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

vii

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

7

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

11

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.

12

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.

22

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)

24

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