Final year project by nsengimana innocent

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DECLARATION
We hereby declare that the research project entitled “AN EXPERIMENTAL STUDY ON USE OF
COW DUNG ASH AND RICE HUSK ASH AS PARTIAL REPLACEMENT OF CEMENT IN
CONCRETE” submitted for degree of bachelor in science is our original work and the research project
has not been submitted to any other university or institution for the award of degree or diploma.
…………………………… ……………………… ……………………………
NSENGIMANA Innocent KUBWIMANA Delphine TWAMBAJIMANA Adeline
REG.NO: 216144701 REG.NO: 216189357 REG.NO: 216280184

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DEDICATION
This research project is dedicated to:
Our supervisor
Our parents
Our brothers and sisters
Family members
Colleagues and
All Friends

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ACKNOWLEDGEMENT
The first and above all, we are greatly indebted to the Almighty God for blessing us with good health and the
motivation to successfully get to the point in our pursuit of achieving a Bachelor of Science degree in Civil
Engineering and project.
We would sincerely like to thank our Supervisor Dr. ABAHO G. Gershome who has been there always to
help us in preparing this work, for putting tremendous efforts from his side to assist us as much as possible.
This work would not have been complete without data support from Mayange Rice Company Ltd. we
particularly thank the managing director for the support he provided to enrich the study.
We wish to express our thankful to the farmers who gave us cow dung used in this study.
Furthermore, we owe our wholehearted thanks to the entire staff of CEGE for their cooperation and assistance
during our undergraduate studies in civil engineering. We hope that we can build upon the experience and
knowledge that we have gained and make a valuable contribution towards this industry in the coming future.
We are also grateful to the government of Rwanda (GoR) who sponsored our undergraduate studies through
REB and BRD Ltd. Without them the program could not be
successfully completed.
Special thanks are extended to SJEC Ltd on behalf of Saint Joseph Technical College (SJTC/Nyamirambo)
for their unforgettable assistance to conduct compressive strength test in their concrete Laboratory.
We would sincerely like to acknowledge all authors of books and other e-sources used in this study.
The last but not least, many thanks go to Eng. HAGENIMANA Clemence, who is laboratory technician,
helped us providing crucial equipment and mitigating ideas.

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ABSTRACT
Rice Husk Ash (RHA) and Cow Dung Ash (CDA) are agriculturally based pozzolanic materials, these
materials are available in huge quantities. This final year project report highlights and presents the results of
the study on the use of Cow Dung Ash and Rice Husk Ash as partial replacement of cement in concrete. The
experiments were conducted to study the impacts of adding Cow Dung Ash and Rice Husk Ash in several
percentages by weight (0%, 5%, 10%, 15%, and 20%) of cement and cure for periods of 28 days before testing
for compression strength. The consistency, workability, sieve analysis of aggregates were also tested in this
research study. The Compressive test results are 37.75 N/mm2
, 31.25 N/mm2
, 31.25N/mm2
and 25.25 N/mm2
for 0%, 5%, 10% and 15% replacement of cement with Cow Dung Ash and Rice Husk Ash respectively at
28days. The Workability results gives 45mm, 49mm, 56mm, 68mm and 75mm respectively for 0%,5%, 10%,
15%, and 20% replacement of cement with Cow Dung Ash and Rice Husk Ash. The consistency test results
are 0.29, 0.32, 0.36, 0.41 and 0.43 for 0%, 5%, 10%, 15% and 20% replacement of cement with Cow Dung
Ash and Rice Husk Ash respectively. The bulk density results are 2452.53 kg/m3
, 2370.8 kg/m3
, 2380.0 kg/m3
and 2348.5 kg/m3
for 0%, 5%, 10% and 15% replacement of cement with Cow Dung Ash and Rice Husk Ash
respectively. The main highlights, it should be highlighted that the more quantity of water is required to
standard consistency as the percentages of Cow Dung Ash and Rice Husk Ash are added. Dung Ash and Rice
Husk Ash concrete is recommended for use when a ten percentage (10%) of Cow Dung Ash and rice husk ash
are not exceeded.
Key words: cement, concrete, cow dung ash, rice husk ash, workability, standard consistency,
Slump test, bulk density, curing, mortar, aggregates, water, compressive strength.

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TABLE OF CONTENTS
DECLARATION .........................................................................................................................................ii
DEDICATION........................................................................................................................................... iii
ACKNOWLEDGEMENT............................................................................................................................ iv
ABSTRACT................................................................................................................................................ v
LIST OF TABLES....................................................................................................................................... ix
LIST OF FIGURES...................................................................................................................................... x
LIST OF ABBREVIATIONS ........................................................................................................................ xi
CHAPTER ONE: GENERAL INTRODUCTION..............................................................................................1
1.1 Background of the study.........................................................................................................................................1
1.2 Problem statement .................................................................................................................................................2
1.3 Research objectives ................................................................................................................................................2
1.3.1 Main objective: ................................................................................................................................................2
1.3.2 Specific objectives............................................................................................................................................2
1.4. Scope of the research ............................................................................................................................................3
1.5 Contribution of the research...................................................................................................................................3
1.5.1 Academic and research contributions .............................................................................................................3
1.5.2 Technical contribution .....................................................................................................................................4
1.6 The proposed methodology....................................................................................................................................4
CHAPTER TWO: LITERATURE REVIEW.....................................................................................................5
2.1 Introduction ............................................................................................................................................................5
2.2 Fundamental definitions.........................................................................................................................................5
2.3 Rice production.......................................................................................................................................................7
2.3.1 Rice production and processing in Rwanda.....................................................................................................7
2.3.2 Properties and application of RHA...................................................................................................................8
2.3.3 Previous Research on use of RHA in construction...........................................................................................8
2.4 Cow dung and cow dung ash ..................................................................................................................................9
2.4.1 Cow dung ash production ................................................................................................................................9
2.4.2 Properties of cow dung ash .............................................................................................................................9
2.4.3 Past research on use of CDA as building material .........................................................................................10
2.5 Cement..............................................................................................................................................................10
2.5.1 Chemical composition of Portland cement....................................................................................................11
2.5.2 Hydration of cements ....................................................................................................................................11
2.5.3 Physical properties of cement .......................................................................................................................12
2.5.4 Types of cement.............................................................................................................................................12
2.5.4 Testing of cement ..........................................................................................................................................13

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2.6 Aggregates ............................................................................................................................................................14
2.6.1 Particle grading and Fineness Modulus .........................................................................................................14
2.6.2 Properties and characterization of aggregates..............................................................................................14
2.6.3 Aggregates testing .........................................................................................................................................14
2.7 Water ....................................................................................................................................................................15
2.8 Concrete................................................................................................................................................................15
2.8.1 Properties of concrete ...................................................................................................................................15
2.8.2 Poncrete grades .............................................................................................................................................15
2.8.3 Advantages and disadvantages of concrete ..................................................................................................16
2.8.4 Concrete mix design.......................................................................................................................................17
2.8.5 Concrete testing.............................................................................................................................................17
2.8.6 Concrete application......................................................................................................................................17
CHAPTER THREE: METHODOLOGY........................................................................................................18
3.1 Introduction ..........................................................................................................................................................18
3.2 Research design ....................................................................................................................................................18
3.3 Materials and Sample preparation .......................................................................................................................18
3.3.1 Cow dung ash preparation.............................................................................................................................18
3.3.2 Preparation of Rice Husk Ash.........................................................................................................................19
3.3.3 Cement...........................................................................................................................................................19
3.3.4 Aggregates .....................................................................................................................................................20
3.3.5 Water .............................................................................................................................................................20
3.4 Materials Testing...................................................................................................................................................20
3.4.1 Preliminary laboratory work..........................................................................................................................20
3.4.2 Test procedures and performance.................................................................................................................22
CHAPTER FOUR: RESULTS ANALYSIS AND DISCUSSION........................................................................34
4.0 Introduction ..........................................................................................................................................................34
4.1 Consistency limit...................................................................................................................................................34
4.2 Fine aggregates sieve analysis ..............................................................................................................................35
4.3 Workability Results ...............................................................................................................................................37
4.4 Density of concrete results ...................................................................................................................................38
4.5 Compressive strength test results ........................................................................................................................40
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS....................................................................42
REFERENCES.........................................................................................................................................43
APPENDICES ..........................................................................................................................................45
Appendix 1: Timeline schedule...................................................................................................................................45
Appendix2: Budget......................................................................................................................................................45
Appendix 3: Project photos.........................................................................................................................................46
Appendix 4: Recommendation Letters .......................................................................................................................47

viii
Appendix5: compressive strength test results............................................................................................................48

ix
LIST OF TABLES
Table 1:Chemical composition of RHA and OPC (Habeeb & Mahmud, 2010).................8
Table 2: Physical Properties of RHA .....................................................................................8
Table 3:Chemical composition of CDA and cement by % weight according to (Omoniyi, Duna, &
Mohammed, 2014)..................................................................................................................10
Table 4: Chemical composition of Portland cement and their functions .........................11
Table 5:Compound of composition of OPC ........................................................................11
Table 6: Poncrete grades IS 456-2000 Table2.....................................................................15
Table 7: Collection data of sieve analysis on fine aggregates.............................................23
Table 8: Collection data of sieve analysis on coarse aggregates ........................................24
Table 9: Collection of data on consistency test....................................................................27
Table 10:Data collection on slump test ................................................................................29
Table 11:Observation data of concrete density on 7 curing days......................................31
Table 12:Observation data of concrete density on 14 curing days....................................32
Table 13:Observation data of concrete density and concrete strength on 28 curing days33
Table 14:Consistency limit for different mix ratio of RHA and CDA in paste of cement34
Table 15: Fine aggregates sieve analysis..............................................................................35
Table 16:Coarse aggregates sieve analysis ..........................................................................36
Table 17:Workability Results ...............................................................................................38
Table 18:Density of concrete results ....................................................................................38
Table 19:Cube strength of CDA+RHA varying the percentage for replacement of cement at 28 days of
curing ......................................................................................................................................39
Table 20:Cube strength of CDA+RHA varying the percentage for replacement of cement at 28 days of
curing ......................................................................................................................................40

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LIST OF FIGURES
Figure 1:Rice husks..................................................................................................................5
Figure 2:Rice husk ash ............................................................................................................6
Figure 3:Production of rice in Rwanda .................................................................................7
Figure 4:Research design flow chart....................................................................................18
Figure 5:Cow dung ash..........................................................................................................19
Figure 6:Rice Husk Ash.........................................................................................................19
Figure 7:Sieve analysis on Fine aggregates .........................................................................22
Figure 8: Sieve analysis on Coarse aggregates....................................................................24
Figure 9:Slump cone test observations ................................................................................29
Figure 10:Line chart representing consistency limit..........................................................34
Figure 11: Fine aggregates Sieve analysis graph ................................................................36
Figure 12:Coarse aggregates sieve analysis graph..............................................................37
Figure 13: Bar chart representing slump test results.........................................................38
Figure 14:Bar chart representation of density of cubes against curing periods..............39
Figure 15:Bar chart representation of compressive strength of cubes against curing periods41

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LIST OF ABBREVIATIONS
%: percentage
ASTM: American Society for Materials and Testing
BRD: Development Bank of Rwanda
CA: Coarse Aggregates
CDA: Cow Dung Ash
CEGE: Civil, Environmental and Geomatics Engineering
CST: College of Science and Technology
Dr: Doctor
Eng.: Engineer
FA: Fine Aggregates
Frw: Franc Rwandais
GoR: Government of Rwanda
HE: His Excellence
IS: Indian Standard
Kg/m3
: Kilogram per cubic meter
kN: Kilo-Newton
Ltd: Limited
M20: M stands for mix, number 20 stands for characteristic compressive strength in MPa
MINAGRI: Ministry of Agriculture and Animal Resources
MPa: MegaPascal
N/mm2
: Newton per square millemeter
NAP: National Agricultural Policy
OPC: Ordinary Portland Cement
RAB: Rwanda Agriculture Board
REB: Rwanda Education Board
REG.NO.: Registration Number
RHA: Rice Husk Ash
S/N: Serial Number
SJEC Ltd: Saint Joseph Engineering Company Limited
SJTC: Saint Joseph Technical College
UR: University of Rwanda

CHAPTER ONE: GENERAL INTRODUCTION
1.1 Background of the study
Concrete is a vital man-made composite construction material that is mostly being used in modern
construction industry worldwide where we live in. This useful construction material is obtained by
mixing appropriate proportion of aggregates (fine and coarse), cement, supplementary cementing
materials, water and additives that allow the mixture to set and harden with time. The demand of
cement in construction concrete technology is highly needed day by day to fill the gaps in
infrastructural development such as buildings, highways, bridges, tunnels, parking, stadium,
railway, airport, hydraulic structures due to industrialization and commercial centers (Pavithra,
2016). The cement production in manufacturing industries leads to the negative effects to the
environment due to emitting of polluted gases like carbon dioxide (CO2) that leads to the air
pollution which has more effects on the climate change and global warming (Pavithra, 2016). The
cement manufacturing factory produces about 6 percent of all CO2 emitted in atmosphere, 0.9 tons
of carbon dioxide is produced by 20 bags of cement manufactured (Arun Kumar & Nazeer,
2014). Supplementary binding materials such fumes as cow dung ash, sawdust, fly ash, silica, rice
husk ash enable concrete technology to use millions of tons of byproducts materials that would be
waste disposal problems (Mehta, 2004). Therefore, as the civil engineers are responsible for
bridging gaps and filling the voids, they always searching for the construction industry which is
friendly to the environment. There is a need to search for supplementary cementitious materials
for utilization as partial replacement for cement. (Mehta, 2004) have discussed on different
materials like sawdust ash, rice husk ash, fly ash, granulated blast furnace slag, as partial
replacement of cement in concrete. In this research project, the concrete strength will be
investigated by conducting an experimental study on use of cow dung ash and rice husk ash as a
partial replacement of cement in concrete.
(Akeke, et al., 2013) found that Ordinary Portland Cement (OPC) could be substituted by Rice
husk ash up to 25% in the concrete production with workability and no loss of strength and 10%
of replacement is good load bearing elements. In Rwanda, cow/cattle are mostly found countryside
as results of program known as “Girinka Programme” initiated by the president of republic. These
efforts can help in reducing the amount of CO2 emitted during cement production. We used the
cow dung that obtained from cow excreta, which were dried in sunlight in the form of cake.

2
Chemically, Cow dung is rich in nitrogen, calcium, potassium and phosphorus (Smith & Wheeler
, 1979). In many developing countries, dried cow dung is used as fuel to cook and the fuel ash is
obtained in the form of black color. Rayaprolu and Raju (2012) have reported that cow dung is a
nitrogen rich material, potassium, phosphorous and calcium. They studied about the use of cow
dung ash as partial replacement of cement in mortar and concrete. As these materials can be used
for the partial replacement of cement, therefore, the proportions of these materials will be replaced
by cement and aggregates in the preparation of concrete cubes of 100mm*100mm*100mm. The
compressive strength of cubes will be applied for cured concrete for the different periods for the
comparison.
1.2 Problem statement
The population in developing countries like Rwanda are highly increasing day by day. So, they
need infrastructures facilities such as buildings, highways, hydraulic structures, airports, parking
to accommodate them effectively. Those infrastructures require construction materials primarily
concrete and others. Nowadays, the cost of building materials especially plastering and
cementitious materials in Rwanda is very high. Environmentally, cement manufacturing industries
produces fumes which contributes to the air pollutions which leads to the global warming and
climatic change. Additionally, large amount of agricultural wastes produced in manufacturing
industries like rice husk has been causing waste disposal problems. This has encouraged people to
use other available local materials like cow dung and fly ash, clay, which are cheap to acquire.
This research focuses on use of cow dung ash and rice husk ash as partial replacement of cement
in concrete.
1.3 Research objectives
1.3.1 Main objective: The main objective of this work is an experimental study on use of cow
dung ash and rice husk ash as partial replacement of cement in concrete.
1.3.2 Specific objectives
✓ To determine the techniques for improving economical concrete with partial replacement
cement by cow dung ash and rice husk ash at appropriate percentages.
✓ To examine the effectiveness of using CDA and RHA as partial replacement of cement by
studying strength parameters.

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✓ To investigate the compressive strength and of concrete with CDA and RHA to that of
normal concrete.
✓ To use supplementary cementitious materials to produce concrete which is affordable and
structural light in weight.
✓ To minimize the environmental effects resulted from the production of cement by using
alternative local available cementitious materials as partial replacement.
✓ To promote the usage of local available wastes with the aim preservation of environment.
✓ To minimize the usage of the raw material large replacement is done using the various by
product materials that are available in the present day.
✓ To use locally available material and to reduce the cost of producing concrete.
✓ To enhance available local materials to improve economical concrete with partial
replacement cement by cow dung ash and rice husk ash at appropriate percentages in search
of solution to the above dual problem.
1.4. Scope of the research
This study is not limited to the application of rice husk ash (RHA) and cow dung ash (CDA) in
construction industry. This paper mainly highlights the significance and necessity of consumption
of the waste material for manufacturing of sustainable concrete for construction. There is a need
to search for supplementary cementitious materials for utilization as partial substitute for cement
in the field of civil engineering. The research shall include the investigation of the strength and
behavior of concrete produced by blending cement with cow dung ash and rice husk ash in
comparison with normal cement concrete, in order to establish the most appropriate percentage to
replace cement. This will be achieved by conducting compressive strength test on cube samples.
The investigations will also include assessment of the impact of using cow dung ash and rice husk
ash in the production of the concrete. Finally, a cost comparison between CDA and RHA blended
concrete cubes and normal concrete cube will be calculated.
1.5 Contribution of the research
1.5.1 Academic and research contributions
This study will contribute academically great role to the students pursuing undergraduate programs
in the field of civil engineering and diploma in construction technology to gain more knowledge
about construction materials and technology. This report of the study serves as basic and guide for

4
future references by other researchers and other academic references. The study enabled the
researchers to gain more experience of coordinating other similar studies. They will be
strengthened with the knowledge of using rice husk ash and cow dung ash to replace partial cement
in concrete and mortar. Appropriate weight will be considered to check the strength.
1.5.2 Technical contribution
The study would be of benefit to many individuals, companies and groups, including building
construction technology and Professional bodies in the building construction industries. Waste
disposal problems will be minimized and protection of environment.
1.6 The proposed methodology
In this study, rice husk ash and cow dung ash will be used for preparing concrete cubes by replacing
different amount of cement percentages. The following methods will be used to make our research
successfully:
❖ Documentation books are necessary to get more theoretical knowledge about the concrete
strength analysis.
❖ Visiting scientific website on internet related to this topic
❖ Visiting the site and collecting the samples from local villages and rice milling
❖ Laboratory tests will be experimented such as sieve analysis tests, bulk density, workability
tests and compressive cube test using CST concrete and material laboratory
❖ Data Analysis and interpretations using Microsoft word for word processing and Microsoft
Excel for results analysis
❖ Recommendations and Conclusions

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CHAPTER TWO: LITERATURE REVIEW
2.1 Introduction
This chapter is intended and aimed to review various findings and research that has been already
conducted on this research topic. It generally highlights some of definitions that are basic and
fundamental for the full understanding this research topic. It clearly shows various findings and
controversy about the research done on the use of CDA and RHA as partial replacement of cement
in concrete.
2.2 Fundamental definitions
Rice husks: it is also known as “rice hull”, rice hull is hard protecting coat of rice seed or rice
grain.
Figure 1:Rice husks

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Rice husk ash: rice milling factories generating large quantities of rice husks. These rice husks
are commonly used as fuel in cooking and rice husk ash is obtained.
Figure 2:Rice husk ash
Cow dung: it is also called cow pats, cow manure, is the waste product excreted by cow. This
material also can be obtained from bovine species include buffalos, bison, yak.
Cow dung ash: when cow dung is exposed to the sun light dry, dried cow dung are used as fuel
to cook. Hence, cow dung ash is obtained in black color by burning dried cow dung.
Cement: binding construction material that sets, hardens and clings to the other materials to cling
together.
Concrete: is a vital man-made construction material obtained by mixing binding materials
(cement, cementitious materials), aggregates, water and other additives for special properties.

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2.3 Rice production
2.3.1 Rice production and processing in Rwanda
Rice was introduced in Rwanda in 1950s through various missions from China and Korea. After
the initial success of growing rice in the valleys near Kigali and in the Southern province, a number
of varieties became popular in 1960s.
(MINAGRI, 2012) reported that Rwanda produces 81,908 metric tons of short grain rice a year.
MINAGRI planned to increase land for cultivating rice through land reclamation projects. Rwanda
aimed to achieve self-sufficiency in in rice by increasing rice production to 7tons/ha by 2018. Land
area for cultivating expanded from 7000ha in 2008 to 2800ha by 2018. (MINAGRI, 2010)
reported that the rice has become one of the major food crops grown in Rwanda, by providing food
security the land area for cultivating rice would be expanded. National Agricultural Policy (NAP)
identifies rice as one of the priority agricultural commodities. (MINAGRI, 2013) reported that the
Rice has become a major commodity in the food baskets of rural- and urban households in Rwanda.
They estimated demand for rice would increase to about 204000tons of milled rice by 2018. This
report focuses on paddy (rice grain with husk) and the milled rice grain, and the is referred to as
the “rice commodity”
Figure 3:Production of rice in Rwanda

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There are 19 rice mills in Rwanda by 2013, 6 in Eastern Province, 5 in western province and 8 in
southern province.
2.3.2 Properties and application of RHA
Rice husk ash is the artificial pozzolans which is rich in silica
Table 1:Chemical composition of RHA and OPC (Habeeb & Mahmud, 2010)
Oxide composition (% by
mass)
SiO2 Al2O3 Fe2O3 MgO CaO Na2O3 K2O LOI
OPC 20.99 6.19 3.86 0.22 65.96 0.17 0.60 1.73
RHA 88.32 0.46 0.67 0.44 0.67 0.12 2.91 5.81
RHA is pozzolanic material and it has different physical properties as provided in table (Ramesh
& Kavitha, 2014)
Table 2: Physical Properties of RHA
Particulars Particulars
Color Grey
Shape texture Irregular
Particle size <45 micron
Odor Odorless
Appearance Very fine
2.3.3 Previous Research on use of RHA in construction
Rice husk is agricultural waste which account for the 649.7 million tons of rice produced
worldwide annually (Habeeb & Mahmud, 2010)
(Varshney, 2015) reported that the RHA agricultural wastes based on pozzolanic material,
generated during rice milling. During milling, 80% weight of rice grains are obtained and 20%
remained are rice hulls.

9
(SHETTY, 2005) discussed that RHA is obtained by burning rice husk in controlled temperature
with aim of protecting environmental pollution. RHA has high SiO2 content so that can be used
as concrete admixture. RHA displays high pozzolanic characteristics and adds to high
impermeability and thigh strength of concrete. RHA basically comprise of amorphous silica
(SiO2), 5% of carbon and 2% of K2O. In USA, the trade name of highly pozzolanic RHA is known
as “Agrosilca”, the specific surface of RHA varies between 40 to 100 m2
/g.
(Dabai & Muhammad, 2009) studied the effect of RHA as cement admixture by testing the
compressive strength of cement cubes produced by replacing cement percentages with the RHA.
The results Cleary showed that suitable strength of concrete at 28 days obtained with RHA could
be replace for OPC at 10% and 20% of replacement. (Gambhir, 2006) highlighted that the average
composition of RHA is 90% amorphous silica, 5% of carbon, and 2% of K2O.
2.4 Cow dung and cow dung ash
Cattle keeping is countrywide in Rwanda even the poor families as result of Girinka Programme
initiated by HE Paul Kagame the president of the republic. The word Girinka is translated as ‘have
a cow” the main objectives of this programme was reducing poverty through dairy cattle farming
and improving live hoods through increased milk consumption and income generation. The
reported that by June 2016 a total of 248566 cows had been distributed to the poor households’
families (RAB, 2017). These cows excrete the wastes known as cow dung; cow dungs are local
available in whole country.
2.4.1 Cow dung ash production
The cow dung cakes are collected and exposed to the sunlight. After drying it, are burnt through
cooking and ash remain as waste. This ash is collected for its intended to use in different projects.
2.4.2 Properties of cow dung ash
Physical properties of cow dung ash are as follow:
✓ It has large ash content
✓ It is bulk
✓ It has low volatile content after burning
✓ Carbon content is low
✓ Burning ratio is low

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Table 3:Chemical composition of CDA and cement by % weight according to (Omoniyi,
Duna, & Mohammed, 2014)
Oxides SiO2 Al2O3 Fe2O3 CaO MgO SO3 K2O Na2O P2O5 MnO5 TiO2
CDA 69.65 4.27 2.99 12.55 2.22 1.36 2.94 .57 1.48 0.63 0.33
Cement 20.26 6.30 3.26 65.51 0.96 0.69 0.88 0.99 0.25 0.21 0.24
2.4.3 Past research on use of CDA as building material
(Smith & Wheeler , 1979) found that cow dung is Nitrogen rich material, calcium, phosphorous
and potassium. (Pavithra, 2016) reported that dry cow dung is utilized as fuel energy for domestic
intention, which generates solid waste ash and observed that cow dung ash in cement concrete is
durable as compared to the normal concrete strength. (Ojedokun & Adeniran, 2014) studied on
CDA as partial replacement of cementing material in concrete, they highlighted that setting times
increases as the percentages of CDA is added. Finally, they advocated to use CDA concrete only
when 10% of CDA is added. They recommend that CDA is suitable for certain floor and wall
which are not subjugated to the heavy loads and is not to use for structures related to the water.
(Kumar & Reddy, 2015) searched on cement replacement in concrete by CDA and found that 5%
of CDA replacement increases the compressive strength. It observed that the 5% of CDA replace
cement in mortar. (Omoniyi, et al., 2014) highlighted that initial and final setting time increases
by 12.2%-59.3%and2.74%-43.90% respectively as the % of CDA increases, this indicates that
CDA is a set retarder. The compressive strength results pointed increases with curing time and
deceases with increases of CDA content. (Sruthy & Krishnan et etal, 2017) studied on normal
concrete strength to that of concrete with CDA, they foregrounded that concrete strength increases
when 8% CDA replace cement.
2.5 Cement
Cement is well-popular building material and has essential place in construction Civil works.
Portland cement is material having cohesive and adhesive properties, which provide binding
medium for distinct ingredients.

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2.5.1 Chemical composition of Portland cement
The three constituents of hydraulic cement ae lime, silica and alumina. In addition, other small
oxides are added (Duggal, 2008).
Table 4: Chemical composition of Portland cement and their functions
S/N Oxide Functions Percentage
1 Lime, CaO Controls strength and soundness. Its
deficiency reduces strength and setting time
60-65
2 Silica, SiO2 Gives strength. Excess of it, causes slow
setting
17-25
3 Alumina, Al2O3 Responsible for quick setting, if in excess, it
reduces strength
3-8
4 Iron oxide, Fe2O3 Gives color 0.5-6
5 Magnesia, MgO Imparts color and hardness, in excess causes
cracks
0.5-4
6 Sulphur trioxide, SO3 Soundness of cement 1-2
These oxides act with each other to form a series of more complex products during fusion.
Table 5:Compound of composition of OPC
Compound in OPC Formula Name Symbol % by mass in cement
Tricalcium silicate 3CaO.SiO2 Alite C3S 25-50
Dicalcium silicate 2CaO.SiO2 Belite C2S 20-45
Tricalcium aluminate 3CaO.Al2O3 Celite C3A 5-12
Tetracalcium alumino
ferrite
4CaO. Al2O3.Fe2O3 Felite C4AF 6-12
2.5.2 Hydration of cements
Hydration of cement is chemical reaction take place between cement and water. The reaction take
place between the active components (C4AF, C3A, C3S, C2S) and water.

12
2.5.3 Physical properties of cement
The cement to be used in construction should satisfy given qualities in order to play its vital role
effectively in structure. The important physical properties of a cement are as follows as described
by (Gambhir, 2006).
Fineness: the cement fineness is a measure of size particles distributions of cement. The rate of
hydration is higher as the cement is finer. So, more surface area is available for chemical reactions.
As per IS standards the passing of cement should not be less than 90% when sieved on a 90 micron
IS sieve.
Setting time: there are two parts of setting time, namely, the initial and the final setting time. The
initial setting time is the time required for cement paste to lose its plasticity. The final setting time
is time taken by cement paste to become hard mass.
Soundness: it is indispensable that cement concrete does not undergo large change in volume after
setting.
Compressive strength: it is one of major properties of cement. The cement mortar cubes having
area of 5000mm2
are prepared and tested at 3-7 days of curing in compressive testing machine.
Heat of hydration: the chemical reaction of cement and water is exothermic. The quantity of heat
takes place during hydration of cement at a given temperature.
Specific gravity: generally, specific gravity of Portland cement is about 3.15. specific gravity is
not an indication the quality of cement but it is used in computing the proportional mix.
2.5.4 Types of cement
By using admixtures, the changing the chemical composition of the Portland cement by varying
the basic four compounds through the use of different raw materials. So, it is possible to obtain the
several types of the cement. Each types of cement have its unique quality for the required
performance.
❖ Ordinary Portland Cement: Ordinary Portland Cement 33 Grade-IS 269:1989
Ordinary Portland Cement 43 Grade-IS 8112:1989
Ordinary Portland Cement 53 Grade-IS 12269:1987
❖ Rapid Hardening Cement IS 8041:1990

13
❖ Extra Rapid Hardening Cement IS 8041:1990
❖ Sulphate Resisting Cement IS 12330:1988
❖ Portland Slag Cement IS 455:1989
❖ Quick Setting Cement IS 455:1989
❖ Super Sulphated Cement IS 6909:1990
❖ Portland Pozzolana Cement IS 1489(Part I) 1991(Fly Ash Based)
❖ Low Heat Cement IS 12600:1989
❖ Masonry Cement IS 3466:1988
❖ Expansive Cement IS 3466:1988
❖ High Alumina Cement IS 6452:1989
2.5.4 Testing of cement
Testing of the cement are broadly into two categories:
a) Field testing
b) Laboratory testing
Field testing: it is sufficient to subject the cement to the site inspection when it is minor works.
The following are the site tests:
➢ Open the cement bag and take a good looking. There should not be any visible lumps.
➢ The color of cement is generally greenish grey.
➢ It feels cool when thrust your hands into cement bag.
➢ Take a handful hand of cement and throw it on a bucket of full of water, the cement particles
should float for some time before they sink.
➢ Check the date of manufacturing to ensure that cement comply to the standards and
specifications.
Laboratory tests:
Fineness test: a measure of size particles cement distribution, the fineness of cement has a major
role on the rate of hydration and hence on the rate of gain of strength.

14
Determination of fineness of cement by sieve test: take a sample of 100g of cement and take it on
a standard IS Sieve No. 9 (90 micron). All lumps should be broken down with fingers. By
mechanical sieving for 15 minutes. The residue should not exceed 10% for ordinary cement.
Standard consistency of cement: for finding out initial setting time, final setting time and
soundness of cement.
Setting time test: determining the initial and final setting times
Strength test: for determining compressive strength of hardened cement paste
Soundness test: determining the change of volume after setting of cement paste.
Heat of hydration test: to ensure the quantity of heat required for the hydration of cement.
2.6 Aggregates
Aggregates make up about 75% of the volume of concrete, so their properties have a large
influence on other properties of the concrete ( Alexander & Mindess, 2005)
2.6.1 Particle grading and Fineness Modulus
Fineness modulus is the numerical index of fineness, it gives meaning and idea on particles mean
size of aggregates. Aggregate samples are sieved by using standard set of sieves. The material
retained on each sieve is coarser than to that of passed to the following sieve. The sum of
cumulative percentages retained on the sieves decided by 100 gives the Fineness Modulus.
The size of sieves to be used conform IS2386 (Part2) 1963 are 80mm, 40mm, 20mm, 10mm,
4.75mm, 2.36mm, 1.18mm, 600 µm, 300 µm and 150 µm. the aggregates pass 4.75mm are termed
as fine aggregates and that of retained on 4.75mm are commonly known as coarse aggregates.
2.6.2 Properties and characterization of aggregates
The aggregates are characterized by size, texture, specific gravity and bulk density, soundness,
sieve analysis, shape, strength, moisture content, chemical properties, durability and grading.
2.6.3 Aggregates testing
The tests on aggregate are sieve analysis, impact value test, abrasive aggregate test, bulk density.

15
2.7 Water
Water is molecular compound of oxygen and hydrogen (H2O). Hydration of cement is caused by
the mixture of the cement and water. So, water play important role on workability, strength and
economical of the concrete. Typically, 150 to 200kg/m3 of are used in production of concrete. The
water that you can drink, you can use it in concrete. The mixing water should be clean, free from
impurities like dust, salts. The presence of impurities in mixing water reduce the strength,
durability of the concrete.
2.8 Concrete
Concrete is the most vital artificial construction material in the world. It is obtained by the mixing
cement, aggregates and water at appropriate proportion. Other pozzolanic materials and additives
may be taken into account to achieve the required properties. The durability, strength and other
quality of concrete depends on concrete constituents, on proportions of mix, on compaction
method, placing techniques and curing.
2.8.1 Properties of concrete
Fresh/or plastic concrete: it is characterized by the workability, segregation, bleeding, setting
time of concrete and uniformity.
Hard concrete: the properties of hardened concrete are strength, durability, elasticity, creep,
shrinkage, cracking.
2.8.2 Poncrete grades
Table 6: Poncrete grades IS 456-2000 Table2
Group Grade Designation Specified Characteristic compressive strength
Of 150mm cube at 20 days in N/mm2
Ordinary concrete M10 10
M15 10
M20 10
Standard concrete M25 25

16
M30 30
M35 35
M40 40
M45 45
M50 50
M55 55
High strength concrete M60 60
M65 65
M70 70
M75 75
M80 80
The mixes of grades M10, M15, M20 and M25 correspond approximately to the mix proportions
(1:3:6), (1:2:4), (1:1.5:3) and (1:1:2) respectively.
2.8.3 Advantages and disadvantages of concrete
Advantages of concrete: concrete has high compressive strength, it is free from corrosion, it
hardens with age, it is more economical than steel, it may be remolded in any shape and size, it is
fire proofing material, it is on site fabrication.
Disadvantages of concrete: it has low tensile strength, shrinkage, creeping, low strength-to-
weight ratio, low ductility etc.
2.8.4 Concrete production
The production of cement concrete follows these processes: batching (measurement of materials),
mixing, transporting, placing, compacting, curing and finishing.

17
2.8.4 Concrete mix design
Concrete mix design is the process of selecting desirable constituents of concrete and determining
relative quantities with aim of producing concrete of the complied strength, durability and
workability as economically possible. The factors affecting mix design are compressive strength,
workability, durability, grade and type of aggregates, cement content and water cement ratio. In
this work, the IS method of mix design used.
2.8.5 Concrete testing
Workability tests on plastic concrete: slump cone test, table flow test, Vee Bee consistency test,
compacting factor test. The aim of these tests is to check and ensure the consistency of the concrete.
Strength tests on hardened concrete: compressive strength test (cube or cylinder),
2.8.6 Concrete application
Concrete plays great role in development of infrastructures such as buildings, highways, airport,
railways, bridges, hydraulic structures, parking etc.

18
CHAPTER THREE: METHODOLOGY
3.1 Introduction
This chapter describes all materials, methods and techniques used in this research.
3.2 Research design
Figure 4:Research design flow chart
3.3 Materials and Sample preparation
3.3.1 Cow dung ash preparation
The cow dung was collected from Gakenke district and Rulindo district in Northern Province.
The cow dung was dried by exposing them to the sunlight, dried cakes were used to cook and
CDA collected as wastes.

19
Figure 5:Cow dung ash
3.3.2 Preparation of Rice Husk Ash
The RHA was collected from Mayange Rice Company Ltd in Bugesera district. After milling the
rice grains, rice husks as waste are collected for any intended purpose and others are burnt. It was
brought in Materials and Concrete Laboratory at UR-CST and then sieved on 90micron ASTM
sieve.
Figure 6:Rice Husk Ash
3.3.3 Cement
Cement used in this work was manufactured by Twiga and is available on market countrywide.
The grade of cement was 32.5N is highly being used in construction industry in Rwanda. The

20
standard consistency in the laboratory. All the tests were carried out in compliance with procedure
laid down in IS 12269 – 1987.
3.3.4 Aggregates
Fine aggregate: The sand used in this research study was no deleterious materials and prepared in
accordance with IS 383:1970.
Coarse aggregates: In this research, CA of 6.3-25mm maximum size were used. Proper
inspection was carried out to ensure that it was free from impurities materials as complied by IS
383:1970.
3.3.5 Water
This is the least expensive but most important ingredient of concrete. Water used was fetched on
water taps in University of Rwanda-College of Science and Technology, Nyarugenge Campus.
3.4 Materials Testing
3.4.1 Preliminary laboratory work
This work based on material testing to check strength of concrete. The materials used in this
research were RHA, CDA, cement, aggregates and water. The mixing design was M20 as grade
of concrete. The supplementary replacement used at 0%, 5%, 10%, 15% and 20%.
Concrete ingredients were batched and mixed in appropriate proportion for M20. Measuring of
materials were done by weight and mixed by concrete mixer machine. The concrete mix proportion
was 1:1.5:3 batching by weight and water-cement ratio of 0.5.
3.4.1.1 Calculations material quantities in mix design of M20
The quantity of cement, sand and coarse aggregates in concrete may be calculated as follow
Concrete Grade=M20
Mix ratios=1:1.5:3
Design parameters:
Density of cement=1440kg/m3
Specific gravity=3.15

21
Density of fine aggregate= 1450-1600kg/m3
Density of coarse aggregates=1450-1500kg/m3
Dry volume of concrete=54% increase by volume of wet concrete.
Wet volume=100% +54% dry volume
=154% dry volume
Therefore, dry volume=1.54 wet volume
Consider 1m3
of concrete in these calculations (wet volume)
M20 1:1.5:3, total ratios=1+1.5+3=5.5
Dry volume=1.54*wet volume=1.54*1=1.54
Cement calculations
Volume of cement in cubic meter=1.54*1/5.5=0.28 m3
Quantity of cement in kg=1.54*1*1440/5.5=403.2kg
Number of cement bags=403.2/50=8.1 bags where 1 bad of cement is 50kg.
Fine aggregates calculations
Volume of FA in cubic meter=1.54*1.5/5.5=0.42m3
Quantity of FA in mass kg=1.54*1.5*1500/5.5=630kg
Coarse aggregates calculations
Volume of CA in cubic meter=1.54*3/5.5=0.84m3
Quantity of CA in mass=0.84*1500=1260kg
The volume of cube mould=10*10*10=1000mm3
=0.001m3
For three trials, the volume becomes=0.001*3=0.003m3
The quantity of cement=0.003*403.2=1.2096kg
The quantity of FA =1.2096*1.5=1.8144kg

22
The quantity of CA =1.8144*2=3.6288kg
3.4.2 Test procedures and performance
3.4.2.1 Sieve analysis for aggregates and cement
Fine aggregates sieve analysis
Aim: To determine the particle size distribution of fine aggregate by conducting dry sieve
analysis.
Theory: the aggregates most pass through 4.75mm ASTM sieve is classified as fine aggregates.
Apparatus: electronic weigh balance, set of ASTM sieves, sample of 2000g, electronic shaker
machine.
Procedures: carefully measure 2000g of dried sample, arrange sieve from pan to the cover
according to the size of mesh holes, put arranged sieves on shaker machine for three minutes and
then measure weight of sample retained on each sieve.
Figure 7:Sieve analysis on Fine aggregates

23
Observations:
Table 7: Collection data of sieve analysis on fine aggregates
ASTM Sieve Size Weight of empty sieve Weight of sieve with retained sample
4.75mm 377.54g 399.61g
3.36mm 407.93g 508.79g
1.18mm 361.98g 1130.01g
600micron 377.34g 878.16g
300micron 312.68g 873.12g
150micron 333.04g 380.25g
Pan 314.02g 314.60g
Coarse aggregates sieve analysis
Aim: To determine the particle size distribution of coarse aggregate by conducting dry sieve
analysis.
Theory: the aggregates most retained on 4.75mm ASTM sieve is classified as fine aggregates.
Apparatus: electronic weigh balance, set of ASTM sieves, sample of 5000g, electronic shaker
machine.
Procedures: carefully measure 5000g of dried sample, arrange sieve from pan to the cover
according to the size of mesh holes, put arranged sieves on shaker machine for five minutes and
then measure weight of sample retained on each sieve.

24
Figure 8: Sieve analysis on Coarse aggregates
Observations:
Table 8: Collection data of sieve analysis on coarse aggregates
ASTM Sieve Size Weight of empty sieve Weight of sieve and retained sample
40mm 856.86g 0
37.5mm 868.31g 0
25mm 916.66g 1450g
20mm 909.03g 4990.87g
16mm 845.06g 1150g
12,5mm 887.28g 950g
10mm 948.42g 950g
Pan 884.42g 900g
Fineness Test of Cement by Sieve Analysis
Aim: To determine the fineness of the cement of the given sample by sieve analysis

25
Theory: The degree of fineness of cement is a measure of the mean size of grains. Fine cement is
good and quicker for cement hydration and attain early strength without change in ultimate
strength. Finer cement is susceptible to shrinkage and cracking.
Apparatus: IS 90µm test sieve, bottom pan, electronic weighing balance and brush.
Procedures:
1. Accurately weigh 100 grams of cement sample and place it over the test sieve. Gently
breakdown the air set lumps if any with fingers.
2. Hold the sieve with pan in both hands and sieve with gentle wrist motion, in circular and
vertical motion for a period of 10 to 15 minutes without any spilling of cement.
3. Place the cover on the sieve and remove the pan. Now tap the other side of the sieve with the
handle of brush and clean the outer side of the sieve.
4. Empty the pan and fix it below the sieve and continue sieving as mentioned in the steps 2 and
3. Totally sieve for 15 minutes and weigh the residue (Left over the sieve)
Observations:
 Type of cement: OPC
 Grade of cement=32.5N/mm2
 Brand of cement: Twiga
 Weight of cement taken =100g
Weight of cement retained after sieving =8g
3.4.2.2 Normal Consistency of Cement and Setting Time of Cement tests
In these tests, the RHA, CDA percentages were taken in account with the aim of comparing
consistency of CDA+RHA and cement to that of normal cement.
Consistency test on cement
Aim: To determine the quantity of water required to produce a cement paste of standard
consistency.
Apparatus: Vicar’s apparatus conforming to IS 5513-1976, weighing balance, gauging, trowel
and stop watch.

26
Theory: The standard consistency of a cement paste is defined as that consistency which will
permit the Vicat plunger to penetrate to a point 5 to 7 mm from the bottom of the
Vicat mould. For finding out initial setting time, final setting time, soundness of cement
and compressive strength of cement, it is necessary to fix the quantity of water to be
mixed in cement in each case.
Procedures:
1. Take accurately 300grams of cement and portable water to prepare paste, starting with
26% water of 300g of cement.
2. Take care that the gauging time is not less than three minutes, and not more than five
minutes and the gauging will be completed before setting occurs.
3. The gauging time counted from the time of adding the water to the dry cement until
beginning to fill the mould.
4. Fill the Vicat mould with this paste.
5. After completely filling the mould, trim off the surface of the paste, making it in level
with the top of the mould.
6. Place the test block with the mould, together with the non-porous resting plate, under the
rod bearing the plunger (10mm diameter), lower the plunger gently to touch the surface
of the test block and quickly release, allowing it to penetrate into the paste.
7. This operation shall be carried out immediately after filling the mould.
8. Prepare trial pastes with varying percentages of water and test as described above until
the amount of water necessary for making the standard consistency as defined above is
obtained.

27
Observations:
Table 9: Collection of data on consistency test
S/N Weight of
cement taken
Weight of
CDA+RHA
Percentage by water of
dry Cement (%)
Amount of
water added (ml)
Penetration
(mm)
1 100% 0% 26 78 4
28 84 5
30 90 7.5
32 96 10
33 99 12
2 95% 5% 26 78 1
28 84 2.5
30 90 3
32 96 5
33 99 7
3 90% 10% 30 78 1
32 84 2
35 105 5
37 111 7
39 117 8
4 85% 15% 32 96 2
34 102 3
36 108 3.5
38 114 4
40 120 5
42 126 7
45 135 11
5 80% 20% 35 105 2
37 111 3

28
40 120 4
42 126 5
44 132 7
46 138 11
Cone slump test
Aim: To determine the workability or consistency of concrete mix of given proportion by slump
test.
Apparatus: Pan to mix concrete, weighing balance, trowel, cone, steel scale, tamping
rod, mixing tray.
Reference code:
•IS: 456-2000, code for plain and reinforced concrete
•IS: 1199-1959 methods of sampling and analysis of concrete
Procedure:
1. Mix the dry constituents thoroughly to get a uniform colour and then add water.
2. The internal surface of the mould is to be thoroughly cleaned and placed on a smooth,
horizontal and non-absorbent surface.
3. Place the mixed concrete in the cleaned slump cone in 4 layers each approximately 1/4 in
height of the mould. Tamp each layer 25 times with tamping rod. Using the tampering rod or a
trowel strike of the excess concrete above the concrete cone. Measure the vertical height of cone
(h1).
4. Slowly and carefully remove in the vertical direction. As soon as the cone is removed the
concrete settles in vertical direction. Place the steel scale above top of settled concrete in
horizontal position and measure the height of cone(h2).
5. Complete the experiment in two minutes after sampling.
6. The difference of two heights (h1-h2) gives the value of slump

29
Observations:
1) Mix proportion =1:1.5:3
2) Date of casting=9th
May,2019
Table 10:Data collection on slump test
% of
RHA+CDA
Proportion Slump
in mmW/C Water RHA+CDA Cement FA CA
0% 0.5 750ml 0g 1500g 2.25kg 4.5kg 45
5% 0.5 750ml 75g 1425g 2.25kg 4.5kg 49
10% 0.5 750ml 150g 1350g 2.25kg 4.5kg 56
15% 0.5 750ml 225g 1275g 2.25kg 4.5kg 68
20% 0.5 750ml 300g 1200g 2.25kg 4.5kg 75
Figure 9:Slump cone test observations

30
Compressive strength of cement concrete
Aim: To determine the cube strength of the concrete of given properties
Apparatus required: mounds for the test cubes, tamping rods
Procedure:
1. Calculate the material required for preparing the concrete of givenproportions.
2. Mix them thoroughly in mechanical mixer until uniform color of concreteis obtained.
3. Pour concrete in the oiled with a medium viscosity oil. Fill concrete is cube moulds in
two layers each of approximately 75mm and ramming each layerwith 35 blows evenly
distributed over the surface oflayer.
4. Fill the moulds in 2 layers each of approximately 50mm deep and ramming each layer
heavily.
5. Struck off concrete flush with the top of the moulds.
6. Immediately after being made, they should be covered with wet mats.
7. Specimens are removed from the moulds after 24hrs and cured in water 28days.
8. Compression tests of cube and cylinder specimens are made as soon as practicable after
removal from curing pit. Test-specimen during the period of their removal from the
curing pit and till testing, are kept moist by a wet blanket covering and tested in a moist
condition.
9.Place the specimen centrally on the location marks of the compressiontesting machine
and load is applied continuously, uniformly and withoutshock.
10. Also note the type of failure and appearance cracks.

31
Observations on 7 curing days
Table 11:Observation data of concrete density on 7 curing days
Specimen
0% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2433.8 2461.8 2459.9 2451.83 kg/m3
Specimen
5% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2404.0 2337.3 2367.8 2369.7 kg/m3
Specimen
10% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2375.3 2371.6 2392.4 2379.8 kg/m3
Specimen
15% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2375.5 2314.2 2350.3 2346.7 kg/m3

32
Table 12:Observation data of concrete density on 14 curing days
Specimen
0% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2435.8 2461.1 2461.3 2452.73 kg/m3
Specimen
5% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2405.9 2338.8 2368.7 2371.13 kg/m3
Specimen
10% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2377.6 2373.6 2394.8 2382.0 kg/m3
Specimen
15% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2377.5 2316.3 2353.4 2349.07 kg/m3

33
Table 13:Observation data of concrete density and concrete strength on 28 curing days
Specimen
0% of RHA+CDA
Trials Mean Value
1 2 3
Load on cubes, KN 380 375 37.75 N/mm2
Density (kg/m3
) 2434.5 2461.5 2461.6 2452.53 kg/m3
Specimen
5% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2405.3 2338.3 2368.8 2370.8 kg/m3
Specimen
10% of RHA+CDA
Trials Mean Value
Density (kg/m3
) 2373.4 2373.0 2393.6 2380.0 kg/m3
Specimen
15% of RHA+CDA
Trials Mean Value
1 2 3
Density (kg/m3
) 2376.7 2316.3 2352.5 2348.5 kg/m3

34
CHAPTER FOUR: RESULTS ANALYSIS AND DISCUSSION
4.0 Introduction
This chapter describes the data observed in laboratory tests. Microsoft excel was used to
analyze data in suitable and understandable form.
4.1 Consistency limit
This test is carried out to determine the standard water required to produce workable paste
of cement and conforming IS4031-1988. The RHA and CDA are mixed with cement to
produce paste as a percentage of weight of cement. The results obtained for consistency limit
test are as follow in table below. The test result show that the much water is required to
obtain the desired consistency as the percentage of CDA and RHA increase. The
consistency limit curve is show in figure 9.
Table 14:Consistency limit for different mix ratio of RHA and CDA in paste of cement
RHA+CDA 0% 5% 10% 15% 20%
Consistency limit 0.29 0.32.5 0.36 0.41 0.43
The figure below shows that the much water
Figure 10:Line chart representing consistency limit
0.29
0.33
0.36
0.41
0.43
0.25
0.27
0.29
0.31
0.33
0.35
0.37
0.39
0.41
0.43
0.45
0 5 10 15 20
Consistencylimit
RHA+CDA%
CONSISTENCY LIMIT
Consistency limt curve

35
4.2 Fine aggregates sieve analysis
This test is carried out to find the distribution particles of fine aggregates passing through the
standard set of sieves complying the test procedure is given IS: 2386 (Part I). The sample of sand
was dried and then sieved in these set of sieves 4.75mm, 3,36mm, 1.18mm, 600mm, 300mm,
150mm and pan. Fineness modulus is required to classify samples varies between 2.0 and 3.5 for
fine aggregates, between 5.5 and 8 for coarse aggregate, and 3.5to 6.5 for all in coarse aggregate.
The following table showing the results obtained for sample of 2000g. the fineness modulus of
sample is 3.18 which is belong between 2 and 3.5, this is shows that is fine aggregates. The grading
graph presents the distribution of aggregates on the sieves used.
Table 15: Fine aggregates sieve analysis
ASTM
Sieve Size
Weight of
retained
cumulative of weight
retained (g)
% Cumulative of
weight retained (g)
% Passing
4.75mm 22.07g 22.07 1.1035 98.8965
3.36mm 100.86g 122.93 6.1465 93.8535
1.18mm 768.03g 890.96 44.548 55.452
600micron 500.82g 1391.78 69.589 30.411
300micron 560.44g 1952.22 97.611 2.389
150micron 47.21g 1999.43 99.9715 0.0285
Pan 0.58g 2000.01 100.0005 -0.0005
318.97 281.03
Fineness modulus (F.M) = ∑ (Cumulative % retained)/100=318.97/100=3.1897
Source: AutoCAD

36
Figure 11: Fine aggregates Sieve analysis graph
Table 16:Coarse aggregates sieve analysis
Sieve size Weight retained
(g)
%weight
Retained (g)
Cumulative
% weight retained
%Passing
40mm 0 0 0 100
37.5mm 0 0 0 100
25mm 533.34 10.67 10.67 89.33
20mm 4081.84 81.64 92.31 7.69
16mm 304.94 6.10 98.41 1.59
12,5mm 62.72 1.25 99.66 0.34
10mm 1.58 0.03 99.69 0.31
4.75mm 15.58 0.31 100 0
Pan 0 0 100 0
Total 5000 100 500.74
Fineness modulus (F.M) = ∑ (Cumulative % retained)/100=500.74/100=5.0074

37
Figure 12:Coarse aggregates sieve analysis graph
4.3 Workability Results
Workability implies the ease to work with which concrete mix is handling and it can be determined
by cone slump test as per IS1199-1988. The following table17 shows the workability of each mix
of concrete varying the % of RHA+CDA with the highest workability value of 75 is obtained for
20% of RHA+CDA in cement.

38
Table 17:Workability Results
RHA+CDA 0% 5% 10% 15% 20%
Slump 45 49 56 68 75
Figure 13: Bar chart representing slump test results
4.4 Density of concrete results
Table 18:Density of concrete results
CDA+RHA 7Days 14days 28days
0% 2451.83 2452.73 2452.53
5% 2369.7 2371.13 2370.8
10% 2379.8 2382.0 2380.0
15% 2346.7 2349.07 2348.5
The Density of the cubes decreases as the percentage content of CDA+RHA increases;
this reveals that the lightness in weight of specimen is due to the presence of CDA+RHA and the
higher the percentage of CDA+RHA the lighter the specimen. Also, the result reveals that the
Density of specimen increases with age. The following bar chart represents that the highest
densities obtained on 14 curing days.
45
49
56
68
75
0
10
20
30
40
50
60
70
80
0 5 10 15 20
Slump
RHA+CDA%
Slump Result

39
Figure 14:Bar chart representation of density of cubes against curing periods
Table 19:Cube strength of CDA+RHA varying the percentage for replacement of cement at
28 days of curing
%
CDA
in
cement
0%
Cube
sizes
(mm2)
Cube
area
(mm2)
Water/
cement
Weight
of cube
(kg)
Density
of cube
(kg/mm3)
Crushing
load
(kN)
Cube
strength
(N/mm2)
100mm
x
100mm
10000 0.5 2.45 2452.53 375.0 37.75
5% 100mm
x
100mm
10000 0.5 2.37 2370.80 312.5 31.25
2451.83
2369.7
2379.8
2346.7
2452.73
2371.13
2382
2349.07
2452.53
2370.8
2380
2348.5
2300
2310
2320
2330
2340
2350
2360
2370
2380
2390
2400
2410
2420
2430
2440
2450
2460
0 5 10 15
ConcreteDensitykg/m3
RHA+CDA %
Density of Concrete Results
7Days 14days 28days

40
10% 100mm
x
100mm
10000 0.5 2.38 2380.80 312.5 31.25
15% 100mm
x
100mm
10000 0.5 2.35 2348.5 252.5 25.25
4.5 Compressive strength test results
Casting date= 9th
May, 2019
Curing days=28days
Testing date= 7th
June 2019
The following Table 20 shows a detailed result presentation of the research work after the
practical and laboratory test. The Cube Strength reduces as the percentage of CDA+RHA
increases, this is a clear indication that further introduction of percentage of CDA+RHA beyond
10% will greatly affect its Strength properties of the specimen negatively.
Compressive strength =
𝐿𝑜𝑎𝑑(𝑁)
𝐴𝑟𝑒𝑎(𝑚𝑚2)
Table 20:Cube strength of CDA+RHA varying the percentage for replacement of cement at
28 days of curing
RHA+CDA Compressive strength of concrete (N/mm2
)
0% 37.75
5% 31.25
10% 31.25
15% 25.25
Figure 15 below clearly shows the pattern of the Cube Strength with various percentages of
CDA+RHA against curing time, the Cube Strength is highest at 28 days with 37.75N/mm2 at 0%
while the lowest Cube Strength is recorded at 28 days with 25.25 N/mm2 at 15%. The compressive

41
strength of concrete deceases with increases percentages of CDA+RHA as shown in figure 12.
The bar chart represents that the compressive strength of concrete remains constant on replacement
of 5% and 10%.
Figure 15:Bar chart representation of compressive strength of cubes against curing periods
37.75
31.25 31.25
25.25
0
5
10
15
20
25
30
35
40
0% 5% 10% 15%
CompressiveStrengthon28curing
days
RHA+CDA
Compressive strength of concrete

42
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
Cow Dung Ash and Rice Husk Ash concrete can be made to perform well in certain floor and wall
applications when a ten percentage (10%) replacement is not exceeded.
The Cow Dung Ash and Rice Husk Ash requires more quantity of water as the percentage
increases in the concrete, therefore it has a serious limitation that must be understood before it is
put to use.
The Cow Dung Ash and Rice Husk Ash have an advantage that offers lightness of weight that
makes it useful construction material.
More water is required to achieve the standard consistency as the amount of CDA+RHA increases.
Compressive strength decreases as the CDA+RHA content increases and increases as the curing
period is prolonged.
With strength as a criterion, CDA+RHA of no more than 15% can be used to produce good and
quality mortar and concrete.

43
REFERENCES
1. Alexander, M. & Mindess, S., 2005. Aggraagates In Concrete. New York: Taylor &
Francis Group.
2. Akeke, G. A., Ephraim, M. E., Akobo, . I. & Ukpata, J. O., 2013. Structural properties of
rice husk ash concrete. International Journal of Engineering and Applied Sciences,
Volume 3, pp. pp 57-62.
3. Arun Kumar, R. & Nazeer, M., 2014. Strength Studies on Metakaolin Blended High-
Volume Fly Ash Concrete. International Journal of Engineering and Advanced
Technology (IJEAT), 3(6), p. 176.
4. Dabai, M. & Muhammad, C., 2009. Studies on the effect of rice husk ash as cement
admixture. Nigerian Journal of Basic and Applied Science (NJBAS), Issue 17(2)252-256.
5. Duggal, S., 2008. BUILDING MATERIALS. third revised ed. New Delhi: New Age
International (P) Ltd., Publishers.
6. Gambhir, M., 2006. CONCRETE TECHNOLOGY. 3 ed. New Delhi: Tata McGraw-Hill
Publishing Company Ltd.
7. Habeeb, G. & Mahmud, H., 2010. Study on properties of Rice Husk Ash and its use as
cement replacement material. Material research-Ibero-American Journal of Materials,
13(2), pp. 185-190.
8. Kumar , P. T. & Reddy, R. H., 2015. A STUDY ON THE REPLACEMENT OF
CEMENT IN CONRETE BY USING COW DUNG ASH. International Journal of
Scientific Engineering and Applied Science (IJSEAS), 1(9).
9. Mehta, 2004. High-performance, High-Volume Fly Ash Concrete for Sustainable
Development. International Workshop on Sustainable Development and Concrete
Technology, 20-21 May.
10. MINAGRI, 2010. Enabling Self Sufficiency and Competitiveness of Rwanda Rice, Kigali:
Arumugam KATHIRESAN.
11. MINAGRI, 2013. Rwanda’s Rice Commodity Chain, Kigali: Arumugam KATHIRESAN.
12. Ojedokun, O. Y. & Adeniran, A. A., 2014. Cow Dung Ash (CDA) as Partial Replacement
of Cementing Material in the Production of Concrete. British Journal of Applied Science
& Technology, Issue 4(24): 3445-3454.
13. Omoniyi, T., Duna, S. & Mohammed, A., 2014. Compressive strength Characteristic of
Cowdung ash blended cement Concrete. International Journal of Scientific &
Engineering Research, 5(7).
14. Pavithra, V., 2016. AN EXPERIMENTAL INVESTIGATION ON CONCRETE BY
USING SOIL AND COW DUNG ASH AS A PARTIAL REPLACEMENT OF FINE

44
AGGREGATE AND CEMENT. International Conference on current Research in
Engineering Science and Technology (ICCREST).
15. RAB, 2017. Girinka Programme, Kigali: RAB.
16. Ramesh, S. & Kavitha, S., 2014. Experimental study on the behavior 0f cement concrete
with RHA. International Journal of Engineering and Applied Sciences, Volume 6.
17. SHETTY, M., 2005. CONCRETE TECHNOLOGY. First Multicolour Illustrative Revised
Edition ed. New Delhi: S. CHAND & COMPANY LTD.
18. Smith , L. & Wheeler , W., 1979. Nutritional and Economic Value of Animal Excretal.
Journal Journal of Animal Science, p. 48.
19. Sruthy , B. & Krishnan et etal, A. G., 2017. An Experimental Investigation on Strength of
Concrete Made with Cow Dung Ash and Glass Fibre. International Journal of
Engineering Research & Technology (IJERT), 6(03), p. 492.
20. Varshney, H., 2015. Utilization of Rice Husk Ash in concrete as cement replacement.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE), p. 28.

45
APPENDICES
Appendix 1: Timeline schedule
Appendix2: Budget
S/N ACTIVITIES AMAOUNT (Frw)
1 Transport 75,000
2 Communication 25,000
3 Sample and data collection 100,000
4 Documentation, internet and printing 50,000
Total 250,000

46
Appendix 3: Project photos
IS Standard sieves Sieved RHA Unsieved RHA
Cubes in curing tank Weighing concrete cubes Sieved CDA
Compressive test at SJEC
Ltd
Compressive testing
machine
Consistency test

47
Appendix 4: Recommendation Letters

48
Appendix5: compressive strength test results

Final year project by nsengimana innocent

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