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This paper aims to identify the factors that cause damages to buildings constructed on expansive soils and suggests practical solutions to avoid swelling problems. Literature of buildings failures associated with expansive soils and techniques experienced to prevent the swelling damages were intensively reviewed. Three regions in Khartoum state, famous expansive soil areas were selected for this study. Ten cases of damaged buildings were randomly selected for investigation. A field survey of damages was conducted to diagnosis and point out the causes, extent and type of damage that was observed in the buildings. It was observed that eight lightweight buildings suffered heavy damages and only two other buildings were slightly damaged. Common failures observed were cracks in walls and floors, foundation movements, column buckling, sagging of beams and slabs in typical damage cases. It was found that poor surface drainage, gardens watering close to buildings, source of water leakage and improper design of foundation contribute to most failures and damages in buildings. Based on the causes of failure and other factors, practical measures are suggested for the damaged buildings. Finally, conclusions are drawn from the study findings.
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International Journal of Multidisciplinary and Scientific Emerging Research
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108| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
Magdi M. E. Zumrawi1, Asim O. Abdelmarouf2, and Abubakr E. A. Gameil3
1Associate Professor, Department of Civil Engineering, Faculty of Engineering, University of Khartoum, Khartoum, Sudan
2,3M.Sc. Student, Department of Civil Engineering, Faculty of Engineering, University of Khartoum, Khartoum, Sudan
Accepted 10 March 2017, Available online 16 May 2017, Vol.6, No.2 (May 2017)
This paper aims to identify the factors that cause damages to buildings constructed on expansive soils and suggests
practical solutions to avoid swelling problems. Literature of buildings failures associated with expansive soils and
techniques experienced to prevent the swelling damages were intensively reviewed. Three regions in Khartoum state,
famous expansive soil areas were selected for this study. Ten cases of damaged buildings were randomly selected for
investigation. A field survey of damages was conducted to diagnosis and point out the causes, extent and type of damage
that was observed in the buildings. It was observed that eight lightweight buildings suffered heavy damages and only two
other buildings were slightly damaged. Common failures observed were cracks in walls and floors, foundation
movements, column buckling, sagging of beams and slabs in typical damage cases. It was found that poor surface
drainage, gardens watering close to buildings, source of water leakage and improper design of foundation contribute to
most failures and damages in buildings. Based on the causes of failure and other factors, practical measures are
suggested for the damaged buildings. Finally, conclusions are drawn from the study findings.
Keywords: Damages; diagnosis; expansive soil; buildings.
1. Introduction
Expansive soils pose a significant hazard to foundations of
buildings founded in them. Such soils can exert uplift
pressures which cause considerable damage to lightly
loaded structures. The annual cycle of wetting and drying
causes the soil to swell and shrink. Thus, the arid and
semi-arid regions are much susceptible to damage from
expansive soils throughout the year. In Sudan, the climate
is semi arid and over one-third of the country land covered
with expansive soils. Unfortunately, this area includes
most of the nation's population cities and development
projects. Many houses in central and eastern regions of
Sudan were damaged due to soil heave, [1].
The presence of expansive soils in Khartoum has
contributed to light buildings damages and subsequently
causing increased annual repair expenditure, [2]. Many
structures constructed on swelling clays have met with
widespread problems associated with serviceability
performance mainly in form of cracks or permanent
deformation. There are many cases of residential buildings
have experienced significant cracking and damages, [2].
Engineering problems due to expansive soils have been
reported in many countries, costing millions of dollars due
to severe damages of structures. Maintenance and repair
cost can exceed the original cost of the foundation and
creates financial burden to the owner, [1].Generally, the
damage will result in economic loss for building owners
and the country at large scale. Although the accusing
finger is mainly pointed at the expansive soils, other
contributing factors such as poor design, poor
construction, inadequate supervision of the construction
processes, poor drainage, gardens and big trees close to the
building, and climatic factors have contributed to the
The object of this research work is to identify the
factors that cause failures to buildings constructed on
expansive soil areas in Khartoum state. Some existing
residential buildings suffered from damages by expansive
soils were taken as a case study. Building sites were
visited to inspect and ascertain some practices on site
likely to cause damage or even collapse of buildings in
order to recommend appropriate remedial measures.
2. Literature Review
2.1 Expansive Soil
Expansive soils are clay soils containing considerable
amount of montmorillonite mineral which has a potential
for swelling or shrinking due to changes in its moisture
content. Expansive soil can be classified into two main
groups with respect to the parent rock. The first group
comprises the basic igneous rocks such as the basalts in
India and South Africa. In this group, the Feldspar and
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
109| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
Pyroxene minerals of the parent rocks have decomposed to
form montmorillonite and other secondary materials. The
second group comprises the sedimentary rocks that contain
montmorillonite as a constituent which breaks down
physically to form expansive soils. Examples of this type
of rock are bedrock shale found in North America and the
shale in South Africa, [3]. The three most important
minerals of expansive clay are montmorillonite, illite and
kaolinite. The montmorillonite is considered as a highly
expansion and the most effective one for swelling
behavior, [4].
Potentially swelling clays can be recognized in the
laboratory by their plastic and swelling properties.
Generally, clays of high plasticity usually have high
swelling potential. Expansive soils are characterized by
plasticity index over 30%, liquid limit exceeding 50% and
have high swelling potential, [3]. In the field, expansive
clays can be recognized in the dry season by the deep
cracks of roughly polygonal patterns, [5]. Three
ingredients that are necessary for soil to swell, clay rich of
montmorillonite mineral; when the natural water content is
around the plastic limit of the soil; and there is a source of
water leakage.
Expansive soils experience volume changes as a result
of moisture changes leading to differential movements
below a building‟s foundation. When a structure builds on
such a soil, it applies an upward pressure on the
foundation. If the foundation transfers a downward stress
which is smaller than the swelling pressure, the foundation
moves upward. These upward and downward movements
of foundations become cyclic seasonal movements during
the entire life span of the structure. These cyclic
movements tend to tear up the walls and eventually
destabilize the whole structure. Light structures, such as
single or double storey buildings, pavements, etc. which
generally transmit smaller stresses to the soil than the
swell pressure are greatly suffered the damage, [6].
2.2 Damages in Buildings
Different Buildings experience various levels of damages
during their life time. Damages may occur within a few
months following construction, may develop slowly over a
period of about 5 years, or may not appear for many years
until some activity occurs to disturb the soil moisture, [7].
The probability of damages increases for structures on
swelling foundation soils if the climate and other field
environment, effects of construction, and effects of
occupancy tend to promote moisture changes in the soil.
The differential movement caused by swell or shrinkage of
expansive soils can increase the probability of damage to
the foundation and superstructure. Differential rather than
total movements of the foundation soils are generally
responsible for the major structural damage. Differential
movements redistribute the structural loads causing
concentration of loads on portions of the foundation and
large changes in moments and shear forces in the structure
not previously accounted for in standard design practice,
[6]. The damages are due to design faults, cheap
construction materials, poor workmanship, poor drainage,
climatic condition and swelling behaviour of expansive
The volume change behavior of expansive soil generates
serious damage to civil infrastructures in Sudan and many
countries over the world. In general, the annual damage in
Sudan exceeds $6million and most of the annual damage
reported occurs in residential and commercial buildings,
[1]. Previous studies indicated a continual increase in
annual damage caused by expansive soil as the population
continues to grow due to the need of new developments to
the expanding residential buildings and commercial
markets,[7][8]. Rosenbalm and Zapata [9] stated that in
the United States alone, the cost to repair structures
damaged by expansive soils has been estimated to be twice
the combined damages of natural disasters. Expansive
soils have reportedly inflicted billions of dollars in
damages and repairs annually to structures, [10].
Evaluation of damages has to base on experience and
knowledge of the history of the building, construction
materials details, crack patterns, and existing physical
condition. This is possible by means of walk through
inspection to identify and categorize both distinct and
hidden damages. For all damages, the professional
inspector must predict a complete set of causes and
effects. The correlation between causes and effects require
experimental and analytical investigation. This is used to
identify, localize and quantify the damages for structural
performance evaluation. Damage evaluation based on
different deterministic criteria in relation with angular
distortion, [11][12].
The most obvious identifications of damage to
buildings are doors and windows that get jammed, uneven
floors, and cracked foundations, floors, masonry walls and
ceilings. Moreover, different crack patterns mean different
causes for different foundation materials. In most cases,
cracks due to shrinkage and expansive clay usually run
from corner towards adjacent opening and are uniform in
width or v-shaped, wider at the top than the foundation
wall, [13][14]. This pattern of cracks happens when the
moisture movement is from the perimeter to the centre of
the house. In some cases, the cracks are wider at the
bottom than the top due to dishing effect as opposed to
dooming effect. This happens when the moisture moves
from centre to the perimeter resulting into the saucer
effect. In the dishing effect, the cracks are wider bottom
than top because of the inwards tilt, [15]. Cracks due to
structural failure are significant cracks and caused due to
improper design and/or quality control failure. Besides
functions and cost such cracks have psychological impact
on the owners and can be encountered in high-rise
building and in non-expansive soil areas. Such cracks
occur very rarely. Crack due to foundation movement are
usually associated with expansive soil, which can exert a
pressure which moves the structure. The pattern of the
cracks depends on whether it is a doming heave or a dish
shaped lift heave. Figure 1 schematically illustrates some
commonly observed exterior cracks in brick walls from
doming or edge down patterns of heave. The pattern of
heave generally causes the external walls in the
superstructure to lean outward, resulting in horizontal,
vertical, and diagonal fractures with larger cracks near the
top, [16].
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
110| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
Figure 1 Cracks patterns on exterior wall resulting from
dome heave of foundation soil, [16]
The classification of the damage is very important to
assess whether the building calls for strengthening, repair,
renovation or demolition. Various researchers ([17],[18],
[11]) put forward many definitions, specifications,
classification and effect of damage in structures as given
in Table 1.
2.3. Practical Solutions for Swelling
In order to minimize or eliminate the danger of damage of
buildings because of heave and shrinkage, the methods
commonly have been used are moisture control, soil
stabilization and structural measures.
2.3.1 Moisture Control Barriers
The main cause of heave and shrinkage is the fluctuation
of moisture under and around the structure. In general, the
natural ground water fluctuates depending on land
topography, geological and weathering conditions. In a
country like Sudan, where there are distinct dry and wet
seasons, the fluctuation of ground water table during these
periods is large.
Generally, expansive soil will not be a problem if the
moisture content is constant throughout the soil. Moisture
fluctuation can be controlled by using horizontal barriers,
vertical moisture barriers, subsurface and surface drainage,
Table 1 Classification and effect of damages in buildings, [11]-[17]
Degree of
Description of damage
Effect of damage
on building
Crack width
Hairline cracks
< 0.1
Very slight
Fine cracks
0.1 to 0.3
Cracks are visible and easily filled. Several slight fractures may appear
inside of the building. Doors and windows may stick
Aesthetic only
0.3 to 2
Cracks that require opening up and patching. Possible replacement of a
small amount of brickwork. Doors and windows stick, service pipes may
May affect serviceability and
stability of the building
2 to 5
Large cracks require extensive repair work involving breaking-out and
replacing sections of walls. Windows and door frames distort and floor
slopes are noticeable. Leaning or bulging walls. Beams lose some bearing.
Utility service disrupted
Serviceability and stability of
the building at risk.
5 to 25
Very severe
Major repair involving partial or complete rebuilding. Beams lose bearing,
walls lean badly and require shoring and windows are broken with
There is a danger of structural
Horizontal moisture barriers can be installed around a
building in the form membranes, rigid paving or flexible
paving. Widely used horizontal barriers are polyethylene
membrane, concrete aprons and asphalts membrane. The
purpose of the horizontal barriers is to prevent excessive
intake of surface moisture, [10].
Vertical moisture barriers are used around the
perimeter of the building to cut off the source of lateral
water migration. Vertical barriers are more effective than
horizontal barriers in terms of slowing the rate of heave
and causing the water content distribution to be more
uniform below the structure. Polyethylene membrane and
concrete can be used as vertical barriers. When such
materials are used as a barrier, this depth should be equal
to or greater than the depth of moisture fluctuation [4].
2.3.2 Adequate Drainage
To control water fluctuation, adequate drainage system for
surface and subsurface water is essential. Drainage is
provided by surface grading and subsurface drains. The
most commonly used technique is grading of a positive
slope away from the structure. The slope should be
adequate to promote rapid runoff and to avoid collecting
near the structure, pond water which could migrate down
the foundation soil. These slopes should be greater than
1% and preferably 5%. Covered drains can be provided to
discharge away the surface runoff water. Subsurface
drains may be used to control a rising water table,
groundwater and underground streams and surface water
penetrating through pervious soil. Subsurface drains or
perforated pipes 15 cm diameter can help to control the
water table before it rises but may not be successful in
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
111| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
lowering the water table in expansive soil, [3]. This
usually is not accomplished due to negligence, cost,
limited property size and other reasons.
2.3.3 Chemical Stabilization
Many chemical admixtures can be used to stabilize
expansive soils but lime has proven to be the most
effective for highly expansive clays. The use of lime to
prevent or minimize soil expansion has been increasing in
favor during the last few decades because it significantly
reduces swelling characteristics and increases soil
strength. Generally the amount of lime required to
stabilize expansive soils ranges from 5 to 8% by weight.
The addition of lime to clay soil provides an abundance of
calcium ions (Ca+2) and magnesium ions (Mg+2). These
ions tend to displace other common cations such as
sodium (Na+) and potassium (K+), in a process known as
cation exchange. Replacement of sodium and potassium
ions by calcium significantly reduces the plasticity of the
expansive clay, [20]. A reduction in plasticity is usually
accompanied by reduced potential for swelling. The
addition of lime increases the soil pH, which also
increases the cation exchange capacity. A change of soil
texture takes place when lime is mixed with clay. Fly ash
and fiber reinforcement in foundation also takes a vital
role for stabilization of expansive soils, [4].
2.3.4 Soil replacement
Soil replacement is the simplest methods for preventing
building damages. The most important requirements for
soil replacement are the type of the material for
replacement, the depth of replacement and the extent to
which the replacement is needed. The material replaced
should be non-expansive and impermeable, [3]. If the
replacing material is highly permeable (coarse sand,
gravels), it transmits the surface moisture directly on the
expansive clay layer. This would bring about differential
movement the same as the surface. Hence, use of sand,
gravel as replacing materials is dangerous. The depth at
which the soil to be replaced depends on the depth of the
active zone. Active zone is the depth at which the soil does
not affected by dry weather, [2].
2.3.5 Structural Measures
The structural measures that should be undertaken in order
to minimize or eliminate damages of structures due to
heaving are dependent on the design of the structures. The
types of foundations commonly used worldwide to support
structural loads in expansive soil are: spread footings,
continuous footings, stiffened raft and bored concrete
piles. The shallow foundations are modified to increase the
bearing pressure so as to minimize heave. Some
modifications have been provided include, [2]:
narrowing the width of the footing base,
placing the foundation wall directly on grade without
a footing,
providing void spaces within the supporting beam or
wall to concentrate loads at isolated points, and
increasing the reinforcement around the perimeter
and into the floor slab to stiffen the foundation
3. Research Methodology
The research methodology which has been followed to
achieve the ultimate goal of the study is conducted by field
and laboratory investigation. Some cases of existing
houses in Khartoum state were selected to assess their
damages. The case study was carefully selected to provide
rich information on expansive soils problems to
lightweight buildings. The research focused on evaluating
damages that occurred on some houses in Khartoum state
in order to come out with the possible causes and practical
remedies. Primarily the study based on recorded
information, field investigation and laboratory tests.
3.1 Project Description
Khartoum is the capital and largest city of Sudan.
Khartoum state is composed of three towns, Khartoum;
Khartoum North; and Omdurman. The three towns are
located around the river Nile and its two main branches,
Blue Nile and White Nile in a triangle shape. Recently,
construction developments are concentrated in areas
extensively covered with expansive soils. The study area
in this work includes most regions of Khartoum state
where expansive soils are dominantly found, namely
Almenshia in Khartoum (KH), Shambat and Alshabia in
Khartoum North (KN) and Alarda in Omdurman (OM),
shown in Figure 2.
Figure 2 The project location in Khartoum state
In Khartoum state, most of the residential buildings are
low rise buildings which are susceptible to damage caused
by expansive soils. These buildings are mainly constructed
from hollow concrete blocks, brick or masonry walls.
Only few buildings are high rise or tall buildings. Most of
the dwellings of Khartoum, particularly in expansive soil
areas have similarities in size, construction material and
construction method. Taking samples from the population
inference can be made about the buildings those
constructed in expansive soil areas.
Ten randomly selected houses in the three towns of
Khartoum state. The houses are located at Almanshia
(three houses) in Khartoum; Shambat (three houses) and
Alshabia (two houses) in Khartoum North; and Alarda
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
112| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
(two houses) in Omdurman. The selected houses for the
study were built in relatively small areas about 300 to 400
m2. Most of the studied houses (seven houses) are single
storey buildings while the remaining are two-storey
buildings. The houses are mostly built using masonry or
hollow block concrete for load bearing walls or partition
walls of reinforced concrete frame. The buildings are
supported on reinforced concrete pad or strip foundations.
3.2. Records Review
A detailed record Review was conducted to obtain some
information about the design and construction of the
project. The documents contain information data about the
building history, structural design, construction materials
information and specifications, previous maintenance
records, and other relevant information such as soil
investigation reports, and temperature, weather or rainfall
data. These collected data are very important for both the
field survey task and the evaluation of building failures.
3.3 Field Investigation
The field investigation program includes site visits to the
ten houses locations, interviews and structured
questionnaire to have more information. A considerable
amount of time was devoted to an arranged number of site
visits in the case study sites to ascertain the visible
prevailing conditions. To back up the site visits, visual
inspections and studies of construction details of the
buildings were carried out. The aim of visual inspections
was to observe different factors affecting the foundation
structures, identify construction type and materials, defects
and signs of movement. Indicators of soil movement such
as diagonal cracks in the walls, sticking doors and
windows and cracks in the floors were identified. In
addition, representative soil samples were collected from
pitholes that excavated in each site.
3.3.1 Site Reconnaissance
The field investigation started with the site reconnaissance
in order to collect information about the house
construction and how the failure occurred from the owners
to assess in investigating the source and reasons of
failures. For each selected house the required data was
first collected by conducting physical observation. This
task has the following three major components: (i)
Identifying construction material of each component of the
building, (ii) Careful observation and analysis of extent of
damage in each building element, and (iii) Studying surface
drainage and ground water table conditions. The second task
was interviewing house owners or contractors who had
been participating in construction of buildings or people
directly involved during the construction period.
3.3.2 Inspection of Distresses
A visual inspection was conducted for each house in order
to examine the extent of damage, identify possible causes
and evaluate the structural defects in the superstructure
members. A questioner was prepared so that properly
organized and consistent data could be collected during
assessment of the selected houses.
It was observed that most of the surveyed houses of single
storey buildings of masonry or hollow block concrete load
bearing walls and supported on strip foundation, suffered
much damages than the two-story buildings that supported
on reinforced concrete pad foundations. One possible
explanation for this could lie in the fact that the single
storey buildings which exert downward pressures lower
than the amount of upward ground pressure exerted by the
swell soils.
The most common exterior damage was to the fence
walls. Most of the surveyed houses, the fence walls are
supported on strip foundation at a shallow depth. It was
clearly observed that the walls nearby gardens are much
suffered serious cracks due to the adverse effect of garden
watering, shown in Figures 3 and 4. Cracks were vertical,
horizontal or diagonal, and almost always through the
mortar joints between bricks. Cracking were from hairline
to more than 20 mm in width. In some cases the whole
wall was separated, as shown in Figure 4.
Figure 3 Sever vertical cracks appeared at the joint
between column and masonry wall of the fence
Figure 4 Severe and deep cracks appear in the exterior
walls of the building
The roots of big trees grown adjacent to the building
resulted in settlement of the foundation wall around the
corner of the building as shown in Figure 5. Also severe
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
113| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
cracks and damages were seen in the exterior walls of the
building due to water leakage in wastewater pipes
occurred at the front part of the building and near bath
Figure 5 Foundation wall partially settled around the
corner due to trees nearby the building
The building internal walls as well as floors much suffered
from serious cracks. It was observed that the cracks are
generally diagonal at approximately 45° occurred above
and below windows and above doorways. Movement of
the walls had distorted door and window frames. The
major type of damage observed in the houses is severe
cracks around corners of doors and windows and reduction
in wall height due to sinking of foundation. However; the
extent of damage in the internal walls ranges from minor
to severe cracks in different direction as shown in Figure
Figure 6 Serious cracks around window in the interior
Floor damage caused by expansive soils is evident in most
houses, shown in Figures 7 and 8. In these figures, it was
observed that floor heave caused uneven level of the
ceramic tiles and serious cracks appear on the slab. The
floor heave resulted in difficulty in opening doors and
windows as clearly seen in Figure 9.
Figure 7 Floor heave resulted in considerable difference in
level about 5.5 cm
Figure 8 Heaving of interior floor causing cracking of slab
Figure 9 Doors not properly close or open due to
movement of floor
Damage to concrete perimeter foundations caused by
differential heave of the foundation soil ranged from
minor hairline and 1 to 2mm cracking to much larger
cracks with anywhere from 50-100 mm of separation and
significant lateral offsets, as shown in Figure 10.
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
114| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
Figure 10 Severe cracking in concrete perimeter wall
showing exposed reinforcing
3.4 Experimental Work
To investigate the causes of failures occurred in the
studied houses, laboratory testing was carried out. For
each building, an open pithole of 2m depth was excavated
in the vicinity of the building. The pits were excavated
manually using pick-axes and shovels. Disturbed soil
samples were collected, packaged and transported to the
laboratory of soil mechanics in university of Khartoum.
Physical and index properties, and swelling
characteristics were determined on the soils by following
relevant procedures. The test results are given in Table 2.
The foundation soil is classified as high plastic clay of
high expansiveness.
Table 2 Geotechnical properties of soils tested
Soil Property
Location of Soil Sample
Clay Content, %
Liquid limit, %
Plastic limit, %
Plasticity index, %
Free swell index, %
Swell Pressure, kPa
Degree of
Very High
Soil classification
4. Results and Discussion
Based on the field survey and soil investigation as well as
thorough study of relevant documents such as working
drawings and drainage patterns of the area, the following
study findings were presented and discussed in the coming
4.1 Observations and Comments
The exterior walls of fences, masonry or hollow concrete
blocks walls of 30 cm thick suffered extensive cracking
due to differential heave. Most of these walls are located
adjacent to gardens of big trees. The garden watering is the
main cause of soil heave that created uplift pressures
greater than the walls weights leading to wall movements
and severe cracking.
The field work and laboratory tests have shown soil
profiles of the studied houses. Tested soil samples from
the project sites have been found to meet the diagnostic
criteria for expansive soils. Laboratory tests of the clay-
sized fraction, liquid limits, plasticity index, and swell
reflect expansive potential due to the presence of clay
minerals. From Table 2, the samples have liquid limits in
the range 57% to 79%, plasticity index 38% to 59%, clay
content (fracture >2µ) 46% to 69% and free swell 90% to
220%. It is observed that the soil obtained from Shambat
has very high expansion while Alarda soil shows moderate
expansion. The most expansive stratum is located at the
depth of about 1 meter from the ground which is thought
to be the active zone. The soils in Khartoum state can put
forth upward swell pressure of about 45 kPa, which is
greater than the average downward pressure of about
40kPa exerted by most of the single-storey buildings.
It was found that a considerable number of lightweight
buildings are built so cheaply by low income urban
dwellers with inadequate sources of finance, thus resulting
into damages whose repair may be not possible or cost
effective and replacement was the only viable option.
Many of the structural problems originate from
improper design or construction, insufficient foundations
and weak or inadequate materials triggered by the swelling
soils. Other factors influencing the degree of damages
include the climatic conditions, age, poor drainage and wet
spots around the foundations, and neglected maintenance
of the buildings. Taken together these factors underlying
building damages are not mutually exclusive. The main
challenge for any inspector is to investigate technically
which one of these is predominant in any particular case.
4.2 Possible Causes of Damages
Based on the study results and available literature, the
main causes of damages or failures in buildings founded
on expansive soil areas are attributed to some factors such
as climatic changes, poor drainage, presence of gardens
nearby buildings, damaged water pipes and improper
foundation design.
4.2.1 Climatic changes
Seasonal changes in rainfall were the principal cause of
the change of soil moisture. This led to downward
movement during summer and upward movement during
winter. The consequent rising and settling of ground
surface occurred in the dry and wet seasons resulting in
seasonal subsidence and seasonal recovery respectively.
The study results and observations indicated that
expansive soils which experienced periodic swelling and
shrinkage during alternate wet and dry seasons caused
considerable damage to structures founded on them. The
damage to structures built on expansive soil in wet
climates usually occurred during drought period and
damage to structure built on dry climate occurred during
rainy season.
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
115| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
4.2.2 Poor drainage
Improper drainage is probably the most important factor
contributing to soil volume change and subsequent
damage to buildings. If water is allowed to stand in
drainage ditches close to buildings, it can penetrate down
and amplify heave, [4]. The main causes of poor surface
drainage can be considered include: surface runoff not
properly drained away from the building; sprinkling of
water for grass and shrub plantation; overflow from
elevated and/or ground water tank; and slope of
surrounding area.
4.2.3 Presence of gardens nearby buildings
Existence of lawns and gardens with fast growing trees in
the vicinity of the building may cause cracks in walls due
to expansive action of roots growing under the foundation.
Roots of some trees generally spread horizontally on all
sides in the effective zone of the foundation soil when
trees are located close to a building, [19].
Trees absorb water from the nearby foundation soil
through their root system and cause shrinkage of soil
especially during the dry season when moisture available
for roots to suck is the least. This is the reason why big
trees should not be located within a distance of 0.5 to 1
times their mature height from the structure. To minimize
the effect of big trees roots, moisture barriers should be
put in place to cover the effective zone of foundation soil,
4.2.4 Damaged water pipes
Shallow water pipes buried in the zone of seasonal
moisture fluctuation, are exposed to enormous stresses by
shrinking soils. If water or sewage pipes break, then the
resultant leaking moisture can aggravate swelling damage
to nearby structures. The effect of a leaking water line is
dependent on the soil moisture condition in the supporting
expansive soil mass prior to the leaking occurrence.
Dishing of floor systems due to clay heave under the
foundations could occur when excessive water is present
due to site leakage at the edges of the structure, [1].
4.2.5 Improper foundation design
Assessment of foundation design sheets and reports
showed that there no any consideration for checking the
safety of building against uplift pressures. This indicates
that there is either a knowledge gap or carelessness in
design offices and/or designers. The authority who is in
charge for approval of these designs also doesn‟t demand
such requirements. Even design documents are not
required for building below two stories which are
vulnerable for damage due to their light weights. Problems
created by expansive soil heave can be properly addressed
by considering the situation during the design phase and
providing detail drawings for house builders.
4.2.6 Construction with low quality materials
The use of low quality materials for construction adversely
affects the performance of the building. This sometimes
occurs in the form of the improper concrete mixture, and
poor foundation of low bearing capacity. The use of
substandard materials for building construction and wall
plastering will affect structural performance. These
materials may accelerate deterioration of the building and
often result in cracking, low strength, shortened service
life, or some combination of these problems. Designers
have come to rely on modern structural materials.
However, manufacturing or fabrication defects may exist
in the most reliable structural materials, such as standard
structural steel sections or centrally mixed concrete.
This study has been undertaken to investigate the causes of
building damage. The findings and conclusions drawn as
The buildings in the case study area exhibit high
variations in type and quality of construction ranging
from cheap traditional materials to modern imported
ones. While the effects of expansive soils
predominate in the lightweight buildings. Light
damages were observed in multi-storey buildings
because they are to some extent constructed of sound
materials heavy enough to prevent swelling pressures
and their foundations are beyond the active zone.
All the tested soils satisfied the expansive soil criteria
and have potential expansion rating from moderate
to „very high‟. The soils contain swelling clay
content more than 30%, have plasticity index
exceeding 30%, free swell more than 90%, and
swelling pressure in excess of 55kPa, which is
greater than the pressure exerted by most of the
lightweight footings almost 45kPa.
The experience of constructing buildings in
Khartoum state without appropriate measures or with
underestimation of the design and construction on
swelling soils has led to damages of the structures.
This study has helped identify the expansive soils
and associated problems in buildings. It provides
some mitigation measures to prevent structural
damages originating from the behaviour of expansive
It was pointed that understanding the causes of
building damage will significantly contribute to the
proper selection of effective repair technique results
in prolonged service life of buildings and significant
savings for the owners.
The experience of the investigator is an important
factor in correctly diagnosing the building failure
causes and determining the best repair technique.
The study has the potential to improve the safety of
the communities by assisting homeowners in
promoting proper design, positive construction and
maintenance altitudes.
Magdi M. E. Zumrawi et al Damages of Buildings on Expansive Soils: Diagnosis and Avoidance
116| International Journal of Multidisciplinary and Scientific Emerging Research, Vol.6, No.2 (May 2017)
Most of the damages caused by expansive soils are
due to poor construction and lack of timely
maintenance by the homeowners and are in most
cases preventable, yet the communities have
insufficient knowledge about the features and
behaviour of the expansive soils.
[1]. Osman, M.A., Charlie, W.A. (1983): “Expansive Soils in
Sudan,” BRRI Current Papers, No. CP.3/83, Building and
Road Research Institute, University of Khartoum,
Khartoum, Sudan.
[2]. Zumrawi, M. M. E.(2015): “Construction Problems of Light
Structures Founded on Expansive Soils in Sudan,” vol. 4,
no. 8, pp. 896902.
[3]. Chen, F. H. (1975): Foundations on expansive soils, First
Edit. Chen and Associates, Consulting Soil Engineers,
Denver, Colo., U.S.A.
[4]. Nelson, J. D. and Miller, D.J. (1991): Expansive soils -
problems and practice in foundation and pavement
engineering, Dept. of civil engineering, Colorado
[5]. Das, A. and Roy, S. (2014): “Effect of Expansive Soil on
Foundation and Its Remedies,” vol. 3, no. 6, pp. 92–95.
[6]. Charlie, W. A., Osman, M. A., and Ali, E. M. (1984):
“Construction on expansive soils in Sudan,” Journal of
Construction Eng. and Management, American Society of
Civil Engineers, Construction Division. Vol. 110 No. 3, pp
[7]. Jones, D. E. and Holtz, W. G. (1973): “Expansive soils – the
hidden disaster,” Civil Engineering-ASCE, 43(8), 49-51.
[8]. Steinberg, M. (1998): Geomembranes and the control of
expansive soils in construction, McGraw-Hill, New York.
[9]. Rosenbalm, D. and Zapata, C.E. (2016): “Effect of Wetting
and Drying Cycles on the Behavior of Compacted
Expansive Soils,” Journal of Materials in Civil Engineering,
American Society of Civil Engineers, ASCE.
[10]. Nelson, J. D. and Miller, D. J. (1992): Expansive soils:
Problem and practice in foundation and pavement
engineering, John Wiley and Sons, New York.
[11]. Hintze, S. (1994): Risk analysis in foundation engineering
with application to piling in loose friction soils in urban
situation, Doctoral Thesis, Division of Soil and Rock
Mechanics, KTH, Sweden.
[12]. Burland, J. B., and Wroth, C. P. (1975): “Settlement of
buildings and associated damage,” Proc. Conf. on
Settlement of Structures, Cambridge, UK, pp 611-654.
[13]. Mika, S. L. J. and Desch, S. C. (1998): Structural surveying,
Macmillan Education LTD, London.
[14]. Ransom, W. H. (1981): Building failures; Diagnosis and
avoidance, E. and FN Spon LTD, New York.
[15]. Day, R. W. (1999): Geotechnical and foundation
engineering design and construction, McGraw-Hill
Companies, New York.
[16]. Wickham J.A. and Joyce, R.M. (1980): Foundations in
Expansive Soils, U.S. Army Engineer Waterways
Experiment Station, CE, Vicksburg, Mississippi.
[17]. Burland, J. B., Broms, B. B., and De Mello, V. F. B. (1977):
“Behaviour of foundations and structures: State of the art
report,” Proc. 9th Int. Conf. on Soil Mech. And Found.
Eng., Vol. 2, Tokyo, pp. 495-546.
[18]. Boscardin, M. D. and Cording, E. J. (1989): “Building
response to excavation induced settlement,” Journal of
Geotechnical Eng., ASCE, Vol. 115, No1, pp 1 21.
[19]. Venkataramana, L. (2003): “Building on Expansive Clay
with Special Reference to Trinidad,” West Indian Journal of
Engineering Vol. 25, No. 2, pages 43 -53.
[20]. Zumrawi, M. M. E. (2016): “Laboratory Investigation of
Expansive Soil Stabilized with Calcium Chloride,” World
Academy of Science, Engineering and Technology
International Journal of Environmental, Chemical,
Ecological, Geological and Geophysical Engineering, Vol.
10, No. 2, pp. 199203.
... The plasticity chart classification is displayed in Fig. 5 with the soils varying in plasticity from non-plastic to up to 21.1%. Some samples plot above the Aline (locations 1,3,4,7,8,9,11,15,17,22,31,35,36) indicating clayey content while some plotted below the Aline (locations 2,5,6,10,12,13,16,18,19,20,21,23,24,25,26,27,28,29,30,32,33,34,37,38) signifying silty content. Those that plotted on the left side of the vertical line have liquid limit (LL) values ranging from 22.8 to 48.2% for all locations while locations 13, 14 and 25 plotted on the right-hand side of the line with LL >50% signifying high compressibility across all these locations. ...
... Study of expansive soils by [30] showed that a liquid limit of up to 80% caused soil settlement in Canada. Other studies by [30]- [34], [24], and [6] recorded liquid limit values of 54 to 83% and classified the soils as expansive soils with greater compressibility tendencies. These values are far greater than values obtained from the current study and as such proof that the studied soils are not related to expansiveness. ...
... The low to medium compressibility and swelling potential of the soils makes it less susceptible to differential settlement of foundation. By integrating the liquid limit, plasticity index and linear shrinkage, the expansive rating of locations 1,2,6,7,8,9,11,12,13,16,17,18,19,20,21,24,25,26,27,28,29,31,34,35,36,37,38 fall in the medium rating while 3, 4, 5, 15, 22, 30 and 32 fall in the low rating giving a general rating of low to medium tendency of expansiveness. This is in line with the rating of expansive soils by [39]. ...
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A study of the engineering properties of the subsurface soil in the Greater Jos Master Plan development area has been carried out to address the paucity of engineering data in the area. The study became necessary because the rapid urbanization has led to limited construction land with more ground prone to instability due to reworking by mining and related activities. The study area is located within Latitudes 09º 48' 20'' to 09º 53'20''N and Longitudes 08º 53' 54'' to 08º 57 '00'' E and extending over 54km2 on Naraguta Sheet 168NE. Surface geological mapping was carried out to confirm the existing geology. Geotechnical properties of soils were determined by analysis of soil samples for 38 locations. While 94 static water level measurements provided additional information on groundwater conditions. The area is underlain by the Jos-Bukuru Complex rocks predominantly biotite granites differentiated on the basis of mode of formation, mineralogy and texture. Soils derived from weathering of the rocks revealed gradual decomposition from gravel, sand, and silt-sized particles to lateritic clays. The soils are considered to have low to medium plasticity/compressibility, expansiveness, and swelling potential across all rock types. The static water table depicts fluctuation in the water table varying between 2.9 and 3.9m. These findings are expected to serve as guide in the choice of design and construction and as a baseline subsurface soil compendium for planning and urban development in the Greater Jos Master plan and for further studies.
... Comprehensive experiments on expansion rates and treatment options for expansive soils are provided in Al-Rawas and Goosen (2006) and Zumrawi et al. (2017). It should be noted that adding stabilizing agents or any foreign substance to soils can occasionally increase the shrink/swell potential of the subsoils. ...
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Louisiana, U.S.A., is among the most vulnerable areas globally to coastal natural hazards, with risk vulnerability likely increasing. The risks associated with non-tropical-cyclone hazards in Louisiana’s coastal zone have been understudied. This research enhances present and future (i.e., 2050) Louisiana risk assessment using locally-weighted, model-based hazard frequency/intensity and population projections. Results suggest that property risks associated with extreme cold temperature and tornado are and will remain costlier than those for hail and lightning. Property risks of extreme cold temperature and hail are projected to decrease with the expected warming temperatures, with those of all four of these hazards peaking in urban areas. Drought is and will remain a far greater risk to crops than these four hazards and extreme high temperatures, with perhaps 95 percent of the crop losses. Despite projected warming, extreme cold will remain a greater crop risk than extreme heat, though the latter often accompanies drought. Regarding present and future (i.e., 2050) Louisiana property risk to other non-severe-weather environmental hazards, wildfire risk peaks in west-central, east-central, extreme northwestern, and southwestern coastal Louisiana. Expansive soil risk peaks in southeastern and extreme southwestern Louisiana, and urban areas. Spatial patterns will remain similar for both hazards, but annual absolute and per capita losses are expected to increase substantially by 2050. The sinkhole risk is relatively small statewide, but property risk for some localized areas is substantial. To assess property risk from flood, ground-zero information collected at the individual building scale offers additional and likely improved building inventory attribute accuracy over existing information sources. A case study of Grand Isle, Louisiana, reveals that the 100-year pluvial flood event today of almost 9-foot flood depths will increase by about 15 percent by 2050, causing a 20 percent increase in structure and content losses to approximately $203 million (2020$). A method is demonstrated to characterize the flood risk through the flood depth vs. return period relationship using the Gumbel distribution and spatial interpolation techniques, for areas of unknown flood depths. Collectively, these results will assist in allocating resources for mitigating and adapting to natural hazards in one of the most weather-hazard-vulnerable U.S. states.
... As a result, this study seeks to proffer solutions to the challenging problem of defects in hospital buildings in Malaysia by exploring the parameters that have not been fully addressed. Some primary factors that cause damage to buildings include the construction of buildings on spread-out Earth, the proximity of gardens to buildings, poor drainage systems, climatic changes, improper foundation designs, and damaged water pipes (Gurmu et al., 2020;Zumrawi et al., 2017). The most prevalent causes of hospital building defects include the following: Faulty electrical systems: lack of energy, power failure, defective electrical installations, problematic lamps, and light fixtures/sockets/circuit breakers/switches/wiring; mold and fungi: the growth of fungi is ordinarily the consequence of excessive dampnessfungi blossoms under favourable conditions with enough moisture and nutrients (Dahal and Dahal, 2020); timber deterioration; poor design; poor construction; termite infestation; dampness and excessive moisture: approximately 71% of the hospital buildings had issues with dampness. ...
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Purpose Hospital building maintenance management constitutes a pertinent issue of global concern for all healthcare stakeholders. In Malaysia, the maintenance management of hospital buildings is instrumental to the Government’s goal of providing efficient healthcare services to the Government's citizenry. However, there is a paucity of studies that have comprehensively explored all dimensions of hospital building defects in relation to maintenance management. Consequently, this study seeks to evaluate the defects of hospital buildings in Malaysia with the aim of proffering viable solutions for the rectification and prevention of the issue. Design/methodology/approach The study utilised a quantitative approach for data collection. Findings The findings indicated that cracked floors, floor tile failures, wall tiles failure, blocked water closets, and damaged windows were some of the flaws that degrade hospital buildings. The study’s outcomes reveal that defects not only deface the aesthetic appearance of hospital buildings but also inhibit the functionality of the buildings and depreciate the overall satisfaction. Research limitations/implications Considering the indispensable role of hospital buildings in the grand scheme of healthcare service provision and ensuring the well-being of people, the issue of defects necessitates an urgent re-evaluation of the maintenance management practices of hospital buildings in Malaysia. Previous studies on the maintenance management of hospital buildings in Malaysia have focused primarily on design, safety, and construction. Practical implications This is particularly important because defects in hospital buildings across the country have recently led to incessant ceiling collapses, fire outbreaks, ceiling, roof collapses, and other structural failures. These problems are typically the result of poor maintenance management, exacerbated by poor design and construction. These disasters pose significant risks to the lives of hospital building users. Originality/value This study offers invaluable insights for maintenance organisations and maintenance department staff who are genuinely interested in improving hospital buildings’ maintenance management to optimise staff's performance and enhance the user satisfaction of hospital buildings in Malaysia and globally.
... The higher alteration intensity will create lower rock mass quality (Eggers, 2016), which causes the soil to become brittle and vulnerable to loose soil. In addition, the occurrence of expansive soil due to clay mineral content in the soil has the potential to cause damage to the access road, weaken foundations and building structures due to movement, and changes in the volume of the soil (Zumrawi, Abdelmarouf, & Gameil, 2017). Unlike petroleum fields, which are generally located in the lowlands and close to the oceans, well pads for geothermal projects in Indonesia are often located on slopes up to 25%, as shown in Figure 7 and Figure 8, also associated with activities volcanic and hydrothermal, as previously described in Figure 4. ...
... Guar gum biopolymers (Acharya et al., 2017), commercially available polymers (Taher et al., 2020), wood/paper industry waste (Ijaz et al., 2020), hydrophobic polyurethane foam (Al-Atroush and Sebaey, 2021), along with physical methods such as granulated tire rubber (Patil et al., 2011) and pile anchoring systems (Sfoog et al., 2020) have also been suggested. Comprehensive experiments on expansion rates and treatment options for expansive soils are provided in Al-Rawas and Goosen (2006) and Zumrawi et al. (2017). It should be noted that adding stabilizing agents or any foreign substance to soils can occasionally increase the shrink/swell potential of the subsoils. ...
Full-text available
The physical properties of soil can affect the stability of construction. In particular, soil swelling potential (a term which includes swelling/shrinking) is often overlooked as a natural hazard. Similar to risk assessment for other hazards, assessing risk for soil swelling can be defined as the product of the probability of the hazard and the value of property subjected to the hazard. This research utilizes past engineering and geological assessments of soil swelling potential, along with economic data from the U.S. Census, to assess the risk for soil swelling at the census-block level in Louisiana, a U.S. state with a relatively dense population that is vulnerable to expansive soils. Results suggest that the coastal parts of the state face the highest risk, particularly in the areas of greater population concentrations, but that all developed parts of the state have some risk. The annual historical property loss, per capita property loss, and per building property loss are all concentrated in southeastern Louisiana and extreme southwestern Louisiana, but the concentration of wealth in cities increases the historical property loss in most of the urban areas. Projections of loss by 2050 show a similar pattern, but with increased per building loss in and around a swath of cities across southwestern and south-central Louisiana. These results may assist engineers, architects, and developers as they strive to enhance the resilience of buildings and infrastructure to the multitude of environmental hazards in Louisiana.
... Expansive soil (ES) is considered a highly problematic soil due to low shear strength when wet with high swelling and high shrinkage characteristics [1]. This type of soil is very common in large areas of the North America continent, Southern as well as sub-Sahara Africa, large part of Australia, Sudan, China, western and central part of India and Mid-east [2][3][4][5][6][7]. In western and central part of India, ES also called black cotton soil (BCS) is abundantly found. ...
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Expansive soil has very low shear strength when wet and high swelling and high shrinkage characteristics. Due to this, it is one of the most problematic types of soil damaging buildings, roads, and pipelines each year throughout the world resulting in huge annual revenue loss. Due to the revenue losses the industrial waste used for amended the expansive soil. Rice husk ash and sugarcane bagasse ash are the industrial waste by-products from the rice mill and sugar mill respectively. This paper presents the behaviour of amended expansive soil with rice husk ash, sugarcane bagasse ash, and liquid alkaline activator stabilizer for highway subgrade. The liquid alkaline activator used is a mixture of sodium metasilicate (Na2SiO3.9H2O) and sodium hydroxide (NaOH) solutions of 1 M and 10 M concentration respectively. Strength and swelling characteristics of amended expansive soil were evaluated. Strength was determined by unconfined compressive strength and soaked California Bearing Ratio values. The swelling was determined by the expansion ratio and free swell index of the treated soil after 7, 14, and 28 days of curing. The strength of subgrade soil was observed to be increasing with the increase in rice husk ash and sugarcane bagasse ash content up to a certain limit and then decreases. The expansion ratios and free swell index were also observed to decrease while the increasing rice husk ash and sugarcane bagasse ash content and curing time increase with a fixed ratio of sodium metasilicate solution (Na2SiO3.9H2O) and sodium hydroxide (NaOH) (70:30) solutions.
Swelling is one of the distresses that affect the pavement condition index (PCI) of airport runways. In northwest Queensland, swelling was observed in three different runways where sealed flexible pavement runways were deformed by the heaving of the expansive clay subgrades due to water intrusion. In the study, the trends of moisture content (MC) and corresponding swelling of these expansive soils were observed at different times. Subsequently, the PCI was calculated for the swelling of these runways using PAVER software. A correlation has been developed between swelling of different severity levels and the corresponding PCI. In addition, the relationship between MC and PCI has been established to demonstrate the influence of MC on the swell behavior, and the influence of seasonal MC variations on PCI was also examined. Finally, the study generated empirical equations to predict the swelling effects on the PCI and subsequent functional performance of the runway pavements constructed on expansive soils. A good correlation has been achieved between the swell parameter and the PCI. The correlation coefficient of determination R ² is computed to be 0.9981, 0.999, and 0.9987 for low, medium, and high severity of the swelling, respectively. The equations fitted with the experimental data well, which demonstrates the reliability of the empirical equations. From the result of swelling against MC and calculated PCI, it is evident that adverse effects are inevitable when water intrusion occurs in swelling soil subgrade. This high plasticity soil can deteriorate pavement performance and cause early pavement damage if allowed to swell.
Since many decades, the town of Moulay Yacoub (MY) has undergone an intensification of its urbanization to meet the demands of rental housing for the visitors of the hydrothermal springs, which is considered as the only attraction of the town. Unfortunately, the majority of the buildings, both private and public, suffer from varying levels of damages where the lithological and geomorphic field features are to blame, without omitting the anthropogenic effects. In fact, the town is built on a marly hill conducive to slope movements, ranging from shallow solifluctions to large landslides, besides the swelling/shrinkage behaviour of these marls. The paper presents a multi-source approach to investigate the activity and the interactions of slow urbanized landslides and expansive soils within the urban perimeter of Moulay Yacoub. Indeed, the desiccation cracks of marly soils reveal their expansive behaviour, also attested by the swelling values. The other geotechnical parameters obtained from laboratory tests show that the shallow marls samples are severely weathered compared to those of the compacted deep ones. The Borehole data and seismic noise survey allows the detection of several impedance contrasts corresponding to the shallow weathered-deep marls interfaces which in some cases represent the rupture surfaces of gravitational processes. The very slow but perennial activities of the later are attested by the inclinometers, the PS-InSAR monitoring and building damages. The case study provides a good opportunity to highlight the complementarity of the multi-source tasks which stand as a further contribution to fostering this kind of integrated approaches at the slope scale.
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The light weight structure built over potentially expansive soils may suffer damage due to the uplift pressure exerted by the soil after moisture increase. The measurement of the swelling pressure can be made in laboratory using direct methods based on the oedometer tests. This test is long time consuming and implies high costs. There is an increasing trend in predicting the value of swelling pressure based on routinely determined geotechnical parameters like dry unit weight, initial water content, clay content, Atterberg limits, cation exchange capacity. This article presents the results of correlation and regression made with the Statistica V.13 software, on 50 soil samples collected from nine countries. The analyses show a high coefficient of correlation (R) of swelling pressure with the plasticity index followed by the liquid limit and clay content. Also, this paper provides empirical equations for indirect estimation of swelling pressure based just on a single soil parameter (PI, LL) or two parameters (PI and LL, PI and Cl).
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13 Expansive soils are problematic soils which pose a risk to the safety of civil 14 engineering structures. These soils can be treated by compaction or by adding 15 additives to the soil. Where the strength and properties of expansive soil cannot be 16 improved via mechanical stabilisation (Compaction), a desirable strength can be 17 achieved through the use of chemical admixture techniques. The swelling and 18 shrinkage of expansive soils cause movement in the soil mass resulting in a 19 deferential settlement in engineering structures such as roads and building leading to 20 cracks and subsequent failure leading to high cost of maintenance. Calcium based 21 additives such as cement and lime have been used in expansive subgrade 22 stabilisation to enhance the strength, reduce swell and subsequent differential 23 settlement. However, the growing concerns on carbon dioxide (CO 2) emission and 24 climate change have reignited the need for a more sustainable soil stabilisation 25 techniques using waste materials. In this study, non-traditional expansive subgrade 26 treatment techniques using sustainable waste materials with respect to their 27 efficiency in improving the geotechnical engineering properties of the subgrade 28 materials have been investigated and reviewed. This study also discusses the 29 engineering problems associated with expansive soils, proposing an effective, 30 efficient, cheaper and sustainable application of non-traditional stabilisers in 31 expansive soil stabilisation. The study concludes that, the addition of non-traditional 32 J o u r n a l P r e-p r o o f 2 stabilisers in expansive subgrade stabilisation using chemical stabilisation 1 techniques can improve the engineering properties of expansive subgrade materials. 2
Conference Paper
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Chemical stabilization is a technique commonly used to improve the expansive soil properties. In this regard, an attempt has been made to evaluate the influence of Calcium Chloride (CaCl 2) stabilizer on the engineering properties of expansive soil. A series of laboratory experiments including consistency limits, free swell, compaction, and shear strength tests were performed to investigate the effect of CaCl 2 additive with various percentages 0%, 2%, 5%, 10% and 15% for improving expansive soil. The results obtained shows that the increase in the percentage of CaCl 2 decreased the liquid limit and plasticity index leading to significant reduction in the free swell index. This, in turn, increased the maximum dry density and decreased the optimum moisture content which results in greater strength. The unconfined compressive strength of soil stabilized with 5% CaCl 2 increased approximately by 50% as compared to virgin soil. It can be concluded that CaCl 2 had shown promising influence on the strength and swelling properties of expansive soil, thereby giving an advantage in improving problematic expansive soil.
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Expansive soils in Sudan have been contributing to light structures failures and subsequently causing increased annual repair expenditure. The study aims to investigate the foundations problems associated with expansive soils and provides practical and economical solutions for construction on expansive soils in Sudan. The research is mainly concerned with field performance of expansive soils with emphasis on design criteria and construction precautions for structures founded on expansive soils. Some cases of existing light buildings and roads in different regions in Sudan, suffered from severe distresses and damages due to expansive soils, were studied. The results obtained clearly indicated that generation of high swelling pressure, which leads to differential heave of structures, is the main cause of failures. Finally, based on the case study investigation and the previous experiences recommended by researchers, proposed construction guidelines to assist the civil engineers to deal with expansive soils at design and construction stages of foundations is outlined and described.
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Expansive soils prevail over a large area of Sudan and have caused significant damages to irrigation systems, water lines, sewer lines, buildings, roads and other structures located on these soils. Damage caused by expansive soils is estimated by the writers to exceed $6,000,000 (8,000,000 Sudanese pounds) annually. The paper summarizes typical damages to show the type, extent and causes of damages and provides information on current design methods being used in Sudan to reduce potential damages. Based on soil surveys and soil properties collected from more than 30 sites, over one-third of Sudan’s 2,600,000 km2 area may have potentially expansive soils. It is recommended that all potential construction sites in the Clay Plain be evaluated for expansive soils.
In recent years building failures and the resulting lawsuits and awards for damages have frequently been in the news. The biggest headlines may have been reserved for structural failures and complete collapses, but we should not forget the less newsworthy failures such as leaky roofs, damp walls, dropped foundations and rotted timber. This book gives practical guidance on the prevention of failure by describing the nature and cause of the most common defects in buildings, and then shows how they should be avoided in design and construction.
In the United States alone, the cost to repair structures damaged by expansive soils has been estimated to be twice the combined damages of natural disasters. Despite the widespread occurrence of these soils, the damage caused by the presence of expansive soils is regularly overlooked because it might take years of distress exposure before extensive damage to infrastructure can be observed. To predict the heave and swelling pressure an expansive soil will experience in the field, it is standard practice to subject a remolded specimen to a wetting process at a particular net normal stress. This practice does not capture the behavior of expansive soils in the field and therefore, it is necessary to assess the long-term environmental effects on their behavior. In this study, an assessment of the effect of multiple wetting/drying cycles on the volume change behavior of two naturally occurring expansive soils was performed. The soils were remolded at different initial compacted conditions, loaded to different net normal stresses, wetted to nearly 100% saturation and then subjected to full drying. In general, it was observed that after four cycles, the swelling or collapse strain and the swell pressure reached equilibrium. When the applied stress exceeded 25% of the swell pressure, both soils exhibited an increase in collapse potential from the previous wetting cycle. However, when the applied stress was less than 25% of the swell pressure, both soils exhibited an increase in swell potential from the previous cycle.
Analytic models and field data are used to develop procedures to evaluate the tolerance of brick-bearing-wall and small frame structures to the ground displacements that develop during opencutting and tunneling. The role of horizontal and vertical ground displacements are discussed and the effects of grade beams, building orientation and building location relative to excavation are examined. Case studies of structures adjacent to opencuts and tunnels are used to verify procedures for estimating potential for structures adjacent to excavations to sustain damage.
Foundations on expansive soils, First Edit. Chen and Associates, Consulting Soil Engineers
  • F H Chen
Chen, F. H. (1975): Foundations on expansive soils, First Edit. Chen and Associates, Consulting Soil Engineers, Denver, Colo., U.S.A.