Soil-cement is frequently used as a construction material for pipe bedding, slope protection, and road construction as a sub-base layer reinforcing and protecting the subgrade. It has good compressive and shear strength, but is brittle and has low tensile strength, so it is prone to forming cracks. Lime can be used to treat soils to varying degrees, depending upon the objective. The least amount of treatment is used to dry and temporarily modify soils. Such treatment produces a working platform for construction or temporary roads. A greater degree of treatment supported by testing, design, and proper construction techniques--produces permanent structural stabilization of soils.

1. 1
“Overview of Soil Stabilization :Cement / Lime”
A Seminar Report Submitted
In Partial Fulfillment of the Requirements
for the Degree of
MASTER OF TECHNOLOGY
in
GEOTECHNICAL ENGINEERING
Submitted by:
ANIKET S. PATERIYA
(Scholar Number: 182111101)
Under the guidance of
Dr. Suneet Kaur
(Assoc. Professor)
DEPARTMENT OF CIVIL ENGINEERING
MAULANA AZAD NATIONAL INSTITUTE OF TECHNOLOGY
BHOPAL-462003
MARCH-2019

2. 2
CHAPTER 1
Introduction:
Soil cement is frequently used as a construction material for pipe bedding, slope protection,
and road construction as a sub base layer reinforcing and protecting the sub grade. It has good
compressive and shear strength, but is brittle and has low tensile strength, so it is prone to forming
cracks.
Soil cement mixtures differ from Portland cement concrete in the amount of paste (cement-
water mixture). While in Portland cement concretes the paste coats all aggregate particles and
binds them together, in soil cements the amount of cement is lower and therefore there are voids
left and the result is a cement matrix with nodules of uncemented material.
Failing granular-base pavements, with or without their old bituminous mats, can be
salvaged, strengthened, and reclaimed as soil-cement pavements. This is an efficient, economical
way of rebuilding pavements. Since approximately 90 percent of the material used is already in
place, handling and hauling costs are cut to a minimum. Many granular and waste materials from
quarries and gravel pits can also be used to make soil-cement; thus, high-grade materials are
conserved for other purposes.
Highway and city engineers praise soil-cement’s performance, its low first cost, long life,
and high strength. Soil-cement is constructed quickly and easily – a fact appreciated by owners
and users alike.
Soil cement is a construction material, a mix of pulverized natural soil with small amount
of Portland cement and water, usually processed in a tumble, compacted to high density. Hard,
semi-rigid durable material is formed by hydration of the cement particles.
Beside soil-cement stabilization, Addition of lime into the soil also leads to beneficial
result, the long-term performance of any construction project depends on the soundness of the
underlying soils. Unstable soils can create significant problems for pavements or structures. With
proper design and construction techniques, lime treatment chemically transforms unstable soils
into usable materials. Indeed, the structural strength of lime-stabilized soils can be factored into
pavement designs.

3. 3
Lime can be used to treat soils to varying degrees, depending upon the objective. The
least amount of treatment is used to dry and temporarily modify soils. Such treatment produces
a working platform for construction or temporary roads. A greater degree of treatment
supported by testing, design, and proper construction techniques--produces permanent
structural stabilization of soils.
Before beginning any construction project, project plans and specifications must be
developed. For highway pavements, the design must accommodate expected traffic volumes
along with environmental, site, and material conditions. All structural designs should be based
upon laboratory tests and mix designs that fit the demands of the particular project and provide
the most economical alternative for the planned use. This report focuses on the subsequent
construction aspects of treating soils with cement and other perspective with lime. The
conventional soil stabilization using soil and lime explained in given report in brief so that their
importance is ease for readers.

4. 4
CHAPTER 2
2 Soil-Cement stabilization:
Before construction begins, simple laboratory tests establish the cement content,
compaction, and water requirements of the soil material to be used. During construction, tests
are made to see that the requirements are being met. Testing ensures that the mixture will have
strength and long-term durability. No guesswork is involved. Except organic soil almost all
other soil can stabilize using cement. The usual proportion of cement is to be added is 5% for
sandy soil it may reduce for well graded soil as well and exact proportion is determine
experimentally after performing compression strength test and durability test.
Construction method of Soil-Cement Stabilization:
1. Pulverising the soil
2. Shaping the sub grade and scarifying the soil
3. Adding and mixing cement
4. Adding and mixing water
5. Compacting
6. Finishing
7. Curing
8. Adding wearing surfacing
Soil-cement can be mixed in place or in a central mixing plant. Central mixing plants
can be used where borrow material is involved. Friable granular materials are selected for their
low cement requirements and ease of handling and mixing. Normally pugmill-type mixers are
used. The mixed soil-cement is then hauled to the jobsite and spread on the prepared subgrade.
Compaction and curing procedures are the same for central-plant and mixed-in-place
procedures.

5. 5
There are four steps in mixed-in-place soil-cement construction; spreading cement,
mixing, compaction, and curing. The proper quantity of cement is spread on the in-place soil
material. Then the cement, the soil material, and the necessary amount of water are mixed
thoroughly by any of several types of mixing machines. Next, the mixture is tightly compacted
to obtain maximum benefit from the cement. No special compaction equipment is needed;
rollers of various kinds, depending on soil type, can be used. The mixture is cemented
permanently at a high density and the hardened soil-cement will not deform or consolidate
further under traffic.
Curing, the final step, prevents evaporation of water to ensure maximum strength
development through cement hydration. A light coat of bituminous material is commonly used
to prevent moisture loss; it also forms part of the bituminous surface. A common type of
wearing surface for light traffic is a surface treatment of bituminous material and chips 0.5- to
0.75-inch thick. For heavy-duty use and in severe climates a 1.5-inch asphalt mat is used.
2.1 Objective of the Work
 To study about soil cement roads.
 To study about construction methods.
 Discuss about various properties of soil cement roads.
 Discuss about advantages and disadvantages of soil cement roads.
2.1.1 Soil Cement Road (Main Application)
Soil-cement is a highly compacted mixture of soil/aggregate, Portland cement, and
water. Soil-cement differs from Portland cement concrete pavements in several respects. One
significant difference is the manner in which the aggregates or soil particles are held together.
A Portland cement concrete pavements mix contains sufficient paste (cement and water
mixture) to coat the surface area of all aggregates and fill the void between aggregates. In soil
cement mixtures, the paste is insufficient to fill the aggregate voids and coat all particles,
resulting in a cement matrix that binds nodules of uncemented material. It is widely used as a
low-cost pavement base for roads, residential streets, parking areas, airports, shoulders, and
materials-handling and storage areas. Its advantages of great strength and durability combine
with low first cost to make it the outstanding value in its field.

6. 6
A thin bituminous surface is usually placed on the soil-cement to complete the
pavement. material used for soil cement are soil cement and water. The use of soil-cement can
be of great benefit to both owners and users of commercial facilities. Its cost compares
favourably with that of granular-base pavement. When built for equal load carrying capacity,
soil-cement is almost always less expensive than other low-cost site treatment or pavement
methods. The use or reuse of in-place or nearby borrow materials eliminates the need for
hauling of expensive, granular-base materials; thus, both energy and materials are conserved.
2.1.2 Performance of Soil Cement
Soil-cement thicknesses are less than those required for granular bases carrying the
same traffic over the same subgrade. This is because soil-cement is a cemented, rigid material
that distributes loads over broad areas. Its slab-like characteristics and beam strength are
unmatched by granular bases. Hard, rigid soil-cement resists cyclic cold, rain, and spring-thaw
damage.
Cement stabilizes soil in two ways.
First, it reduces soil plasticity, especially for the soil in which there is high amount of
clay particles.
The second is cementation which is very important because clay is not its main
composition.
In fine grained silty and clayey soils, the hydration of cement develops strong linkages
between the soil aggregates to form a matrix that effectively encases the soil aggregates. Old
soil-cement pavements in all parts of the continent are still giving good service at low
maintenance costs.
If soil particle smaller than cement size then cement formed weaker bond thus it affects
strength of composite matrix.
Specimens taken from roads show that the strength of soil-cement actually increases
with age; some specimens were four times as strong as test specimens made when the roads
were first opened to traffic. This reserve strength accounts in part for soil-cement’s good long-
term performance.

7. 7
2.2 Types of soil cement
2.2.1 Cement-modified soils (CMS)
A cement-modified soil contains relatively small proportion of Portland cement. The
result is caked or slightly hardened material, similar to a soil, but with improved mechanical
properties - lower plasticity, increased bearing ratio and shearing strength, and decreased
volume change.
2.2.2 Soil-cement base (SCB)
A soil-cement base contains higher proportion of cement than cement-modified soil. It
is commonly used as a cheap pavement base for roads, streets, parking lots, airports, and
material handling areas. Specialized equipment, such as a soil stabilizer and a mechanical
cement spreader is usually required. A seal coat is required in order to keep moisture out. For
uses as a road construction material, a suitable surface coating, usually a thin layer of asphalt
concrete, is needed to reduce wear.
In comparison with granular bases, soil cement bases can be thinner for the same road
load, owing to their slab-like behaviour that distributes load over broader areas. In-place or
nearby located materials can be used for construction - locally found soil, stone, or reclaimed
granular base from a road being reconstructed. These conserves both material and energy.
The strength of soil-cement bases actually increases with age, providing good long-
term performance.
2.2.3 Cement-treated base (CTB)
A cement-treated base is a mix of granular soil aggregates or aggregate material with
Portland cement and water. It is similar in use and performance to soil-cement base.
Importance factor affecting strength of soil-cement matrix are as follow:
 Nature of soil: The presence of higher size granular material increases the strength
of mixture. Almost every inorganic soil is pulverised and stabilized with cement.
Expansive soil is difficult to be stabilized. Organic matter and sodium sulphate are

8. 8
harmful and weaken the soil-cement. Well graded soil with less than 50% fraction
finer than 15-micron sieve and plasticity less than 20% found to give best result.
It effective when clay soil LL is less than 45% and PI is less than about 25%.
 Cement content: The strength increases with increase cement content in soil.
Beside ordinary Portland cement High -early cement can also be use effective than
normal cement (Lambe,1962). Cement content in range 4 to 14% is generally
needed. Granular soil (3 to 10%) and clay soil (7 to 16%). This determine after
conduct laboratory test on given in situ soil.
 Moisture content: Water is needed to activate chemical reaction in cement and for
facilitating compaction. Soil-cement mixtures exhibit moisture content vs density
relation similar to ordinary soil. Same as OMC for achieve maximum dry density.
Maximum strength is achieved at moisture content slightly less than this.
 Admixtures: Certain chemical are sometime added either to reduce cement content
or in order to make soil suitable for stability. Lime and calcium chloride commonly
use in clays and soil containing organic matter. Etc.
2.3 Advantages
 Engineering Benefits
Stiffness: Soil-cement is a low-cost pavement base offering the feature most
essential for long-lasting parking and storage areas-stiffness. Large paved areas
must maintain their original grade and must not develop depressions or potholes if
they are to drain freely during rains, thereby preventing puddles and damage from
water that seeps through and weakens the underlying soil. The stiffness of a cement-
stabilized base acts to distribute loads over a wider area, reducing subgrade stresses
and allowing the maintain its original grade for many years without costly
resurfacing or repairs. Soil-cement does not rut or consolidate. As a cemented
material, it does not soften when exposed to water. When rutting occurs in an
unstabilized base material or the underlying subgrade soil, a simple overlay of the
pavement surface is insufficient to correct the cause of the rutting. With a stabilized
base, rutting is confined to the asphalt surface layer and is relatively simple and less
expensive to correct.

9. 9
Great Strength: Cores taken from soil-cement pavements furnish proof of its
strength. Samples taken after 15 to 20 years show considerably greater strength than
sample taken when the pavement was initially built. Because the cement in soil-
cement continues to hydrate for many years, soil-cement has “reserve” strength and
actually grows strength and actually grows stronger. Soil-cement thickness
requirements are less than those for granular bases carrying the same traffic over the
same subgrade. This is because soil-cement distributes loads over broad areas. slab-
like characteristics and beam strength are unmatched by granular bases. Strong, stiff
soil-cement resists cyclic cold, rain and spring-thaw damage.
Superior Performance: More than 70 years of collective experience have
demonstrated that different kinds of soil-cement mixtures can be tailored to specific
pavement applications, all achieving superior performance as a result of soil-
cement’s strength. Thousands of miles of soil-cement pavement in every state in
the United States and in all the Canadian provinces are still providing good service
at low maintenance costs. Cement-treated bases are designed to be virtually
impermeable, so that even under frost conditions no ice lenses can form in the base
layer. With a granular, unbound material, if poor drainage exists or groundwater
rises, the base can easily become saturated, causing significant strength losses. The
cement-stabilized layer, on the other hand, will maintain significant strength even
in the unlikely event it becomes saturated. The higher stiffness of cement-treated
bases leads to lower pavement deflections and lower asphalt strains, resulting in
longer fatigue life for the asphalt surface. The use of soil-cement actually reduces
the occurrence of fatigue cracking, a common pavement failure.
 Most soil can be stabilized.
 It is designed material whose properties and production can be very carefully tested
and controlled.
 It is durable material and is not affected by variations in moisture content or
temperature.
 It is having fractural strength and offend classified as semi-rigid material.

10. 10
2.4 Disadvantages:
 Cement is costly material.
 As cement hydrated volumetric change may take place give shrinkage crack.

11. 11
CHAPTER 3
3 Soil-lime stabilization:
3.1 What is Lime?
Lime in the form of quicklime (calcium oxide – CaO), hydrated lime (calcium
hydroxide – Ca[OH]2). Quicklime is manufactured by chemically transforming calcium
carbonate (limestone – CaCO3) into calcium oxide. Hydrated lime is created when quicklime
chemically reacts with water. It is hydrated lime that reacts with clay particles and permanently
transforms them into a strong cementitious matrix.
Most lime used for soil treatment is “high calcium” lime, which contains no more than
5 percent magnesium oxide or hydroxide. On some occasions, however, "dolomitic" lime is
used. Dolomitic lime contains 35 to 46 percent magnesium oxide or hydroxide. Dolomitic lime
can perform well in soil stabilization, although the magnesium fraction reacts more slowly than
the calcium fraction.
3.2 Lime Stabilization of Soils
Soil stabilization significantly changes the characteristics of a soil to produce long-term
permanent strength and stability, particularly with respect to the action of water and frost.
Lime, either alone or in combination with other materials, can be used to treat a range
of soil types. The mineralogical properties of the soils will determine their degree of reactivity
with lime and the ultimate strength that the stabilized layers will develop. In general, fine-
grained clay soils (with a minimum of 25 percent passing the #200 sieve (75 μm) and a
Plasticity Index greater than 10) are considered to be good candidates for stabilization. Soils
containing significant amounts of organic material (greater than about 1 percent) or sulphates
(greater than 0.3 percent) may require additional lime and/or special construction procedures.
Lime can permanently stabilize fine-grained soil employed as a subgrade or subbase to
create a layer with structural value in the pavement system. The treated soils may be in-place
(subgrade) or borrow materials. Subgrade stabilization usually involves in-place “road
mixing,” and generally requires adding 3 to 6 percent lime by weight of the dry soil.

12. 12
3.3 Application:
3.3.1 Airport:
Lime has an extensive history as a soil treatment option for airport construction.
Examples include the Denver International, Dallas Ft. Worth, and Newark airports. Many
airports in the United States are expanding by lengthening runways, taxiways, and parking
aprons. New and expanded terminals are also under construction as shown in following Figure
1.
Figure 1: Lime stabilization project at an airport
[Source: NLA (1985)]
Most airports build on existing properties or purchase adjacent properties, and therefore
have little control over terrain and soil conditions. If marginal or poor soil conditions are
encountered, the owner can choose to remove and replace the existing soils or treat them.
Construction techniques for lime treatment of soils in airport construction are essentially the
same as those for roads. However, the Federal Aviation Administration (FAA) has
specifications for construction and soil treatment methods. Soil Stabilization: Creating sound
foundations beneath runways is critical. Slurry lime is becoming the most often specified lime-
based treatment option due to the potential for dry lime dusting of airplanes and mechanical
equipment.
3.3.2 Commercial:

13. 13
New construction of large stores or shopping centres with the accompanying parking
areas is an increasingly common application for lime stabilization or modification. Location of
these facilities tends to be based on customer accessibility, not on soil characteristics. Unstable
soils may be present. Sites may be in wet, low-lying areas. Rarely are sites level or on grade.
The contractor must cut and fill the site and compact soils to prescribed soil densities.
Stabilization/modification techniques are generally required in that place.
Lime Stabilization: Material excavated for building pads can be limed in lifts as it is
removed and stored in a stockpile for a few weeks. These treated soils should have a water
content 1 to 3 percent above optimum to ensure that the lime reaction has enough water for
completion. This practice saves construction time as the mellowing is occurring in the material
stockpile. The treated and mellowed material can then be compacted in lifts without delay as it
is returned to the building pad. Roadways and parking areas need to be designed to
accommodate the expected vehicle traffic. Ignoring the nature of the underlying soils creates
the potential for pavement failures. Lime stabilization can provide sound pavement foundations
and reduce the thickness of the overlying layers.
Lime Modification: Completion time for commercial projects is a prime constraint.
Projects tend to focus on opening dates that correspond with seasonal purchases, such as
holidays and summer landscaping. On many occasions the contractor finds he has to work
during rainy weather. Lime can be used to dry overly wet soil prior to compaction. Lime
modification can be used to maintain a firm working table that sheds moisture. This will assist
in keeping workers, equipment, and materials out of the mud, reduce weather-related delays,
and assist in keeping the project on schedule.
3.3.3 Housing:
The development of subdivisions begins with the establishment of access roads and
related utilities, followed by the construction of sidewalks, driveways, and homes. Lime
stabilization can be used to create structural foundations for building pads, sidewalks, and
streets. Lime modification offers a convenient construction technique for minimizing the
effects of weather and marginal soils. Often, housing construction continues through all
seasons, wet or dry, because borrowed money makes maintaining construction schedules
paramount. The ability to reduce delays is one way to increase profits. Soil treatment
procedures are similar to those described earlier.

14. 14
3.3.4 Embankment Stabilization:
Often, inferior or overly wet borrow materials are used to construct embankments. Lime
treatment can be used to stabilize these soils either when they are first constructed, or as part
of repairing failed embankments. Usually the unstable soil is moved to a mixing area where
construction equipment can be used to conduct the operations. For soils with high clay content,
lime is used; whereas for soils with low clay content, lime -pozzolan (e.g., fly ash) mixtures
are used. These treated soils should have a water content 1 to 3 percent above optimum to
ensure that the lime reaction has enough water for completion. After mixing, watering, and
mellowing, the material is returned to the embankment, shaped, and compacted to required
specification. Construction time is saved as the mellowing occurs in the material stockpile.
Limed material is compacted without delay in lifts as it is returned to the embankment. For
embankments where soil drying is the primary goal, the soil is often treated with lime after it
is brought into the embankment location. The untreated soil is placed in lifts, typically 8 to 12
inches thick. Each lift is treated with lime and thoroughly mixed, lowering the soil moisture
content. The lift is then compacted, another lift of soil is placed and the process is repeated
until the embankment is complete. Again, it is important to ensure that adequate moisture exists
or is added, particularly if quicklime is used. If quicklime is used, it is essential that all particles
have undergone hydration
3.4 Lime Modification & Soil Drying
There are two other important types of lime treatment used in construction operations:
First, because quicklime chemically combines with water, it can be used very
effectively to dry wet soils. Heat from this reaction further dries wet soils. The reaction with
water occurs even if the soils do not contain significant clay fractions. When clays are present,
lime’s chemical reaction with clays causes further drying. The net effect is that drying occurs
quickly, within a matter of hours, enabling the grading contractor to compact the soil much
more rapidly than by waiting for the soil to dry through natural evaporation. “Dry-up” of wet
soil at construction sites is one of the widest uses of lime for soil treatment. Lime may be used
for one or more of the following: to aid compaction by drying out wet areas; to help bridge
across underlying spongy subsoil; to provide a working table for subsequent construction; and
to condition the soil (make it workable) for further stabilization with Portland cement or

15. 15
asphalt. Generally, between 1 and 4 percent lime will dry a wet site sufficiently to allow
construction activities to proceed.
Second, lime treatment can significantly improve soil workability and short-term
strength to enable projects to be completed more easily. Examples include treating fine-grained
soils or granular base materials to construct temporary haul roads or other construction
platforms. Typically, 1 to 4 percent lime by weight is used for modification, which is generally
less than the amount used to permanently stabilize the soil. The changes made to lime-modified
soil may or may not be permanent. The main distinction between modification and stabilization
is that generally no structural credit is accorded the lime-modified layer in pavement design.
Lime modification works best in clay soils.
3.5 The Chemistry of Lime Treatment
When lime and water are added to a clay soil, chemical reactions begin to occur almost
immediately.
 Drying: If quicklime is used, it immediately hydrates (i.e., chemically combines
with water) and releases heat. Soils are dried, because water present in the soil
participates in this reaction, and because the heat generated can evaporate additional
moisture. The hydrated lime produced by these initial reactions will subsequently
react with clay particles. These subsequent reactions will slowly produce additional
drying because they reduce the soil’s moisture holding capacity. If hydrated lime or
hydrated lime slurry is used instead of quicklime, drying occurs only through the
chemical changes in the soil that reduce its capacity to hold water and increase its
stability.
 Modification: After initial mixing, the calcium ions (Ca++) from hydrated lime
migrate to the surface of the clay particles and displace water and other ions. The
soil becomes friable and granular, making it easier to work and compact. At this
stage the Plasticity Index of the soil decreases dramatically, as does its tendency to
swell and shrink. The process, which is called “flocculation and agglomeration,"
generally occurs in a matter of hours. Lime content of 3 to 18% by volume are used
to reduce plasticity of clay.

16. 16
 Pozzolanic or cementation reaction: These are time and temperature dependent
when silica, alumina of soil reacts with calcium in lime it forms very stable calcium
silicate and aluminates that act like natural cement similar to Portland cement. Soil
with PI as high as 37 can be stabilised with 9 to 24% by volume of hydrated lime.
For higher plasticity double application of lime may be needed one part to reduce
plasticity and other one to induce cementation reaction.
 Carbonation: It is undesirable reaction that occur when lime instead of react with
soil combine with carbon dioxide and form calcium carbonate, this occur when soil
not contain desire amount of pozzolanic clay or excessive amount of lime. calcium
carbonate is plastic material it increases the plasticity and bind limes so that it
cannot react with pozzolanic materials. That shows excessive lime does not produce
beneficial results.
3.6 Construction Overview
Because lime can be used to treat soils to varying degrees, the first step in evaluating
soil treatment options is to clearly identify the objective.
The construction steps involved in stabilization and modification are similar. Generally,
stabilization requires more lime and more thorough processing and job control than
modification. Basic steps include
a. scarifying or partially pulverizing soil,
b. spreading lime,
c. adding water and mixing,
d. compacting to maximum practical density, and
e. curing prior to placing the next layer or wearing course.
When central (off-site) mixing is employed instead of road (in-place) mixing in either
stabilization or modification, only three of the above steps apply: spreading the lime-aggregate-
water mixture, compacting, and curing.

17. 17
1.7 Importance Factor Affecting Strength of Soil-lime Matrix Are as Follow:
 Compaction Characteristic: The properties continue to change as curing continues. The
maximum density of treated Material decreases with curing time and lime content.
However, the optimum moisture content, Increase with curing time and lime content.
 Plasticity and workability: Plasticity index decreases and shrinkage limit increases. Soil
with high plastic index initially required high lime content.
 Volume change: significant reduction in swell potential and swell pressure occur.
 Strength: Lime increase the cohesion and significantly and minor changes in angle of
internal friction. Cohesion increase with increase in unconfined compression strength
and large shear strength gains developed in cured soil-lime mixture.
3.8 Advantages and Disadvantages of Different Lime Applications:
The type of lime stabilization technique used on a project should be based on multiple
considerations, such as contractor experience, equipment availability, location of project (rural
or urban), and availability of an adequate nearby water source.
Some of the advantages and disadvantages of different lime application methods
follow:
Dry hydrated lime:
Advantages: Can be applied more rapidly than slurry. Dry hydrated lime can be used
for drying clay, but it is not as effective as quicklime.
Disadvantages: Hydrated lime particles are fine. Thus, dust can be a problem and
renders this type of application generally unsuitable for populated areas.
Dry Quicklime:
Advantages: Economical because quicklime is a more concentrated form of lime than
hydrated lime, containing 20 to 24 percent more “available” lime oxide content. Thus, about 3
percent quicklime is equivalent to 4 percent hydrated lime when conditions allow full hydration
of the quicklime with enough moisture. Greater bulk density requires smaller storage facilities.
The construction season may be extended because the exothermic reaction caused with water
and quicklime can warm the soil. Dry quicklime is excellent for drying wet soils. Larger
particle sizes can reduce dust generation.

18. 18
Disadvantages: Quicklime requires 32 percent of its weight in water to convert to
hydrated lime and there can be significant additional evaporation loss due to the heat of
hydration. Care must be taken with the use of quicklime to ensure adequate water addition,
mellowing, and mixing.
These greater water requirements may pose a logistics or cost problem in remote areas
without a nearby water source. Quicklime may require more mixing than dry hydrated lime or
lime slurries because the larger quicklime particles must first react with water to form hydrated
lime and then be thoroughly mixed with the soil.
Slurry Lime:
Advantages: Dust free application. Easier to achieve even distribution. Spreading and
sprinkling applications are combined. Less additional water is required for final mixing.
Disadvantages: Slower application rates. Higher costs due to extra equipment
requirements.
May not be practical in very wet soils. Not practical for drying applications.
3.9 Advantages:
 Lime stabilization improved the strength, stiffness and durability of fine-
grained soil, Effective in heavy clay soils.
 When use in clay, lower the LL and PI of soil.
 The strength of such matrix increases with addition of material like lime
cement, Fly-ash and surkhi.
 It produces maximum density under higher optimum moisture content then
in untreated soil.
 Lime stabilization also use for highly unstable plastic and swelling clay.
3.10 Disadvantages:
This mainly suitable for clayey coil, Soil contain more than 2% organic content may not
suitable.

19. 19
CHAPTER 4
4 Case Study: In-Situ Stabilization of Road Base Using Cement
4.1 Introduction:
Cement stabilization is one of the most common techniques for stabilizing recycled
road base material, and offers a longer pavement life. With the cement effect, the increase
in stiffness of the stabilized layer would provide better load transfer to the pavement
foundation. The recycling method provides an environmentally friendly option as the
existing road base materials will not be removed. This paper presents a case study at a trial
section along the North-South Expressway in Malaysia, where the Falling Weight
Deflectometer (FWD) was adopted to determine the in-situ stiffness of the cement
stabilized road base material. The FWD would assess the compressive strength and the
material stiffness of the cement stabilized layer. The improvement in the stiffness of the
stabilized base layer was monitored, and samples were tested during the trial. FWD was
found to be useful for the structural assessment of the cement stabilized base layer prior to
the placement of asphalt layers. Results from the FWD were also used to verify the
assumed design parameters for the pavement. Using the FWD, an empirical relationship
between the deflection and the stiffness modulus of the pavement foundation is proposed
in this paper.
4.1.1 Cement Stabilization Works:
The first operation involved in the in-situ recycling was milling the existing 175mm
bituminous materials using a “Wirtgen-W1000”. The in-situ aggregate moisture content
was determined by drying a sample of aggregate in a pan at the verge of the road located
next to the paved shoulder. The balance water content (the difference of the optimum and
in-situ aggregate moisture contents) was then calculated. Cement was then manually
spread on the surface of the existing road base material, and the rate of cement spreading
was based on the mix design requirements.
A summary of the design parameters adopted in the cement stabilized base (CTB)
design is as follows:

20. 20
 Design water content within 4.5+0.5% of the dry mass of aggregate and
cement.
 Design cement content was 3.5% (by mass of the dry aggregate). The cement
content was decided based on the targeted compressive strength (4 MPa to 8
MPa). In this case, the cement content of 3.5% achieve desired compressive
strength specified in the specification
 A minimum effective stiffness modulus of 1000MPa to be achieved after 28
days of curing.
 The average 7-days compressive strength determined from a group of 5 cubes
of the CTB road-base shall be between 4 and 8MPa.
 The average in-situ wet density shall not be less than 94% of the average wet
density of the corresponding group of 5 cubes.
The in-situ recycling was then performed to a depth of 200mm using a “Caterpillar-
CAT 350” stabilizer machine. The aggregate and cement were mixed in the mixing
chamber of the stabilizer machine. The CTB was then leveled using a motor grader. The
measurements allowed the thickness of asphalt to be determined. Compaction of the
recycled base layer was then carried out using a “Dynapac” vibratory. After a curing
period of 7-days, bituminous materials to a nominal thickness of 190 mm were laid over
the CTB base.
4.1.2Results from Trial Section
The in-situ cube compressive strength was determined from the prepared cube
specimens taken at 3, 7, and 28 days after CTB construction and tested on the subsequent
day. The results are summarized in Table 1, which indicate that the average compressive
cube strength of the CTB at 7-days was 6.00MPa, which was within the specified
requirements of 4.0 to 8.0MPa. The results of in-situ compressive strength measured from
the prepared core samples are also summarized in Table 1. The results show that an
average of the 7-day compressive strength obtained from the core samples is 6.0MPa
which is equivalent to the in-situ compressive strength obtained from the cube specimens.
The FWD data obtained from the field test were normalized to a pressure 200, 350 and

21. 21
700 kPa for the testing performed on the existing granular road base, CTB and completed
asphalt surfaces, respectively. The seven normalized deflection readings were measured
by geophones at distances (0, 300mm, 600mm, 900mm, 1200mm, 1500mm and
2100mm) from the center of the loading plate.
Figure 2: Falling weight deflectometer (FWD)
[Source: researchgate.net]
Age at
test
(days)
In-situ compressive
strength (MPa)
from core samples
In-situ compressive
strength (MPa) from
cube specimens
1 - 3
3 - 5.5
4 4.5 -
7 - 6.0
8 6.0 -
29 7.5 -
Table 1: Compressive strength of the CTB layer
[Source: G. W. K. Chai et al (2005)]
FWD test carried out on the existing road base gave a center deflection reading of 900
microns at 85 percentile value. For tests performed on the CTB, the deflections were
observed to decrease between 3 and 7 days due to curing of the CTB base. The FWD
center deflection value at 85 percentiles for the 3 and 7 days are 500 micron and 400
microns, respectively. For the 28-days, FWD center deflection at 85 percentile gives a
value of 300 micron. The profiles of the center deflection parameter before and after the

22. 22
stabilization have been plotted against chain-age and are shown in Fig. 3.
Figure 3: FWD center deflection profiles before and after cement stabilization A: (3 and 7
days); B: (28 days)
[Source: G. W. K. Chai et al (2005)]
The FWD data were back-analyzed using ELSYM5 (1986) computer program to
determine the effective stiffness after each stage of testing. A three-layer pavement
structure was used to model the CTB base, granular sub-base and sub-grade layers for the
3 and 7-days strength evaluation. For the 28-days, a 4-layer model was used for the asphalt,
CTB base, granular sub-base and sub-grade layers. The effective stiffness modulus at 85
percentile values for the various pavement layers at different stages of construction are
presented in Table 2. The stiffness of the CTB layer increased from 700 MPa at 3-days to
1350 MPa at 28-days after curing. It was also noted that, the stiffness of the CTB is greater
than the adopted design stiffness of 1000MPa, and the CTB stiffness value had been
achieved on site from the compressive strength (after 28 days) and FWD deflection data
gathered at the test site, a relationship between the compressive strength-deflection (D1)
can be derived. Statistical regression analyses have been performed to establish the
empirical relationship (as shown in Figs. 4 and 5). The relationship for compressive
strength and FWD deflection is illustrated in following Equation:
Su  7.4543 ln(D1)  51.002
Where, Su is compressive strength of CTB (MPa), and D1 is the reading from FWD
deflection sensor (micron).

23. 23
Based on the empirical relationship shown in Fig. 5, another useful engineering
relationship between the stiffness modulus and compressive strength of CTB is proposed,
and is shown in following Equation:
E  381 Su 0.6047
Where, E is the back-calculated stiffness modulus (MPa)
Test stages Effective stiffness modulus
(MPa)
at 85 percentile values
Pavement Layers CTB Road
base
Granular Road base
Before Recycling
- 280
CTB after 3 days 700 -
CTB after 7 days 1150 -
Asphalt Surface after
28 days
1350 -
Table 2: Effective stiffness modulus of the CTB layer
[Source: G. W. K. Chai et al (2005)]
Figure 4: Compressive strength and deflection D1 relationship from FWD.
[Source: G. W. K. Chai et al (2005)]

24. 24
Figure 5: Stiffness modulus and compressive strength relationship from field test
[Source: G. W. K. Chai et al (2005)]
4.1.3 Conclusions
A pavement section of 100m in length on the Southbound Carriageway of the
North-South Expressway (West Malaysia) has been rehabilitated by strengthening the
existing granular road base using cement stabilization. The performance of the completed
pavement was investigated through FWD and laboratory testing. For tests performed on
the CTB, the deflections were observed to decrease between 3 and 7 days due to curing of
the CTB base. The use of cement stabilized base leads to a significant improvement in the
structural capacity of the pavement. An empirical relationship between the in situ
compressive strength and the deflection of the CTB layer has been proposed. Further, the
study illustrated an empirical relationship between the stiffness modulus and the in-situ
compressive strength of the CTB. These two engineering relationships can be useful for
the monitoring the performance of the CTB layer when stabilization is in progress. The
significant finding from the trial test showed that, the use of FWD will verify design
parameters such as the in-situ effective stiffness modulus of the CTB layer. FWD test can
also be used to demonstrate that the required compressive strength and stiffness modulus
of the CTB had been achieved on site. Thus, the expected design life, based on the actual
in-situ properties of the pavement, could be determined in greater confidence.

25. 25
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Stabilization of Road Base Using Cement - A Case Study in Malaysia”, School of
Engineering, Griffith University, Australia.
 Lamb, T.W. (1962). “Soil Stabilization in foundation engineering”. - G. A. Leonard
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 NLA (National Lime Association). (1985). “Lime Stabilization Construction
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