experimental evaluation of self-healing concrete …
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EXPERIMENTAL EVALUATION OF SELF-HEALING CONCRETE
USING BACTERIA: BACILLUS SUBTILIS AND SPOROSARCINA
PASTEURII
MSc. THESIS
ELSHADAY ESHETU MULATU
HAWASSA UNIVERSITY, HAWASSA , ETHIOPIA
JUNE 2019
EXPERIMENTAL EVALUATION OF SELF-HEALING CONCRETE
USING: BACILLUS SUBTILIS AND SPOROSARCINA PASTEURII
ELSHADAY ESHETU
A THESIS SUBMITTED TO THE INSTITUTE OF TECHNOLOGY
SCHOOL OF CIVIL ENGINEERING FOR THE PARTIAL
FULFILLMENT OF THE REQUIREMENTS ON THE DEGREE OF
MASTER OF SCIENCE IN CIVIL ENGINEERING
(STRUCTURAL ENGINEERING)
SCHOOL OF GRADUATE STUDIES
HAWASSA UNIVERSITY
HAWASSA, ETHIOPIA
REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
IN STRUCTURAL ENGINEERING
JUNE 2019
HAWASSA, ETHIOPIA
HAWASSA UNIVERSITY
INSTITUTE OF TECHNOLOGY
SCHOOL OF CIVIL ENGINEERING
SCHOOL OF GRADUATE STUDIES
DECLARATION SHEET
I hereby declare that this MSc. Thesis “Experimental Evaluation of Self-Healing
Concrete Using Bacteria: Bacillus Subtilis and Sporosarcina Pasteurii” is my original
work and has not been presented for a degree in any other university, and all sources of
material used for this work are clearly acknowledged.
Name: Elshaday Eshetu Mulatu.
Signature: __________________
Place: Hawassa University
Date of submission: ___________________
SCHOOLS OF GRADUATE STUDIES
HAWASSA UNIVERSITY
ADVISORS’ APPROVAL SHEET
This is to certify that the Thesis Entitled “Experimental Evaluation of Self-Healing Concrete
Using Bacteria: Bacillus Subtilis and Sporosarcina Pasteurii” submitted in Partial Fulfillment
of the Requirements for the Degree of Master’s of Science with specialization In Structural
Engineering, the Graduate Program of the Department of Civil Engineering, has been
carried out by Elshaday Eshetu Mulatu ID.No PGstru/015/09, under our supervision.
Therefore we recommend that the student has fulfilled the requirements and hereby can
submit the thesis to the department.
TEMESEGEN WONDIMU (PHD) __________________ 03/06/19
Name of major advisor Signature Date
ASNAKE KEFELEGN (MSC) _____________ 05/06/19
Name of co-advisor Signature Date
HAWASSA UNIVERSITY
SCHOOLS OF GRADUATE STUDIES
EXAMINER’S APPROVAL SHEET
As members of the Board of examiners of the final Master’s degree open defense, we
certify that we have read and evaluated the thesis prepared by Elshaday Eshetu Mulatu
under the title “Experimental Evaluation of Self-Healing Concrete Using Bacteria:
Bacillus Subtilis And Sporosarcina Pasteurii " and examined the candidate. This is
therefore to certify that the thesis has been accepted in partial fulfillment of the
requirement for the degree of Master’s of Science in Structural Engineering.
Name of Chair Person Signature Date
________________ ________ ____________
Name of Internal Examiner Signature Date
________________ ____________ ___________
Name of External Examiner Signature Date
________________ ____________ ____________
SGC Approval Date
Final approval and acceptance of the thesis is contingent upon the submission of the final
copy of the thesis to the school of Graduate Studies (SGS) through the
Department/School Graduate Committee (DGC/SGC) of the candidate’s department.
Thesis approved by
__________________ __________________ __________________
DGC/SGC Signature Date
Certification of the Final Thesis
I hereby certify that all the corrections and recommendation suggested by the Board of
Examiners are incorporated into the final Thesis “Experimental Evaluation of Self-
Healing Concrete Using Bacteria: Bacillus Subtilis and Sporosarcina Pasteurii” by
Elshaday Eshetu Mulatu.
__________________ __________________ __________________
Name of the Designate Signature Date
Date: __________________
i
DEDICATION
To
My Families
May God will keep you safe always!!!
ii
ACKNOWLEDGMENT
My sponsor ERA needs to have a great recognition for financially supporting my post-
graduation program.
I cannot even think to start research titled like this
without his guidance.
co-advisor Mr. Asenak Kefelegn (MSc.) for his kind
help during the entire tenure of my research. He made the skeleton and sole for research
work.+
Mr. Mihiretu and Mr. Robele, Civil Engineering school head and ERA coordinator
respectively, deserve a genuine appreciation for their support clearing the path for the
difficulties I face on the time of learning as well as doing this research. And also I am
thankful for secretary in the Department, Miss. Sofanit for her amazing patience and
support.
Mr. Henok from Hawassa University has been a wonderful and generous person who has
been on great help throughout the tenure. I admire him for his positive outlook and his
ability to smile despite of any situation.
Mr. Endale from S/N/N/P/R construction office, for giving me his generous help and the
expensive thing, his time. The lab work could be impossible with-out his positivity.
iii
EBI deserves a genuine appreciation. I found them very helpful for their good customer
service and fast response to the queries related to requests on micro-organisms. A special
thanks to Mr. Dereje (Ph.D.), who deserves the unlimited appreciation for his support.
I am thankful to the Food and Nutrition Laboratory Officers and Technicians. They all
deserve recognitions, especially Mr. Berhe (MSc.) for giving me every support I needed
to have the microbiological experiment. Without his help, the experimental work won’t
be easy and I could not have finished on time.
I am extremely grateful to my parents for their love, prayers, caring and sacrifices for
educating and preparing me for my future. I am very much thankful to my mother, Mrs.
Yeshiwareg M. and father Mr. Eshetu M. for their love, understanding, prayers and
continued support to complete my research work. Also I express my thanks to my
grandparents, sisters, brother, aunts and uncles for their support and valuable prayers.
Mr. Gelana D., Mr.
Akiya , Mr. Henok and Mrs. Ement T.
Specially Miss. Elshabeth A, her support was limitless which helped me to complete this
research successfully. I am lucky to have friends like them.
Elshaday Eshetu
iv
TABLE OF CONTENTS
Contents Page
DEDICATION ................................................................................................................... i
ACKNOWLEDGMENT ................................................................................................... ii
TABLE OF CONTENTS ................................................................................................. iv
LIST OF TABLES ........................................................................................................... ix
LIST OF FIGURES .......................................................................................................... xi
LIST OF TABLES IN APPENDICES ............................................................................ xiii
LIST OF FIGURES IN APPENDICES .......................................................................... xiv
LIST OF ABBREVIATION / ACRONYM .................................................................... xvi
ABSTRACT .................................................................................................................. xvii
CHAPTER ONE ............................................................................................................... 1
1. INTRODUCTION ..................................................................................................... 1
1.1 Background of Study ......................................................................................... 1
1.2 Self-healing Concrete ......................................................................................... 2
1.3 Research Question ............................................................................................. 5
1.4 Objective ........................................................................................................... 5
General Objective ........................................................................................ 5
Specific Objective ........................................................................................ 5
v
1.5 Statement of the Problem ................................................................................... 6
1.6 Significance of the Study ................................................................................... 6
1.7 The Scope of the Study ...................................................................................... 7
1.8 Structure of Thesis Report .................................................................................. 7
CHAPTER TWO .............................................................................................................. 9
2 LITATURE REVIEW ............................................................................................... 9
2.1 Introduction ....................................................................................................... 9
2.2 Crack in Concrete ............................................................................................ 12
Causes of Cracking in Concrete .................................................................. 13
Types of Crack in Concrete Structure ......................................................... 13
2.2.2.1 Structural Cracks ................................................................................. 13
2.2.2.2 Non-Structural Cracks ......................................................................... 14
2.3 Ways and Techniques for Crack Minimization ................................................. 14
2.4 Healing Approaches and Process ...................................................................... 16
Self-Healing Method .................................................................................. 16
Self-Healing: Biological Approach ............................................................. 17
Healing Working Process ........................................................................... 18
Effects of Bacteria on Concrete .................................................................. 20
2.5 Factors Affecting the Strength and Healing Ability of Bio-Concrete ................ 21
vi
Concentration of Bacteria ........................................................................... 21
Type of Media the Bacteria Grow............................................................... 22
2.6 Mechanism of Bacteria Self-Healing Using Bacteria ........................................ 22
CHAPTER THREE ......................................................................................................... 24
3 Material and Method................................................................................................ 24
3.1 Introduction ..................................................................................................... 24
3.2 Materials .......................................................................................................... 24
Fine Aggregate ........................................................................................... 24
Coarse Aggregate ....................................................................................... 24
Water ......................................................................................................... 25
Cement ....................................................................................................... 25
Microbial ................................................................................................... 25
3.2.5.1 Bacillus Subtilis .................................................................................. 25
3.2.5.2 Sporosarcina Pasteurii ......................................................................... 26
Nutrient Media ........................................................................................... 27
3.2.6.1 Urea-CaCl2 Medium ............................................................................ 27
3.2.6.2 Nutrient Broth Medium ....................................................................... 27
3.3 Methods ........................................................................................................... 28
Biological Experiment ................................................................................ 29
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3.3.1.1 Method for Applying Bacteria ............................................................. 29
3.3.1.2 Micro Organism Growth ..................................................................... 29
3.3.1.3 Batch Culturing of Bacillus Species .................................................... 30
3.3.1.3.1 Procedure for Mass Culturing ......................................................... 30
Concrete Making experiment ..................................................................... 35
3.3.2.1 Concrete specimen preparation ............................................................ 35
3.3.2.2 Concrete Casting ................................................................................. 36
Experimental Analysis ............................................................................... 37
3.3.3.1 Treatments used for the experimental work ......................................... 37
3.3.3.2 Slump Test .......................................................................................... 39
3.3.3.3 Compressive Strength ......................................................................... 39
3.3.3.4 Flexural Strength ................................................................................. 40
3.3.3.5 Crack Healing Evaluation.................................................................... 41
3.3.3.5.1 Visual Inspection ............................................................................ 41
3.3.3.5.2 Load And Unload of Flexural Load on Beam Specimens ................ 42
CHAPTER FOUR ........................................................................................................... 43
4 TEST RESULT AND DISCUSSION ...................................................................... 43
4.1 Introduction ..................................................................................................... 43
4.2 Workability ...................................................................................................... 43
viii
4.3 Compressive Strength ...................................................................................... 44
4.4 Flexural Strength Test ...................................................................................... 54
4.5 Self-Healing Efficiency .................................................................................... 55
4.5.1 Visual inspection ........................................................................................ 55
4.5.2 Load and unload of Flexural Load on Beam Specimens ............................. 59
4.6 Flexural Strength Test after Crack Healing the Micro-Cracks ........................... 60
CHAPTER FIVE ............................................................................................................. 61
5 CONCLUSION AND RECOMMENDATION ........................................................ 61
5.1 Conclusion ....................................................................................................... 61
5.2 Recommendation ............................................................................................. 62
REFERENCE .................................................................................................................. 64
APPENDICES ................................................................................................................ 70
Appendix A: Photos showing the accessing Bacteria, preparing ingredients for culturing
the bacteria, collection of materials (equipment) and culturing the bacteria. ..................... 70
Appendix B: Collecting materials for concrete cubic and Beam production .................... 72
Appendix C: Material Properties Test for concrete mixing .............................................. 76
Appendix C 1: Fine Aggregate Physical Properties Test .............................................. 76
Appendix C 2: Coarse Aggregate physical properties test ............................................ 79
Appendix C 3: Summary on Physical Properties Test .................................................. 82
Appendix C4: Mix Design ........................................................................................... 82
Appendix D: Chemical Composition, Compressive Strength and Flexural Strength ......... 85
Appendix E: Driving Flexural Strength for Three Point Loading Set-Up ......................... 90
ix
LIST OF TABLES
Table Page
Table 2.1 : Structural Cracks Formed in Main Structural Elements ................................. 13
Table 3.1: Chemicals Contents in 13 g of Nutrient broth.................................................. 28
Table 3.2: Ingredients for Urea- CaCl2 Media Preparation .............................................. 31
Table 3.3 Ingredients for Nutrient Broth Media Preparation ............................................ 31
Table 3.4: Mix Ratios for the Trial Mix ........................................................................... 36
Table 3.5: Mix-ID Description for Bio-Concrete ............................................................. 38
Table 3.6: Test Program .................................................................................................. 39
Table 3.7: Mixing Proportion for Beam Mixes ................................................................ 40
Table 4.1: Compressive Strength for 7 Days for Controlled Specimens ........................... 44
Table 4.2: Compressive Test Result For 7 Days For U-BS 1%,3% And 5% ..................... 45
Table 4.3: Compressive Test Result For 7 Days For U-SP 1%,3% And 5% ..................... 45
Table 4.4: Compressive Test Result For7 Days For N-BS 1%, 3% and 5% ..................... 45
Table 4.5: Compressive Test Result for 7-Days for N-SP 1% ,3% and 5% ....................... 46
Table 4.6: 7th day Compressive Strength Percentage Relative to Controlled Specimens ... 46
Table 4.7: Compressive Test Result for 14-Days for Controlled ..................................... 47
Table 4.8: Compressive Test Result for 14-Days for U-BS 1% ,3% and 5% .................... 47
Table 4.9: Compressive Test Result for 14-Days for U-SP 1%, 3% and 5% ..................... 48
Table 4.10: Compressive Test Result for 14-Days for N-BS 1%,3% and 5% ................... 48
Table 4.11: Compressive Test Result for 14-Days for N-SP 1% ,3% and 5% ................... 48
Table 4.12: 14th day Compressive Strength Percentage Relative to Controlled Specimens 49
Table 4.13: Compressive Test Result for 28-Days for Controlled .................................... 50
Table 4.14: Compressive Test Result for 28-Days for U-BS 1% ,3% and 5% .................. 50
x
Table 4.15: Compressive Test Result for 28-Days for U-SP 1%,3% and 5% .................... 50
Table 4.16: Compressive Test Result for 28-Days for N-BS 1%,3% and 5% ................... 51
Table 4.17: Compressive Test Result for 28 Days for N-SP 1%,3% and 5% .................... 51
Table 4.18: 28th day Compressive Strength Percentage Relative to Controlled Specimens 51
Table 4.19: Flexural Strength of Bio-Concrete Beam Compared with Controlled ............ 54
Table 4.20: Flexural Strength Test after healing............................................................... 60
xi
LIST OF FIGURES
Figure Page
Figure 1.1 “Scenario of Crack-Healing by Concrete-Immobilized Bacteria” ..................... 4
Figure 2.1: Formation of Calcium Carbonate from Bacterial Cell Wall ............................ 18
Figure 3.1: Bacillus Subtilis Species ................................................................................ 26
Figure 3.2: Sporosarcina Pasteurii Species ....................................................................... 26
Figure 3.3: The Accessed Microbial: Bacillus Subtilis and Sporonciana Pasturii.............. 27
Figure 3.4: Ingredient for Preparing Media for the Bacteria ........................................... 30
Figure 3.5: Conical Flasks Used for Media Preparation ................................................... 30
Figure 3.6: Measuring Chemicals for Media Preparation and Labeling ............................ 32
Figure 3.7: Putting on the Conical Flask on Hot Plate for Mixing All Ingredients ............ 32
Figure 3.8: Urea- CaCl2 Media ........................................................................................ 33
Figure 3.9: Nutrient Broth Media..................................................................................... 33
Figure 3.10: Inoculating Bacteria in to Each Medium-One .............................................. 33
Figure 3.11: Inoculating Bacteria in to Each Medium-Two .............................................. 34
Figure 3.12: Distribution of Bacteria Culture for Urea-CaCl2 Media ................................ 34
Figure 3.13: Distribution of Bacteria Culture for Nutrient Broth Media ........................... 34
Figure 3.14: Curing of Cubes........................................................................................... 35
Figure 3.15 Mixing Bacteria with Concrete Ingredients .................................................. 36
Figure 3.16: Setup for Flexural Testing of Concrete by 3rd Point Loading ....................... 40
Figure 3.17 Casting Beam with Timber Mold .................................................................. 41
Figure 3.18: Beam Flexure Test of Specimens by Third-Point Loading Method............... 41
Figure 4.1 Slump Test Result for Cubic Specimens ......................................................... 43
Figure 4.2: Slump Test Result for Beam Specimens ........................................................ 43
xii
Figure 4.3: 7th -Days Compressive Strength for Controlled and Bacteria Concrete ........... 47
Figure 4.4: 14th -Days Compressive Strength for Controlled and Bacteria Concrete ......... 49
Figure 4.5: 28th -Days Compressive Strength for Controlled and Bacteria Concrete ......... 52
Figure 4.6: Highest value in compressive strength performed by N-SP-3% ...................... 52
Figure 4.7:Values 7th, 14th and 28th Days Compressive Strength Result............................ 53
Figure 4.8: Compressive strength for All Cubic Specimens ............................................. 53
Figure 4.9: Flexural Strength for Different Beam Specimens ........................................... 54
Figure 4.10: Beam Crack ( Before Self-Healing) ............................................................ 56
Figure 4.11: Beam Crack (After Self-Healing-1) ............................................................. 56
Figure 4.12: Beam Crack (After Self-Healing-2) ............................................................. 56
Figure 4.13: Self-Healing Progress by N-BS.................................................................... 56
Figure 4.14: Calcium Carbonate Precipitation.................................................................. 57
Figure 4.15: Crack Healing by U-BS ............................................................................... 57
Figure 4.16: Crack Healing by N-SP................................................................................ 58
Figure 4.17: Crack Healing by N-SP................................................................................ 58
Figure 4.18 CaCO3 Present identification from Sample taken from precipitate in CS ....... 59
Figure 4.19: Flexural Strength on Three Stage of Loading ............................................... 60
xiii
LIST OF TABLES IN APPENDICES
Table B 1: Measuring Slump for Cubic Specimen Mixes ................................................. 74
Table C 1: Test Results of Sieve Analysis of Fine Aggregate........................................... 78
Table C 2: Grading Requirement for Aggregate in Normal-weight Concrete ................... 79
Table C 3: Result for Material Properties Tests ................................................................ 82
Table D 1: Chemical Composition on Different Oxide Content of 5 Cement Production
Factories .................................................................................................................. 85
Table D 2: Chemicals Contents in 13 g of Nutrient Broth (HiMedia™ 1919)................... 86
xiv
LIST OF FIGURES IN APPENDICES
Figure A 1: Picture Taken at EBI for Accessing the Microbial ........................................ 70
Figure A 2: Preparing and Measuring Ingredients for Media Preparation ......................... 70
Figure A 3: Dissolving and Mixing Nutrients Using Hot Plate ......................................... 71
Figure A 4: Removing media Serializing and Inoculating the Bacteria ............................. 71
Figure A 5: Preparing Nutrients for Mass Culturing Bacteria for Further Use .................. 71
Figure B 1 Collecting Aggregates Fine Aggregate and Coarse Aggregate ........................ 72
Figure B 2: Measuring Silt Content and Specific Gravity in Fine Aggregate .................... 72
Figure B 3: Arranging Raffling Box for Dividing Fine Aggregate in Quarter ................... 72
Figure B 4: Blowing by Using Rod to Determine the Specific Gravity of CCA................ 73
Figure B 5: Measuring Cement for Mix ........................................................................... 73
Figure B 6: Mixing Concrete Paste with Bacteria and Measuring the Slump .................... 73
Figure B 7: Compacting and Curing Takes Place after De-Molding the Cubes-1 ............. 74
Figure B 8: Curing Takes Place after De-Molding the Cubes-2 ........................................ 74
Figure B 9: Measuring Weight of Cube for Casting for the Compression Strength ........... 75
Figure B 10: Compression and Flexural Testing Machine with Specimens ...................... 75
Figure B 11: Beam Setup for Measuring the Flexural Strength ........................................ 75
Figure D 1: The chemical composition of Muger OPC with Mass Percent Expressed by
Graph ...................................................................................................................... 86
Figure D 2: The 7 Days Test Result For Load vs. Time Graph-Photo from the Testing
Machine................................................................................................................... 86
Figure D 3: 14 Days Test Result for Load vs. Time Graph of CC for 3 Samples .............. 87
Figure D 4: 14 Days Test Result for Load vs. Time Graph of U-BS-1% for 3 Samples ... 87
Figure D 5: 14 Days Test Result for Load vs. Time Graph of U-Bs-3% for 3 Samples .... 87
xv
Figure D 6: 14 Days Test Result for Load vs. Time Graph of U-BS-5 % for 3 Samples ... 87
Figure D 7: Load vs. Time Graph for U-SP 1% for 3 Samples ......................................... 88
Figure D 8: Load vs. Time Graph for U-SP 3% for 3 Samples ......................................... 88
Figure D 9: Load Vs. Time Graph for U-SP 5% Three Cubic Specimens ......................... 88
Figure D 10: Load vs. Time Graph of N-BS-1% for 3 Specimens .................................... 88
Figure D 11: Load vs. Time Graph for N-BS 3% for 3 Specimens ................................... 89
Figure D 12: Load vs. Time Graph for N-SP 1 % for 3 Specimens .................................. 89
Figure D 13: Load Vs. Time Graph for N-SP 3 % for 3 Specimens .................................. 89
Figure D 14: Load Vs. Time Graph for N-SP- 5 % for 3 Specimens ................................ 89
Figure E 1: Three Point Loading Set-Up .......................................................................... 90
Figure E 2: Free Body Diagram for Section A-B ............................................................. 90
Figure E 3: Free Body Diagram for Section A-C ............................................................. 90
Figure E 4: Shear Force Diagram for Three Point Loading .............................................. 91
Figure E 5: Bending Moment Diagram for Three Point Loading ...................................... 91
xvi
LIST OF ABBREVIATION / ACRONYM
ACI America Concrete Institute
ASTM American Society of Testing Material
CCA Compacted Coarse Aggregate
CS Concrete Specimens
EBI Ethiopian Bio-Diversity Institiute
EDS Energy dispasive X-ray Spectroscopy
g/L Gram per Liter
PH Potential of Hydrogen
Kg Kilo-gram
L Liter
M20 Mix for 20 MPa in Compressive strength
MICP Microbiological Induced Calcium Carbonate Precipitation
ml Mili Liter
NaCl Sodium Chloride
N-BS Bacillus Subtilis with Nutrient Broth media
N-SP Sporosarcina Pasteurii with Nutrient-Broth Nutrient Media
OPC Oridenary Portland Cement
U-BS Bacillus Subtilis with Urea-CaCl2 Nutrient Media
U-SP Sporosarcina Pasteurii with Urea-CaCl2 Nutrient Media
xvii
ABSTRACT
Self-healing concrete using bacteria has a great potential to be used as a way to repair
cracks appearing in concrete structures in an excellent, cost-effective and eco-friendly
manner along with an improved mechanical performance of concrete. In this research the
biological concrete was prepared by using two bacterial species called Bacillus Subtilis
and Sporosarcina Pasteurii which were cultured using different media. Three different
mixes of this biological concrete were prepared by replacing 1%, 3% and 5% of water
with bacteria solutions. The concrete specimens were tested to evaluate the impact on
compression strength, flexural strength and ability in self-healing. From the experimental
test results it was found that the compressive strength, flexural strength and self-healing
ability of bacteria concrete at 7 days, 14 days and 28 days of curing age increased
compared to controlled concrete. The healing ability of concrete has been checked by two
mechanisms: by visualization and by loading and un-loading of flexural load on beam
specimens to form micro-cracks in the concrete. Both species show healing ability after t
cracks were introduced to the samples, specially Sporosarcina Pasteurii with nutrient
broth media shows the greatest result on the self-healing examination. From all
experimental works done, Sporosarcina Pasteurii bacteria performed better and from the
nutrients, Nutrient Broth is found to be the best nutrient for culturing the bacterial to
make the bio-concrete. Also adding 3% of the bacterial solution from the amount of water
needed in the mix-design, is found to be optimum. It is concluded that using self-healing
concrete is a best solution for filling the structural cracks which is a cause of major
concern.
Key words: Bacillus Subtilis, Bio-concrete, compression strength, flexural strength, self-
healing, Sporosarcina Pasteurii
1
CHAPTER ONE
1. INTRODUCTION
1.1 Background of Study
Concrete is a construction material which is resulted from mixtures of cement, fine
aggregates, coarse aggregates and other replacing material or admixtures (to modify the
property of concrete) blend together with the required amount of water.
Concrete is one of the most long-lasting man-made building materials and known by its
strength to resist compression force. However, it has a weak capacity on holding tension
force. Factors like exposure to harsh weather, reactions with common elements, and poor
construction can lead to failure of concrete. In construction industries, concrete is the
most common form of structural material used for building foundations, columns, beams,
slabs shear walls and other load-bearing elements.
Concrete technology deals with the study of properties of concrete and its practical
applications. Steps to be followed in making concrete. It starts from selecting suitable
qualities and quantities of materials which are tested to meet standards for material
properties. Then followed with calculating mix proportion using specified grade of
concrete and the result gained from the previous test. It is mandatory to follow the mix
design procedure in any selected standard. The tested ingredients then mixed together and
made concrete paste. Then after transporting the concrete to site and putting it in to the
formwork for casting will be tracked. Concrete should be vibrated properly in order to
remove the entrapped air which is a concern for strength perspective. After a suitable
duration of time, the formwork is removed followed by curing.
2
However, at post hardening of concrete since several difficulties like cracks and
deflections are seen in concrete due to the application of service load. Crack is one of the
major issue which challenges the service period of concrete. Crack by itself doesn’t mean
failure but due to crack, there might be other failures to be followed. So that this problem
should need more attention to minimize as well as to solve the problem. Crack in concrete
is an inevitable phenomenon but it can be controlled or minimized by having proper
design and construction, good selection of material and having maintenance and repairing
works. Once the crack developed in concrete structure, the cost of repairing and
maintenance work become demanding to treat the damage. The repairing and
maintenance work have its own problem, to solve this problem smart concrete called Self-
healing (Bio-concrete) introduced to provide a best solution to solve cracks developed in
concrete.
1.2 Self-healing Concrete
In general, there are two ways for achieving self-healing concrete. One is autogenous self-
healing concrete, which needs no introducing of any self-healing agent. The other is
Autonomies self-healing, it need self-healing agent to be introduce to make a self-healing
concrete.
In the past Era of construction industry authogenous healing of concrete was seen. This
natural process of healing had an ability to cover around 0.05 mm to 0.1 mm. The
mechanism of healing by nature of the concrete was due to in concrete act as a capillary
and become suitable for the water particle seep through the width of cracks. In this water
movement non-reacted cement particles react with water and hydration of cement takes
place. During this process the cement particles become enlarge; authogenous healing
happened finally (The contructors Civil Engineering, 2019). However, when the crack
3
becomes wider and wider, It is treated with different techniques used to heal the cracks,
bacteria concrete or bio-concrete is one of such method which has a great potential to this
days construction technology. The crack width sealed by the structure it-self due to the
addition of bacteria is through the mechanism of dry and wet cycles, and then finally
helps in completely healing the concrete cracks.
It was mentioned by Jonkers and Schlangen (1999) that, there was a new smart material
which have been introduced to our construction industry, self-healing concrete. Self-
healing concrete means a concrete which is capable of repairing its own crack without the
involvement of human beings action. Studies in previous decades of concrete
construction, concrete was undergoing self- healing without the addition of any materials
or organisms. This was due to the amount of cement used for the mix of concrete were
much more than the amount to achieve the right mix and some cement particles left
anhydrates and cast as they are. After time passes, concrete gets hardened and have
services load. Then it gets crack due to this and moisture inters to the crack, those
anhydrate cement particles become hydrated and form a paste this helps concrete to heal
from its crack and fill the gap by itself. However, nowadays this is not working as it was
before because the amount of cement introduce to the concrete mixing is limited by the
mix design. Now a days it is rare to find authogenous concrete. This is mainly the
designing of materials quantities leads a cement to be less compared to that of the
previous trend of construction.
In the current study, solving the problem facing by repairing and maintenance is the main
goal. In addition to this improving the concrete strength is the specific target. There are
also other benefits added to the easy of repairing technique using the mechanism of bio-
concrete technology, concrete structures strength.
4
The bacteria used in these new technologies are proved on producing urease enzyme
which helps to precipitate calcium carbonate, one of the main component of cement found
in making of concrete, this urea enzyme referred as microbial concrete enzyme.
(Jagadeesha , et al. 2013). There are some bacterial tested for their ability in producing
urease enzyme production like Aerobacter aerogenes, B. megaterium, Subtilis, Bacillussp.
CR2, B. thuringiensis, D. halophila, Halmonas eurihalina, Helicobacter pylori, Kocuria
flava CR1, L. sphaericusCH5, Methylocystis parvum, Myxococcus xanthus, Proteus
mirabilis, Pseudomonas denitrificans, SpoloactoBacillussp., Sporosarcina ginsengisoli
and Sporosarcina Pasteurii Perez–Perez et al. 1994; Rivadeneyra et al. 1996, 1998;
Stocks-Fischer et al. 1999; Ben Chekroun et al. 2004; Karatas et al. 2008; Chen et al.
2009; Achal et al. 2011, 2012b; Dhami et al. 2013b, 2014; Gorospe et al. 2013; Achal and
Pan 2014; Ganendra et al. 2014; Kang et al. 2014a (cited in Anbu, et al. 2016)
Figure 1.1 “Scenario of Crack-Healing by Concrete-Immobilized Bacteria” (Zwaag 2007)
It was reported in literature by Vidhya, et al. (2016) conclude that, the bacterial concrete
made from the bacteria makes a concrete structure gives aesthetically pleasant view. Also,
this bacteria concrete had benefits on enhancing the durability of the structures by
reducing the permeability (Vidhya , et al. 2016) .
5
1.3 Research Question
This study addresses the research questions which are listed below.
• Does bacterium concrete play a role on healing and improving the strength of
concrete?
• Which species of bacteria have a positive influence on the healing as well as the
mechanical property of concrete?
• Is changing the nutrient for the bacteria growth has an influence on the strength
improvement of concrete?
• Which percentage of bacteria solution gives an optimum strength for the Bio-
Concrete mix?
1.4 Objective
General Objective
The overall goal of this experimental study is to test self- healing ability of a bio-concrete
by using two species, Bacillus Subtilis and Sporosarcina Pasteurii.
Specific Objective
• To examine and compare the strength of conventional concrete with bacterial
concrete.
• To know which species of bacteria, have positive influence on the healing as well
as improving compressive strength of concrete.
• To compare which nutrient media that the bacteria grow has better result on
improving the strength of bio-concrete.
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• To understand the optimum percentage of bacteria solution, which is suitable for
the Bio-Concrete mix.
1.5 Statement of the Problem
Controlling crack is unquestionable during the time of design; because the consequence
may result failure. Concrete become concern to the public users, while crack is developed
on concrete i.e. people looks the crack and disturbed. The aesthetic value becomes
interrupted. The serviceability of the structure become affected or crack hurts the
serviceability of the structure. Crack can lead to many problems to structure so that it
needs more attention. In clearly understanding, to eliminate cracks in concrete structure is
not possible but it is practicable to maintain and repair it after seeing the appearance of
the crack. This repairing and maintenance had its own problem, for example to repair the
crack people have to be involved and should have to be known where it developed. It is
not easy to repair and maintain crack happened anywhere, even if it is possible the cost of
repair work is too much expensive. Therefore, the problem of crack needs a better
solution, making a concrete which is experienced self-healing that is Bio-Concrete.
1.6 Significance of the Study
There are many researchers conducted on this field of study area but the gap is in Ethiopia
the study is limited and almost null compared to other counties. Searching solution
regarding to cracks were not practicable in Ethiopia. Observing cracks was been seen as a
normal future of construction. This thesis provides many contributions in order to repair
cracks as well as improving the strength. It helps as an opening for further investigation
on specified bacteria and other non-photogenic spore forming bacteria with the way of
application for concrete works. This helps to have the application on mega projects like
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dam, bridges etc. During the process of self-healing the type of crack and its places of
crack formation is not affect the self-healing process which makes the use of the
technique will be preferable.
1.7 The Scope of the Study
This study is specifically focused on self-healing concrete by using Bacillus Subtilis and
Sporosarcina Pasteurii. Thus, the laboratory tests of conventional and bio-concrete were
carried out by using comprehensive and flexural strength testing machines. Additionally,
flexural strength of the self-healed concrete was also verified.
Load versus deflection could not be studied since the limited output of the machine. Self-
healing of concrete was studied here using visual inspection and loading and unloading of
beams were only studied since it was too difficult to get SEM and EDS. Also, durability
of the concrete was not performed for the reason of absence in testing machine.
1.8 Structure of Thesis Report
After this introduction chapter, a literature review on self-healing concrete is presented in
Chapter 2. On this part cracks and their causes were discussed well and also it solution
especially using self-healing concrete with the close the understanding of self-healing
mechanism were discussed. Various means which will be inducing the healing process,
the concentration of the bacteria and their nutrients type have an influence on the bio-
concrete were also mentioned.
Chapter 3 the material and methodology of the study, testing procedures and materials
used by describing various activities of the research are mentioned. From the materials
microbial, nutrient media for the bacteria, aggregates (coarser and fine), water and cement
were used. On the second subsection part of this thesis, the method was briefly explained,
8
mainly there are mainly two experimental works performed, one is the biological
experiment: mass culturing the bacteria and the other is constructional: making the
concrete cube specimen. Then testing the compressive strength and observing healing
ability of the biological and controlled concrete is followed.
Chapter 4, this chapter first discusses on observed results on material properties, slump
test and goes to compressive strength result for 7, 14 and 28 days were discussed. Then
the healing ability in beam specimens were argued and also the flexural strength test
result are mentioned for the control beam, the bacterial beam with load unload situation
and the bacterial beam without load unload. In general, this chapter presents a detailed
analysis and discussion of the results that are obtained by all tests performed in the study.
Chapter 5 present conclusions based on the result got in the previous chapter and
recommendation for future works are discussed here.
9
CHAPTER TWO
2 LITATURE REVIEW
2.1 Introduction
Concrete become the most widely used building material in the modern construction,
which reached improved and keep expanding starts from the very first application at the
mid 19th century to today stage. It is not a new thing for the concrete to exhibit cracks
both on the surface as well as inside it. Crack is a kind of global problem which affects
the buildings aesthetic and durability of the structure. Also further it can destroy the
integrity and safety of the structure (Nama, et al. 2015).
It is Noticeable that concrete structures get crack when they carry service load. Different
codes and standards convey that cracks in concrete should have to be considered and
specifies that, it can be handled by design codes. ACI code for example, on section 10.6.7
state that it has to be promising to handle the crack width by limiting the maximum
reinforcement bar spacing and cover for both one-way slabs and beam ( Wight and
Macgregor, 2012).
According to the report by Building research (2018) damages in concrete due to cracks
resulted via two main causes, one is the primary cause which lead to structural damage.
This is due to improper arrangement in amount as well as in detailing of reinforcing bars.
The secondary causes for crack formations are exercising natural phenomenon of concrete
itself like temperature effect, shrinkage etc. The report additionally stated the formation
of cracks on the surface of concrete mainly as a result of shrinkage, corrosion of
reinforcement bars, temperature effect and creep effect in long term. This could be worse
when there is a process of carbonation and chloride attack which points on corrosion of
10
reinforcement bar that leads to decline the durability as well as strength of the structure.
As a part of solution the report recommended that controlling the crack width of concrete
can be achieved by improving and increasing the quality of concrete.
A research by Kelly (1963) articulates about cracks as: cracks are classified in different
types depending on different parameter. For example, they classified with respect to their
depth as: surface crack (map cracks and single continues cracks), shallow, deep and
through. According to Kelly statement the main reasons for the concrete to be cracked
during its fresh time (plasticity stage) to hardened time is for reliving the stress that is
beyond its tolerating capacity. He has driven on the demonstration of crack formation
causes are too many. However there is no simplified easy solution that can be done.
According to a study by Gandhimathi, et al. (2012) defines self-healing concrete as
“without the action of human beings, concrete can feel and heal its own crack”. Whatever
the crack type is, it starts to cure itself with the introduction of bacteria. These bacteria
can stay in the dormant (inactive) stage inside the concrete for up to 200 years.
Gandhimathi, et al. (2012) point out that not all bacteria give similar result when added to
the ingredients of concrete but the most special and common type of bacteria are used to
achieve the property. According to their study bacteria Bacillus Spherila was used to
make self-healing concrete. Their study meanly focuses on understanding the mechanical
properties like compressive strength of self-healing concrete with varying the percentages
of bacteria used. According to the authors the process of self-healing are stated in four
steps, (1) material like calcite formation (2) blocking of the path by sedimentation of
particles (3) continued hydration of cement particles (4) surrounding cement matrix
swelling. According to them, bacteria increase the strength as well as the durability of
concrete after cracking. They suggested for further investigation to achieve best result
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using buffer solution (phosphate buffer) and Urea CaCl2 to keep the bacteria survive at
high PH environment.
Saranya, et al. (2018) explained about self-healing concrete, which has an ability to heal
itself after damage occur based on bacteria introduced to it. Saranya suggested these self-
healing bacteria can cure it whenever crack happens to it, increase the durability, avert
from corrosion and prevent leakage problems. Saranya detailed that self- healing concrete
importance is not bounded by just extending the service life of the concrete but also
reduce the cost of maintenance and repair work. On Saranya study, the bacteria used in
the concrete are mixed with its food, calcium lactate. The bacteria stay dormant until a
crack develops on the concrete and contact with water. There is three processing method
for the bio-concrete preparation, (1) by direct adding of bacteria Bacillus Saranya (2) by
developing bacteria with the help of adding chemicals and (3) extraction of bacteria and
directly sprayed or injected in structure surface were cracks are developed. The test result
gives a positive reaction on the first method when comparing the bio-concrete for the test
made in compressive strength, flexural strength and split tensile strength. This study
refers that the bacteria concrete develop a good solution for concrete structure.
Monishaa and Nishanthi (2017) Explained that although the materials used for all types of
construction, concrete is referred to as the best by its strength as well as different
properties like durability, fire resistance made it delectable. As the authors mentioned this
could be affected because concrete is weak in tension, cracks start to develop and
propagate incredulity became on its durability, the strength of concrete and step up to
corrosion on reinforcing bars are the major issues that come up due to cracks. The only
defect in the use of concrete is weak in tension the Possibility of formation of the crack is
more. Apart from this, freeze-thaw action and shrinkage also lead to cracking in concrete.
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The durability of concrete is highly affected due to cracks and it leads corrosion of
reinforcing bars. So it is very essential to find a suitable repairing mechanism to regain
the strength of concrete. In concrete structures, repair of cracks usually involves applying
a cement slurry or mortar which is bonded to the damaged surface. Repairs can
particularly be time consuming and expensive. For crack repair, a variety of techniques is
available like impregnation of cracks with epox based fillers, latex binding agents such as
acrylic, polyvinyl acetate, butadiene styrene, etc. But traditional repair works like epoxy
injection have a number of disadvantageous aspects such as effectiveness in the repair
work.
Another study by Kumar, et.al (2015) done on the investigating performance of biological
concrete where formed by the bacteria inserted to concrete. They found that the
compressive strength due to the induced bacteria in M20 grade concrete becomes
maximum. They also mentioned that using microbiological concrete perform a self-
healing ability in addition to the increase in strength.
2.2 Crack in Concrete
Crack is full or partial departure of concrete in two or more fragments formed by breaking
or fracturing. It is one of the most common problem in concrete and which is need to be
avoided is crack. Different sources can be contributed for crack to be developed.
According to ACI 318-08, the present provisions for spacing are intended to limit surface
cracks to a width that is generally acceptable in practice but may vary widely in a given
structure.
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Causes of Cracking in Concrete
There are many causes to a block of concrete to be crack. The most significant ones are:
shrinkage, temperature, chemical reaction, poor construction practices, and error in
designing and detailing construction, overload and early removal of formwork, elastic
deformation and creep, corrosion of concrete.
Types of Crack in Concrete Structure
As mentioned in section 2.2.1 cracks can be developed due to many reasons. Manly
cracks are resulted from poor construction or improper selection of construction material
.in addition to temperature and shrinkage effects. Cracks divided generally in to two:
Structural and Non-structural Cracks.
• Structural Cracks
This type of cracks are developed due to incorrect design, faulty construction or
overloading which may end up resulting danger of the safety for the structure. Structural
cracks that are formed in main structural elements; beams, slabs, columns are listed in
Table 2.1 below.
Table 2.1 : Structural Cracks Formed in Main Structural Elements (Nama, et al. 2015)
Beam Columns Slabs
Flexural cracks Horizontal cracks Flexural cracks
Shear flexural cracks Diagonal Cracks Top flexural cracks
Torsional cracks Corrosion / bond cracks Shrinkage cracks
Bond slip
Disturbance
Tension
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• Non-Structural Cracks
Cracks which are formed due to internal forces developed in materials like crazing,
plastic shrinkage, plastic settlement, corrosion of concrete, alkaline aggregate, sulphate
attack, steel corrosion and so on. Also cracks can be classified as thin, medium and wide,
depending on their width.
a) Thin- less than 1mm
b) Medium- between 1mm to 2mm
c) Wide –more than 2mm width
2.3 Ways and Techniques for Crack Minimization
There are several methods of repairing cracks in concrete structure. Also it is very vital to
know about the type and nature of cracks that have appeared in the building to select the
most suitable and cost-effective method of repair. It is understood that choosing the right
method of repairing concrete crack in buildings can help to save a lot of time, money, and
energy and can give long-lasting results.
This are the most practical techniques for cracks in concrete, this are: Epoxy injections,
routing and sealing, stitching the cracks, drilling and plugging, gravity filling, dry
packing, overlay, surface treatments (Emanuel, 2017). Before applying those techniques it
is necessary to know where to apply and which is suitable to the existed crack.
Epoxy injection
The method consists of creating entry and venting ports at close intervals along the
cracks, sealing the crack on exposed surfaces, and injecting the epoxy under pressure.
Limited in fixing non-moving cracks in concrete walls, slabs, columns and piers. In this
15
technique, the crack is made broader at the surface with a grinder, and then the groove is
filled with a flexible sealant.
Stitching
This technique is done to provide a permanent structural repairs solution for masonry
repairs and cracked wall reinforcement. It is done by boring holes on both sides of the
crack, cleaning the holes and anchoring the legs of the staples in the holes with a non-
shrink grout.
Drilling and Plugging
This method is only appropriate when cracks run in reasonable straight lines and are
accessible at one end. This method is mostly used to repair vertical cracks in retaining
walls.
Gravity Filling
Low viscosity monomers and resins can be used to seal cracks with surface widths of
0.001 to 0.08 in.by gravity filling. High molecular weight methacrylates, urethanes, and
some low viscosity epoxies have been used successfully.
Dry packing
It is the hand placement of a low water content mortar followed by tamping or ramming
of the mortar into place and also helps in producing intimate contact between the mortar
and the existing concrete.
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Polymer Impregnation Monomer Systems
Can be used for effective repair of some cracks a monomer system is a liquid consisting
of monomers which will polymerize into a solid. The most common monomer used for
this purpose is methyl methacrylate.
Concrete had an experience on autogenic healing, and high strength ability due to the
large amount of non-hydrated cement particles found due to low water to cement ratio in
the matrix of material composition to form the concrete Edvardsen (1999) and Neville
(1990) ( as cited in Jonkers & Schlangen, 2008)
2.4 Healing Approaches and Process
Self-Healing Method
Healing approach first came from the study takes place at the previous decades of in
which the construction works of early age Before the concrete technology comes, self-
healing properties of concrete were observed as an autogenic behavior of it, this is due to
the amount of cement ingredient introduce in the concrete making mix were much more
than the amount needed so that some cementitious particle left the hydration process
while all the concrete ingredients mixes with water. Those cement particles which are left
un-hydrated after the concrete gets harden and experience service loads or other types of
load and get cracked; this start to hydrate with the help of moisture entered by the crack
formed. However, nowadays the amount of cement introduce to the nixing of concrete are
limited by the mix in design, so that it is rare to find un-hydrated cement particles which
later helps for the autogenic self-healing behavior.
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There are some techniques that help concrete to enhance this natural property of concrete.
Today’s technology leads construction industry to develop self-healing using some
materials and micro-organism. Concrete is become experiencing it’s healing whenever
gets damaged. Techniques used to make a self-healing concrete material are,
Microcapsules, Bacteria, Shape memory polymers and flow Networks are some that can
be mentioned (Teall, et al. 2016). From those self-healing mechanisms using bacteria is
preferable technique.
Self-Healing: Biological Approach
A study by Kumar, et al. (2015) showed that the use of bacterial concrete by undertaking
M25 grade of normal concrete and M20 grade of bacterial concrete. Then comparing the
result from the tested value then finally concluding that using bio-concrete is beneficiary,
not only it is eco-friendly, and sustainable material, but also cost-effective because of the
normal M25 grade of concrete can be replaced by M20 of bacterial concrete which means
that the cost of the construction is therefore reduced. The methods of Self-healing are
decent methods for rehabilitation of micro-cracks in concrete. To be a perfect self-healing
system, the healing agent discharge after sensing the damage or cracks. Adding bacteria
will form a previous layer on the cracks of concrete which confirms the precipitation of
calcium carbonate. Concrete is a highly alkaline material, the bacteria added is capable of
withstanding alkali environment (Vijay, Murmu and V. Deo 2017). The help of these
Micros biologically induces calcium carbonate precipitation to fill the micro cracks and
bind the other materials such as sand, gravel in concrete. The involvement of
microorganism in calcite precipitation can increase the durability of concrete. Smaller
cracks less than 0.2 mm in concrete can be filled by concreting itself. But if cracks are
more than 0.2 mm fails to heal by the concrete itself which create a passage to deleterious
18
materials. In self-healing concrete, the formation of any cracks leads to activation of
bacteria from its stage of hibernation. By the metabolic activities of bacteria, during the
process of self-healing, calcium carbonate precipitates into the crack and heal it. Once the
cracks are completely filled with calcium carbonate, bacteria return to the stage of
hibernation. In the future, if any cracks form the bacteria gets activated and filled the
cracks. Bacteria act as a long-lasting healing agent and this is called as Microbiological
Induced Calcium Carbonate Precipitation (MICP).
Figure 2.1: Formation of Calcium Carbonate from Bacterial Cell Wall
Source: De Muynck,, et al. as (cited in Anbu, et al. 2016)
Healing Working Process
From Zwaag (2007) statement ‘‘Bacteria on fresh crack surfaces become activated due to
water ingress ion, start to multiply and precipitate minerals such as calcite (CaCO3),
which eventually seal the crack, and protect the steel reinforcement from further external
chemical attack’’ (Zwaag 2007). Cracks that are on the surface of the concrete structure
will be healed by biologically produced lime stone which are going to result the self-
healing concrete. When cracks occur on concrete structure, and water starts to seep in
through, the spores of the bacteria begin the microbial activities on contact with the water
19
and oxygen. In the process of precipitating calcite crystals through nitrogen cycle, the
soluble nutrients are converted to insoluble CaCO3. The CaCO3 solidifies in the cracked
surface, thereby sealing it up.
𝐶𝑎𝑂 + 𝐻2𝑂 → 𝐶𝑎(𝑂𝐻)2 (1)
(Calcium Lactate) (Lime)
𝐶𝑎(𝑂𝐻)2 + 𝐶𝑂2 → 𝐶𝑎𝐶𝑂3 + 𝐻2𝑂 (2)
The mechanism of healing of concrete based the bacteria results from their potential to
precipitate calcium. The more calcium precipitate by the bacteria the further healing can
be achieved.
A study by Bhaskar (2016) argued that crack healing ability can be studied by pre-loading
and reloading the beam made by bacteria. While re-loading was at the first pre-loaded and
healed from the crack. Now load applied to the healed, new cracks were formed and
observed placed in another position, different from the former crack. From the result
gained by Bhaskar conclud that the bacteria make a concret to recover from its damage.
A study by Thakur, et al. (2016) Concrete could heal its own hairline cracking. Holes and
pores of wet concrete are healed. Combined calcium with oxygen and carbon di oxide to
form calcite is vital for healing small cracks which arrest the discharge of water.
Microbial-Induced Calcite Precipitation (MICP)
The application of using Microbial-induced Calcite Precipitation (MICP) is proved by
many researchers MICP used as sustainable and great efficiency in engineering
applications not bounded by in concrete technology and Cementation material but also
used on improving the properties of soil in both mechanical and geotechnical (Guobin, et
20
al. 2017). Bacillus Subtilis another species from Bacillus genus, also called as Hay
Bacillus or Grass Bacillus which are found commonly in human and ruminants’
gastrointestinal tract and in soil. Studies frontward from the 2000s, this organism Bacillus
Subtilis are commonly used in laboratory studies for their abilities of spore formation.
Bacteria spore have no role in reproduction they have no metabolic activity which means
they stay dormant in the structures and highly resistant to contrasting environmental
conditions like heat, dehydration, radiation, and chemical (Achama, 2013). The possible
reason for this is calcite mineral precipitation in the pores reduced the average pore radius
of concrete by obstructing the large voids in the hydrated cement paste. Since
interconnected pores are significant for permeability, the water permeability are reduced
relatively in bacteria treated specimens ( Nehru T, Rao and Reddy, 2017).
Effects of Bacteria on Concrete
The compression strength of concrete was increased by 25% in 28 days due to
immobilization of bacteria stated in Rama Chandran, et al. (as cited in Irwan, 2014). After
having the experimental study Saranya et al. (2018) revealed that bacterial concrete has
better strength in the compression strength which resulted 10% increment when compared
to the controlled concrete. And also this eco-friendly concrete gets a self-healing ability
additionally. Not only this but also the durability of different building material was
increased. The study was conducted using three different methods another study by
Rakesh Chidara, et al. (2012) Stated that using a microbial species called Sporosarcina
Pasteurii bacteria results a concrete to gain an early strength and also leads it to increase
the overall compressive strength with admixture of sodium carbonate and calcium
chloride added in to the concrete .The addition of bacteria also never alters the slump and
the initial setting time of concrete. The test was performed with different chemical
21
composition and by varying concentration by studying the influence of compression
strength at curing time of 3, 7, 14 and 28 days (Chidara, Nagulagama and Yadav, 2014).
A study by Monishaa and Nishanthi, (2017) was performed having different
concentration of Bacillus Subtilis strain (104, 105 and 106), the tested characteristics of the
concrete, i.e. compression strength, splitting tensile test, and flexural strength are all
improved. But mostly in all tests the 105 cell/ml concentration gives an optimum strength
(Monishaa and Nishanthi , 2017).
As Soundarya, et al. (2019) Investigated bacteria should capable of resisting the PH value
of concrete, which is ranged from the value 11 to 13 when cement gets contacted with
water. Bacterial species like Bacillus Subtilis, Bacillus Spharicus, and Bacillus Cereus are
preferred by their alkaline nature, they can resist alkali other than their non-pathogenic for
the healing of concrete. They also mentioned that the optimum results were gained from
the bacterial concentration having 105 cells per ml of Bacillus Subtilis.
2.5 Factors Affecting the Strength and Healing Ability of Bio-Concrete
Concentration of Bacteria
From previous studies done on this bio-concrete, the parameters were mostly depended on
changing the concentration from 105 cell/ ml to 109 cell/ml. From this result the most
promising result was acquired by Sahoo, (2016) having 107 cell/ml doses of Bacillus. This
dose of bacteria improve the 7th-day compressive strength was 58.2 % larger than
conventional cement mortar. The mortar compressive strength by a bacteria species called
Bacillus Pasteurii for the 28 days were by 23.4 % more. Finally, from their study they
concluded optimum doses for mixing mortar with bacteria has to be 107 cell/ml with
respect to enhancing the compressive strength.
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Type of Media the Bacteria Grow
The type of nutrient media highly influences the self-healing mechanism of the bacteria.
The bacteria become influenced by the type and the number of nutrient ingredients
affecting the bacterial growth. Many studies use nutrient broth as a nutrient for the
bacteria and some use other supplements with the addition of this nutrient broth.
In this present study these two nutrients for the growth of the bacteria are used, to
differentiate which nutrient is more suitable, i.e. Which means that which media type
have a positive effect on healing as well as increasing the mechanical strength of the
concrete.
A novel developed by Yoosathaporn, et al. (2016) revealed that Bacillus Subtilis which is
cultured in CME-media had an ability to facilitate the growth of crystalline calcium
carbonate. This result observed with the aid of SEM and EDS analysis.
2.6 Mechanism of Bacteria Self-Healing Using Bacteria
The main reason behind the improvement in compressive strength of concrete with the
addition of bacteria is due to the accumulation of 𝐶𝑎𝐶𝑂3 on the microorganism cell
surface. This makes to fill the pores found in the matrix of cement-sand.
Calcium carbonate which are formed by the reaction of calcium ions produced by
Sporosarcina Pasteurii bacteria and the calcium ions does not directly react with the
particles consisted by cement (C3S, C2S, C3A and C4AF), However it acts like a catalyst
for the cement hydration reaction. Here the equations below express the process both on
calcium carbonate formation (1) and cement producing chemicals reaction with water (2)
(Chidara, Nagulagama and Yadav, 2014). The study also states that the resistance
23
cementitious material towards the damage process is due to the presence of carbonate
crystals found on the surface of the bacteria.
𝐶𝑂(𝑁𝐻2)2 + H2O → 𝑁𝐻2𝐶𝑂𝑂𝐻 + 𝑁𝐻3
𝑁𝐻2𝐶𝑂𝑂𝐻 + H2O → 𝑁𝐻3 + 𝐻2𝐶𝑂 3
𝐻2𝐶𝑂 3 → 2𝐻+ + 𝐶𝑂 32−
𝑁𝐻3 + 2H2O → 2𝑁𝐻4+ + 2𝑂𝐻−
𝐻𝐶𝑂3− + 𝐻+ + 2𝑂𝐻− → 𝐶𝑂 32− + 2 H2O
𝐶𝑎2+ + 𝐶𝑂 32− → 𝐶𝑎𝐶𝑂 3 (1)
C3S , C2S, C3A , C4AF + H2O → 𝐶 − S − 𝐻 𝑔𝑒𝑙 + 𝐶𝑎(𝑂𝐻)2 (2)
Fashyap and Radhaakrisna ( as cited in Chidara, Nagulagama and Yadav 2014)
The intial setting time will not be affected by the bacteria added to concrete as a manual
addition of calcium carbonat which act like an accelaroter, Because the maximum
activity is about 16 hrs , which obviously do not affect the intial setting time (Chidara,
Nagulagama and Yadav, 2014)
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CHAPTER THREE
3 Material and Method
3.1 Introduction
In general, the materials used for this study were team up to make the final testable bio
concrete and conventional specimens. The materials and ingredients were prepared to
make 108 cubic and 9 beam specimens totally.
Equipment’s used for culturing bacteria in biological laboratories were: none shaking
Incubator, Autoclave, Electron balance, Conical flask, graduated cylinder, measuring
cylinder refrigerator, Photo meter. For testing mechanical strength in constructional
laboratory: ADR Touch Control PRO range of compressive strength machine, Technotest
flexural strength Testing machine, which conforms to the requirements of ASTM E 4. For
testing material property: Vacant apparatus, Sieve Shaker, Weight balance, Oven and
another common laboratory apparatus were used.
3.2 Materials
Fine Aggregate
Locally available natural river sand (fine aggregate) used and found around Hawassa city
called Dimtu was used. This sand was prepared as ASTM requirement by having studied
its material property and after it confirms the standards it used for the study.
Coarse Aggregate
The coarse aggregate is crashed natural stone and it was also found from locally available
market in Hawassa city around Kebel 01.
25
Water
Normal drinkable tap water is used for the concrete mix but on the part of biological
experiment distilled water was used.
Cement
Muger 42.5 grade OPC cement was used for this study, the chemicals found in all
cements called C4AF found in Muger cement at higher in content which helps to control
the strength as well as the heat of hydration and its rapid setting time. The selection of
cement was presented in Appendix D: Chemical Composition, Compressive Strength and
Flexural Strength.
In Muger OPC, the C3A was less from the others. Therefor Muger 42.5 OPC cement was
selected for this study.
Microbial
The experiment was design two species of non- pathogenic, spore forming and urease
producing bacteria. These bacteria are genus of Bacillus which are isolated and identified
from soil samples. The bacteria are: Sporosarcina Pasteurii and Bacillus Subtilis and they
were accessed from EBI .Then the two bacteria species are mass cultured using nutrient
media.
• Bacillus Subtilis
Bacillus Subtilis is a rod-shaped, Gram-positive bacterium that is found in soil and the gut
of humans and some types of animals. Bacillus Subtilis is commonly included in
probiotic supplement formulations. It's a useful and beneficial probiotic that supports
26
digestion, enzyme assembly, immune and digestive system health. Below are the main
health assistances of this specific probiotic strain (Edward, 2017).
Figure 3.1: Bacillus Subtilis Species
• Sporosarcina Pasteurii
Sporosarcina Pasteurii previously known as Bacillus Pasteurii is a bacterium with the
ability to precipitate calcite and harden sand given a calcium source and urea, through the
process of MICP or biological cementation.
Figure 3.2: Sporosarcina Pasteurii Species
27
The cell concentration for both bacterial species is found from the turbidity test
result is 105 cell/ml of bacterial solution.
Nutrient Media
In this current study two types of nutrient media were prepared for both bacterial species
(Bacillus Subtilis and Sporosarcina Pasteurii), Urea-CaCl2 medium and Nutrient broth
medium.
• Urea-CaCl2 Medium
Urea–cacl2 medium was prepared using 3 g/l nutrient broth, 20 g/l urea, 2.12g/l
NaHCO3, 10 g/l NHCl, and 3.7 g/l CaCl2·2H2O [6, 14]. The pH of the Urea-CaCl
medium was adjusted to 6.0 using 6 NHCl solutions. The urea-CaCl2 culture medium was
used to facilitate after the microorganisms were grown. Tiano Petal (as cited in Lee , et al.
2015).
Figure 3.3: The Accessed Microbial: Bacillus Subtilis and Sporonciana Pasturii
• Nutrient Broth Medium
Nutrient Broth No. 3 used (HiMedia™ ,1919). In nutrient broth, there are a beef extract,
yeast extract, NaCl and peptone found. Form of autolysis beef, the beef extract is
28
prepared as dehydrated and in the form of paste is supplied as a powder. Peptone is casein
(milk protein) that has been as a digested with the enzyme pepsin. Constituent’s acts as a
primary nitrogen source in an enrichment growth medium peptone is dehydrated and
supplied as a powder. Peptone and Beef extract contains a mixture of amino acids and
peptides (Gandhimathi, et al. 2012). ''The beef extract also contains water-soluble digest
products of all other macromolecules (nucleic acids, fats, Polysaccharides) as well as
vitamins trace minerals. NH4C compound helps to maintain the PH of the media''.
Table 3.1: Chemicals Contents in 13 g of Nutrient broth
Chemicals Found in
Nutrient Broth
In 13 g of Nutrient
Broth
In 1 g of Nutrient
Broth
In 0.75 g of
Nutrient Broth
Beef extract (g) 1 0.077 0.05775
Yeast extract(g) 2 0.154 0.1155
Peptone (g) 5 0.39 0.2925
Sodium Chloride
(NaCl)
5 0.39 0.2925
3.3 Methods
This study combines both the biological and the Civil Engineering knowledge. Two main
experimental works were carried out in this research. One was for preparing bacteria
which is ready to mix with the concrete and other is for making the cubic and beam
specimens for testing.
After accessing the bacteria species from EBI (Ethiopian Bio-diversity Institute), those
bacteria needs to be cultured in order to get the required amount for the mixing with
concrete. Therefore the preparation of bacteria was carried out at Food and Nutrition
29
laboratory which is found in Hawassa Agricultural camps. All laboratory works regarding
to civil Engineering were done in Hawassa University Civil Engineering, Construction
Material Laboratory.
Biological Experiment
• Method for Applying Bacteria
As cited by Jonkers (1999) bacteria had the ability to improve the self-healing property as
well as on improving the mechanical strength of the concrete. Jonker also underlines that
these bacteria have a better effect if they use at the period of mixing of concrete
ingredients rather than applying after a crack was developed (Jonkers and Schlangen,
1999).
• Micro Organism Growth
The experiment was designed on having two species of non- pathogenic, spore-forming
and urease-producing bacteria. These bacteria are the genus of Bacillus: Sporosarcina
Pasteurii and Bacillus Subtilis. For examining which bacteria have a tendency to improve
compressive strength with healing ability. The two bacteria species are mass cultured
using different nutrient medium. Namely calcite precipitate medium (Urea-CaCl2) and
Nutrient broth. For investigating which bacteria species by which nutrient medium will
give a better growth for selected bacteria. The bacteria were mass cultured by following
procedures for batch culturing of the bacteria stated in section 0.0.0 . At the beginning
by properly making ready the nutrient media used for the growth of the microbial
followed by the other procedure knowing the behavior of the bacteria is mandatory and it
is to a bacteria type to resist must resist the alkaline- type environmental plus the warm
temperature situation due to the heat of hydration.
30
• Batch Culturing of Bacillus Species
After having one vial amount for each two different species of bacteria from EBI, the
mass culture were followed. After preparing all the ingredients for making the nutrient
media, the following procedure was used for mass-culture for further study.
Figure 3.4: Ingredient for Preparing Media for the Bacteria
Figure 3.5: Conical Flasks Used for Media Preparation
• Procedure for Mass Culturing
The culture began by making available all media ingredients, two 500ml volume flask
and two 250 ml volume flask. Using 500 ml volume flasks were prepared two 250 ml
broth media to grow both species separately. Then 200 ml distilled water was added for
31
each two prepared 500 ml flasks and 50 ml distilled water into smaller flasks (250 ml
volume). Then all calculated ingredient that are required to prepare 250 ml, mentioned in
Table 3.2 below. Then weighting all the components except urea putting into big flasks
will follow. The Urea ingredient needed to be separated here and, weight required amount
of urea and put into smaller flask each containing 50 ml distilled water.
Table 3.2: Ingredients for Urea- CaCl2 Media Preparation
Ingredients -1 Required Quantity in g/L
Nutrient broth 3
Urea 20
NaHCO3 2.12
NH4Cl 10
CaCl2.2H2O 28.5
Table 3.3 Ingredients for Nutrient Broth Media Preparation
Ingredients -2 Required Quantity g/L
Nutrient broth 13
After carefully measure all the ingredients using analytical balance. As it has been
suggested by Omoregie (2016) the media helping the bacteria to precipitate more calcite
are used here, nutrient broth ( 3g/L),Urea (20g/L) ,NaHCO3 (2.12g/L),NH4Cl (10.0g/L)
and CaCl2.2H2O (28.5g/L ) (Omoregie, 49).
32
Figure 3.6: Measuring Chemicals for Media Preparation and Labeling
• Ingredient- 2 means ingredients for Nutrient media preparation
Then adding the distilled water and all the necessary ingredients to the conical flasks it is
mandatory to cover each flasks with double layer aluminum foil and mix it well. Heat
media of the big flasks, not the flask having urea on hot plate until it become boiling.
Figure 3.7: Putting on the Conical Flask on Hot Plate for Mixing All Ingredients
33
Figure 3.9: Nutrient Broth Media
Then after mixing the ingredients well and boiling, it should be autoclaved to the
temperature at 121 °C and 2.5 Pa. Pressure. After reached to the desirable temperature
reached the autoclave was released until the flasks with the ingredients reaches
temperature of 45 °C. Succeeding this mixing the prepared media (200 ml) with urea
solution (50 ml) carful by transferred in to the urea solution.
Figure 3.10: Inoculating Bacteria in to Each Medium-One
Inoculate 0.5 ml both Bacillus Subtilis and Sporosarcina Pasteurii culture taken from the
gene bank into each big flasks (500 ml volume) containing on both media.
Then put it in to the incubator with for about 24hrs at 35 °C. After it stayed for 48 hrs it
had removed from the incubator. Now it is ready for further mass culturing. To get 1L of
Figure 3.8: Urea- CaCl2 Media
34
those specie, Prepare 2 (1500ml-2000ml each) sterilized flasks then The above procedure
were repeated.
Figure 3.11: Inoculating Bacteria in to Each Medium-Two
The same procedure also followed here to get 3L of those species (1.5 litter each species
with each medium) by preparing 8 (1500ml-2000ml) sterilized flasks. The prepare 750 ml
media in each flask followed similar procedures.
Finally bacterial cultures transferred in 500 ml volume for each medium flask into newly
prepared media (125ml for each)
For Urea-CaCl2 media- Medium One
Figure 3.12: Distribution of Bacteria Culture for Urea-CaCl2 Media
Figure 3.13: Distribution of Bacteria Culture for Nutrient Broth Media
35
After getting all amount of bacteria solution needed for both species of bacteria. Then the
bacteria solution were applied to the concrete past with different amount which is varied
by percentage of water needed for the mix as,1%,3% and 5%.
Concrete Making experiment
• Concrete specimen preparation
C-30 grade concrete was designed and 117 cubes having dimension of
150mm×150mm×150mm and 9 beams with dimension 150mm×150mm×600mm are
made. The cubic specimens are generally casted with and without bacteria and designated
as U-BS, U-SP, N-BS, N-SP and the CC respectively. Similarly the beams are also casted
to study the flexural strength and healing ability, as U-BS-B1, U-SP-B1, N-BS-B1, N-SP-
B1 and U-BS-B2, U-SP-B2, N-BS-B2, N-SP-B2 respectively. After casting and stayed
for about 24 hours the concrete become de-molded and submerged immediately to curing
bath which contains pure drinkable water.
Figure 3.14: Curing of Cubes
36
Mix Ratio
The mixing ratio has been calculated by ACI mix design to make C-30 by having the
physical properties of the materials which makes concrete. All the calculations for mix
design are attached on Appendix D. Then the ratio becomes:
Table 3.4: Mix Ratios for the Trial Mix
Water Cement Fine Aggregate Coarse Aggregate
63 100 205 302
0.63 1 2.05 3.02
• Concrete Casting
Method for preparing the bacterial concrete was a direct adding of the bacteria solution.
The bacteria demanded for applying to concrete was already prepared as explained in
previous section.
Figure 3.15 Mixing Bacteria with Concrete Ingredients
37
Experimental Analysis
• Treatments used for the experimental work
Mainly three treatments used for this experimental work, Bacteria species, Nutrient of the
bacteria and amount of bacteria solution. Figure 3.16 shows how many variables used
for the experimental work.
Figure 3.16: Treatments used for the experimental work
Concrete Cube Specimens
Bacillus Subtilis
Nutrient Broth
1%
7th day (3cubes)
14th day
(3 cubes)
28th day
(3cubes)
3% 5%
Urea-CaCl2
Sporosarcina Pasteurii
38
Table 3.5: Mix-ID Description for Bio-Concrete
No. Mix-ID Description
1 U-SP-1 1% Sporosarcina Pasteurii with urea-CaCl2 nutrient media +Mix
proportion
2 U-SP-3 3% Sporosarcina Pasteurii with urea-CaCl2 nutrient media +Mix
proportion
3 U-SP-5 5% Sporosarcina Pasteurii with urea-CaCl2 nutrient media +Mix
proportion
4 U-BS-1 1% Bacillus Subtilis with urea-CaCl2 nutrient media +Mix proportion
5 U-BS-3 3% Bacillus Subtilis with urea-CaCl2 nutrient media +Mix proportion
6 U-BS-5 5% Bacillus Subtilis with urea-CaCl2 nutrient media +Mix proportion
7 N-BS-1 1% Bacillus Subtilis with Nutrient broth nutrient media +Mix
proportion
8 N-BS-3 3% Bacillus Subtilis with Nutrient broth nutrient media +Mix
proportion
9 N-BS-5 5% Bacillus Subtilis with Nutrient broth nutrient media +Mix
proportion
10 N-SP-1 1% Sporosarcina Pasteurii with Nutrient broth nutrient media +Mix
proportion
11 N-SP-3 3% Sporosarcina Pasteurii with Nutrient broth nutrient media +Mix
proportion
12 N-SP-5 5% Sporosarcina Pasteurii with Nutrient broth nutrient media +Mix
proportion
13 CC Normal Mix-Proportion for cubic specimens
14 U-SP-B1 & B2 5% Sporosarcina Pasteurii with urea-CaCl2 nutrient media +Mix
proportion for beams
15 U-BS-B1 & B2 5% Bacillus Subtilis with urea-CaCl2 nutrient media +Mix proportion
for beams
16 N-BS-B1 & B2 5% Bacillus Subtilis with Nutrient broth nutrient media +Mix
proportion for beams
17 N-SP- B1 & B2 5% Bacillus Subtilis with Nutrient broth nutrient media +Mix
proportion for beams
18 CC-B Normal Mix-Proportion for beam specimens
39
• Slump Test
Slump test is taken to check the workability is under the right range. For the current study
the slump was chosen according to the desired target mean strength for cylinder concrete
for C-30 slump is chosen to be from 25mm to 75mm.
• Compressive Strength
This test is performed by loading 150𝑚𝑚 × 150𝑚𝑚 × 150𝑚𝑚 Cubic specimen in
compression using the test machine called ADR Touch Control PRO range of
compressive strength machine. The maximum failure load and its corresponding strength
were taken from the test machine.
Table 3.6: Test Program
Mix- ID Weight
of Water
(Kg)
Weight of
Coarse
Aggregate
(kg)
Weight of
Coarse
Aggregate
(kg)
Weight of
Cement
(kg)
Amount of
Bacteria
(L)
Controlled 7.78 37 38 12.3 0
U-BS-1 7.702 25 26 8.2 0.0778
U-BS-3 7.55 37 38 12.3 0.2334
U-BS-5 7.39 37 38 12.3 0.389
U-SP-1 7.7 37 38 12.3 0.0778
U-SP-3 7.47 37 38 12.3 0.2334
U-SP-5 7.39 37 38 12.3 0.389
N-BS-1 7.31 37 38 12.3 0.0778
N-BS-3 7.08 37 38 12.3 0.2334
N-BS-5 6.69 37 38 12.3 0.389
N-SP-1 6.61 37 38 12.3 0.0778
N-SP-3 6.38 37 38 12.3 0.2334
N-SP-5 5.99 37 38 12.3 0.389
40
• Flexural Strength
As per ASTM: C78-94 the specimens which are to be tested for flexural strength should
be wet not surface dried because flexural strength may decrease if the specimen is not
moist. For this study the test is implemented by three points loading of 150𝑚𝑚 ×
150𝑚𝑚 × 700𝑚𝑚 plain beams shown in Table 3.7, satisfying the requirements for the
dimension that the span should be equal or more than three times the depth as shown
which is specified in ASTM standards .
Figure 3.16: Setup for Flexural Testing of Concrete by 3rd Point Loading
Table 3.7: Mixing Proportion for Beam Mixes
Mix- ID Weight
of
Water
(L)
Weight of Coarse
Aggregate (kg)
Weight of
Coarse
Aggregate
(kg)
Weight of
Cement
(kg)
Amount of
Bacteria
(L)
CC-F 4 19 13 6.4 0
U-BS-B1 3.8 19 13 6.4 0.2
U-SP-B1 3.8 19 13 6.4 0.2
N-BS-B1 3.8 19 13 6.4 0.2
N-SP-B1 3.8 19 13 6.4 0.2
U-BS-B2 3.8 19 13 6.4 0.2
U-SP- B2 3.8 19 13 6.4 0.2
N-BS- B2 3.8 19 13 6.4 0.2
N-SP- B2 3.8 19 13 6.4 0.2
41
Figure 3.17 Casting Beam with Timber Mold
Figure 3.18: Beam Flexure Test of Specimens by Third-Point Loading Method
• Crack Healing Evaluation
The methods used for evaluating self-healing ability of bio-concrete on this study are two:
visual inspection on cubic samples and re-loading a flexural load on beam specimens to
form micro-cracks.
➢ Visual Inspection
After introducing the crack and taking the picture of cracks with high resolution power
camera and record it, then keep taking pictures until healing is observed. On the process
Plastic cover for easily removal
of the beam from the mold
Timber mold
42
of creating and measuring the crack formed there is a situation as the cracks widths are
not identical for those specimens needed for studying the healing ability (Tziviloglou, Pan
and Schlangen 2017). For this study circumstances, the cracks were simply observed by
and took picture for every part of the crack every 3 days the progress was saved in
picture.
➢ Load And Unload of Flexural Load on Beam Specimens
Wight and Macgregor (2012) stated that micro-crack occurs when the concrete is loaded
by until 30 % of its ultimate compressive strength. At the 28th day age beams loaded to 30
% of its ultimate flexural strength and then it returned back to curing and then after 7th
day, after letting to get healed the beam again loaded, but this time for its ultimate load.
43
CHAPTER FOUR
4 TEST RESULT AND DISCUSSION
4.1 Introduction
This chapter refers the results gained by the experiment conducted in the tests mentioned
in chapter 3. From all testes, expected results were found. Workability, compressive
strength, flexural strength and finally self-healing analysis result were brief discussion.
4.2 Workability
The workability during mixing was kept in the range that specified on the mix design part
of this study. The slump values for all mix are listed in Figure 4.1 and Figure 4.2 below.
The addition of bacterial solution did not influence the workability of the concrete mix.
Figure 4.1 Slump Test Result for Cubic Specimens
Figure 4.2: Slump Test Result for Beam Specimens
0
50
100
CC U-SP U-BS N-SP N-BS
Slu
mp
Valu
e
Slump value for Cube mix
0%
1%
3%
5%
020406080
Slu
mp
Valu
e
Bacteria ID
Slump value for Beam mix
0%
5%
44
4.3 Compressive Strength
The strength of both selected bacteria species were improved 7-days, 14-days and 28-days
aged concrete. The compressive strength of bio-concrete is found to be higher when
nutrient broth is used as a nutrient for the bacteria culturing than U-CaCl2 for both
bacteria species. This result showed in Table 4.1 up to 4.19 and Figure 4.3 up to Figure
4.9. In both the bacteria species and the type of nutrients used for study revealed that a
good result on improving the compressive strength of the bio-concrete than the
conventional concrete. The percentage change varied on bacterial solution made the bio-
concrete strength higher in most of the results and lower in some relative to the controlled
concrete. However, 3 % of addition of bacteria solution for both bacteria species by the
two nutrient media showed that a great improvement in all specimens. Great performance
showed by the bacteria called Sporosarcina Pasteurii with a huge improving in
compressive strength for all age concrete specimens. The highest percentage increment on
these bacteria was recorded as 36% for the 7th –day compressive strength, 29.3% for, 14th-
day compressive strength and 29% for 28th-day compressive strength. From the
compressive strength test result showed that without any addition of raw material
adjustment in the mix design i.e. the same mix design used for all specimens, the
experimental work using on bio concrete improved the compressive strength of the
concrete structure over the convenient one.
Table 4.1: Compressive Strength for 7 Days for Controlled Specimens
N
o.
Mix-
ID
Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compressiv
e Strength
(MPa)
Average
compres
sive
strength
(MPa) L W H
1
CC 7 days 0.15 0.15 0.15 8.59 0.003375 364.646 16.045
15.979 CC 0.15 0.15 0.15 8.23 0.003375 337.688 14.859
CC 0.15 0.15 0.15 8.56 0.003375 387.086 17.033
45
Table 4.2: Compressive Test Result For 7 Days For U-BS 1%,3% And 5%
No. Mix-ID Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compres
sive
Strength
(MPa)
Average
compressive
Strength
(MPa) L W H
1
U-BS-1 7 days 150 150 150 8.25 3375000 388 17 16.69
U-BS-1 150 150 150 8.25 3375000 369.352 16.416
U-BS-1 150 150 150 8.71 3375000 374.812 16.658
2
U-BS-3 7 days 150 150 150 8.18 3375000 394.691 17.542 18.47
U-BS-3 150 150 150 8.51 3375000 428.2 19.031
U-BS-3 150 150 150 8.38 3375000 423.645 18.829
3
U-BS- 7 days 150 150 150 8.49 3375000 343.373 15.261 14.86
U-BS-5 150 150 150 8.6 3375000 333.245 14.811
U-BS-5 150 150 150 8.47 3375000 326506 14.5
Table 4.3: Compressive Test Result For 7 Days For U-SP 1%,3% And 5%
No. Mix-
ID
Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compre
ssive
Strengt
h (MPa)
Average
compressive
strength (MPa) L W H
1 U-SP-1 7
days
150 150 150 8.12 3375000 401.24 17.66
17.23 U-SP-1 150 150 150 8.36 3375000 403.39 17.75
U-SP-1 150 150 150 8.07 3375000 370.03 16.28
2 U-SP-3 7
days
150 150 150 8.42 3375000 438.74 19.31
19.12 U-SP-3 150 150 150 8.52 3375000 435.77 19.18
U-SP-3 150 150 150 8.33 3375000 429.07 18.88
3 U-SP- 7
days
150 150 150 8.29 3375000 382.3 16.82
17.44 U-SP-5 150 150 150 8.71 3375000 378.84 16.67
U-SP-5 150 150 150 8.12 3375000 423.64 18.83
Table 4.4: Compressive Test Result For7 Days For N-BS 1%, 3% and 5%
No. Mix-ID Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load (KN)
Compress
ive
Strength
(MPa)
Average
compressive
strength
(MPa) L W H
1 N-BS-1 7 days 150 150 150 8.41 3375000 373.49 16.44 18.02
N-BS-1 150 150 150 8.56 3375000 437.91 19.27
N-BS-1 150 150 150 8.41 3375000 417.02 18.35
2 N-BS-3 7 days 150 150 150 8.41 3375000 436.03 19.19 19.32
N-BS-3 150 150 150 8.51 3375000 454.81 20.01
N-BS-3 150 150 150 8.51 3375000 426.28 18.76
3 N-BS- 7 days 150 150 150 8.58 3375000 473.77 20.85 18.55
N-BS-5 150 150 150 8.89 3375000 415.06 18.26
N-BS-5 150 150 150 8.40 3375000 375.53 16.53
46
Table 4.5: Compressive Test Result for 7-Days for N-SP 1% ,3% and 5%
No. Mix-ID Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load (KN)
Compressive
Strength (MPa)
Average compressive
strength (MPa) L W H
1 N-SP-1 7 days 150 150 150 8.4 3375000 509.87 22.66 20.97
N-SP-1 150 150 150 8.34 3375000 481.89 21.42
N-SP-1 150 150 150 8.25 3375000 423.64 18.829
2 N-SP-3 7 days 150 150 150 8.17 3375000 512.23 22.77 21.70
N-SP-3 150 150 150 8.27 3375000 521.28 23.17
N-SP-3 150 150 150 8.34 3375000 431.48 19.18
3 N-SP- 7 days 150 150 150 8.31 3375000 411.33 18.28 20.55
N-SP-5 150 150 150 8.35 3375000 488.42 21.71
N-SP-5 150 150 150 8.38 3375000 487.14 21.65
Table 4.6: 7th day Compressive Strength Percentage Relative to Controlled Specimens
Cubic-ID CC U-BS-1 U-BS-
3
U-BS-5 U-SP-1 U-SP-3 U-SP-
5
N-BS-1 N-BS-3 N-SP-1 N-SP-3 N-SP-5
Average
Compressive
strength
15.9
8
16.69 18.47 14.86 17.23 19.12 17.44 18.02 19.32 20.97 21.70 20.55
Percentage
increase from the
controlled group
0% 4% 16% -7% 8% 20% 9% 13% 21% 31% 36% 29%
47
Figure 4.3: 7th -Days Compressive Strength for Controlled and Bacteria Concrete
Table 4.7: Compressive Test Result for 14-Days for Controlled
No. Mix-
ID
Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compressi
ve Strength
(MPa)
Average
compressive
strength
(MPa)
L W H
1
CC 14
days
150 150 150 8.18 3375000 543.33 24.15
23.36 CC 150 150 150 8.72 3375000 535.97 23.82
CC 150 150 150 8.36 3375000 497.34 22.10
Table 4.8: Compressive Test Result for 14-Days for U-BS 1% ,3% and 5%
N
o
.
Mix-ID Test
Age
Dimension (mm) Weig
ht
(kg)
Volume
(mm3)
Failur
e Load
(KN)
Compr
essive
Streng
th
(MPa)
Average
compressive
strength
(MPa)
L W H
1
U-BS-1 14
days
150 150 150 8.63 3375000 456.57 20.29 20.70
U-BS-1 150 150 150 8.36 3375000 464.35 20.64
U-BS-1 150 150 150 8.47 3375000 476.52 21.18
2
U-BS-3 14
days
150 150 150 8.11 3375000 503.59 22.38 23.70
U-BS-3 150 150 150 8.65 3375000 565.07 25.11
U-BS-3 150 150 150 8.58 3375000 530.78 23.59
3
U-BS- 14
days
150 150 150 8.45 3375000 467.01 20.76 21.14
U-BS-5 150 150 150 8.6 3375000 495.03 22.00
U-BS-5 150 150 150 8.45 3375000 464.76 20.66
48
Table 4.9: Compressive Test Result for 14-Days for U-SP 1%, 3% and 5%
No Mix-ID Test
Age Dimension (mm) Weig
ht
(Kg)
Volume
(Mm3)
Failur
e Load
(KN)
Compressi
ve Strength
(MPa)
Average
Compressi
ve Strength
(MPa)
L W H
1
U-SP-1 14
days
150 150 150 8.43 3375000 492.30 22.29
23.03 U-SP-1 150 150 150 8.42 3375000 546.93 24.31
U-SP-1 150 150 150 8.13 3375000 505.77 22.50
2
U-SP-3 14
days
150 150 150 3375000 568.45 25.27
23.44 U-SP-3 150 150 150 8.39 3375000 505.77 22.48
U-SP-3 150 150 150 8.62 3375000 507.72 22.57
3
U-SP-5 14
days
150 150 150 8.65 3375000 468.48 20.82
21.27 U-SP-5 150 150 150 8.49 3375000 476.21 21.17
U-SP-5 150 150 150 8.31 3375000 491.35 21.84
Table 4.10: Compressive Test Result for 14-Days for N-BS 1%,3% and 5%
No. Mix-ID Test
Age Dimension (mm) Weig
ht
(Kg)
Volume
(mm3)
Failure
Load
(KN)
Compressi
ve
Strength
(MPa)
Average
Compressiv
e Strength
(MPa)
L W H
1 N-BS-1 14
days
150 150 150 8.37 3375000 563.12 25.03 25.00
N-BS-1 150 150 150 8.51 3375000 583.25 25.92
N-BS-1 150 150 150 8.41 3375000 540.96 24.04
2 N-BS-3 14
days
150 150 150 8.09 3375000 630.64 28.03 26.94
N-BS-3 150 150 150 8.04 3375000 584.16 25.96
N-BS-3 150 150 150 8.38 3375000 603.53 26.82
3 N-BS-5 14
days
150 150 150 8.64 3375000 609.40 27.08 27.51
N-BS-5 150 150 150 8.45 3375000 637.44 28.33
N-BS-5 150 150 150 8.29 3375000 610.30 27.12
Table 4.11: Compressive Test Result for 14-Days for N-SP 1% ,3% and 5%
No. Mix-ID Test
Age Dimension (mm) Weight
(Kg)
Volume
(mm3)
Failure
Load
(KN)
Compress
ive
Strength
(MPa)
Average
Compressi
ve Strength
(MPa)
L W H
1
N-SP-1 14
days
150 150 150 8.36 3375000 577.02 25.65
25.56 N-SP-1 150 150 150 8.27 3375000 566.35 25.17
N-SP-1 150 150 150 8.33 3375000 582.24 25.88
2
N-SP-3 14
days
150 150 150 8.43 3375000 769.16 34.19
30.19 N-SP-3 150 150 150 8.61 3375000 656.58 29.18
N-SP-3 150 150 150 8.32 3375000 612.18 27.21
3
N-SP-5 14
days
150 150 150 8.58 3375000 605.14 26.94
27.78 N-SP-5 150 150 150 837 3375000 674.29 29.97
N-SP-5 150 150 150 8.66 3375000 597.41 26.43
49
Table 4.12: 14th day Compressive Strength Percentage Relative to Controlled Specimens
Cubic ID CC U-BS-1 U-BS-3 U-SP-1 U-SP-3 U-SP-5 N-BS-1 N-BS-3 N-BS-5 N-SP-1 N-SP-3 N-SP-5
Average
Compressive
strength
23.36 20.70 23.70 23.03 23.44 21.27 25.00 26.94 27.51 25.56 30.19 27.78
Percentage
increase from the
controlled group
0.0% -12.8% 1.6% -1.4% 0.3% -8.9% 7.0% 15.3% 17.8% 9.4% 29.3% 18.9%
Figure 4.4: 14th -Days Compressive Strength for Controlled and Bacteria Concrete
50
Table 4.13: Compressive Test Result for 28-Days for Controlled
No. Mix-
ID
Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compressive
Strength
(MPa)
Average
compressive
strength
(MPa)
L W H
1 CC 28
days
150 150 150 8.49 3375000 566.35 25.171 26.45
CC 150 150 150 8.4 3375000 585.84 26.04
CC 150 150 150 8.75 3375000 633.46 28.15
Table 4.14: Compressive Test Result for 28-Days for U-BS 1% ,3% and 5%
No. Mix-ID Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failur
e Load
(KN)
Compr
essive
Strengt
h
(MPa)
Average
compress
ive
strength
(MPa)
L W H
1
U-BS-1 28
days
150 150 150 8.3 3375000 623.22 27.7
27.61 U-BS-1 150 150 150 8.49 3375000 627.22 27.88
U-BS-1 150 150 150 8.53 3375000 612.86 27.24
2
U-BS-3 28
days
150 150 150 8.48 3375000 673.46 29.93
28.84 U-BS-3 150 150 150 8.17 3375000 601.77 26.75
U-BS-3 150 150 150 8.44 3375000 671.5 29.85
3
U-BS-5 28
days
150 150 150 8.84 3375000 545.21 24.26
23.97 U-BS-5 150 150 150 8.45 3375000 603.46 23.82
U-BS-5 150 150 150 8.66 3375000 535.85 23.82
Table 4.15: Compressive Test Result for 28-Days for U-SP 1%,3% and 5%
No
.
Mix-ID Test
Age
Dimension (mm) Weig
ht
(kg)
Volume
(mm3)
Failur
e Load
(KN)
Compre
ssive
Strength
(MPa)
Average
compressi
ve
strength
(MPa)
L W H
1
U-SP-1 28
days
150 150 150 8.57 3375000 668.84 29.73
29.27 U-SP-1 150 150 150 8.43 3375000 666.13 29.61
U-SP-1 150 150 150 8.27 3375000 640.87 28.48
2
U-SP-3 28
days
150 150 150 8.36 3375000 652.82 29.01
30.09 U-SP-3 150 150 150 8.55 3375000 676.09 30.05
U-SP-3 150 150 150 8.38 3375000 701.88 31.19
3
U-SP-5 28
days
150 150 150 8.35 3375000 683.57 30.38
28.24 U-SP-5 150 150 150 8.55 3375000 623.12 27.69
U-SP-5 150 150 150 8.29 3375000 599.55 26.65
51
Table 4.16: Compressive Test Result for 28-Days for N-BS 1%,3% and 5%
No. Mix-ID Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compres
sive
Strength
(MPa)
Average
compressiv
e strength
(MPa)
L W H
1 N-BS-1 28
days
150 150 150 8.4 3375000 609.47 27.09 28.76
N-BS-1 150 150 150 8.5 3375000 678.76 30.17
N-BS-1 150 150 150 8.24 3375000 653.12 29.03
2 N-BS-3 28
days
150 150 150 8.23 3375000 722.41 32.11 32.34
N-BS-3 150 150 150 8.38 3375000 680.26 30.23
N-BS-3 150 150 150 8.17 3375000 780.14 34.67
3 N-BS-5 28
days
150 150 150 8.23 3375000 725.49 32.24 29.35
N-BS-5 150 150 150 8.14 3375000 668.16 29.7
N-BS-5 150 150 150 8.2 3375000 587.23 26.1
Table 4.17: Compressive Test Result for 28 Days for N-SP 1%,3% and 5%
No. Mix-ID Test
Age
Dimension (mm) Weight
(kg)
Volume
(mm3)
Failure
Load
(KN)
Compres
sive
Strength
(MPa)
Average
compressiv
e strength
(MPa)
L W H
1 N-SP-1 28
days
150 150 150 8.22 3375000 695.64 30.92 31.53
N-SP-1 150 150 150 8.43 3375000 754.85 33.55
N-SP-1 150 150 150 8.58 3375000 677.74 30.12
2 N-SP-3 28
days
150 150 150 5.56 3375000 851.61 37.85 34.20
N-SP-3 150 150 150 8.18 3375000 728.38 32.37
N-SP-3 150 150 150 8.49 3375000 728.23 32.37
3 N-SP-5 28
days
150 150 150 8..26 3375000 689.29 30.64 31.35
N-SP-5 150 150 150 7.35 3375000 673.57 29.94
N-SP-5 150 150 150 8.12 3375000 753.01 33.47
Table 4.18: 28th day Compressive Strength Percentage Relative to Controlled Specimens
Cubic ID CC U-
BS-1
U-
BS-3
U-
BS-5
U-
SP-1
U-
SP-3
U-
SP-5
N-
BS-1
N-
BS-3
N-
BS-5
N-
SP-1
N-
SP-3
N-
SP-5
Average
Compressi
ve strength
26.45 27.61 28.84 23.97 29.27 30.09 28.24 28.76 32.34 29.35 31.53 34.20 31.35
Percentage
increase from the
controlled
group
0% 4% 9% -9% 11% 14% 7% 9% 22% 11% 19% 29% 18%
52
Figure 4.5: 28th -Days Compressive Strength for Controlled and Bacteria Concrete
Figure 4.6: Highest value in compressive strength performed by N-SP-3%
53
Figure 4.7:Values 7th, 14th and 28th Days Compressive Strength Result
Figure 4.8: Compressive strength for All Cubic Specimens
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
26.45 27.61 28.84
23.97
29.27 30.0928.24 28.76
32.3429.35
31.5334.20
31.35
Cubic Mix vs. Compressive Strength
7th-day average Compressive strength 14th-day average Compressive strength
28th-day average Compressive strength
15.98 16.6918.47
14.8617.23
19.1217.44
18.02
19.32
18.55 20.97
21.70
20.55
23.36
20.7023.70
21.14
23.0323.44
21.27
25.0026.94 27.51
25.56
30.1927.78
26.4527.61 28.84
23.97
29.27 30.0928.24
28.76
32.34
29.3531.53
34.20
31.35
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
7 th day
14th day
28th day
54
4.4 Flexural Strength Test
Using the formula in Appendix E the flexural strength is calculated and summarized in
Figure 4.9 and Error! Reference source not found..
Figure 4.9: Flexural Strength for Different Beam Specimens
Table 4.19: Flexural Strength of Bio-Concrete Beam Compared with Controlled
Beam ID Peak Load (N) R (Modulus Of
Rapture)
Percent
Increase
U-BS-B1 13770 3.67 -1%
U-SP-B1 17020 4.54 22%
N-BS-B1 16110 4.3 15%
N-SP-B1 17290 4.61 24%
CC-B 13970 3.73 0%
From the above figures and tables the result showed that the flexural strength of the
bacterial concrete was showed improved by all the bacteria mixed concrete beams except
U-BS-B1, which shows almost the same with the conventional beam. The highest
55
strength was attained by beam ID N-SP-B1 which attain a value 4.61 MPa Modulus of
rapture. This means that it has an increment by 24 %. This result also became supportive
with the statements that indicate compressive and tensile strength of concrete have a
direct relation ( Wight and Macgregor 2012).
4.5 Self-Healing Efficiency
4.5.1 Visual inspection
Crack healing analysis done by visual observation of crack healing progress seen in
Figure 4.10, Figure 4.11Figure 4.12 Figure 4.13
.
56
Figure 4.10: Beam Crack ( Before Self-Healing)
Figure 4.11: Beam Crack (After Self-Healing-1)
Figure 4.12: Beam Crack (After Self-Healing-2)
Figure 4.13: Self-Healing Progress by N-BS
57
Figure 4.14: Calcium Carbonate Precipitation
From the visualization mechanism of analysis, it is seen that both bacteria species fills the
cracks which is developed in concrete.
Figure 4.15: Crack Healing by U-BS
58
Figure 4.16: Crack Healing by N-SP
Figure 4.17: Crack Healing by N-SP
The white powder thing on the crack surface is proven of being calcium carbonate
(CaCO3) by having a test sing photometer as shown in Figure 4.18
59
Figure 4.18 CaCO3 Present identification from Sample taken from precipitate in CS
4.5.2 Load and unload of Flexural Load on Beam Specimens
By leaning on the theory specified in concrete structure text book written by a flexural
load up to 30% of the ultimate strength applied on beam samples having Beam-ID as U-
SP- B1, U-BS- B1, N-SP- B1, and N-BS- B1. The first loading i.e., after 28th day which is
the specimens achieved its strength, up to 30 % load were applied to form the micro-
cracks and then the specimens left for healing those micro-cracks by curing for about 7
days again flexural load is applied. After 7 day of curing beam specimens become to test
for the ultimate flexural strength and their values were recorded. From the loading and
unloading way of testing the healing mechanism, it is observed that the ultimate flexural
strength of this micro cracked beams become near to that of those specimens which are
neither loaded for having microcracks. Therefore, this shows that the bacterium fills the
voids caused by cracks and other cases. On both ways of testing Sporosarcina Pasteurii
shows a fast healing progress, highly precipitate calcium carbonate helps it to fill the
voids.
60
4.6 Flexural Strength Test after Crack Healing the Micro-Cracks
Table 4.20: Flexural Strength Test after healing
Beam ID Initial Loading at Age 14 After 28-Day Curing
Reloading
After 28 day +7-Day
Ultimate Flexural Strength
Pick
load(KN)
Flexural Strength
(N/mm2)
Pick
load(KN)
Flexural
Strength
(N/mm2)
Pick
load(KN)
Flexural
Strength
(N/mm2)
U-BS-B2 2.96 0.79 3.66 0.98 19.22 4.76
U-SP-B2 3.72 0.99 6.64 1.77 17.85 4.76 N-BS-B2 2.16 0.58 13.15 3.51 17.18 4.58
N-SP-B2 3.66 0.98 4.3 1.15 19.38 5.17
Figure 4.19: Flexural Strength on Three Stage of Loading
61
CHAPTER FIVE
5 CONCLUSION AND RECOMMENDATION
5.1 Conclusion
This research was intended to study self-healing action of bacteria incorporated within the
concrete specimens. Mainly self-healing ability of concrete was studied for two
constituents: one is by differing the species of spore-forming bacteria; Bacillus Subtilis
and Sporosarcina Pasteurii were selected. The other factor is by differing the nutrients
required for keeping bacteria active are considered. Both constituents were integrated
during casting and three different percentages (1%, 3% and 5% by the amount of water
required for the mix) were considered. This was performed in order to determine the
optimum quantity of bacteria solution as healing agent in addition that gave the best result
in inducing self-healing. Two different Nutrients (Nutrient broth and Urea-CaCl2) were
selected as nutrient media needed for the growth of the microbial. From the objectives,
one was to investigate self-healing ability/efficiency of these selected bacterial species by
differing the spices and the other were by changing the type of medium as well as the
amount of the bacterial solution in the mix to get the best amongst them compressive
strength and flexure/bending strength were tested to observe the adverse effect of the
bacteria into the concrete matrix. In this study, the improvement in mechanical properties
and self-healing efficiency of the bacterial concrete was mainly investigated by measuring
properties at different ages such as 7-days, 14-days, and 28-days compressive strength.
62
Therefore, based on the above investigation the following conclusions are made:
• Self-healing efficiency of bio-concrete was clearly seen and proven in both method
of testing. This result is due to the bacteria effect by filling the voids appear as a
result of cracks. By the bacterial action that can induce those calcium carbonates or
limestone into the pores that found in concrete and closed them to their ability in
urease enzyme production.
• Bio-concrete strength absolutely enhanced the compressive strength when
compared with conventional concrete by 36%, 29% and 29.3% for 7th, 14th, and
28th –day of curing.
• The flexural strength also improved using the bacteria they by 24 % using N-SP
relative to the conventional concrete.
• In all tests performed Sporosarcina Pasteurii shows a promising result than Bacillus
Subtilis and the best nutrient media for the growth as well as improving the strength
was nutrient broth.
• It observed that from all mixes of bio-concrete, 3 % of addition of bacteria
solution shows best result in improving the flexural and compressive strength.
5.2 Recommendation
More investigation needed in this area and following recommendation was given
• Using other bacteria species which are tested for their urease-enzyme production.
Advised to examining their self- healing ability.
• The application could be costly for making bio-concrete than conventional concrete.
Mass-culturing the bacteria are the main reason and this is due to the cost for their
media preparation. To minimize these, it is suggested to use wastes from the
63
industries like wood production and wastewater treatment has are suitable for their
growth.
• Conducting durability, splitting tensile test and load versus deflection curves for better
understanding the effect of bacteria.
• To know the effect of bacteria on concrete structure include 56th day and more curing
time.
• Better to study the bacterial reaction with the reinforcement in concrete structure.
64
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70
APPENDICES
Appendix A: Photos showing the accessing Bacteria, preparing ingredients for
culturing the bacteria, collection of materials (equipment) and culturing the
bacteria.
Figure A 1: Picture Taken at EBI for Accessing the Microbial
Figure A 2: Preparing and Measuring Ingredients for Media Preparation
71
Figure A 3: Dissolving and Mixing Nutrients Using Hot Plate
Figure A 4: Removing media Serializing and Inoculating the Bacteria
Figure A 5: Preparing Nutrients for Mass Culturing Bacteria for Further Use
72
Appendix B: Collecting materials for concrete cubic and Beam production
Figure B 1 Collecting Aggregates Fine Aggregate and Coarse Aggregate
Figure B 2: Measuring Silt Content and Specific Gravity in Fine Aggregate
Figure B 3: Arranging Raffling Box for Dividing Fine Aggregate in Quarter
73
Figure B 4: Blowing by Using Rod to Determine the Specific Gravity of CCA
Figure B 5: Measuring Cement for Mix
Figure B 6: Mixing Concrete Paste with Bacteria and Measuring the Slump
74
Table B 1: Measuring slump Value for cubic specimen mixes
Bacteria amount
(%)
CC U-SP U-BS N-SP N-BS
0% 30
1% 26 37.5 42 51
3% 37 40 46 74
5% 46 43 53 74.5
Figure B 7: Compacting and Curing Takes Place after De-Molding the Cubes-1
Figure B 8: Curing Takes Place after De-Molding the Cubes-2
75
Figure B 9: Measuring Weight of Cube for Casting for the Compression Strength
Figure B 10: Compression and Flexural Testing Machine with Specimens
Figure B 11: Beam Setup for Measuring the Flexural Strength
76
Appendix C: Material Properties Test for concrete mixing
After collecting cement, fine aggregate and coarse aggregates the material properties were
studies.
Appendix C 1: Fine Aggregate Physical Properties Test
Silt Content of fine aggregate
By using the laboratory manual written by Abebe Deniku (2002) construction lab
Manual, the silt content for fine aggregate in percentage should be less than 6 % if it is
suitable for creating a concrete.
The amount of silt (A) = 5 ml
The amount of pure sand (B= 238ml.
% 𝑜𝑓 𝑠𝑖𝑙𝑡 𝑐𝑜𝑛𝑡𝑒𝑛𝑡 =𝐴
𝐵× 100% =
4
125× 100% = 3.2 %
Therefore the amount of silt found in fine aggregate is 3.2 % which is below the limit so
that it can be used for mixing the concrete.
Specific Gravity
Sample weigh (A) = 5 g
Weight of pycnometer (w) =270g
Weight of water introduced (Va)=800ml
𝐶 = 0.9976(𝑉𝑎) + 500 + 𝑊
𝐶 = 0.9976(800) + 500𝑔𝑚 + 270𝑔𝑚
77
C=1,267.608 gm
𝐵 = 0.9976(1000) + 𝑊
𝐵 = 0.9976(1000) + 270𝑔
𝐵 = 1,267.6 𝑔𝑚
𝐴 = 4.81𝑔𝑚
Then the bulk and other specific gravity will be calculated as follows
𝑩𝒖𝒍𝒌 𝒔𝒑𝒆𝒄𝒊𝒇𝒊𝒄 𝒈𝒓𝒂𝒗𝒊𝒕𝒚 =𝐴
𝐵+500−𝐶=
481
1267.6+500−1569.808=2.4
Bulk specific gravity (saturated − surface − dry basis)
𝑩𝒖𝒍𝒌 𝑺𝒑. 𝒈𝒓. =𝐵
𝐴−𝐶=
500
1267.6+500−1569.80=2.5
Apparent Specific gravity =𝐴
𝐵+𝐴−𝐶=
481
1267.6+481−1569.806=2.69
Absorption capacity (%)=500−𝐴
𝐴=
500−481
4810× 100 =3.9
The requirement of specific gravity of suitable fine aggregates varies from 2.6 to 2.8.
Hence the sample having bulk specific gravity of 2.5 is suitable for concrete casting.
Moisture Content
Fine aggregate sample taken for this experiment (A) =500gm
Weight of fine aggregate after having the oven dry (B) = 0.499Kg
Moisture content percent for fine aggregate can be computed as,
𝐴−𝐵
𝐵=
500𝑔𝑚−499𝑔𝑚
499𝑔𝑚= 0.2%
78
Fineness Modulus
To get the fineness modulus of fine aggregate the sieve analysis should have to be
performed first. The outcome of fineness modulus is on water demand for the mix, i.e. the
finer the aggregate the higher the demand of water and vice versa.
Here is the sieve analysis result for the specified fine aggregate type.
Table C 1: Test Results of Sieve Analysis of Fine Aggregate
Sieve
Size
(mm)
Sieve
(A)
Sieve
and
sample
wt.
(B)
Wt. of
Sample
Retaine
d
(C)
%
Retaine
d
(D)
Cum.
%
Retaine
d
% of
Pass
AST
M
C-33-
02a
%
pass
100 100
4.75 0.41 0.42 0.05 2 2 98 95-
100
2.36 0.45 0.47 0.02 4 6 94 80-100
1.18 0.45 0.5 0.05 10 16 84 50-85
600 0.41 0.56 0.15 30 46 44 25-60
300 0.37 0.56 0.19 38 84 16 5-30
150 0.27 0.34 0.07 14 98 2 0-10
Pan 0.55 0.56 0.01 2 100 0 0
Total 0.5 248
F.M 2.48
The fine aggregate sample is ranges from 2.2 to 2.6 which is fine type of sand.
.
79
Appendix C 2: Coarse Aggregate physical properties test
Particle Size Gradation
The fineness modulus of the aggregate is 2.525 , it is not relevant for calculating the mix
design .
The Particle gradation distribution of the aggregate is fulfills the ASTM limit except the
10 mm aggregate, but it is also approximate. Mix design will be made with maximum size
of aggregate 19 mm (anything retained on this sieve will be removed) and 20% by weight
will be added from 10mm aggregate sample.
Table C 2: Grading Requirement for Aggregate In Normal-Weight Concrete
(ASTM C-30)
Sieve Size Sieve
wt.
Sieve and
sample
wt.
Wt. of sample
retained
%
retained
Cum.
%
retained
% of
pass
ASTM
limits
37.5 1450 1450 0 0 0 100 95-100
19 1400 2490 1090 54.5 54.5 45.5 30-70
9.5 1230 1900 670 33.5 88 12 10-35
4.75 1190 1430 240 12 100 0 0-5
Pan 660 660 0 0
Total 252.5
FM= 2.525
Unit weight
a) Compacted weight
Weight of compacted coarse aggregate with the cylinder (After making a 3 layer
aggregate and blowing each layer 25 times by rod)= 16.1Kg
80
Weight of empty cylinder =8.14Kg
Weight of compacted coarse aggregate= Weight of compacted coarse aggregate with the
cylinder - Weight of empty cylinder =16.1Kg-8.14Kg=7.96Kg
Radius of the cylinder (r)=15cm ,Height of the cylinder (h) =28.8cm
Volume of the cylinder= (𝜋𝑟2) ∗ ℎ = 𝜋(0.15)2 ∗ 0.286 = 0.00498 m3
Unit weight of compacted aggregate = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑐𝑜𝑚𝑝𝑎𝑐𝑡𝑒𝑑 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟=
8.14
0.00498 =1634.54Kg/m3
b) Loose Unit weight
Weight of empty cylinder =8.14Kg
Weight of loose coarse aggregate with the cylinder=14.69Kg
Weight of loose coarse aggregate= Weight of loose coarse aggregate with the cylinder -
Weight of empty cylinder=14.69Kg-8.14Kg=6.55Kg
Radius of the cylinder (r) =15cm, Height of the cylinder (h) =28.8cm
Volume of the cylinder= (𝜋𝑟2) ∗ ℎ = 𝜋(0.15)2 ∗ 0.286 = 0.00498 m3
Unit weight of Loose aggregate = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑐𝑜𝑚𝑝𝑎𝑐𝑡𝑒𝑑 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟=
6.55
0.00498=1323.76Kg/m3
The approximate loose and compacted unit weight of aggregate commonly used in
normal-weight concrete ranges from about 1280 to 1920 kg/m3. Hence sample used for
this study is in this range and suitable for concrete.
81
Specific Gravity
• Sample of coarse aggregate=5kg
• Wight of the sample in the Saturated surface dry condition (B) = 5.03 Kg
• Weight of sample immersed in the container (C) = 3.10Kg
• Oven dry sample (A) =4.970Kg
Then the bulk and other specific gravity will be calculated as follows
𝐵𝑢𝑙𝑘 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑔𝑟𝑎𝑣𝑖𝑡𝑦 =𝐴
𝐵−𝐶=
4.97 𝐾𝑔
5.03𝐾𝑔−3.1𝐾𝑔=2.58
Bulk specific gravity (saturated − surface − dry basis)
𝐵𝑢𝑙𝑘 𝑆𝑝. 𝑔𝑟. =𝐵
𝐵−𝐶=
5.03
5.03−3.1=2.61
Apparent Specific gravity =𝐴
𝐴−𝐶=
4.97
4.97−3.1=2.66
Absorption capacity (%) =𝐵−𝐴
𝐴× 100 =
5.03−4.97
4.97× 100 =1.21%
The relative density range is 2.30 to 2.90 and the absorption is below 4%. The samples
used for this study attain the absorption and relative densities are all with the range and
can be used for concrete.
Moisture Content
Fine aggregate sample taken for this experiment (A) =2Kg
Weight of fine aggregate after having the oven dry (B) = 1.99Kg
Moisture content percent for fine aggregate can be computed as,
𝐴−𝐵
𝐵=
2𝐾𝑔−1.99𝐾𝑔
1.99𝐾𝑔× 100 = 0.5%
82
Appendix C 3: Summary on Physical Properties Test
Table C 3: Result for Material Properties Tests
Experiments Values
Bulk Specific gravity of fine aggregate 2.53
Bulk specific gravity of coarse aggregates 2.61
Apparent Specific gravity of fine aggregate 2.69
Apparent Specific gravity of coarse aggregates 2.66
Fineness modulus for fine aggregate 2.48
Moisture content for fine aggregate 0.2
Moisture content for Coarse aggregate 2.66
Water absorption of fine aggregate 4.17
Water absorption of coarse aggregate 1.21
Appendix C4: Mix Design
Choosing appropriate slump value between 25 to 75mm and having the maximum
aggregate size of 19mm weight of water and air contents can be estimated using ACI (
A1.5.3.3 TABLE A1.5.3.3 ) therefore the approximate weight of water estimated from
the code is 190 kg/m3
and with air content 2%. The water to cement ratio now can calculated as:
W/C= 𝑊𝑒𝑔ℎ𝑡 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑐𝑒𝑚𝑒𝑛𝑡 0.54 =
190
𝑊𝑐
83
𝑊𝑐 =190
0.54=
351.85𝐾𝑔
𝑚3≈ 352 𝐾𝑔/𝑚3
Using Table A1.5.3.6 the content of coarse aggregate calculated after having the value of
fineness modulus and maximum aggregate size. Using Interpolation technique the vale
from table became 0.645 . then the weight of course aggregate calculated as, 0.645
*1634.54Kg/m3
Unit weight of coarse aggregate = 1634.54Kg/m3
Weight of course aggregate = 0.645 *1634.54Kg/m3=1054.3 Kg
m3 ≈ 𝟏𝟎𝟓𝟓Kg/m3
Fine Aggregate content can be estimated by volume
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑎𝑖𝑟 (𝑉𝑎) = 2 % = 2
100=0.02
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 (𝑉𝑤) = 190
1000= 0.190𝑚3
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑐𝑒𝑚𝑒𝑛𝑡 (𝑉𝑐) = 3.52
3.15 ∗ 1000= 0.112𝑚3
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝐶𝑜𝑎𝑟𝑠𝑒 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 (𝑉𝑐𝐴) = 1054
2.61 ∗ 1000= 0.404𝑚3
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓𝑓𝑖𝑛𝑒 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 (𝑉𝐹𝐴) =?
V concrete =Va + Vw + Vc + Vca + Vfa
1 m3=0.02 m3 +0.19 m3 + 0.112 m3+0.404Vfa
Vfa = 1m3 -0.726 m3=0.274 m3
WFA= VFA *SSD*1000= 0.274*2.53*1000=693.22 Kg/m3≈ 𝟔𝟗𝟒 Kg/m3
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 (𝑊𝑤) = 190𝐾𝑔/𝑚3
84
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐶𝑒𝑚𝑒𝑛𝑡 (𝑊𝑐) = 352𝐾𝑔/𝑚3
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐶𝑜𝑎𝑟𝑠𝑒 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 (𝑊𝑐𝑎) = 𝟏𝟎𝟓𝟓Kg/m3
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐹𝑖𝑛𝑒 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 (𝑊𝑓𝑎) = 694Kg/m3
Step-5: Adjustment
Moisture content for fine aggregate =0.5%
Moisture content for Coarse aggregate =0.2%
Absorption (%) of fine aggregate =1%
Absorption (%) of coarse aggregate =4.17%
Deducting water absorption from moisture content,
FA=0.5% and CA= 3.97%
The fine and the coarse aggregate absorb the water by the above percentile amount.
WCA = 𝟏𝟎𝟓𝟓 Kg/m3 - 5
100∗ (
𝟏𝟎𝟓𝟓Kg
m3)=
𝟏𝟎𝟓𝟓Kg
m3+ 5.275 Kg/m3
=1060.275 Kg/m3
WFA =694Kg
m3 −
3.97
100∗ (694) Kg/m3
=694Kg
m3 − 27.55 Kg/m3
=721.55Kg/m3
Ww=190Kg/m3+5
100∗ ቀ
𝟏𝟎𝟓𝟓Kg
m3ቁ +
3.97
100∗ (694) Kg/m3=222.67 Kg/m3
85
Step-5: Trial-mix
Volume of the cube = 0.15 𝑚 × 0.15 𝑚 × 0.15𝑚 = 0.003375 𝑚3
N= number of cubic sample
Allowing 15% wastage
N*0.003375*15% (0.003375) = 84*0.003375+0.00051=0.28401
Ww=222.67 Kg/m3*0.28401=62.37Kg≈63kg
Wca=0.28401* 1060.275 Kg/m3=301.13Kg≈302kg
Wfa=0.28401*721.55Kg/m3=𝟐𝟎𝟓Kg
Wc=0.28401*352𝐾𝑔/𝑚3 = 𝟏𝟎𝟎Kg
Water Cement Fine
aggregate
Coarse
aggregate
63 100 205 302
0.63 1 2.05 3.02
Appendix D: Chemical Composition, Compressive Strength and Flexural
Strength
Table D 1: Chemical Composition on Different Oxide Content of 5 Cement Production Factories
Oxides of Mugher in Derba in National
in Dangote in Habesha in
Cements mass% mass% mass% mass% mass%
CaO 63.63 62.33 64.55 63.96 62.99
SiO2 20.84 21.15 20.48 20.37 20.18
Al2O3 5.4 5.46 5.13 4.94 5.08
Fe2O3 3.48 3.29 3.33 3.35 3.46
MgO 1.33 1.83 1.42 1.66 2.26
SO3 2.5 2.61 2.63 2.72 2.57
K2O 0.49 0.73 0.43 0.3 0.41
Na2O -0.14 0.08 0.04 0 0.26
Cl 0.009 0.009 0.009 0.009 0.009
Final mix ratio =1: 2.05: 3.02
86
Figure D 1: The chemical composition of Muger OPC with Mass Percent Expressed
by Graph
Table D 2: Chemicals Contents in 13 g of Nutrient Broth (HiMedia™ 1919)
Chemicals found in
Nutrient broth
In 13 g of Nutrient
broth
In 1 g of Nutrient
broth
In 0.75 g of
nutrient broth
Beef extract (g) 1 0.077 0.05775
Yeast extract(g) 2 0.154 0.1155
Peptone (g) 5 0.39 0.2925
Sodium chloride (NaCl) 5 0.39 0.2925
Figure D 2: The 7 Days Test Result For Load vs. Time Graph-Photo from the Testing
Machine
87
Figure D 3: 14 Days Test Result for Load vs. Time Graph of CC for 3 Samples
Figure D 4: 14 Days Test Result for Load vs. Time Graph of U-BS-1% for 3 Samples
Figure D 6: 14 Days Test Result for Load vs. Time Graph of U-Bs-3% for 3 Samples
0
200
400
600
800
0.0
52.7
5.3
5 810.6
513.3
15.9
518.6
21.2
523.9
26
.55
29.2
Load
[K
N]
Time [sec]
CC (1)
CC (2)
CC (3)
0
100
200
300
400
500
600
0.05
1.45
2.85
4.25
5.65
7.05
8.45
9.85
11.2
512
.65
14.0
515
.45
16.8
518
.25
U-BS-1
U-BS-1
U-BS-1
0
200
400
600
0.0
5
1.3
5
2.6
5
3.9
5
5.2
5
6.5
5
7.8
5
9.1
5
10.4
5
11.7
5
13.0
5
14.3
5
15.6
5
U-BS-3
U-BS-3
U-BS-3
0
100
200
300
400
500
600
0.0
5
1.4
2.7
5
4.1
5.4
5
6.8
8.1
5
9.5
10.8
5
12.2
13.5
5
U-BS-5
U-BS-5
U-BS-5
Figure D 5: 14 Days Test Result for Load vs. Time Graph of U-BS-5 % for 3
88
Figure D 7: Load vs. Time Graph for U-SP 1% for 3 Samples
Figure D 8: Load vs. Time Graph for U-SP 3% for 3 Samples
Figure D 9: Load Vs. Time Graph for U-SP 5% Three Cubic Specimens
0
100
200
300
400
500
600
0.0
5
1.5
2.9
5
4.4
5.8
5
7.3
8.7
5
10.2
11.6
5
13.1
14.5
5
16
17.4
5
U-SP-1
U-SP-1
U-SP-1
0100200300400500600
0.05
1.75
3.45
5.15
6.85
8.55
10.2
5
11.9
5
13.6
5
15.3
5
17.0
5
18.7
5
20.4
5
22.1
5
23.8
5
25.5
5
U-SP-3
U-SP-3
U-SP-3
0
100
200
300
400
500
600
0.0
5 1
1.9
5
2.9
3.8
5
4.8
5.75 6.
7
7.6
5
8.6
9.5
5
10.
5
11.4
5
12.4
13.3
5
14.
3
U-BS-5
U-BS-5
U-BS-5
0
100
200
300
400
500
600
0.0
5
1.25
2.4
5
3.6
5
4.8
5
6.0
5
7.2
5
8.4
5
9.6
5
10.8
5
12.0
5
13.2
5
14.4
5
15.6
5
16.8
5
18.0
5
N-BS-1%
N-BS-1%
N-BS-1%
Figure D 10: Load vs. Time Graph of N-BS-1% for 3 Specimens
89
Figure D 11: Load vs. Time Graph for N-BS 3% for 3 Specimens
Figure D 12: Load vs. Time Graph for N-SP 1 % for 3 Specimens
Figure D 13: Load Vs. Time Graph for N-SP 3 % for 3 Specimens
Figure D 14: Load Vs. Time Graph for N-SP- 5 % for 3 Specimens
0
100
200
300
400
500
600
700
0.05
1.25
2.45
3.65
4.85
6.05
7.25
8.45
9.65
10.8
512
.05
13.2
514
.45
15.6
516
.85
18.0
5
N-BS-3%
N-BS-3%
N-BS-3%
0
200
400
600
800
0.05 2.
9
5.75 8.
6
11.4
5
14.3
17.1
5
20
22.8
5
25.7
28.5
5
31.4
34.2
5
37.1
Load
[KN
]
Time [sec]
Load Vs Time Graph
N-SP-1(1)
N-SP-1(2)
N-SP-1(3)
0
200
400
600
800
1000
0.05 2.3
4.55 6.8
9.05
11.3
13.
5515
.81
8.05
20.3
22.
5524
.82
7.05
29.3
Load
[K
N]
Time [sec]
Load vs. Time Graph
N-SP-3(1)
N-SP-3(2)
N-SP-3(3)
0
200
400
600
800
0.0
5
2.95
5.8
5
8.7
5
11.6
5
14.5
5
17.4
5
20.3
5
23.2
5
26.1
5
29.0
5
31.9
5
34.8
5
37.7
5
40.6
5
Load
[K
N]
Time [sec]
Load Vs. Time Graph
N-SP-5(1)
N-SP-5(2)
N-SP-5(3)
90
Appendix E: Driving Flexural Strength for Three Point Loading Set-Up
For a rectangular sample, the resulting stress under an axial force is given by the
following calculated as (three point loading set-up).
Figure E 1: Three Point Loading Set-Up
For Region AB 𝟎 ≤ 𝒙 ≤ 𝟎. 𝟓𝑳
Figure E 2: Free Body Diagram for Section A-B
σ 𝑭𝒚 = 𝟎 =𝑭
𝟐− 𝑽(𝑿)
𝑉(𝑋) =1
2𝐹
𝑀 𝑐𝑢𝑡 = 0 =1
2𝐹𝑥 + 𝑀
𝑀(𝑥) = 𝑀1
2𝐹𝑥
For Region BC 𝟎. 𝟓𝑳 ≤ 𝒙 ≤ 𝑳
Figure E 3: Free Body Diagram for Section A-C
91
𝐹𝑦 = 0 =𝐹
2− 𝐹 − 𝑉(𝑋)
𝑉(𝑋) =−1
2𝐹
𝑀 𝑐𝑢𝑡 = 0 =−1
2𝐹𝑥 + 𝐹(𝑋 − 𝐿) + 𝑀(𝑥)
𝑀(𝑥) =1
2(𝐹𝐿 − 𝐹𝑋)
Figure E 4: Shear Force Diagram for Three Point Loading
Figure E 5: Bending Moment Diagram for Three Point Loading
This stress is not the right stress, since the cross section of the sample is considered to be
unchanging (engineering stress).
P=is the axial load (force) at the fracture point
b= is width
d= is the depth or thickness of the material
The resulting stress for a rectangular sample under a load in a three-point bending setup Figure E
1is given by the formula below.
𝜎𝑥 =𝑀𝑧𝑌
𝐼𝑧 , 𝜎𝑥 =
3𝑃𝑑
2𝑏𝑑2
Equation 1 Formula for calculating the Modulus of rapture