils Effect on Fatigue life of Enzyme Treated Lateritic and Shedi
soils
62 62 62 63 63
77.0 7.1 7.2 7.3
FIELD STUDYGENERAL DETAILS OF THE SITE FIELD PREPARATION AND
CONSTRUCTION LONG TERM EFFECT OF ENZYME ON SOIL
64-6764 64 64 66
88.0 8.1
CONCLUSIONSCONCLUSIONS FUTURE SCOPE
68-6968 69
REFERENCES PHOTOGRAPHS BIO-DATA
70-72 73-75 76
iv
LIST OF TABLES Table No3.1 3.2 3.3
Title
Page No26 26 27 28 30 31 31 32 32 34 35 39 51 52 54 55 56 57
Testing Programme for Basic Properties Testing Programme for
Fatigue Performance Properties of terrazyme
3.4 Ge Geotechnical properties of Laterite and Shedi soil 3.5
Liquid limit, Plastic limit& Plasticity index 3.6 3.7 3.8 3.9
3.10 3.11 4.1 4.2 4.3 5.1 5.2 5.3 5.4 7.1 7.2 7.3 IS Light
Compaction Results IS Heavy Compaction Results Unconfined
Compression values for Lateritic Soil Unconfined Compression values
for Shedi soil Unsoaked and Soaked CBR test results Permeability
Test Results Fatigue life of untreated soil specimens at different
stress levels Correlation equations for Lateritic soil Correlation
equations for Shedi soil Thickness of the layers for the initial
stage in analysis (for subgrade soil CBR 2%, dual-tandem) Thickness
of the layers for the final stage in analysis (for stabilized Base,
dual-tandem) Stress Values at response points 1 and 13 for virgin
base Stress Values at response points 1 and 13 for stabilized
base
Index properties of the soil at the site before the application
of Enzyme 65 Results of Dynamic Cone Penetration Test conducted
after enzyme treatment Field CBR Values 65 66
v
LIST OF FIGURES Fig No.3.1 3.2 3.3 3.4 4.1 4.2 4.3 4.4 4.5 4.6
4.7 4.8 4.9 5.1 5.2 5.3 5.4 5.5 7.1
ContentsGrain size Analysis Graph for Lateritic and Shedi soil.
Variation of Unconfined Compression Test Results with Different
Enzyme Dosages & Different Curing Period for LS and SS
Page No.29 33 34 35 37 41 43 45 47 48 50 51 52 55 56 57 58 58
67
Variation of CBR Results with 4% Enzyme Dosages & for
Different Curing Period LS Variation of CBR Results with 2% Enzyme
Dosages & for Different Curing Period SS Schematic Diagram of
Accelerated Fatigue Load Test Set-up Effect of Enzyme content on
Fatigue life of Enzyme treated Lateritic soil specimen at different
stress level and 2Hz Frequency Effect of Enzyme content on Fatigue
life of Enzyme treated Shedi soil specimen at different stress
level and 2Hz Frequency Effect of Curing period on Fatigue life for
different percentage of Enzyme treated Lateritic soil Effect of
Curing period on Fatigue life for different percentage of Enzyme
treated Shedi soil Effect of stress level on Fatigue life of for
different percentage of Enzyme treated Lateritic soil Effect of
stress level on Fatigue life of for different percentage of Enzyme
treated Shedi soil Correlation between fatigue life and UCC for
Lateritic soil Correlation between fatigue life and UCC for Shedi
soil Plan of the dual-tandem indicating the response points Plan
and Cross-section of pavement for virgin base Plan and cross
section of pavement for stabilized base Stress variation at
response point 1 Stress variation at response point 13 Correlation
between DCP readings to CBR values
vi
CHAPTER 1 INTRODUCTION1.0 GENERALEngineers are often faced with
the problem of constructing facilities on or with soils, which do
not possess sufficient strength to support the loads imposed upon
them either during construction or during the service life of the
structure. Many areas of India consist of soils with high silt
contents, low strengths and minimal bearing capacity. These
negative soil performance characteristics are generally attributed
to the nature and quantity of the fines present in the material.
For better performance of structures built on such soils, the
performance characteristics of such soils need to be improved. The
poor engineering performance of such soils has forced Engineers to
attempt to improve the engineering properties of poor quality
soils. There are various methods that could be used to improve the
performance of poor quality soils. These methods range from
replacing with a good quality soil to methods that involve complex
chemical process. The choice of a particular method depends mainly
on the type of soil to be improved, its characteristics and the
type and degree of improvement desired in a particular application.
Recently bio-enzymes have emerged as a new chemical for soil
stabilization. Bio-enzymes are chemical, organic, and liquid
concentrated substances which are used to improve the stability of
soil subgrade for pavement structures. Bio-Enzyme is convenient to
use, safe, effective and dramatically improves road quality.
Stabilization of soils is an effective method for improving the
properties of soil and pavement system performance. The objectives
of any stabilization technique used are to increase the strength
and stiffness of soil, improve workability and constructability of
the soil and reduce the Plasticity Index. For any given soil many
stabilization methods, using different stabilizing agents, may be
effective to improve the soil properties in-place rather than
removing and replacing the material. Availability or financial
considerations may be the determining factor on which a stabilizing
agent is selected.
1
1.1 BRIEF HISTORY OF THE AREA UNDER INVESTIGATIONDakshina
Kannada is one of the districts of Karnataka, lying between the
Arabian Sea on the west and Western Ghats on the east (12 27' -13
58' north latitude and 74 34' - 74 40' east longitude). The total
area of the district is about 8,436 sq.km. The land under
cultivation is only about 2000 sq.km. Dakshina Kannada has a forest
area of about 4600 sq.km yielding a variety of timber. Annual
rainfall ranges from 2000 to 4000 mm, mean temperature ranges from
850 F to 900 F with relative humidity of about 85 to 90 percent.
Lateritic soils: Lateritic soils have been found in this region
because of high rainfall, high temperature and high humidity with
alternate wet and dry period, which is an ideal condition for
laterisation. Nearly 40 percent of the soils are laterites. The
colour ranges from red to yellowish red. The depth of this soil
varies from 30 cm to 150 cm. The laterites have been mostly
originated from igneous rocks and are well drained, residual with
the presence of excessive Fe and Al. These soils have defective
grain size distribution, with high plasticity index. Shedi soils:
Shedi soil is available at a depth of few meters from the ground
surface. Interestingly, above this poor layer, laterite soil, which
is having comparatively high strength, is present. Shedi soil is
very problematic soil for engineering activity. Its strength is
high in dry condition, where as, significant reduction of strength
takes place when there is increase in moisture content. This type
of soil can be found in almost all parts of Dakshina Kannada
district. Due to rapid industrialization many industries, roads,
railway lines and other structures are coming up. The ground
profile is highly undulating in Dakshina Kannada district. Hence
roads or railway cuttings are very common. The stability of slopes
mainly depends on this shedi soil profile, because laterite can
withstand relatively steeper slopes. As filling material also shedi
soil poses problems.
1.2 USE OF ENZYME STABILIZATIONExtensive research has been
conducted studying the application of traditional stabilization
additives such as lime, cement and fly ash (Santoni et al. 2001).
However, engineering research studying non-traditional
stabilization additives such as enzymes are less documented. The U.
S. army conducted soil stabilization by use of 2
additives as early as the 1940s (Fine and Remington 1972) in the
construction of airfields for heavy bombers. The US Army conducted
extensive research on soil stabilization for roads and airfields.
Field Manual 5- 410 Chapter 9 (1997) is a detailed chapter on the
design, analysis and application of soil stabilization techniques.
Soil stabilization techniques for civilian uses are currently a
common practice with applications for roads and foundation
performance improvement. According to Andromalos et al. (2000) soil
mixing was first developed in the United States in the 1950s (Liver
et al. 1954). In the late 1960 and early 1970s the Swedish used a
mixed in place lime stabilization process (Ryan et al. 1989). In
their paper (Andromalos et. al. 2000) the authors presented the
design, analysis and application procedures of soil mixing in
liquefaction mitigation and various other geotechnical
applications. Krizek, (1992) conducted a study to evaluate the
benefits gained by incorporating base course material with either
fiber reinforced soil cement or compactable recycled aggregate
cement into pavement systems. In his paper the author presented the
cost benefits analysis of soil stabilization and presented a design
procedure for pavement base course improvements using his proposed
techniques. Santoni et. al., (2001) conducted a laboratory
experiment to evaluate the stabilization of silty-sand (SM)
materials with traditional and nontraditional chemical or liquid
stabilizers. Their research focused on the load bearing capacity as
the basis of performance characterization. They tested four types
of enzymes and found that none of the enzymes tested improved the
unconfined compressive strength of the soil under the dry or wet
conditions. Write-Fox and Macfarlane (1993) studied the
stabilization performance of two types of enzyme stabilizers in
addition to the performance of an asphalt emulsion and lime
additive product. The stabilizers were tested on a highly plastic
fat clay material and were based on the unconfined compressive
strength test. Their results indicated that the undrained shear
strengths of the enzyme products were 21% higher than the control
specimens this suggested that the products in the concentrations
used, added a stabilizing quality to the relatively dry specimens.
When the specimens were immersed in distilled water, the enzyme
products nearly or completely disintegrated by slaking. This
indicated that the products tested may not offer waterproofing
qualities, using the recommended dilutions.
3
1.3 OBJECTIVES OF THE STUDYBased on the detailed literature
review, the objectives of the present work are (1) To evaluate the
engineering properties and fatigue behavior of Bioenzyme stabilized
soil. (2) Analysis the pavement by using these materials. (3)
Evaluation of field performance.
1.4 SCOPE OF THE WORKTo fulfill the above objectives, laboratory
experiments are performed on Lateritic and Shedi soils stabilized
with enzyme. Laboratory Experiments are performed to evaluate the
effectiveness of enzyme in stabilizing the soils. Doing so the
strength aspect is considered. Various influencing parameters such
as dosage of enzyme, Curing period are given due consideration in
evaluating the effectiveness. Once the effectiveness of the enzyme
in improving the strength characteristics are established, the
optimum dosage of enzyme for maximum strength improvement is
arrived at The performance of enzyme stabilized soils are tested
for, repeated loading by considering different stress levels and
frequency. The pavement analysis is carried out by using KENPAVE
software. A pavement stretch is constructed to observe the
performance of pavement.
1.5 ORGANIZATION OF THE THESISAfter the first introductory
Chapter, detailed reviews of literature performed towards
understanding the enzyme stabilization is presented in Chapter 2.
Chapter 3 examines the performance of Bioenzyme stabilized soil
under static loading condition. Two different soils with wide range
of plasticity index, is used for the study. The properties such as
Liquid limit, Plastic limit, Compaction characteristics, unconfined
Compression strengths and the California bearing ratio test are
determined for stabilized soil. The parameters such as dosage of
enzyme, curing periods are studied. The main focus in this chapter
is to ascertain the effectiveness of 4
enzyme and their effect on different types of soils. The
parameters such as dosage of enzyme and curing period are selected
for further study under fatigue loading condition. Chapter 4 deals
with the studies made to understand the behavior of enzyme
stabilized soil under fatigue loading. The results of the
experiments conducted under monotonic loading conditions are used
as a basis for these experiments under fatigue loading. All the
fatigue loading experiments are conducted in an automated fatigue
loading apparatus. An attempt has been made in this chapter to
bring out the effect of different parameters on fatigue life and
the deformation. Chapter 5 presents the design of pavement
according to IRC-37 guidelines and it also covers the analysis of
the pavement structure using KENPAVE software. Chapter 6 discusses
the test results and analysis of the laboratory experiments carried
out in this investigation. Chapter 7 to compare the results
obtained in the laboratory and the field. Where 1.35 Km stretch of
Bioenzyme stabilized soil is used. Chapter 8 presents the general
conclusions and future scope of the thesis.
5
CHAPTER 2 LITERATURE REVIEW2.0 SOIL STABILIZATIONSoil
stabilization is the process of improving the engineering
properties of the soil and thus making it more stable. It is
required when the soil available for construction is not suitable
for the intended purpose. In its broadest sense, stabilization
includes compaction, preconsolidation, drainage and many other such
processes. However, the term stabilization is generally restricted
to the strength properties. A cementing material or a chemical is
added to a natural soil for the purpose of stabilization. The
decreasing availability and increasing cost of construction
materials and uncertain economic climates force engineers to
consider more economical methods for building roads. An obvious
solution is to use locally available materials. However, all too
often, these materials fall outside of required specifications.
This situation becomes even more critical when an increasing demand
for roads in underdeveloped rural areas and informal settlements
comes into play.
2.1APPLICATIONS OF SOIL STABILIZATIONThe process of soil
stabilization is useful in the following applications, Reducing the
permeability of soils Increasing the bearing capacity of foundation
soils Increasing the shear strength of soils Improving the
durability under adverse moisture and stress conditions Improving
the natural soils for the construction of highways and airfields
Controlling the grading of soils and aggregates in the construction
of bases and Sub bases of the highway and airfields.
2.2 STABILIZATION OF LATERITIC SOILSThe main purpose of
stabilization is to improve the soil strength, bearing capacity and
durability under adverse moisture and stress conditions. Soil
stabilization has been extensively used in the roads, airfields,
earthen dams and embankments, in erosion 6
controls, etc. Likewise, there are increasing pressures on the
mining, forestry and agricultural industries to minimize the
production costs of their roads while delivering optimum
performance and low maintenance costs. An economically feasible
solution for achieving these objectives is the use of enzyme soil
stabilization. Yoder (1959) has categorized the various types of
stabilizers according to the properties imparted to the soil. The
types of admixtures include cementing agents, modifiers,
waterproofing, water retaining, and miscellaneous chemicals. The
behavior of each of these admixtures differs vastly from the
others, each has its particular use, and conversely, each has its
own limitations.
2.3 TYPES OF STABILIZATION TECHNIQUESBroadly, soil stabilization
takes the following forms. 1. 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, and by compacting the mixture to a
desired density. Compacting a soil at appropriate moisture content
itself a form of mechanical stabilization. 2. 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.
2.4
BIO-ENZYMES AS CONSTRUCTION
SOIL
STABILIZERS
IN
ROAD
Bio-Road products are a basic fermented and formulator of soil
treatment products that create enzyme stabilization of base and
sub-base soils used in road construction. We have found from our
extensive worldwide experience that enzyme stabilization is
effective when the soil contains a sizable fine-grained component.
Little if any improvement is achieved in clean sands or gravels. In
a study of the performance of over 40 miles of road surfacing
stabilized with enzymes, the US Federal Highway Administration
found that the best performance was obtained with well graded
aggregates mixed with higher clay contents (5% to 15%