Bacterial concrete uses bacteria to self-heal cracks in concrete over time. The document discusses: 1) How bacteria like Bacillus subtilis are mixed into concrete while dormant and remain inactive for 200 years. 2) When cracks form and water enters, the bacteria activate, consuming oxygen and nutrients to precipitate calcite crystals that fill the cracks. 3) Research shows bacterial concrete can reduce water and chloride permeability by 88% while increasing compressive strength by 25% compared to traditional concrete. The bacteria's self-healing mechanism could extend the lifespan of concrete structures with minimal human intervention.

1. Sinhgad Technical Education Society’s
SINHGAD INSTITUTE OF TECHNOLOGY AND SCIENCE, NARHE, PUNE
Department Of Civil Engineering.
2013 – 2014
TE Civil Semester 2
Presented by:
Niraj Rajesh Prasad
Under Guidance:
-Jain Sir
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.
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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.
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5. Characteristics Bacillus Subtilis
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
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6. Bacillus subtilus SEM image
Bacillus subtilus Bacillus subtilus on agar plate
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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
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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.
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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
Results in (Mpa) for Concrete and bacteria cell concentration 10^5/ml mixing water
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10. Optimum Concentration of cell
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11. SEM images for cell concentration
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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.
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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.
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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)
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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.
 www.onlinelibrary.wiley.com/journal/10.1002/(ISSN)1547-5905
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16. Thank You