This document discusses the use of bacterial concrete, which uses microbiologically-induced calcium carbonate precipitation to improve the properties of concrete. Various bacteria like Bacillus pasteurii and Bacillus sphaericus are able to continuously precipitate calcium carbonate. Bacterial concrete has been shown to increase the compressive, tensile, and flexural strength of concrete by up to 25% compared to conventional concrete. It can also help reduce cracks and improve the strength regeneration of cracked concrete. The cost of bacterial concrete is only 4-5% higher than conventional concrete. Scanning electron microscope images provide evidence of calcite precipitation in cracks by the bacteria.

1. Bacterial Concrete refers to a new generation of concrete in
which selective cementation by microbiologically-induced CaCO3
precipitation has been introduced for remediation of micro cracks.
Various researchers have use the ureolytic bacteria’s like
Bacillus pasteurii, bacillus subtilis etc…Bacillus Sphaericus yet
other ureolytic bacteria which showed strong potential in
precipitating the insoluble calcium carbonate were selected as a
test organism.

2. • To increase the compressive strength of concrete
• To increase the flexural strength of concrete
• To reduce plastic shrinkage cracks through the action of
bacteria
• To improve strength regaining capacity of the failure
concrete.
• To reduce voids through the precipitation of calcites

3. Bacillus sphaericus, a common soil
bacterium, can continuously precipitate
calcite under favourable conditions .This
phenomenon is called microbiologically
induced calcite precipitation.
Due to its inherent ability to precipitate
calcite continuously bacterial concrete can
be called as a “Smart Bio Material”.
BACILLUS SPHAERICUS

4. Components Grams
Trypticase 10
Yeast Extract
1.48
Tricine
4.5
Ammonium Sulphate
5
Glutamic Acid
2
Agar 1.6%

5. Components Grams (per liter)
Nutrient Broth 2.1
NaHCO3 1.48
NH4CL 7
CaCl2 25.2
Urea 7

6. Bacterial Water
Nutrient Broth
B. Sphaericus
Further
use
Normal Water

8. General Equation:
(Ca2++ CO3
2-→ CaCO3↓)
In concrete;
Ca2+ + Cell → Cell-Ca2+ . . . . (1)
Cl- + HCO3
- + NH3 → NH4Cl + CO3
2- . . (2)
Cell-Ca2+ + CO3
2- → Cell-CaCO3↓ . . . (3)

9. STUDY OF
MATERIALS
MATERIAL TESTING
DESIGN MIX PROPORTION
CONVENTIONAL CONCRETE BACTERIAL CONCRETE
CASTING OF SPECIMENS
TESTING
RESULT AND DISCUSSION
CONCLUSION

10. M25
MATERIAL CODE PROVISION PROPERTIES RESULTS
Cement IS 4031-1988 & IS 12269-1987
Grade 53
Specific gravity 3.15
Initial setting time 30 minutes
Final setting time 600 minutes
Fine aggregate
IS 383-1970 & IS 2386(Part III)
-1963
Grading zone III
Specific gravity 2.87
Water Absorption 1.0%
Free Surface Moisture 0.2%
Bulk Density 1700.15 Kg/cu.m
Coarse
aggregate
IS 383-1970 & IS 2386-1963
Specific gravity 2.73
Water Absorption 0.12%
Free Surface Moisture NILL
Bulk Density 1642.07 Kg/cu.m
Mix proportion IS 10262-1982 &IS10262-2009 1 : 1.28 : 2.86 (w/c =0.45)

11. Cube size 150x150x150mm
Cube without bacteria
Cube with bacteria
9 NOS
9 NOS
EXPERIMENTAL STUDIES

12. No.
of
days
Compressive strength of
conventional concrete
N/mm2
Compressive strength
of bacterial concrete
N/mm2
% increase
in
strength
7 21.52 24.17 12.32
14 25.36 29.86 17.78
28 31.02 38.73 24.86
TEST RESULT

13. SPLITTING TENSILE STRENGTH TEST
cylinder size 150x300mm
cylinder without bacteria
cylinder with bacteria
9 NOS
9 NOS

14. No.
of
Days
Split tensile strength of
conventional concrete
(N/mm2)
Split tensile strength
of bacterial concrete
(N/mm2)
% increase
in
strength
7 2.78 3.16 13.80
14 3.62 4.14 14.38
28 3.85 4.56 18.45
TEST RESULTS

15. FLEXURAL STRENGTH TEST
prism size 150x150x700mm
prism without bacteria
prism with bacteria
9 NOS
9 NOS

16. No. of
Days
Flexural strength of
conventional concrete
(N/mm2)
Flexural strength of
bacterial concrete
(N/mm2)
% increase in
strength
7 2.88 3.26 13.19
14 3.73 4.28 14.74
28 3.92 4.53 15.56
TEST RESULTS

17. CRACK REMEDIATION TEST
Cube drilled to a depth of 10mm
and width 5mm
Cube Size 150x150x150 mm
solid Cube without cracks 3NOS
Cracked specimen 3NOS
Remediation With cement paste 3NOS
Remediation With Bacterial paste 3NOS

18. TEST RESULT
S.NO Description of Specimen
Compressive Strength
(N/mm2)
1 Solid specimen 26.35
2 Cracked specimen 20.20
3 Conventional Remediation 23.15
4 Bacterial Remediation 25.87
Increase in percentage = 11.75 %

19. SEM INVESTIGATION

20. FORMATION OF CALCITE IN CRACKS

21. PARTICULARS
CONVENTIONAL CONCRETE BACTERIAL CONCRETE
Quantity/Nos Unit Rate(Rs) Cost(Rs) Quantity/Nos Unit Rate Cost(Rs)
MATERIAL COST
Coarse Aggregate 0.770 cu.m 1800.00 1386.00 0.77 cu.m 1800.00 1386.00
Fine Aggregate 0.385 cu.m 1500.00 577.50 0.385 cu.m 1500.00 577.50
Cement 11.50 bags 330.00 3795.00 11.50 bags 330.00 3795.00
Steel 80 kg/m3 55.00 4400.00 80 kg/m3 55.00 4400.00
Form work 200.00 200.00
Bacteria - - - - - 450.00
Growth Medium - - - - - 100.00
TOTAL MATERIAL COST = 10358.50 = 10908.5
LABOUR COST
Head mason 1 500.00 500.00 1 500.00 500.00
Mason 1 450.00 450.00 1 450.00 450.00
Mazdoor 3 300.00 900.00 3 300.00 900.00
Bhishti 1 225.00 225.00 1 225.00 225.00
blacksmith 1 450.00 450.00 1 450.00 450.00
Travelling/purchase Lump Sum Amount 500.00 Lump Sum Amount 500.00
TOTAL LABOUR COST = 3025.00 = 3025.00
Water charges 2% of Total material & labour cost 267.67 278.67
Engineer profit 5% of Total Cost 669.17 696.67
GRAND TOTAL ≈ 14321.00 ≈ 14910.00

22. • The compressive strength of concrete is increased.
• Reduced maintenance cost.
• Used as a repair material.
• Reduce plastic shrinkage cracks
• Rebar corrosion is reduced due to high
impermeability
• Self healing of cracks due to bacterial action
MERITS

24. • The compressive strength of bacterial concrete is increased up to
25%
• The splitting tensile strength of bacterial concrete is increased up
to 19%
• The strength regaining capacity of bacterial concrete is increased
to 10 – 12 % over conventional treatment.
• Cost of the bacterial concrete is increased only 4 – 5 % .
• These calcite producing organisms are eco-friendly and not
deleterious to man kind so they can be used in repairing the
concrete structure.
CONCLUSION

25. 1. Dick J, De Windt W, De Graef B, Saveyn H, Van der Meeren P, De Belie N,
Verstraete W. 2006, “Bio-deposition of a calcium carbonate layer on degraded
limestone by Bacillus species”. Biodegradation, Vol. 17(4): 357-367.
2. Bang SS, Galinat JK, Ramakrishnan V. 2001, “Calcite precipitation induced by
polyurethane-immobilized Bacillus pasteurii”. Enzyme Microb Technol, Vol.
28(4-5): 404-409.
3. Stocks-Fischer S, Galinat JK, Bang SS. 1999 “Microbiological precipitation of
CaCO3”. Soil Biol Biochem. Vol. 31(11): 1563-1571.
4. Nolan E, Basheer PAM, Long AE. 1995, “Effects of three durability enhancing
products on some physical properties of near surface concrete”. Construction
Build Mater. 9(5): 267-272.
5. Hammes F, Boon N, de Villiers J, Verstraete W & Siciliano SD. 2003 “Strain-
specific ureolytic microbial carbonate precipitation”. App. 69(8): 4901–4909.
REFERENCES

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