Abstract: To improve
engineering properties of soil and making the soil more stable   soil stabilization
methods are used. This paper highlights soil stabilization by using cement. Cement
is a material which is added to natural soil for the purpose of stabilization. The main purpose of the soil stabilization is
to increase the bearing capacity of the soil. its resistance to
weathering process and soil permeability. Unstable soils can create significant
problems for pavements or structures, therefore soil
stabilization techniques are necessary to ensure the good stability of soil,
this paper deals with the complete analysis of improvement of soil properties
by using cement.

Key words: cement, soil, compactors, liquid limit, plastic limit,
shrinkage limit.

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INTRODUCTION: soil stabilization is used to reduce the
permeability and compressibility of soil mass in earth structures and to
increase its shear strength. soil stabilization required to increase the
bearing capacity of foundation soils. The main use of stabilization is to
improve the natural soils for the construction of highways and airfields. The
long-term performance of any construction project depends on the soundness of the
underlying soils. The main
principal of stabilization are used for controlling the grading of soils and
aggregates in the construction of bases and sub-bases of the highways and
airfields. Cement stabilization is done by mixing pulverized soil and Portland
cement with water and compacting the mix to attain a strong material. The
material obtained by mixing soil and cement is known as soil-cement the
soil-cement becomes a hard and durable structure material as the cement
hydrates and develops strength.

TYPES OF SOIL-CEMENT

1. Normal soil-cement: Consists of 5 to14% of cement
by volume. The quantity of cement mixed with soil is sufficient to produce a
hard and durable construction material. The quantity of water used should be
just sufficient to satisfy hydration requirements of the cement and to make the
mixer workable.

2. Plastic soil-cement: This type of soil-cement also
contains 5 to 14% by volume, but it has more quantity of water to have wet
consistency similar to that of plastering mortar at the time of placement. The
plastic soil cement can be placed on steep or an irregular slope where it is
difficult to use normal road-making equipment .it has also been successfully
used for water-proof lining of canals and reservoirs. The plastic soil-cement
can be used for protection of steep slopes against erosive action of water.

3. Cement modified soil: it is a type of soil-cement
that cantinas less than 5% of cement by volume. It is a semi-hardened product
of soil and cement.

                                                      

S.no

properties

Local soil

1

Liquid limit (%)

43

2

Plastic limit (%)

28

3

Shrinkage limit (%)

19

4

Specific gravity
(%)

21

5

Gravel (%)

2.67

6

Sand (%)

4

7

Silt (%)

50

8

Clay (%)

26

9

Natural moisture
content (%)

23

10

Maximum dry density
(gm/cm^3)

8

11

Plasticity index
(%)

1.98

12

Optimum moisture
content (%)

16

 

 

 

 

 

 

 

 

Table 1:
physical properties of soil

MATERIAL AND METHODS:

Construction
methods:

1. mix-in-place method: in this method of construction,
mixing of soil-cement is done at the place where it would be finally placed. it
consists of:

The sub grade is cleared of all undesirable materials such as
boulders, debris; stumps. it is then leveled to the required formation level.
The leveled sub grade is scarified to a depth equal to the proposed thickness
of the soil cement. The required of water is sprinkled over the surface and wet
mixing is done till the mixture has a uniform colour. Compaction is done using
suitable methods. The thickness of the layer should not be more than 15 cm. compaction
should not take more than 2hours.

The compacted soil-cement is moist cured for at least 7 days
by providing a bituminous primary coat.

The pulverized soil is properly shaped to the required grade
and the required quantity of cement is spread uniformly over the surface. It is
then intimately mixed dry with rotary tillers or mixers.

 

2. plant-mix method:

Stationary plant: in this method, the excavated soil is
transported to stationary plant located at a suitable place. The required
quantity of cement is added to the soil in the plant. Mixing is done after
adding water. The time required depends upon the type of the soil. The mixed
material discharged in6to dumper trucks and transported back to the sub grade. it
is spread and properly compacted. The stationary plant is useful for obtaining
a uniform mix. The method quite expansive as compared with mix-in-place method.
Travelling plant: a travelling plant can move along the road under construction.
The soil, after placement of cement over it, is lifted up by an elevator and
discharge into the hopper of the mixer of the travelling plant. Water is added
and proper mixing is done. The mix is then discharge on the sub grade and
spread by a grader. It is then properly compacted. The travelling plant method,
like stationary plant, is useful for accurate proportioning and uniform mixing.
The depth of treatment also properly controlled and a uniform sub grade surface
is attained.

CEMENT STABILIZED SUBGRADE
CONSTRUCTION PROCEDURE

Construction of cement stabilized sub grade soil follows
this procedure:

Sub grade material was spread on the top of embankment layer
(150mm + 25% loose) and lightly compacted. Total work area marked with grids of
the area required for one bag of cement (2.5m X 2.5m) .Cement spread at the
rate of one bag per grid. Soil and Cement mix by mechanical Harrow followed by
tractor mounted rotovator. Moisture added to the soil (+/-1% of OMC). Compaction
is process completed done. Quality Control tests conducted as per the
frequency.

 

Fig-1
Soil stabilization by using cement

 

Fig-2
Soil stabilization by using cement

 

 

CONCLUSION:

Improve the mechanical qualities of local road construction soils.
Strength gain is primary outcome due to chemical reaction between the soil and
cement. Increase load bearing capacity of soil by which maintain its structural
integrity. Harmful moisture penetration can be diminish gradually from the
soil. This process of cement stabilization is economic which in turn reduces
the cost of construction and will lasts longer life of the road.

REFERENCES:

1 currin.D.D.,allen. J.j.little, D.N.,
1976.validation of soil stabilization index system with manual development.
Frank j. seisler research laboratory. United States air force academy, Colorado.

2 Broms,
B.B., 1986.stabilization of soft clay with lime and cement columns in south
east asia.applied research project.

3 Das,B.,1994.principle
of geotechnical engineering,3rd edition.PWS_kent  publishing company,boston.

4 Derucher,K.N.,
korfitatis, G.P., ezeldin. A.S., materials for civil and highway
engineerings.prentice-hall.

5
Dr.K.R.arrora of geotechnical engineering of soil mechanics and foundation
engineering.

6Sadek,D.,
roslan,H., abubakar,D.A.,2008.engineering properties of stabilized tropical
peat soils.bund,EJGE13,pp 7-8

7saitoh,S.Y.,Suzuki,shirai.,
1985.hardening of soil improvement by deep mixing method.proc.of the 11th
ISCMFE,san Francisco,vol.3

 

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