Some of the most affected structures

GEOTECHNICAL ENGINEERING
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ABSTRACT
Expansive soils have the unique property of volume variation with changes in the weather
conditions. The composition of the expansive soil is well known to have montmorillonite- clay
mineral. These are usually part of the residual sedimentary soils such as clay-stones and shales.
The type of the soils is mainly found in the semi-arid and arid areas which are known as to
experience very wide changes in the conditions of the climate. These soils are known to cause
problems to the engineering constructions including buildings. Some of the most affected
structures are lightweight constructions which are easily uplifted during the wet seasons only to
sink during hot summers when the soil shrinks. Expansive soils are more common in the arid
zones since the prevailing conditions favor clay mineral materialization particularly the group of
smectite which includes montmorillonite among other members of the illites. Stabilization of the
soil refers to a geotechnical process which focuses on the improvement of the soil mechanical
properties so that it’s engineering characteristics are enhanced. This particular paper has focused
on different method of expansive soil stabilization while considering the use of lime as the main
stabilizer.

ACKNOWLEDGEMENT
I would like to sincerely express my gratitude to Prof........ for his patience, guidance, invaluable
pieces of advice and support throughout this study as well as her timely corrections in the
document. I count myself lucky to have him as my supervisor. Nevertheless, special thanks to
my classmates for the materials and other types of support that I received. I would like to thank
my parents and other members of the family who have always been available for both moral and
materials support. Their endless love and advice made me sail through.

Contents
ABSTRACT.................................................................................................................. 2
ACKNOWLEDGEMENT................................................................................................. 3
Contents..................................................................................................................... 4
List of Figures.......................................................................................................... 5
List of Tables........................................................................................................... 6
INTRODUCTION........................................................................................................... 7
LITERATURE REVIEW.................................................................................................. 9
Structure’s damage on the Expansive Soils............................................................9
Bentonite Clay....................................................................................................... 13
Origin................................................................................................................. 13
Mineralogy of Bentonite Clay............................................................................. 14
Swelling.............................................................................................................. 16
Expansive Soil Stabilization...................................................................................17
Expansive Soil Stabilization Using Lime................................................................17
OBJECTIVES.............................................................................................................. 18
METHODOLOGY........................................................................................................ 18
Compaction Tests.................................................................................................. 18
Test of One-Dimension Consolidation....................................................................19
Test of Volume Shrinkage..................................................................................... 20
Measurement of Suction........................................................................................ 21
Chilled-Mirror Psychrometer..................................................................................22
Determination of Flexural Strength.......................................................................24
Test of California Bearing Ratio(CBR)....................................................................26
Atterberg Limits.................................................................................................... 28
UCS Tests.............................................................................................................. 29
CONCLUSION............................................................................................................ 30
RECOMMENDATIONS................................................................................................ 30
REFERENCES............................................................................................................ 31
APPENDIX................................................................................................................. 34

List of Figures
Figure 1: .................................Shrinking mechanism of the expansive soils
Figure 2 :................................. Condition of the edge heave
Figure 3 : ................................Conditions of the edge shrink and well as center heave
conditions
Figure 4: ...................................Some of the common cracks found in the building located
in the foundations which are considered to be shallow.
Figure 5: ........................................Compaction Tests
Figure 6: ................................................Set up of Consolidation test as well as data
analysis using DS7 software.
Figure 7: ...................................................Test procedure of the volumetric shrinkage
method
Figure 8: ...................................................Test procedure using chilled mirror device.
Figure 9: .....................................................Samples of the special molds used in the
preparation of the beams of compacted soil as well as other static compaction equipment
Figure 10: .................................................Set up of flexural test as well as load
application on the beam of the soil. Also in the figure is the produced curve of the deflection that
was gotten during the test.

Figure 11.........................................................Procedure of CBR tests
Figure 12... ...................................................Limits of Atterberg versus the percentage
of lime used
List of Tables
Table 1........................... Cation Exchangeable Capacity of the clay soil.
Table 2............................ Classifications of the expansive soil based on the respective
index.

INTRODUCTION
The expansive soil concept can be utilized in the description of soils that have significant volume
variation because of the changing water content of the soil. This type of soil is known to
dominate semi-arid and arid zones of the planet earth in which the evaporation rates are higher
than the precipitation rate yearly. These soils are known to cause problems to the engineering
constructions including buildings. Some of the most affected structures are lightweight
constructions which are easily uplifted during the wet seasons only to sink during hot summers
when the soil shrinks (Pandian, and Krishna 2013). Expansive soils are more common in the arid
zones since the prevailing conditions favor clay mineral materialization particularly the group of
smectite which includes montmorillonite among other members of the illites. These groups of the
clay have their specific unique characteristics like greater specific surface area, smaller sized
particles and finally higher levels of the CEC which is the cation exchange capacity.
Table 1: Cation Exchangeable Capacity of the clay soil

The swelling behaviour of the expansive soils has led to several damages in yearly basis. This is
notably in the arid areas where many buildings and other structures of the construction are
observed to be having cracks. Other observable impacts include pavement crumbling, crumbling
of the highways and channels and finally cracking of the structures of the foundation. Irrigation
systems in these areas have been affected too leading to the exposure and bursting of the sewer
lines, water lines and reservoir lines.
As the construction technology continues to develop, there is increased attention on the
behaviour of the expansive soil particularly shales and clay internationally. There is a joint effort
by all the engineers from different parts of the parts to solve this particular problem. They have
been sharing information regularly in attempt to come up with the best possible design of the
structures which can be best suited for this type of soil. Some of the countries which have
registered such development in this technology include South Africa, Canada, United States and
Australia.
Construction of lightweight structures on the expansive soil remains to be one of the serious
challenges faced by the civil engineers today. This headache begins with thinking of the type of
foundation which will best suit the soil and the specific structural design. Alternatively, they
have thought of the technique of soil stabilization using the most effective and economical ways
which includes addition of material admixtures with none swell properties so that the volume
change and other characteristics of the soil can be modified.
LITERATURE REVIEW
The composition of the expansive soil is well known to have montmorillonite- clay mineral.
These are usually part of the residual sedimentary soils such as clay-stones and shales. The type