This document summarizes a seminar report on bacterial concrete. It introduces the concept of using bacteria to self-heal cracks in concrete. Bacterial concrete is made by mixing dormant Bacillus subtilis bacteria and calcium lactate nutrients into the concrete. When cracks form and water enters, the bacteria spores germinate and metabolize the nutrients to precipitate calcite crystals that fill the cracks. Research shows bacterial concrete has lower permeability and increased strength compared to conventional concrete. It provides long-term self-healing without further human intervention that can extend the lifespan of concrete structures.
Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self - repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and Calcium chloride medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places.
In this study, bacterial concrete is to be prepared under grade of concrete OPC 43.The design mix proportioning also carried under IS code provision. Testing of specimens are carried at 7 days ,14 days and 28 days of curing by Compression Testing Machine and Universal Testing Machine for corresponding specimens. The Compressive Strength and Flexural Strength of Bacterial Concrete are found.
Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self - repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete. This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and Calcium chloride medium. The effect on the compressive strength and stiffness of the cement mortar cubes due to the mixing of bacteria is also discussed in this paper. It was found that use of bacteria improves the stiffness and compressive strength of concrete. Scanning electron microscope (SEM) is used to document the role of bacteria in microbiologically induced mineral precipitation. Rod like impressions were found on the face of calcite crystals indicating the presence of bacteria in those places.
In this study, bacterial concrete is to be prepared under grade of concrete OPC 43.The design mix proportioning also carried under IS code provision. Testing of specimens are carried at 7 days ,14 days and 28 days of curing by Compression Testing Machine and Universal Testing Machine for corresponding specimens. The Compressive Strength and Flexural Strength of Bacterial Concrete are found.
Self healing of cracks or self-filling of cracks by the help of bacterial process after hardening is known as self healing concrete, It is also known as bacterial concrete. Bacterial concrete refers to a new generation concrete in which selective cementation by microbiologically-induced CaCO3 precipitation has been introduced for remediation of micro-cracks. Self-repairing of cracks without any external aide.
Significant increase in compressive strength and flexural strength when compared to normal concrete.
Resistance towards freeze-thaw attacks.
Reduction in permeability of concrete.
Reduces the corrosion of steel due to the cracks formation and improves the durability of steel reinforced concrete.
Bacillus bacteria are harmless to human life and hence it can be used effectively.
The usage of cement has been increased
throughout the world which has severe effect on the
environment. replacement of cement in concrete is in very
much need, for which several materials came into existence
like flyash, silicafume GGBS and geopolymers etc.one such
material which will act as cementinious materials is used in
the study which will reduce cracks and fissures in concrete
by utilizing microbiologically induced calcite (CaCo3
)
precipitation called Bio Mineralization produced by Bacillus
subtilis in the presence of chemicals. In this project,
bacterial concrete is prepared under grade of concrete M25
and Natural fiber is added in total volume of concrete in
desired level which will cure the cracks automatically by
forming calcium carbonate precipitate as well as to achieve
more Compressive strength and Flexural strength. To avoid
corrosion, the bacterial concrete along with natural fibers is
used which results in self healing process.
In this study, the behavior of bacterial fibre
concrete was investigated experimentally. Various
parameters like compressive strength, flexural strength and
splitting tensile strength of specimens for bacterial fibres
concrete have been studied. Then these values for bacterial
and bacterial fibre concrete are compared with the
conventional concrete.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
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Self healing of cracks or self-filling of cracks by the help of bacterial process after hardening is known as self healing concrete, It is also known as bacterial concrete. Bacterial concrete refers to a new generation concrete in which selective cementation by microbiologically-induced CaCO3 precipitation has been introduced for remediation of micro-cracks. Self-repairing of cracks without any external aide.
Significant increase in compressive strength and flexural strength when compared to normal concrete.
Resistance towards freeze-thaw attacks.
Reduction in permeability of concrete.
Reduces the corrosion of steel due to the cracks formation and improves the durability of steel reinforced concrete.
Bacillus bacteria are harmless to human life and hence it can be used effectively.
The usage of cement has been increased
throughout the world which has severe effect on the
environment. replacement of cement in concrete is in very
much need, for which several materials came into existence
like flyash, silicafume GGBS and geopolymers etc.one such
material which will act as cementinious materials is used in
the study which will reduce cracks and fissures in concrete
by utilizing microbiologically induced calcite (CaCo3
)
precipitation called Bio Mineralization produced by Bacillus
subtilis in the presence of chemicals. In this project,
bacterial concrete is prepared under grade of concrete M25
and Natural fiber is added in total volume of concrete in
desired level which will cure the cracks automatically by
forming calcium carbonate precipitate as well as to achieve
more Compressive strength and Flexural strength. To avoid
corrosion, the bacterial concrete along with natural fibers is
used which results in self healing process.
In this study, the behavior of bacterial fibre
concrete was investigated experimentally. Various
parameters like compressive strength, flexural strength and
splitting tensile strength of specimens for bacterial fibres
concrete have been studied. Then these values for bacterial
and bacterial fibre concrete are compared with the
conventional concrete.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
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1. GOVERNMENT POLYTECHNIC NAYAGARH
Department Of Civil Engineering.
2023 – 2024
Presented by:
Somanath Nahak
Regd.no-L22130001009
Semister - 4th
Under Guidance:
Sushree Sasmita Sahoo
Department of Civil
Engineering
A seminar report on
Bacterial Concrete
2. Introduction
Cracks In concrete
Concretes are very susceptible to cracking which allows chemicals and
water to enter .
Cracking in the surface layer of concrete mainly reduces its durability.
When micro cracks growth reaches the reinforcement corrosion occurs
in the reinforcement.
Synthetic polymers such as epoxy treatments are used for repair of
concrete and they harm to the environment.
2
3. IS requirements for Serviceability R.C.C
Clause 35.3.2 IS 456 (cracking)
Cracking of concrete should not adversely affect durability & appearance of
structure.
Surface width of cracks should not exceed 0.3mm.
Exposure to moisture the width is limited to 0.2mm.
Our aim satisfy the serviceability requirement at entire life of structure.
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4. Bacterial Concrete
Use of these Bio mineralogy concepts in concrete defined a new
material called “Bacterial Concrete”
Bacillus subtilis mixed with concrete in dormant stage and they
remain hibernated for 200 years.
Gets activated when exposed to water or moisture.
Precipitating calcite crystals through metabolism cycle the soluble
nutrients are converted to insolubleCaCO3.
4
5. Characteristics Bacillus Subtilis
5
Characteristics Bacillus Subtilis
Shape, size, gram stain Long rods, 0.6-0.8 μm in width and 2.0 to 3.0 μm in
gram positive
Fermentation:
Lactose
Dextrose
Sucrose
No acid, no gas
No acid, no gas
Acid and gas
H2S production Absent
Indole production Present
Colony morphology Irregular, dry, white, opaque colonies
7. How does bacteria remediate cracks?
Concrete is mixed with bacteria (bacillus subtilus) at dormant stage.
To survive in this high alkaline environment for long durations form spores (highly
resistant for 200 years ) withstanding during concrete mixing.
A calcium lactate nutrient supplied along with bacteria in suspension helps in
producing calcite crystals.
The spores of the bacteria germinate on contact with the water and nutrients while
cracks and get activated
7
8. Cont.
As the bacteria feeds oxygen is consumed and the soluble calcium lactate is
converted to insoluble limestone.
The limestone solidifies on the cracked surface, thereby sealing it up.
Tests all show that bacteria embedded concrete has lower water and chloride
permeability by 88%
Reaction:
Ca 2+ + Cell --------> Cell- Ca 2+
Cell- Ca 2+ +CO3-----> Cell-CaCO 3
The crystals expand until the entire gap is filled.
8
9. Results by Research papers
Strength Study
@ 28 days age
Conventional Concrete Bio Concrete
M20 M30 M20 M30
Compressive Strength 28.18 37.14 32.74 41.06
Split Tensile Strength 3.26 4.51 3.93 5.13
Flexural Strength 4.68 5.11 6.11 6.73
9
Results in (Mpa) for Concrete and bacteria cell concentration 10^5/ml mixing water
12. Advantages
Perpetual and expected cracking that occurs in every concrete structure due to its
brittle nature can be controlled.
Repairs without a human work crew.
Self-healing concrete also prevents the exposure of the internal reinforcements.
It has made to extend the life span of a concrete structure of any size, shape.
Material consumption reduced in form of cement.
12
13. Conclusion
Microbial mineral precipitation resulting improve the overall behaviour of concrete.
The greatest improvement in compressive strength occurs at cell concentrations of
10^5 cells/ml mixing water.
The study result shows that 25% increase in 28 day compressive strength.
Less permeability and corrosion resistance.
13
14. References
Ramachandran S.K., Ramakrishnan V. and Bang S.S., Remediation of concrete
using microorganisms, ACI Materials Journal 98(1), 3-9 (2001)
Stocks-Fischer S., Galinat J.K., and Bang S.S., Microbiological precipitation
of CaCO3. Soil Biology and Biochemistry, 31(11), 1563-1571 (1999)
Tai C.Y. and Chen F.B., Polymorphism of CaCO3 precipitated in a
constant-composition environment. AIChE Journal, 44(8), 1790-1798 (1998)
www.onlinelibrary.wiley.com/journal/10.1002/(ISSN)1547-5905
https://youtube.com/shorts/2eScG2xO9bE?feature=share
14
15. References
S. SUNIL PRATAP REDDY International Journal of Earth Sciences and
Engineering ISSN 0974-5904, Vol. 03, No. 01, February 2010, pp. 116-
124.
V.Ramakrishnan, K.P.Ramesh and S.S.Bang, “Bacterial
Concrete”Proceedings of SPIE Vol.4234 pp.168-176, Smart Materials.
15
