The document discusses various techniques for soil stabilization used in road construction. It defines soil stabilization as treating soil to maintain or improve its performance. Key techniques include mechanical stabilization by blending soils, and chemical stabilization by adding lime, cement or other chemicals. Mechanical methods improve strength through compaction and grading, while chemical additives cause reactions improving properties like strength and durability over time. The document provides details on various soil stabilization mixtures and their applications in road construction.

1. SOIL STABILISATION
D P Majithiya
ME Highway & Transport 1st semester

2. SOIL STABILIZATION
 Soil stabilization is a process of treating a soil in
such a manner as to maintain, alter or improve the
performance of the soil as a road construction
material. The changes in the soil properties are
brought about either by the incorporation of
additives or by mechanical blending of different soil
types.
OR simply
 Soil stabilization refers to the process of
changing soil properties to improve strength and
durability. There are many techniques for soil
stabilization, including compaction, dewatering
and by adding material to the soil.

3. PURPOSE OF SOIL STABILIZATION
1. To improve the strength of sub-bases, bases and
sometimes surface courses, in case of low cost roads
2. To bring about economy in the cost of road.
3. To make use of inferior quality of locally available
soils/material. ( every time it is not possible to find
required or specified strength in locally available
material at that time we can go for soil stabilization
methods)*
4. To improve certain undesirable properties of soils,
such as excessive swelling or shrinkage, high
plasticity, difficulty in compacting etc.
5. To facilitate compaction and increase load-bearing
capacity
6. To reduce compressibility and thereby settlements.
7. To improve permeability characteristics.

4. COMPONENTS OF STABILIZATION
 Soil
 Stabilizing agent
 Cement
 Lime
 Fly ash
 Blast furnace slag

5. STAGES INVOLVED IN SOIL STABILIZATION
PROCESS
1. Evaluating the properties of given soil
2. Deciding the lacking property of soil and choose
effective and economical method of soil
stabilization
3. Designing the Stabilized soil mix for intended
stability and durability values

6. DIFFERENT TECHNIQUES OF SOIL
STABILIZATION
types of soil stabilization techniques
Mechanical stabilization chemical stabilization
or stabilization by
additives such as
- soil-aggregate mixture -lime
-soil- clay mixture -cement
-sand-gravel mixture -sodium silicate
- stabilization of soil with -Calcium chloride
soft aggregates -bituminous material
-resinous material

7. MECHANICAL SOIL STABILIZATION
 In this techniques the stability of 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 the
desired density. Compacting a soil at an
appropriate moisture content is itself a form of
mechanical stabilization

8. PRINCIPLE OF MECHANICAL STABILIZATION
 Mechanical stabilization is achieved by intelligently
blending locally occurring material so as to obtain a
desired grading. compaction of soil is also a form of
Mechanical stabilization. (It is well known as a dense,
well graded mass offers high resistance to lateral
displacement under a load).
 If well graded material is compacted , densification of
the mass takes place. The mechanical strength of mass
is due to the internal friction and the cohesion. (internal
friction is supplied by the coarser particles gravels,
sand, silts where as cohesion is due to the clay friction.)

9. APPLICATION OF PRINCIPLE OF MECHANICAL
STABILIZATION
1. Soil-aggregate mixture.
2. Sand-clay mixture.
3. Sand-gravel mixture.
4. Stabilization of soil with soft aggregate.

10. CHEMICAL STABILIZATION
 Under this category, soil stabilization depends
mainly on chemical reactions between stabilizer
(cementitious material) and soil minerals
(pozzolanic materials) to achieve the desired effect.
 Different techniques of soil stabilization
 Soil-lime mixture
 Soil-cement mixture
 Chloride stabilization and Stabilization with other
chemicals

11. SOIL BITUMEN STABILIZATION
 The addition of a bitumen binder to a soil improves
its properties considerably.
1. If the soil lacks cohesion, the bitumen coats the soil
particles, binds them together and supplies cohesion
2. Bitumen being a waterproof material , the mixture
becomes less prone to the adverse effect caused by
ingress of water
3. If bitumen binder sprayed on dry surface of low-cost
road, it prevent dust and stop the entry of moisture into
the road

12. SOIL BITUMEN STABILIZATION
 The following are various bituminous stabilization
techniques
1. Sand-bitumen
2. Soil-bitumen
3. Soil-aggregate-bitumen
4. Spraying bitumen on earth/gravel road

13. ADVANTAGES OF SOIL STABILIZATION
 It Improves The Strength Of The Soil, Thus, Increasing The Soil Bearing
Capacity.
 It Is More Economical Both In Terms Of Cost And Energy To Increase The
Bearing Capacity Of the Soil Rather Than Going For Deep Foundation Or Raft
Foundation.
 It Is Also Used To Provide More Stability To The Soil In Slopes Or Other Such
Places.
 Sometimes Soil Stabilization Is Also Used To Prevent Soil Erosion Or Formation
Of Dust, Which is Very Useful Especially In Dry And Arid Weather.
 Stabilization Is Also Done For Soil Water-proofing; This Prevents Water From
Entering Into The soil And Hence Helps The Soil From Losing Its Strength.
 It Helps In Reducing The Soil Volume Change Due To Change In Temperature Or
Moisture content.
 Stabilization Improves The Workability And The Durability Of The Soil.

14. REFERENCES
 http://www.industrialresourcescouncil.org/applicatio
ns/soilstabilization
 Youtube.com
 Principles and practices of highway engineering by
Dr. L. R. Kadyali

15.  Thank you

16. SOIL-AGGREGATE MIXTURE.
 Soil-aggregate is a material in which soil and aggregate particles are
mixed in suitable proportion such that the resulting mixture conforms
to a dense and stable mix when properly compacted.
 This technique is used in countries abroad for the construction of
base courses, and in the case of low traffic roads for the surface
course as well
 The particle-size distribution of the mixture is a major factor in
determining the stability. The aggregate should be so graded that a
grain to grain contact exists, producing internal friction.

17. SOIL-AGGREGATE MIXTURE.
 Specification for soil-aggregate sub-base courses
Sieve
designation
Percent by weight passing the sieve for a
nominal maximum size of
80 mm 40 mm 20 mm
80 mm 100 - -
40 mm 80-100 100 -
20 mm 60-80 80-100 100
10 mm 45-65 55-80 80-100
4.75 mm 30-50 40-60 50-75
2.36 mm - 30-50 35-60
600 micron 10-30 15-30 15-35
75 micron 0-10 0-10 0-10

18. SAND-CLAY MIXTURE.
 The sand-clay road is composed of a favorable
mixture of clay, silt and sand. This blending can
alter the undesirable properties of clay significantly.
we can use this mixture to construct about 200 mm
thickness road and as a surfacing course for low-
traffic roads. When used as sub-base mix should
have a minimum soaked CBR of 20, When used as
base for heavily traffic road mix should have a
minimum soaked CBR of 80
 This mixture give good result only if proper
equipments are used and quality control is done.

19. SAND-CLAY MIXTURE.
 Specification for sand-clay mixture
Sieve
designation
Percent by weight passing
25 mm 100 - -
10mm - 100 -
4.75 mm 70-100 80-100 100
2.36 mm - 50-80 80-100
2.00 mm 55-100 - -
1.18 mm - 40-65 50-80
600 micron - - 30-60
425 micron 30-70 - -
300 micron - 20-40 20-45
75 micron 8-25 10-25 10-45

20. SAND-GRAVEL MIXTURE.
 In tropical countries, the materials obtained from
the disintegration of laterite are extensively found
in a natural admixture of clay and coarse fractions
and is known as lateritic gravel. In india, this
material is locally known as moorum. Often the
natural moorum contains to much of plastic material
which lower its value as road pavement material. A
suitable admixture of moorum with sand will not
only result in a better gradation and increased
strength but also will reduce the plasticity. Sand
moorum mixture find ready application in sub-base
and bases in india.

21. STABILIZATION OF SOIL WITH SOFT AGGREGATES
A method of stabilization of soil using soft aggregates is known as Mehra’s
method
the principle behind this method is to embed in a soil mortar, coarse
aggregates roughly one-third of the total volume. The aggregates are
normally soft aggregates such as over-burnt brick ballast, kankar, moorum or
laterite. Because of the larger proportion of the soil mortar, the resulting
material has no grain to grain contact in the coarse aggregates, which merely
float in the soil. Each aggregate is thus enveloped all round in the compacted
soil and is thus protected from the crushing effect of traffic. This enables the
soft aggregate to retain its strength and angular character for an indefinite
period . About 10 percent of the coarse aggregates which are collected are
not mixed with the soil but are saved and spread on the layer of the soil-
aggregate mixture before rolling.
the soil-aggregates mixture is compacted to maximum dry density at
optimum moisture content

22. SOIL-LIME STABILIZATION
 When lime is added to a fine-grained soil, a number of reactions
take place. Some of them occur immediately while others are slow
to occur. One of the early reactions is base-exchange. Clay
particles are usually negatively charged with exchangeable ions of
sodium, magnesium, potassium or hydrogen adsorbed on the
surface. The strong positively charged ions of calcium present in
lime replace the weaker ions of sodium, magnesium, potassium or
hydrogen resulting in a preponderance of positively charged
calcium ions on the surface of the clay particles. This in turn
reduces the plasticity of the soil. The clay particles tends to
agglomerate into large sized particles (flocculation), imparting
friability to the mixture
After above first reaction are complete, any additional quantity
of lime will react chemically with the clay minerals. The aluminous
and siliceous materials in the clayey soil will react with the lime in
presence of water to form cementitious gels, which increase the
strength and durability of the mixture. This pozzolanic reaction are
slow and extend over a long period of time, several years in some
instance
another possible source of strength is the formation of calcium
carbonate due to the absorption of carbon dioxide from air.

23. SOIL-CEMENT STABILIZATION
 Cement is a standard material whose quality is
tested and assured . Because of its very high
flexural strength, it has a vary high load spreading
property. Thus soil-cement is able to spread the
load over a wider area and bridge over locally weak
spots of the underlying sub-grade or sub-base.
The main disadvantages are
1. The cost being higher than lime-soil
2. The need of high degree of quality control
3. If volumetric change take place when cement
hydrates it results in early shrinkage cracks

24. CHLORIDE STABILIZATION
 calcium chloride has deliquescent and hygroscopic
properties. By the former is meant the ability of
material to absorb moisture from the air and
become liquid, the latter is meant the ability of
material to absorb and retain moisture without
necessarily becoming liquid.
granular soils lack stability when they are too
dry. By adding calcium chloride their moisture
content can be stabilized and the soil can be used
successfully in road construction.
We can also apply a number of other chemicals like
sodium silicate, Resins , molasses, fly ash, etc.