Effect of varying temperatures on the quality of concrete with 5% addition of clay.

EFFECT OF VARYING TEMPERATURES ON THE PROPERTIES OF
CONCRETE WITH 5% ADDITION OF CLAY.
BY
BAGYA KEVIN RAMDUMA
U11AT1065
A PROJECT SUBMITTED TO THE DEPARTMENT OF ARCHITECTURE,
FACULTY OF ENVIRONMENTAL DESIGN, AHMADU BELLO UNIVERSITY,
ZARIA-NIGERIA. IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR
THE AWARD OF BACHELOR OF SCIENCE DEGREE IN ARCHITECTURE.
AUGUST, 2015

Effect Of Varying Temperatures On the properties of concrete Bagya Kevin Ramduma (U11AT1065).
With 5% clay addition.
i
DECLARATION
I declare that the work in this project report entitled “Effect of varying temperatures
on the properties of concrete with 5% addition of clay” has been performed by me
in the Department of Architecture, Ahmadu Bello University, Zaria. The information
derived from literature has been duly acknowledged in the text and a list of references
provided. No part of this project was previously presented for another degree or
diploma at this or any other institution.
_______________________________ _____________________________
Bagya Kevin Ramduma Date

ii
CERTIFICATION
This project report entitled “Effect of varying temperatures on the quality of
concrete with 5% addition of clay” by Kevin Ramduma BAGYA meets the
regulations governing the award of the degree of Bachelor of Science in Architecture
of the Ahmadu Bello University, and is approved for its contribution to knowledge
and literary presentation.
_____________________________ _____________________________
Dr. H. T. Kimeng. Date
(Project Supervisor/Coordinator)
_____________________________ _____________________________
Dr. M. D. Ahmad Date
(Head of Department)

iii
DEDICATION
This project is dedicated to my parents, Mr. and Mrs. Kevin B. B. Dilli.

iv
ACKNOWLEDGEMENT
My profound gratitude goes to God Almighty for His guidance and blessings through
which this work was carried out successfully. I appreciate him for his infinite wisdom,
and guidance throughout my stay in this great citadel of learning.
I express my sincere appreciation to the members of my family. My story cannot begin
without theirs’. They are the strongest and most impacting force in my life. It would
be impossible to tell about my accomplishments without starting with their influence
especially my parents. Their commitment and sacrifices to the success of my academic
pursuits are priceless.
I also wish to acknowledge the support of the Department of Architecture for making
research materials available and the conducive environment under which this work
was carried out.
A special appreciation goes to my unique supervisor, Dr. Henry T. Kimeng who has
been a mentor, a guide, and a source of inspiration. I appreciate him for his moral and
financial support towards the success of this Project. I cannot overemphasize his
enormous contribution to this work.
My special gratitude also goes to Arc. Henry Umeh, Dr. J. J. Maina, Dr. Batagarawa,
Arc. H. O. Saliu, Arc. Eneh, Dr. S. N. Oluigbo, Arc. Mustapha, Arc. Ahmad Sani, Arc.
I. G. Aliyu, Dr. Tukur, Dr. Ango, Arc. Zainab, Dr. H. S. Katsina, Arc. Evanero, Arc.
Abdullahi, Dr. Rakiya, Arc. Ejeh, Arc. Murtala, Arc. Nasir, Arc. Halliru, Dr.
Babangida, Dr. Mas’ud, QS. Sankey, Arc. Tulpule, Arc. Lukman, Arc. Gafar, Arc.
Badiru, Arc. Ladifa, and all the other Staffs (Academic and non-academic) of this great
department whose names were not mentioned.
I specially want to acknowledge Mr. Jamilu, Mr. Fred, Mr. Noel Kimeng, Mallam
Saidu and all the laboratory attendants of the Department of Building, Department of
Civil Engineering and the Industrial Development center (IDC), Samaru-Zaria for
their enormous support and guidance throughout the lab experiment phase of the work.
I will also like to recognize the support of my course mates: Sule Stephen, Yusuf
Jonathan, Ibrahim Mohammed, Abdul, Auwal, Hilda, Zahemen, Abel, Moses Okorie,

v
Collins Onahi, Maria, Sakina, Jinko, Ejizy, Angela, David Gyet and Aliyu Gwoza,
who we shared ideas and concepts that made this work a success.
Lastly, I will like to appreciate my friends: Atsahyel Bernard, Musa Zuntuwa, Tokai,
Sito Robinson, P-Jamz, Ceasar, Miriam Zuntuwa, Ibrahim Ishaku, Cashiff, Elzmaine,
Adam, Gaboi, Thomas Kefas, Zeebox, Sany-Brushes, Newland and to all others that
were a part of the success of this work whose names could not be mentioned, I say a
very big thank you.

vi
ABSTRACT
The high rate of building collapse in Nigeria has been a source of concern to
professionals and stakeholders in the building construction industry. Research has
shown that 100% of buildings collapsed in Nigeria were made from reinforced
concrete (Lekan, 2011). Cement which is a main binder in concrete production is
expensive particularly in developing countries like Nigeria, therefore increasing the
demand to explore pozzolanic potentials of clay. In the local construction industry,
shabby construction practices such as mixing concrete on the bare ground or the
deliberate addition of clay to concrete has effect on the properties of such concrete.
Fire hazards subject concrete structures to high temperature conditions which lead to
uneven expansion of the structure, causing cracks and eventually, failure of the
structure. High temperatures have effect on concrete properties such as appearance,
durability and compressive strength. Though extensive research has been done on the
effect of clay impurities on various properties of concrete, this project aims at
assessing the effect of varying temperatures on the properties of concrete containing
clay addition.
Fifteen 150mm×150mm×150mm samples of concrete cubes of mix ratio 1:2:4,
water/cement ratio of 0.45 and 5% clay addition were cast and cured for 28 days.
After curing, the samples were subjected to varying temperatures (100°C, 200°C,
300°C, 400°C and 500°C) and crushed. The findings from the results of the experiment
revealed that, concrete cube samples subjected to temperatures above 400°C failed to
meet the required 21N/mm2
compressive strength for normal weight concrete used for
structural purposes.

vii
TABLE OF CONTENTS
DECLARATION.........................................................................................................i
CERTIFICATION.....................................................................................................ii
DEDICATION.......................................................................................................... iii
ACKNOWLEDGEMENT........................................................................................iv
ABSTRACT...............................................................................................................vi
TABLE OF CONTENTS.........................................................................................vii
LIST OF PLATES .....................................................................................................x
LIST OF TABLES ....................................................................................................xi
LIST OF APPENDICES .........................................................................................xii
LIST OF ABBREVIATION.................................................................................. xiii
CHAPTER ONE ........................................................................................................1
1.0 INTRODUCTION......................................................................................1
1.1 Background to the Problem..........................................................................1
1.2 Problem Statement. ......................................................................................2
1.3 Aim and Objectives......................................................................................3
1.4 Research Questions......................................................................................3
1.5 Justification. .................................................................................................3
1.6 Scope............................................................................................................4
CHAPTER TWO .......................................................................................................5
2.0 LITERATURE REVIEW..........................................................................5
2.1 FAILURE IN BUILDINGS.........................................................................5
2.2 CAUSES OF BUILDING FAILURES IN NIGERIA. ................................6
2.2.1 Natural Factors.....................................................................................6
2.2.2 Socio-economic habits of Nigerians. ...................................................7
2.2.3 Foundation Failure. ..............................................................................7
2.2.4 Constructional Problem........................................................................8
2.2.5 Poor supervision during construction...................................................9
2.2.6 Poor Materials......................................................................................9

viii
2.2.7 Use of Low Quality Concrete ............................................................10
2.2.8 Operational Problems.........................................................................10
2.2.9 Poor Maintenance...............................................................................11
2.3 EFFECT OF FIRE ON CONCRETE STRUCTURES..............................11
2.4 CONCRETE AS A BUILDING MATERIAL...........................................12
2.4.1 Cement. ..............................................................................................13
2.4.2 Aggregate. ..........................................................................................15
2.4.3 Water..................................................................................................18
2.4.4 Fresh Concrete. ..................................................................................20
2.5 ADMIXTURES. ........................................................................................24
2.6 POZZOLANA............................................................................................26
2.6.1 Calcined Clay Pozzolanas..................................................................28
2.6.2 Fly Ash...............................................................................................28
2.6.3 Silica Fume. .......................................................................................29
2.6.4 Rice Husk Ash. ..................................................................................29
2.6.5 Metakaolin..........................................................................................30
2.6.6 Ground Granulated Blast Furnace Slag..............................................30
CHAPTER THREE .................................................................................................31
3.0 MATERIALS AND METHODS ............................................................31
3.1 MATERIALS.............................................................................................31
3.1.1 Ordinary Portland cement ..................................................................31
3.1.2 Fine Aggregate...................................................................................31
3.1.3 Coarse Aggregate...............................................................................32
3.1.4 Water..................................................................................................33
3.1.5 Clay ....................................................................................................33
3.2 METHODS ................................................................................................34
3.2.1 Production of Concrete cube samples................................................34
3.2.2 Properties of aggregate.......................................................................36
3.2.3 Testing of Hardened Concrete cubes. ................................................38
3.2.4 Exposure of Samples to Varying Temperature..................................40
CHAPTER FOUR....................................................................................................41
4.0 RESULTS, ANALYSIS AND DISCUSSIONS......................................41

ix
4.1 PROPERTIES OF AGGREGATES. .........................................................41
4.1.1 Bulk Density of Aggregates...............................................................41
4.1.2 Particle size distribution.....................................................................42
4.2 WORKABILITY TEST OF CONCRETE.................................................44
4.3 PROPERTIES OF HARDENED CONCRETE.........................................44
4.3.1 Density ...............................................................................................44
4.3.2 Water absorption of concrete samples ...............................................45
4.3.3 Abrasion resistance ............................................................................45
4.3.4 Compressive strength of concrete samples. .......................................45
CHAPTER FIVE......................................................................................................47
5.0 SUMMARY, CONCLUSION AND RECOMMENDATION..............47
5.1 SUMMARY...............................................................................................47
5.2 CONCLUSION..........................................................................................47
5.3 RECOMMENDATION .............................................................................48
5.3.1 Recommendation for future research.................................................48
REFERENCES.........................................................................................................50
APPENDIX ..............................................................................................................55

x
LIST OF PLATES
Plate 2.1 Synagogue Church's 6-storey building collapse...........................................5
Plate 3.1 Dangote Cement. ........................................................................................31
Plate 3.2 Fine Aggregate. ..........................................................................................32
Plate 3.3 Coarse Aggregate.......................................................................................32
Plate 3.4 Potable Water.............................................................................................33
Plate 3.5 Clay.............................................................................................................33
Plate 3.6 Production of concrete cube samples.........................................................34
Plate 3.7 Slump Test...................................................................................................35
Plate 3.8 Particle size distribution test. .....................................................................36
Plate 3.9 Bulk Density test .........................................................................................37
Plate 3.10 compressive Strength Testing, Civil Engineering Concrete lab. ABU,
Zaria...........................................................................................................................39
Plate 3.11 Gemco-Holland Electric Kiln, Industrial Development Centre, Samaru,
Zaria...........................................................................................................................40

xi
LIST OF TABLES
Table 4.1 Bulk Density of Aggregates........................................................................41
Table 4.2 Sieve Analysis of Fine Aggregates.............................................................42
Table 4.3 Sieve Analysis of Coarse Aggregates.........................................................43
Table 4.4 Sieve Analysis of Clay................................................................................43
Table 4.5 Workability of concrete mix.......................................................................44
Table 4.6 Average Density of Cubes before and after heating. .................................44
Table 4.7 Percentage of Water absorption of Concrete Sample................................45
Table 4.8 Abrasion resistance test of concrete samples. ...........................................45
Table 4.9 Average Compressive strength of concrete Samples at varying
temperatures...............................................................................................................46

xii
LIST OF APPENDICES
Appendix A: Bulk density of Aggregates……………………………………………55
Appendix B: Sieve analysis of Aggregates………………………………………….57
Appendix C: Density of concrete cubes……………………………………………..59
Appendix D: Water absorption at 28 days………………………………………......61
Appendix E: Abrasion resistance of samples at 28 days………………………...…..62
Appendix F: Compressive strength test at 28 days…………………………………..63
Appendix G: Presentation Slides…………………………………………………...….….65

xiii
LIST OF ABBREVIATION
ABU: Ahmadu Bello University.
ASTM: American Standard for testing materials.
BS: British standard.
EIA: Environmental Impact Assessment.
IS: Indian Standard.
ISO: International Standards Organization.
NIS: Nigerian Institute of Standards.
SCOAN: Synagogue Church of all Nations.
SON: Standards Organization of Nigeria.

1
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background to the Problem.
The importance of buildings to man’s existence as he lives and interact with his
environment cannot be overemphasized. Buildings either temporary, permanent or
monumental structures need to be properly planned, designed, constructed and
maintained to obtain the desired satisfaction, comfort and safety. (Olagunju, Aremu,
& Ogundele, 2013).
The high rate at which buildings collapse in Nigeria has been a source of serious
concern to professionals like Architects, Builders and Structural Engineers. (Fakere,
Fadiro, & Fakere, 2012). A recent study (Lekan, 2011) points out that the causes of
building collapse can be attributed to factors such as bad design, fire, poor quality
materials and construction methods among others. Building collapse have adverse
psychological and economic effects on human beings due to loss of properties,
physical injuries and even loss of lives. Lekan 2011 further states that, 100 percent of
the buildings collapsed in Nigeria were constructed from reinforced concrete.
Concrete is a hard strong building material made by mixing a cementing material (as
Portland cement) and a mineral aggregate (as sand and gravel) with sufficient water to
cause the cement to set and bind the entire mass. Cement which is the main binder in
concrete production, is expensive particularly in developing countries (Duna &
Omoniyi, 2014), therefore there is an increasing demand to explore the pozzolanic
potentials of clay substitute for cement in the local construction industry (Otoko &
Ephraim, 2014). Sometimes, an admixture, which is an additional material, is added

2
in order to modify or change certain properties of concrete such as air entraining, or
to retard or hasten setting. (Desire & Leopold, 2013).
The quality of materials used in the production of concrete has an effect on its strength
and physical properties (Ngugi, Mutuku, & Gariy, 2014). Aggregates used for
construction purposes usually contain impurities such as clay, silt and organic matter.
In their report, (Desire & Leopold, 2013) stated that the content of clay particles in
aggregates should never be greater than 1%. Alternative water sources used for
concrete production, due to shortage of potable water also contain clay and silt
impurities which affect the quality of concrete produced (Olugbenga, 2014). The
Nigerian Standards Organisation specified that the silt and clay impurities in sand
should not exceed the stipulated 8%. (Olanitori & Olotuah, 2005)
Many researches have been previously conducted on the evaluation of materials’
performance when exposed to high temperature (Sherif & Chanim, 2013). (Usman,
Faisal, & Kamran, 2006) Found out that increase in temperature increases the initial
strength of concrete while at the same time it reduces the long term strength.
1.2 Problem Statement.
Fine aggregates used for concrete production usually contain impurities such as clay,
silt and organic matter. Clay and silt impurities are also present in some water sources
used as alternatives due to shortage of potable water for construction. In building
construction sites, construction workers usually mix concrete on the bare ground, this
practice adds to the impurities in the concrete. These impurities obtained from
different sources affect the strength and physical properties of concrete.

3
Subjecting concrete structures to high temperature conditions lead to uneven
expansion of the structure which causes cracks and eventually, failure of the structure.
Therefore, there is a need to assess the effect of temperature on concrete containing
clay and silt additions since most concrete used for construction contain such
impurities in varying quantities.
1.3 Aim and Objectives.
The aim of the research is basically to assess by means of experiment and review of
literature the effect of varying temperature on the properties of concrete containing
5% clay addition.
The Objectives set to achieve the above aim include;
i. To investigate the effect of temperature on the compressive strength of
concrete containing 5% clay addition.
ii. To analyze from the data obtained from experiment whether the allowable 8%
clay impurities specified by the Standards Organization of Nigeria will still be
valid when concrete containing clay addition is subjected to temperature.
1.4 Research Questions.
i. What effect does clay impurities have on the properties of concrete?
ii. What effect does temperature have on the strength of concrete with 5%
addition of clay?
1.5 Justification.
Fire Hazards are threat not only to human lives and properties but also to building
structures. In Nigeria, during fire outbreaks, buildings are subjected to high

4
temperatures for long periods of time due to delay or absence of the fire service units.
This prolonged exposure to high temperature affects the strength of the concrete
structure which might even lead to its collapse.
Although a lot of studies have been previously conducted on the effect of clay particles
on the strength of concrete, little has been done on the impact of temperature on
concrete containing impurities such as clay, silt and organic matter. This is what this
project is set to achieve
1.6 Scope.
In this study, Concrete cubes of dimension 150×150×150mm produced with Portland
cement and 5% clay addition, and cured for 28 days were used. The concrete cubes
will be subjected to varying temperatures of 100, 200, 300,400 and 500°C only.

5
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 FAILURE IN BUILDINGS.
A structure is said to have failed when it reaches its limit state, which is the state when
it becomes unsuitable for its intended use. (Mosley, Bungey, & Hulse, 2007). Building
collapse, though a common phenomenon all over the world is more rampant and
devastating in developing countries. The incidence of building failures and collapses
have become major issues of concern in the development of this nation as the
frequencies of their occurrence and the magnitude of the losses in terms of lives and
properties are now becoming very alarming. (Fagbenle & Oluwunmi, 2010). In their
report, (Alamu & Gana, 2014) noted that, between 1976 and 2012 there have been
over 66 documented cases of building collapse in Nigeria in which no fewer than 480
lives were lost and several others injured. A more recent devastating case is the
collapse of a 6-storey guest house belonging to the Synagogue Church of all Nations
(SCOAN) in Lagos which occurred on the 12th
of September, 2014 resulting in the
death of 116 persons and loss of properties worth millions. (Deolu, 2015).
Plate 2.1 Synagogue Church's 6-storey building collapse (Source: http://www.ctvnews.ca/world/south-african-
president-says-67-died-and-dozens-injured-in-nigerian-building-collapse-1.2009076)

6
It is of interest to note that 100 percent of the buildings collapsed in Nigeria are made
of reinforced concrete. (Lekan, 2011). Some of the reasons associated with these
failures may be associated to poor workmanship, poor supervision, poor materials,
non-compliance of specifications and standards and lack of enforcement of building
codes, among others. According to an NBRRI (Nigerian Building and road research
Institute.) report, 70% of building failure is caused by the engagement of quacks.
(Kazeem, Joy-Felicia, & Wasiu, 2014).
In Nigeria, the Standard Organization of Nigeria (SON) with the Nigeria International
Standards (NIS) were put in place by the Federal Government to ensure the quality of
both materials and finished goods that are produced in the country. Attainment of
quality in all its ramifications starts from the conception stage of any project through
the completion stage, which therefore means that all members of the construction team
have a “duty of care” to the building user (Anosike, 2011).
2.2 CAUSES OF BUILDING FAILURES IN NIGERIA.
2.2.1 Natural Factors.
In their report, (Amadi, Eze, Igwe, Okunlola, & Okoye, 2012) pointed out that the
natural factors that give rise to the collapse of buildings can be subdivided into two:
the geological phenomenon that causes building failures and geo-materials that lead
to building collapse. These geological phenomenon include; volcanic eruption,
subsidence, erosion and flooding, earthquake, landslide, mud-flow and debris-flow,
faulting, rain-storm, thunder-storm and lightening. No one has control over natural
occurrence, but may be minimised if Environmental Impact Assessment (EIA) is made
mandatory to all developers or building approval applicants before commencement of

7
any building project construction. This will help to determine the feasibility of
constructing the building on the proposed site. (Olagunju, Aremu, & Ogundele, 2013).
2.2.2 Socio-economic habits of Nigerians.
A number of professionals (stakeholders) such as Architects, Quantity Surveyors,
Land Surveyors, Builders/Contractors, Engineers (Structural, Civil, Mechanical,
Electrical, and Geotechnical) exist in the building industry, but in most cases their
services are not sought for due to one reason or the other, It has been observed that
due to high cost of consultancy fees needed to engage the services of these
professionals, most Nigerians prefer to cut cost by engaging the services of non-
professionals (quacks) who lack the needed experience in the construction sector. This
is reflected in poor workmanship and low standard of construction, which results in
structural failure and collapse of part or the entire building. (Amadi, Eze, Igwe,
Okunlola, & Okoye, 2012). In his report, (Adenuga, Professionals in the built
environment and the incidence of building collapse in Nigeria., 2012) pointed out that
the right professional are not appointed into the right positions in local Authorities
responsible for checking structural drawings.
2.2.3 Foundation Failure.
There are several reasons that may lead to foundational failure in building structures.
Adenuga (2012), gave some of the reasons for this failure to include any or the
combinations of some of these below;
i. Absence of a proper investigation of the site or wrong interpretation of the
results of such investigation.
ii. Faulty design of the foundation.

8
iii. Bad workmanship in the construction of the foundation.
iv. Use of poor construction materials during the construction of the foundation.
v. Insufficient provision in the design construction for exceptional natural
phenomena such as thermal and biological conditions, rainfall and floods etc.
2.2.4 Constructional Problem.
The construction stage is the most critical and sensitive stage in the building process
as any fault or omission can result into ultimate failure and collapse. This is a stage
when the work done in the planning stage and the design stage will be implemented.
(Olusola, Ojambati, & Lawal, Technological and Non –Technological Factors
Responsible for the occurence of collapse buildings in south-western Nigeria, 2011).
Designs must be faithfully reproduced in construction or fabrication and this includes
good workmanship and use of specified quality of materials in the construction. To
ensure this, adequate construction supervision must be available especially to solve
problems that may not have been foreseen during design. (Olusola, Ojambati, &
Lawal, Technological and Non –Technological Factors Responsible for the occurence
of collapse buildings in south-western Nigeria, 2011) further stated reasons for
constructional problems as follows;
i. Lack of basic technical and construction materials knowledge among
contractors and lack of skills and enough practical training in artisans and
craftsmen.
ii. Faulty foundation design and construction.
iii. Poor workmanship in construction.
iv. Use of poor construction materials.

9
2.2.5 Poor supervision during construction.
According to (Olusola, Ojambati, & Lawal, Technological and Non –Technological
Factors Responsible for the occurence of collapse buildings in south-western Nigeria,
2011) a structure is said to be as good as its construction and not its design. Every
stage of the work must be supervised by an appropriate qualified professional.
Building failures that result from poor workmanship poor building materials and non
compliance with specifications can be avoided through proper supervision by qualified
professionals during every aspect of the construction stage. A number of building
collapse which resulted due to poor supervision were recorded by (Ayedun, Durodola,
& Akinjare, 2012) in their report.
2.2.6 Poor Materials.
The continuous use of sub-standard and untested local materials for building
construction has been identified by (Amadi, Eze, Igwe, Okunlola, & Okoye, 2012) as
one of the major causes of building failure in Nigeria. According to (Oyewande, 1992)
the use of these inferior materials in building construction accounts for up to 10%
contributory factor to building collapse cases in Nigeria. Likewise, the use of blocks
made by most block industries in Nigeria needs to be discouraged, due to failure of
Most block industries in Nigeria to meet the standard requirements specified by the
Standard Organization of Nigeria (SON). Since the strength of the blocks depend on
the ratio of cement to sand used for moulding them, the right proportion must be used
to ensure that they are strong and durable. Due to its high demands in the building
industry, the block industries in Nigeria have equally increased the quantity thereby
compromising the quality in the bid to get the most number of blocks per bag of
cement (Ayuba, Olagunju, & Akande, 2012). (Mohammed, 2004) further stressed that

10
most block making industries in the country use the same mixture of sand and cement
to produce different sizes of blocks.
2.2.7 Use of Low Quality Concrete
The constituent materials for concrete are: cement, fine aggregate, coarse aggregate
and water. Concrete is a very variable material, having a wide range of strengths.
Concrete generally increases its strength with age. (Oyewande, 1992) observed that
the strength of reinforced concrete depends on the proportion of cement, sand, stones
and iron rods. These constituents are always used in the design of high- rise structures.
It is important that the aggregates for making concrete should be free of all sorts of
impurities (BS 882, 1992). The maximum percentage of silt/clay content of sand for
which the compressive concrete strength will not be less than 21N/mm2
is 3.4% for
mix ratio 1:2:4 (Olanitori & Olotuah, 2005). It is very important to control the quality
of the aggregate to be used in concrete making. Most importantly, the effect of the
silt/clay content of sand on the compressive strength of concrete must be controlled.
Emphasis has been on the use of poor quality aggregates, poor workmanship and the
use of lean concrete mix with low cement quantity as the reasons for the low quality
of concrete used for building constructions in Nigeria. In their paper, (Kazeem, Joy-
Felicia, & Wasiu, 2014) identified the use of inappropriate cement grade as a possible
cause of collapse of buildings in Nigeria.
2.2.8 Operational Problems.
These occur when alterations made to the structure are not taken into consideration
during design. This usually occurs when there is an upward economic change in the
value of the building location. (Olusola, Ojambati, & Lawal, Technological and Non

11
–Technological Factors Responsible for the occurence of collapse buildings in south-
western Nigeria, 2011). In his report, (Adenuga, Professionals in the built environment
and the incidence of building collapse in Nigeria., 2012) identified operational errors
as one of the least causes of building failure, but also pointed out the collapse case of
Sague School in Port-Harcourt which claimed over 50 lives to be attributed to it.
2.2.9 Poor Maintenance
Maintenance of buildings should start from the construction style and continue
throughout the lifespan of the building. (Adenuga, 1999) Stressed that much attention
is not paid to maintenance in Nigeria and the government is most guilty. Adequate
maintenance of buildings is necessary for the safety and durability of the structure.
Poor management and maintenance in buildings lead to the development of cracks on
the walls, differential settlement and premature aging of the structure. These
deficiencies when not checked could result to building failure. (Amadi, Eze, Igwe,
Okunlola, & Okoye, 2012).
2.3 EFFECT OF FIRE ON CONCRETE STRUCTURES.
In the building industry, adequate attention has not been paid to fire as a causative
factor that is responsible for building collapse in Nigeria. (Ayuba, Olagunju, &
Akande, 2012). One of the advantages of concrete over other building materials is its
fire-resistive properties. It is regarded as a fireproof because of its incombustibility
and its ability to withstand high temperature without collapse. However, its properties
can change dramatically when exposed to high temperatures which may lead to
deterioration in its mechanical properties. Temperatures up to 95°C have little effect
on the strength and other properties of concrete. Above this threshold cement paste
undergoes shrinkage (contraction) due to dehydration and aggregates expand due to

12
temperature rise which results in overall expansion of concrete and reduction in its
strength.
One of the most complex and hence poorly understood behavioural characteristics in
the reaction of concrete to high temperatures or fire is the phenomenon of “explosive
spalling” which is the explosive ejection of chunks of concrete from the surface of the
material, due to the breakdown in surface tensile strength. This phenomenon is often
assumed to occur only at high temperatures, yet it has also been observed in the early
stages of a fire and at temperatures as low as 200°C. If severe, spalling can have a
deleterious effect on the strength of reinforced concrete structures, due to enhanced
heating of the steel reinforcement. (Fletcher, Welch, Torero, Carvel, & Usmani, 2007).
Most building materials are not only inflammable, but also encourage the spread of
fire. This situation often makes a little fire ignition to spread very fast into a
conflagration. Fire when fully blown out, both the structure’s reinforcements and
concrete will be weakened. It is even worse, when the steel reinforcements are exposed
to the naked fire, they may fail in the process to provide the necessary support for both
the live and dead loads. In the event, it may lead to partial or total collapse of the
building. It is therefore pertinent to use high fire resistant materials for building
construction and for professionals in building industry to be fire safety conscious, most
especially in material specification. (Olagunju, Aremu, & Ogundele, 2013).
2.4 CONCRETE AS A BUILDING MATERIAL.
Use of this material in building construction is relatively recent and may have begun
less than a century ago. (Muhammad & Waliuddin, 1996). Concrete, a relatively new
construction material when compared to steel, is now the most widely used building
and civil engineering construction material. This prime position in the construction

13
practice could be attributed to such factors as; low cost, ability to be moulded into any
desired shape on construction site or in precast concrete industry, strength, durability,
fire resistance, thermal insulation, weightiness, chemical resistance properties etc.
(Garba, 2004). Concrete manufacturing involves the mixing of ingredients like
cement, sand, aggregates and water. (Parbhane & Shinde, 2012). After curing concrete
becomes as hard and impervious as stone. Steel rods or glass fibres are sometimes
used to reinforce the strength of concrete mixtures. Concrete can be mixed in bulk and
placed in forms to achieve any desired shape. The surface can be finished with a
variety of textures. Concrete surface maintenance costs are very low. (Gibbons, 1999).
2.4.1 Cement.
Cement is a fine grey powder which when reacted with water hardens to form a rigid
chemical mineral structure which gives concrete its high strengths. Cement is in effect
the glue that holds concrete together. The credit for its discovery is given to the
Romans, who mixed lime (CaCO3) with volcanic ash, producing a cement mortar
which was used during construction of such impressive structures as the Colosseum.
The invention of Portland cement is however attributed to Joseph Aspdin, a Leeds
builder and bricklayer, even though similar procedures had been adopted by other
inventors, Joseph Aspdin patented Portland cement on 21st
October, 1824. The name,
Portland cement was given owing to the resemblance of this hardened cement to the
natural stone occurring at Portland in England.
Cements are made in a wide variety of compositions for a wide variety of uses. They
may be named for the principal constituents, such as calcareous cement, which
contains silica, and epoxy cement, which contains epoxy resins; for the materials they
join, such as glass or vinyl cement; for the object to which they are applied, such as

14
boiler cement; or for their characteristic property, such as hydraulic cement, which
hardens underwater, or acid-resisting cement, or quick-setting cement (Gupta &
Gupta, 2004).
Cements set, or harden, by the evaporation of the plasticizing liquid such as water,
alcohol, or oil, by internal chemical change, by hydration, or by the growth of
interlacing sets of crystals. Other cements harden as they react with the oxygen or
carbon dioxide in the atmosphere. Cement is a material having adhesive and cohesive
properties which make it capable of bonding with stones, bricks/blocks and sand etc.
into a compact mass. On adding water to cement, a chemical reaction (hydration) takes
place, liberating a large quantity of heat. On hydration of cement, gel is formed which
binds the aggregate particles together and provides strength and water tightness to
concrete on hardening. Thus cement has the property of setting and hardening under
water by virtue of a chemical reaction with it. Cements mainly can be classified into
two groups, viz.
i. Natural cement: a type of cement obtained by burning lime stone containing
20-40% clay and crushing it powder. It is brown in colour and sets very quickly
when mixed with water. It is very akin to hydraulic lime. The only difference
between hydraulic lime and natural cement sets is that, lime starts to slake on
mixing water with it while natural cement slake immediately after adding
water to it.
ii. Artificial cement or Portland cement: This is classified as Portland cement and
Special Cement. The Portland cement is further divided into Ordinary PC,
Rapid hardening and Low Heat cement. Types of Special cement are Quick

15
setting, High alumina, and Blast furnace cement among others. (Anosike,
2011).
2.4.1.1 Manufacture of Portland cement.
The raw materials required for the manufacture of Portland cement are calcareous
materials such as limestone or chalk, and argillaceous materials such as shale or clay.
The process of the manufacture of cement consists of grinding the raw materials,
mixing them in certain proportions depending on their purity and composition and
burning them in a kiln at a temperature of about 1300 to 1500°C, at which temperature
the material sinters and partially fuses to form nodular shaped clinker. The clinker is
cooled and ground to fine powder with addition of about 3 to 5% of gypsum. The
product formed is Portland cement. There are two processes known as “wet” and “dry”
processes depending upon whether the mixing and grinding of raw materials is done
in wet or dry conditions.
2.4.2 Aggregate.
In concrete, aggregates (fine and coarse) usually occupy about 70-75% (Neville &
Brooks, 2011) and between 60 – 80% of the total volume of the concrete mass. The
aggregates have to be graded so the whole mass of concrete acts as a relatively solid,
homogeneous, dense combination with the smallest particles acting as inert filler for
the voids that exist between the larger particles (Nawy, 2008). This therefore suggests
that the selection and proportioning of aggregates should be given due attention as it
not only affects the strength, but the durability and structural performance of the
concrete also. Aggregates provide better strength, stability and durability to the
structure made out of cement concrete than cement paste alone. Aggregate is not truly
inert because its physical, thermal and chemical properties influence the performance

16
of concrete. While selecting aggregate for a particular concrete, the economy of the
mixture, the strength of the hardened mass and durability of the structure must first be
considered, (Gupta & Gupta, 2004).
2.4.2.1 Classification of Aggregate
Aggregates can be divided into several categories according to different criteria.
a. Size.
i. Coarse aggregate: Aggregates predominately retained on the No. 4 (4.75 mm)
sieve. For mass concrete, the maximum size can be as large as 150 mm.
ii. Fine aggregate (sand): Aggregates passing No.4 (4.75 mm) sieve and
predominately retained on the No. 200 (75 μm) sieve.
b. Sources.
i. Natural aggregates: This kind of aggregate is taken from natural deposits without
changing their nature during the process of production such as crushing and
grinding. Some examples in this category are sand, crushed limestone, and gravel.
ii. Manufactured (synthetic) aggregates: This is a kind of man-made materials
produced as a main product or an industrial by-product. Some examples are blast
furnace slag, lightweight aggregate (e.g. expanded perlite), and heavy weight
aggregates (e.g. iron ore or crushed steel).
c. Unit weight
i. Light weight aggregate: The unit weight of aggregate is less than 1120 kg/m3. The
corresponding concrete has a bulk density less than 1800 kg/m3. (Cinder, blast-
furnace slag, volcanic pumice).
ii. Normal weight aggregate: The aggregate has unit weight of 1520-1680 kg/m3
. The
concrete made with this type of aggregate has a bulk density of 2300-2400 kg/m3

17
iii. Heavy weight aggregate: The unit weight is greater than 2100 kg/m3
. The bulk
density of the corresponding concrete is greater than 3200 kg/m3
. A typical
example is magnetite, limonite, and a heavy iron ore. Heavy weight concrete is
used in special structures such as radiation shields.
2.4.2.2 Deleterious Substances in Aggregate.
Deleterious substances are impurities capable of causing damage to the immediate
environment where they occur. According to (Singh & Singh, 2006), as a thumb rule,
the total amount of deleterious materials in a given aggregates should not exceed 5%.
The methods of determining their contents are prescribed by BS 812: Part 118: 1989
and BS 812: Part 117: 1988, respectively. Natural aggregates may be sufficiently
strong and wear resistant but even then, they may not be satisfactory for concrete
making if they contain organic impurities which interfere with the hydration of
cement. The organic matter consists of products of decay of vegetable matter in the
form of humus or organic loam, which is usually present in sand rather than in coarse
aggregate, and it is easily removed by washing. Deleterious substances can be
classified into the following three categories:
i. Impurities which interfere with the process of hydration of cement.
ii. Coatings on aggregates which prevent the development of good bond between
aggregate and the cement paste and
iii. Unsound or weak particle.

18
2.4.2.3 Effects of Deleterious Materials on Aggregates.
i. They interfere with the hydration of cement.
ii. They affect bond between cement paste and aggregates.
iii. They reduce the strength and durability of concrete.
iv. They modify the setting action of cement concrete and contribute to
efflorescence.
2.4.3 Water.
Water is an important ingredient of concrete. Part of mixing water is utilized in the
hydration of cement and the balanced water is required for imparting workability to
concrete. Thus the quantity and quality of water is required to be looked into very
carefully. Most specifications recommended the use of potable water for making
concrete. (Nikhil, Sushma, Gopinath, & Shanthappa, 2014). Almost any natural water
that is drinkable and has no pronounced taste or odour can be used as mixing water
for making concrete. However, some waters that are not fit for drinking may be
suitable for use in concrete. (Gupta & Gupta, 2004). Water of questionable suitability
can be used for making concrete if mortar cubes made with it have 7-day strengths
equal to at least 90% of companion specimens made with drinkable or distilled water.
(ASTM-C-109) Acceptable criteria for water to be used in concrete are given in
(ASTM-C-94)
Excessive impurities in mixing water not only may affect setting time and concrete
strength, but also may cause efflorescence, staining, corrosion of reinforcement,
volume instability, and reduced durability. Therefore, certain optional limits may be
set on chlorides, sulphates acid alkalis, and solids in the mixing water or appropriate

19
tests can be performed to determine the effect the impurity has on various properties.
Some impurities may have little effect on strength and setting time, yet they can
adversely affect durability and other properties. Water containing less than 2000 parts
per million (ppm) of total dissolved solids can generally be used satisfactorily for
making concrete (Gupta & Gupta, 2004).
2.4.3.1 Use of Sea water in Concrete.
Seawater containing up to 35,000 ppm of dissolved salts is generally suitable as
mixing water for concrete not containing steel. About 78% of the salt is sodium
chloride, and 15% is chloride and sulphate of magnesium. Although concrete made
with seawater may have higher early strength than normal concrete, strengths at later
ages (after 28 days) may be lower. This strength reduction can be compensated for by
reducing the water-cement ratio. Seawater is not suitable for use in making steel
reinforced concrete and it should not be used in pre-stressed concrete due to the risk
of corrosion of the reinforcement, particularly in warm and humid environments. If
seawater is used in plain concrete (no steel) in marine applications, moderate sulphate
resistant cements, should be used along with a low water-cement ratio. Sodium or
potassium in salts present in seawater used for mix water can aggravate alkali-
aggregate reactivity. Thus, seawater should not be used as mix water for concrete with
potentially alkali-reactive aggregates. Seawater used for mix water also tends to cause
efflorescence and dampness on concrete surfaces exposed to air and water. (Shetty,
2005).
2.4.3.2 Effect of impurities on properties of concrete.
Carbonates and Bicarbonates of potassium and sodium: - The carbonates and
bicarbonates of sodium and potassium affect the setting time of cement. T1he presence

20
of sodium carbonate accelerates the setting time, while bicarbonates may either
accelerate or retard the setting of the cement.
Algae: - It may be present on the surface of aggregate or in mixing or washing water.
It combines with cement forming a layer on the surface of aggregate and reduces the
bond between the cement paste and aggregate. Also, algae have the air entraining
effect in large quantities in the concrete resulting in lowering the strength of concrete.
Mineral Oils: - Mineral oils not mixed with vegetable or animal oils have no adverse
effect on the concrete strength. Concentration of mineral oils up to 2% by weight of
cement has been found to increase the strength of concrete. 8% concentration of
mineral oil reduces the strength slightly. Vegetable oils have adverse effect on the
strength of concrete at later ages.
Water for Washing of Aggregates: - The most important effect of the use of impure
water for washing aggregate is the deposition of coating of salts and silt, organic
matter, etc. on the surface of the aggregate particles. The coating of the impurities
forms a layer between the gel and the aggregate surfaces resulting poor bond between
them, poor bond between aggregate and cement paste reduces the compressive
strength of concrete to a great extent. Thus the concentration of impurities in water
which cause deleterious coatings on particles are more harmful than those present in
mixing water. However, water used to wash the truck mixer is satisfactory as mixing
water as the solids in this water are proper cement ingredients.
2.4.4 Fresh Concrete.
Fresh concrete or plastic concrete is a freshly mixed material which can be moulded
into any shape. The relative quantities of cement, aggregates and water mixed together,

21
control the properties of concrete in the wet state as well as in the hardened state.
Concrete is produced in accordance with BS EN 206 - 1: 2000 Concrete: Specification,
Performance, Production and Conformity.
2.4.4.1 Workability
The strength of concrete of a given proportion is affected very much by the degree of
compaction. According to (Neville et al, 2004) and (Gupta et al, 2004) workability is
the amount of useful internal work necessary to produce full compaction. Therefore,
it is desirable that the fresh concrete can be transported and placed without segregation
and bleeding, compacted and finished easily. It should be noted that a workability of
concrete suitable for mass concrete is not necessarily sufficient for thin or heavily
reinforced concrete or inaccessible sections. However, whatever may be the mode of
compaction, whether by ramming or by vibration, the essential feature of the process
is to eliminate the entrapped air from the concrete until it has achieved as close a
configuration as possible for a given mix. It is obvious that the presence of voids in
concrete reduces the density and greatly reduces the strength; 5% of voids can lower
the strength by as much as 30%. Consistency of Concrete relates to the degree of
wetness of concrete within limits. Wet concrete is more workable than dry concrete,
but concretes of the same wetness (consistency) may vary in workability. Workability
depends on a number of interacting factors: water content, size of aggregate particles,
coarse and fine aggregate ratio, particle interference, particle interlocking, presence of
admixtures, fineness of cement, time, temperature and water content of the mix.
2.4.4.2 Segregation
This is the separation of the constituent materials of concrete of a heterogeneous
mixture so that their distribution is no longer uniform. In a good concrete all the

22
ingredients should be properly distributed to make a homogeneous mixture. The
segregation of concrete will not only produce weak but also non- homogeneous
concrete which would develop undesirable properties in the hardened concrete. The
difference in the size of aggregate particles and the specific gravity of the mix
constituents are the main cause of segregation, but the extent can be controlled by the
choice of suitable grading and by careful handling. It must be stressed that, concrete
should always be placed direct in the position in which it is to remain and must not be
allowed to flow or be worked along the form. The danger of segregation can be
reduced by the use of air entrainment. Conversely, the use of coarse aggregates whose
specific gravity is appreciably greater than that of fine aggregates can lead to increased
segregation (Barry, 1999).
2.4.4.3 Bleeding
Bleeding, also known as water gain, is a form of segregation in which some of the
water in the mix tends to rise to the surface of freshly placed concrete, being of the
lowest specific gravity of all the ingredients. This is caused by the inability of the solid
constituents of the mix to hold all of the mixing water when they settle downwards.
Bleeding can be expressed quantitatively as the total settlement (reduction in height)
per unit height of concrete. When the cement paste has stiffened sufficiently, bleeding
of concrete ceases. As a result of bleeding, the top of every layer of concrete placed
may become too wet, and if the water is trapped by superimposed concrete, a porous
and weak layer of non-durable concrete will result. If the bleeding water is remixed
during the finishing of the top surface, a weak wearing surface will be formed. This
can be avoided by delaying the finishing operations until the bleeding water has
evaporated and also by the use of wood floats and by avoidance of over-working the

23
surface. On the other hand, if evaporation of water from the surface of the concrete is
faster than the bleeding rate, plastic shrinkage may result.
2.4.4.4 Setting time of concrete
Setting time, both initial and final indicate the quality of cement. Setting time of
concrete differs widely from setting time of cement. Setting time of concrete do not
coincide with the setting time of cement with which the concrete is made. The setting
time of concrete depends upon the water-cement ratio, temperature conditions, type of
cement, use of mineral admixture, use of plasticizers-in particular retarding plasticizer.
The setting parameter of concrete is more of practical significance for site engineer s
than setting time of cement. When retarding plasticizers are used, the increase in
setting time, the duration up to which concrete remains in plastic condition is of special
interest. The setting time of concrete is found by penetrometer test. This method of
test is covered by IS 8142: 1976 and ASTM C – 403.
2.4.4.5 Compaction of concrete.
This is the method of eliminating entrapped air from the concrete, either by means of
rodding, ramming or by vibrating. The purposes of compacting concrete being to
obtain a dense mass of concrete without voids, to get the concrete to surround all
reinforcement and to fill all corners. During the process of manufacture of fresh
concrete a considerable amount of air is entrapped forming voids in it. Voids present
in concrete in the form of small pores reduce the strength and density of concrete.
There are two kinds of concrete voids namely, water void and air void. Honey-combed
concrete does not develop good bond with reinforcement. Water may penetrate
through these voids and corrode the steel. The operations adopted for obtaining a true

24
and uniform concrete surface are called finishing operations. A tamper usually leaves
a slightly ridged surface. Thus it needs finishing.
2.4.4.6 Curing of concrete
Curing of concrete is the process of maintaining satisfactory moisture content and a
favourable temperature in concrete during the period immediately after the placement
of concrete so that hydration of cement may continue till the desired properties are
developed sufficiently to meet the requirements of service. The reasons for curing
concrete are to keep the concrete saturated or as nearly saturated as possible, until the
originally water filled space in the fresh cement paste has been filled to the desired
extent by the product of hydration of cement, to prevent the loss of water by
evaporation and to maintain the process of hydration, to reduce the shrinkage of
concrete and to preserve the properties of concrete. The necessity of curing arises from
the fact that hydration of cement can take place only in water filled capillaries. For
this reason, a loss of water by evaporation from the capillaries must be prevented.
Further water lost internally by self-desiccation has to be replaced by water from
outside. Water required for chemical reaction with cement i.e. for hydration is about
25 – 30% of water added to the cement; the rest of the water is used for providing
workability.
2.5 ADMIXTURES.
Materials scientists, chemists, engineers, and manufacturers’ technical representatives
have helped the concrete industry to improve the ability to control work times,
workability, strength, and durability of Portland cement concrete by adding
supplementary substances called admixtures. (Mihai & Bogdan, 2008). Admixtures
are materials other than cement, water and aggregates that are used as ingredient of

25
concrete and are added to the batch immediately, before or during mixing. These days
concrete is being used for a wide variety of purposes to make it suitable in different
conditions. In these conditions ordinary concrete may fail to exhibit the required
quality performance or durability. In such cases, admixtures are used to modify the
properties of ordinary concrete so as to make it suitable for any situation. (Shetty,
2005). The history of admixtures is as old as the history of concrete. But a few type of
admixtures called water reducers or high range water reducers, generally referred as
plasticizers and super plasticizers are of recent interest.
It will be slightly difficult to predict the effect and the result of using admixtures
because, many a time, the change in the brand of cement, aggregate grading, mix
proportions and richness of mix alter the properties of concrete. Sometimes many
admixtures affect more than one property of concrete. At times, they affect the
desirable properties adversely. Sometimes more than one admixture is used in the
same mix. The effect of more than one admixture is difficult to predict. Therefore
caution must be taken in the selection of admixtures and in predicting the effect of the
same in concrete. The major reasons for using admixtures are:
i. To reduce the cost of concrete construction.
ii. To achieve certain properties in concrete more effectively than by other means.
iii. To maintain the quality of concrete during the stages of mixing, transporting,
placing, and curing in adverse weather conditions.
iv. To overcome certain emergencies during concreting operations.
Despite these considerations, it should be borne in mind that no admixture of any
type or amount can be considered a substitute for good concreting practice. The
effectiveness of an admixture depends upon factors such as type, brand, and

26
amount of cementing materials; water content; aggregate shape, gradation, and
proportions; mixing time; slump; and temperature of the concrete. Admixtures can
be classified by function as follows:
i. Air-entraining admixtures
ii. Water-reducing admixtures
iii. Plasticizers.
iv. Accelerating admixtures.
v. Retarding admixtures.
vi. Hydration-control admixtures.
vii. Corrosion inhibitors.
viii. Shrinkage reducers.
ix. Alkali-silica reactivity inhibitors.
x. Coloring admixtures.
xi. Miscellaneous admixtures such as workability, bonding, damp-proofing,
permeability reducing, grouting, gas-forming, anti-washout, foaming, and
pumping admixtures. (Shetty, 2005).
2.6 POZZOLANA
In Nigeria, annual cement consumption value is 19.5 million metric tonnes out of
which only 9.5 million metric tonnes are produced locally. The abruptly high demand
for cement owed to increased population and infrastructural development has resulted
in the rapid depletion of unsustainable natural resources, problems of Carbon dioxide
(CO2) emission and high cost of cement. In order to solve these problems, as well as
improve mortar/concrete performance, the exploration of cheaper materials that could

27
be used as partial substitute for cement in mortar and/or concrete has become a focus
point by researchers and specialists all over the world. (Salau & Osemeke, 2015). This
has led to the exploration of pozzolanic materials either as an addition to cement in
the manufacturing process or as a replacement for a portion of the cement in the mortar
and concrete production.
According to (Shetty, 2005) and the (Canadian Standards Association, 2000),
Pozzolanic materials are siliceous and aluminous materials, which in themselves
possess little or no cementitious value, but will, in finely divided form and in the
presence of moisture, chemically react with calcium hydroxide liberated in hydration,
at ordinary temperature, to form compounds possessing cementitious properties. The
invention of Portland cement in the 19th century resulted in the reduction in the use of
lime pozzolana binders. Today, pozzolanas are used in combination with Portland
cement due to their additional technical benefits.
Pozzolanas can be classified as natural and artificial (Kwabena, 2012). The general
term, pozzolana, is used to designate natural as well as industrial co-products that
contain a percentage of vitreous silica. This vitreous silica reacts at ambient
temperature with the lime produced by the clinker minerals to form hydrated calcium
silicates. In the past, natural pozzolans such as volcanic earths, tuffs, trass, clays, and
shales, in raw or calcined form, have been successfully used in building various types
of structures such as aqueducts, monuments and water retaining structures. Natural
pozzolans are still used in some parts of the world. However, in recent years, many
industrial waste by-products such as fly ash, slag, silica fume, red mud, and rice husk
ash are rapidly becoming the main source of mineral admixtures for use in cement and
concrete (Concrete Admixtures Handbook, 1996). Artificial pozzolanas are those

28
materials in which the pozzolanic property is not well developed and hence usually
have to undergo pyro-processing before they become pozzolanic (Hammond, 1983).
Artificial pozzolanas include materials such as fly ash, blast furnace slag, burnt clay,
siliceous and opaline shales, rice husk ash, burnt sugar cane stalks and bauxite waste.
2.6.1 Calcined Clay Pozzolanas.
When clay is calcined at a temperature of 700 to 750ºC, the clay is dehydrated and its
crystalline structure is totally disorganized. In doing so the water molecules are driven
off and a quasi-amorphous material is obtained. Active silica tetrahedral then reacts
with the lime liberated by the hydration of C3S and C2S of Portland cement. However
the addition of calcined clay increases the water demand in concrete. Most calcined
clay pozzolanas contain silica (SiO2) in excess of 50% as the most active constituent.
Other important constituents are the alumina (Al2O3) and hematite (Fe2O3) (commonly
referred to as total R2O3) which usually exceed 20%. An important criterion for a good
burnt clay pozzolanas as well as most other pozzolanas in terms of constituents is that
the sum of SiO2, Al2O3 and Fe2O3 contents should exceed 70%.
2.6.2 Fly Ash
Fly ash is a finely divided residue resulting from the combustion of powdered coal and
transported by the flue gasses and collected by electrostatic precipitator. In UK it is
referred to as pulverised fuel ash. Fly ash is the most widely used pozzolanic material.
In recent times, the importance and use of fly ash in concrete has grown so much that
it has almost become a common ingredient in concrete, particularly for making high
strength and high performance concrete. Extensive research has been done on the
benefits that could be accrued in the utilisation of fly ash as a supplementary
cementitious material. High volume fly ash concrete is a subject of current interest

29
among researchers. Use of high quality fly ash results in reduction of water demand
for desire slump. With the reduction of unit water content, bleeding and drying
shrinkage will also be reduced. Since fly ash is not highly reactive, the heat of
hydration could be reduced through replacement of part of the cement with fly ash.
2.6.3 Silica Fume.
Silica fume, also referred to as micro silica or condensed silica fume, is a by-product
material that is used as a pozzolan. This by-product is a result of the reduction of high-
purity quartz with coal in an electric arc furnace in the manufacture of silicon or
ferrosilicon alloy. Silica fume rises as an oxidized vapour from the 2000°C (3630°F)
furnaces. When it cools it condenses and is collected in huge cloth bags. The
condensed silica fume is then processed to remove impurities and to control particle
size. Condensed silica fume is essentially silicon dioxide (usually more than 85%) in
non-crystalline form. Since it is an airborne material like fly ash, it has a spherical
shape. It is extremely fine with particles less than 1 μm in diameter and with an average
diameter of about 0.1 μm, about 100 times smaller than average cement particles. It
should be noted that silica fume by itself do not contribute to the strength dramatically,
although it does contribute to the strength property by being very fine pozzolanic
material and also creating dense packing and pore filler of cement paste. Its use
simplifies production of high performance concrete and makes it easier to achieve
compressive strengths in the range of 60 to 90 Mpa. For higher strengths, the use of
silica fume is essential if it is available and economical.
2.6.4 Rice Husk Ash.
Rice husk ash is obtained by burning rice husk in a controlled manner without causing
environmental pollution. When properly burnt it has high SiO2 content and can be used

30
as a concrete admixture. Rice husk ash exhibits high pozzolanic characteristics and
contributes to high strength, enhances workability and high impermeability of
concrete.
2.6.5 Metakaolin
Considerable research has been done on thermally activated ordinary clay and
kaolinitic clay. These unpurified materials are often called metakaolin. Although it
showed certain amount of pozzolanic properties, it is not highly reactive. High reactive
metakaolin is made by water processing to remove unreactive impurities to make
100% reactive pozzolan. High reactive Metakaolin shows high pozzolanic reactivity
and reduction in Ca(OH)2. It is also observed that the cement paste undergoes distinct
densification. The improvement offered by this densification includes an increase in
strength and decrease in permeability.
2.6.6 Ground Granulated Blast Furnace Slag.
Ground granulated blast-furnace slag is a non-metallic product consisting essentially
of silicates and aluminates of calcium and other bases. The molten slag is rapidly
chilled by quenching in water to form a glassy and sand like granulated material. The
chemical composition of blast furnace slag is similar to that of cement clinker and fly
ash. The replacement of cement with Ground Granulated Blast-furnace slag will
reduce the unit water content necessary to obtain the same slump. This reduction of
unit water content will be more pronounced with increase in slag content and also on
the fineness of slag. Research works have shown that the use of slag leads to the
enhancement of intrinsic properties of concrete in both fresh and hardened conditions
such as reduced heat of hydration, refinement of pore structure and increased
resistance to chemical attack.

31
CHAPTER THREE
3.0 MATERIALS AND METHODS
3.1 MATERIALS
The materials used for this study include: ordinary Portland Cement (OPC),
Aggregates, Water and Clay which were all obtained from various places in Zaria,
Nigeria.
3.1.1 Ordinary Portland cement
Ordinary Portland cement is the most popular cement used in the construction of
buildings. The Dangote brand of Ordinary Portland cement of class 42.5N (according
to EN 197-1) was used in the concrete mix for the production of cube samples which
is in accordance to BS 12: 1996 specification.
Plate 3.1 Dangote Cement. (Source: Author’s fieldwork)
3.1.2 Fine Aggregate
Ordinary river sand was used at saturated dry state for casting the concrete cubes
samples. The sand was sieved passing through 0.85mm test sieve and retained on

32
0.60mm test sieve. The sand was sieved to remove organic impurities and aggregates
of bigger sizes.
Plate 3.2 Fine Aggregate. (Source: Author’s fieldwork)
3.1.3 Coarse Aggregate
Locally sourced granite from a commercial quarry in Zaria was used in the concrete
cube samples. Angular shaped coarse aggregates of 20mm maximum size were used.
Plate 3.3 Coarse Aggregate. (Source: Author’s fieldwork)

33
3.1.4 Water
The water used in the mix was sourced from a tap in the department of building,
A.B.U, Zaria. The water is safe for drinking and is in accordance to general
requirement of mixing water.
Plate 3.4 Potable Water (Source: Author’s fieldwork)
3.1.5 Clay
Locally sourced clay from the ceramics section of Industrial Design department,
A.B.U. Zaria, was used as partial replacement of the fine aggregate in the samples. It
was sieved to remove organic impurities.
Plate 3.5 Clay (Source: Author’s fieldwork)

34
3.2 METHODS
3.2.1 Production of Concrete cube samples
Using the design mix specified by BS 5328-1: 1997, a total of 15 specimens of size
150x150x150mm were produced with 5% partial replacement of fine aggregate with
clay. Cement, fine aggregate and coarse aggregate, were mixed homogeneously using
the 1:2:4 mix ratio, and a water/cement ratio of 0.45 was used. The concrete cube
steel formwork was lubricated before the mix is poured to prevent the concrete from
sticking to the mould. The specimens were poured into the moulds in three layers with
each layer being compacted manually by tampering 25 times with a standard
tampering rod and finally levelled. The cubes were then bolted to prevent leakage of
the mortar.
The cubes were then labelled 15 minutes after levelling for proper identification, and
were demoulded after 24 hours and cured for 28 days under same atmospheric
condition by full immersion in water. The curing of cubes was done in accordance to
BS 1881: part III.
Plate 3.6 Production of concrete cube samples. (Source: Author’s fieldwork)

35
3.2.1.1 Workability Test
To determine the workability of each mix of freshly mixed concrete, slump test was
carried out in accordance to BS 188-102: 1983. The metal slump mould used is 300mm
high, top diameter of 100mm and bottom diameter of 200mm. The mould was
lubricated to prevent the concrete from sticking to it, and was placed on a metal plate
base and held firmly at the bottom.
The mould is then filled with the concrete mix in three layers with a hand scoop. Each
layer was compacted twenty five times with a standard rammer. After compaction, the
top of the mould was then levelled and the mould gently removed by lifting up
vertically after which it was placed beside the moulded fresh concrete. A vertical ruler
with a straight edge was placed horizontally on top of the mould to pass above the
freshly casted concrete. The difference between the top of the displaced fresh concrete
and the top of the mould was then measure with a graduated rule.
Plate 3.7 Slump Test. (Source: Author’s fieldwork)

36
3.2.2 Properties of aggregate.
The properties of aggregates tested for are particle size distribution and bulk density.
3.2.2.1 Particle size distribution.
This refers to the distribution of various sizes of particles in an aggregate sample. It is
done to determine the particle size distribution (gradation) in a sample of aggregate to
be used for the concrete. The particle size distribution for fine aggregate was
determined by sieve analysis which is in accordance with the specifications of BS 812-
103.1 (1985). 500g of fine aggregate was weighed and the aggregate was passed
through the BS sieves of 4.75mm, 2.36mm, 1.18mm, 600μm, 300μm, 150μm and pan.
The sieve operation was performed by shaking the stack till the quantity retained on
each sieve was constant. Weight retained on each sieve was recorded. The weight
passing and the percentage passing were determined. The weight passing was summed
and compared with the weight of the sample at the beginning of the analysis. The result
of the sieve analysis is shown in the next chapter.
Plate 3.8 Particle size distribution test. (Source: Author’s fieldwork)

37
3.2.2.2 Bulk Density.
Bulk density is the weight of aggregate held by container of unit volume when filled
or compacted under defined condition. Aggregate bulk density is usually specified as
loose or compacted. The apparatus used included hand scoop, measuring scale, a cubic
wooden formwork and a tampering rod. The bulk density of fine aggregate was
determined based on saturated surface dry. The wooden formwork of dimension
150mm x 150mm x 150mm was weighed empty after it has been cleaned. It was then
filled with fine aggregate in three equal layers with each layer tampered 25 times with
the tampering rod for compaction. The top of the container was levelled and the filled
container was weighed. The same procedure was repeated for the coarse aggregate and
clay used for production of the cubes.
Plate 3.9 Bulk Density test. (Source: Author’s fieldwork)
Bulk Density is calculated as follows:
Weight of empty container = W
Weight of container + aggregate = w1
Volume of container = V
Bulk Density (SSD) =
(𝑤1−𝑤)
𝑉

38
3.2.3 Testing of Hardened Concrete cubes.
The hardened concrete cubes were subjected to water absorption test, density test,
compressive strength test and abrasion resistance test after curing for 28 days.
3.2.3.1 Density Test
The density of concrete cubes were determined by placing each dried sample of
concrete cube on a measuring scale to determine its weight. The weight was then
divided by the volume of cube used. Density is calculated using the relation:
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =
Mass of concrete cube (Kg)
Volume of cube (m3)
3.2.3.2 Compressive Strength Test.
Compressive strength test was conducted on the cubes using an electric crushing
machine. The test was done in accordance to BS 1881: part 116. After curing, the
concrete cubes were removed from water and allowed to drain. The test was conducted
after the cubes were subjected to varying temperature in the kiln. Each cube was placed
between the plates of the machine and subjected to increasing load pressure until
failure occurred. The failure is measured in Kilo Newton (KN) and the relation below
was used to determine the compressive strength.
Compressive strength =
𝑃
𝐴
Where:
P = failure load (KN)
A = cross sectional area (mm2
)

39
Plate 3.10 compressive Strength Testing, Civil Engineering Concrete lab. ABU, Zaria. (Source: Author’s
fieldwork)
3.2.3.3 Abrasion resistance test.
Abrasion resistance test was done after curing for 28 days using coefficient method by
subjecting the concrete cube samples to mechanical erosion by brushing for 60 circles
in backward and forward motion for about 60 seconds with a 3.5kg mass attached to
the brush.
Percentage weight loss =
𝑤𝑒𝑖𝑔ℎ𝑡 𝑏𝑒𝑓𝑜𝑟𝑒 𝑐𝑟𝑢𝑠ℎ𝑖𝑛𝑔−𝑤𝑒𝑖𝑔ℎ𝑡 𝑎𝑓𝑡𝑒𝑟 𝑐𝑟𝑢𝑠ℎ𝑖𝑛𝑔
𝑤𝑒𝑖𝑔ℎ𝑡 𝑏𝑒𝑓𝑜𝑟𝑒 𝑐𝑟𝑢𝑠ℎ𝑖𝑛𝑔
× 100
3.2.3.4 Water absorption test.
The concrete cubes were removed from water after curing for 28 days before oven
dried at 105°C for 24 hours. The samples were cooled and weighed after removing
from oven, they were then immersed in water for another 24 hours and weighed after
removing from water. The water absorption test was done in accordance to ASTM C
140.
Increase in mass as a percentage of initial mass is expressed as its absorption and is
mathematically expressed as
Water absorption =
𝑁𝑒𝑤 𝑤𝑒𝑖𝑔ℎ𝑡−𝐴𝑖𝑟 𝑑𝑟𝑦 𝑤𝑒𝑖𝑔ℎ𝑡
𝐴𝑖𝑟 𝑑𝑟𝑦 𝑤𝑒𝑖𝑔ℎ𝑡
× 100
Where;

40
Air dry weight = weight of concrete cube after oven dried.
3.2.4 Exposure of Samples to Varying Temperature.
The exposure of concrete cube samples was done after curing for 28 days. The
apparatus used for the heating is the GEMCO-HOLLAND electric kiln which has a
maximum operating temperature of 1400°C.
15 concrete cubes were weighed before loading into the kiln. 3 cubes were removed
and labelled when the temperature in the kiln’s chamber reached 100°C. The
procedure was repeated at 200, 300, 400 and 500°C. The cubes were then weighed
after they have cooled.
Plate 3.11 Gemco-Holland Electric Kiln, Industrial Development Centre, Samaru, Zaria. (Source: Author’s
fieldwork)

41
CHAPTER FOUR.
4.0 RESULTS, ANALYSIS AND DISCUSSIONS
This chapter presents results of tests conducted on aggregates used for the study, the
fresh concrete and also the results of tests conducted on the hardened concrete
samples. The results of tests carried out on hardened concrete samples include; Water
absorption, density, abrasion resistance, and compressive strength. Workability test
was carried out on the concrete in its fresh state. Sieve analysis was done on the coarse
aggregate.
4.1 PROPERTIES OF AGGREGATES.
4.1.1 Bulk Density of Aggregates.
As shown in table 4.1, the aggregates used for the production of the concrete cube
samples have a bulk density of 1620.74 Kg/m3
, 1623. 70 Kg/m3
, 1567. 41 Kg/m3
for
fine aggregate, coarse aggregate and clay respectively. The fine aggregate and coarse
aggregate are therefore good for the production of normal weight concrete. According
to Garba (2004), a normal dry weight aggregate should not have a compacted bulk
density of less than 1200Kg/m3
.
Table 4.1 Bulk Density of Aggregates
Aggregate Weight of
Aggregate (Kg)
Volume of
container (m3)
Bulk Density
(Kg/m3)
Fine (sand) 5.47 0.003375 1620.74
Coarse
(crushed granite)
5.48 0.003375 1623.70
Clay 5.29 0.003375 1567.41

42
4.1.2 Particle size distribution.
4.1.2.1 Sieve analysis of fine aggregate.
Table 4.2 below shows the particle size distribution of the fine aggregate used for the
study. It can be seen that the 5mm sieve is 96.99%. However, most of the fine
aggregates were retained on the 0.60mm sieve. 745g of the total weight passed through
the sieve were retained and 485g retained on the 0.3mm sieves. According to Garba
(2004), the more the content of aggregates less than its suitability for concrete making.
Aggregate fraction from 4.75mm to 150 microns is termed fine aggregate. (Shetty,
2005)
Table 4.2 Sieve Analysis of Fine Aggregates.
BS Sieve size
(mm)
Weight
retained (g)
Percentage
retained (g)
Cumulative percentage
passing (%)
4.75 60 3.01 96.99
2.36 115 5.76 91.23
1.18 475 23.81 67.42
0.60 745 37.34 30.08
0.30 485 24.31 5.77
0.15 95 4.76 1.01
Pan 20 1.00 0.01
4.1.2.2 Sieve analysis of coarse aggregate.
Table 4.3 below shows the particle size distribution of the coarse aggregate used for
the study. From the table, it can be seen that the highest percentage of coarse
aggregates were retained on the 10mm sieve. 1220g of the total weight that passed
through the sieve were retained. 562.5g were retained on the 4.75 mm sieve. Shetty

43
(2005), pointed out that the aggregate fraction from 80mm to 4.75mm is termed as
coarse aggregate.
Table 4.3 Sieve Analysis of Coarse Aggregates.
BS Sieve size
(mm)
Weight retained
(g)
Percentage
retained (%)
passing (%)
4.75 562.5 28.02 71.98
10 1220 60.77 11.21
20 180 8.97 2.24
Pan 45 2.24 0
4.1.2.3 Sieve analysis of clay.
Table 4.4 below shows the particle size distribution of the clay used for the study.
From the table, it can be seen that most of the clay sizes were retained on the 1.18mm
sieve. 465g of the total weight that passed through the sieve were retained.
Table 4.4 Sieve Analysis of Clay.
BS sieve size
(mm)
Weight
retained (g)
Percentage
retained (%)
passing (%)
4.75 45 2.24 97.76
2.36 375 18.66 79.10
1.18 465 23.13 55.97
0.60 360 17.91 38.06
0.30 260 12.94 25.12
0.15 150 7.46 17.66
Pan 355 17.66 0

44
4.2 WORKABILITY TEST OF CONCRETE.
Table 4.5 below shows the result of the slump test carried out on the fresh concrete
used for the study. From the table, it can be deduced that there is a reduction in
workability with increase in clay percentage. Due to its water demanding properties,
adding clay to concrete increases the water demand of the concrete thereby reducing
its workability (Osei & Jackson, 2012).
Table 4.5 Workability of concrete mix.
Clay (%) Slump (mm)
0 25
5 6
4.3 PROPERTIES OF HARDENED CONCRETE.
4.3.1 Density
Table 4.6 below shows the average density (at 28 days) of the samples before and after
they have been subjected to varying temperature. From the table, it can be seen that
there is a reduction in density with increase in temperature.
Table 4.6 Average Density of Cubes before and after heating.
Temperature (°C) Average Density of cubes
before heating (Kg/m3)
Average Density of cubes
after heating (Kg/m3)
100 2526 2509
200 2519 2469
300 2477 2459
400 2453 2380
500 2432 2331

45
4.3.2 Water absorption of concrete samples
Table 4.7 below shows the percentage of water absorption of the concrete samples.
From the table, it can be gleaned that there is an increase in the water absorption
capacity of the concrete samples with increase in clay concentration. This is due to the
high water retaining property of clay.
Table 4.7 Percentage of Water absorption of Concrete Sample.
Percentage of Clay (%) Water Absorption (%)
0 0.34
5 2.42
4.3.3 Abrasion resistance
Table 4.8 below the result of the abrasion resistance test carried out on the concrete
samples. From the table, it is shown that there is no significant change in the abrasion
resistance of the samples as the percentage of clay addition increased from 0 to 5%
Table 4.8 Abrasion resistance test of concrete samples.
Percentage of clay (%) Percentage weight loss (%)
0 0.024
5 0.024
4.3.4 Compressive strength of concrete samples.
Table 4.9 below shows the average compressive strength of the concrete samples
subjected to varying temperature. The table shows an increase in compressive strength

46
of the cubes as the temperature increased from 100 to 200°C and then a continuous
reduction in compressive strength at temperatures above 200°C.
Table 4.9 Average Compressive strength of concrete Samples at varying temperatures.
Temperature (°C) Average Failure Load
(KN)
Average Compressive strength
(N/mm2)
100 570.00 25.33
200 673.33 29.92
300 650.00 28.89
400 500.00 21.92
500 466.67 20.74
Figure 1. Average Compressive strength of concrete Samples at varying temperatures.
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600
Compressivestrength(N/mm2)
Temperature (°C)
Compressive strenght of concrete with 5% clay

47
CHAPTER FIVE
5.0 SUMMARY, CONCLUSION AND RECOMMENDATION
5.1 SUMMARY
The effect of varying temperatures on various properties of concrete containing 5%
clay addition has been studied. The concrete behaviour with temperature is according
to Euro-code 2(1995). The work yielded the following results:
i. From the results of the workability test conducted, there is a reduction in the
workability of concrete with increase in clay concentration.
ii. The density of concrete containing 5% clay addition meets the required density
for normal weight concrete.
iii. The results of the water absorption test shows that there is an increase in the
absorption capacity of concrete with increase in clay concentration.
iv. There is no significant change in the abrasion resistance of concrete containing
5% clay addition.
v. The compressive strength recorded at 100°C is 25N/mm2
. The highest strength
recorded was 29.92N/mm2
at 200°C while at temperatures above 400°C, the
cubes failed to meet the required compressive strength of 21N/mm2
as
specified in Garba (2004) for normal weight concrete used for structural
purposes.
5.2 CONCLUSION
Based on the experimental work conducted for the study, the following conclusions
were made.

48
i. At temperatures above 400°C the compressive strength of concrete containing
5% clay addition will fail to meet the required strength for normal weight
concrete used for structural works. Therefore the 8% allowable clay impurities
specification by the standards organization of Nigeria (SON) will be invalid at
temperatures above 400°C.
ii. At temperatures above 200°C there is reduction in compressive strength of
concrete containing 5% clay with increase in temperature.
5.3 RECOMMENDATION
The use of concrete containing up to 5% clay addition is recommended for concrete
works though it has an increased water absorption capacity and is less workable.
For concrete structures subjected to temperatures above 400°C, further tests should be
conducted on such buildings so as to ensure the safety of its continuous use, this is
based on the assumption that the said building might have been constructed with
concrete containing up to 5% clay addition since the maximum allowable specified by
the Standards Organization of Nigeria (SON) is 8%.
5.3.1 Recommendation for future research
i. Research should be conducted on the effect of varying temperature on
Sandcrete blocks containing varying percentages of clay addition. According
to (Ewa & Ukpata, 2013), sandcrete blocks are the most widely used walling
units in Nigeria, accounting for 90% of houses.
ii. According to (Neetu, et al., 2013), Ordinary Portland cement concrete is
known to be susceptible to acid attack. The high content of CaO makes it
vulnerable as it is readily soluble in acid environment. Therefore, further

49
research should be done on the effect of acid attack on the properties of
concrete containing varying percentages of clay addition.

50
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