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Bioconcrete Biomineralization and Self Healing
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1
Question
What is bioconcrete?
Page 2
Answer
Self-healing concrete that embeds bacteria to repair cracks.
2
Question
What type of bacteria spores are embedded in self-healing bioconcrete?
Page 2
Answer
Dormant spores of Bacillus species.
3
Question
What nutrient is provided with the dormant Bacillus spores in bioconcrete?
Page 2
Answer
Calcium lactate.
4
Question
What triggers the dormant bacteria spores in bioconcrete to germinate?
Page 2
Answer
Water and oxygen entering through cracks.
5
Question
What do germinated bacteria in bioconcrete produce to seal cracks?
Page 2
Answer
Calcium carbonate (\(CaCO_3\)).
6
Question
What seals the microcracks in self-healing bioconcrete?
Page 2
Answer
Precipitated calcium carbonate (\(CaCO_3\)) from bacteria.
7
Question
What is the name of the process by which bacteria in bioconcrete heal cracks?
Page 2
Answer
Biomineralization.
8
Question
What is the chemical formula of the precipitate that heals cracks in bioconcrete?
Page 2
Answer
\(CaCO_3\) (calcium carbonate).
9
Question
How does biomineralization in bioconcrete restore watertightness?
Page 2
Answer
By precipitating \(CaCO_3\) that seals microcracks.
10
Question
What strength-related benefit does self-healing bioconcrete provide?
Page 2
Answer
Partially recovers strength.
11
Question
How does bioconcrete reduce maintenance needs?
Page 2
Answer
By self-healing cracks through bacterial biomineralization.
12
Question
What is one key durability improvement from bioconcrete's self-healing?
Page 2
Answer
Improved longevity due to restored watertightness and strength.
13
Question
In bioconcrete, where are the dormant spores located before activation?
Page 2
Answer
Embedded in the concrete matrix with calcium lactate.
14
Question
Why do bacteria in bioconcrete only activate after cracking?
Page 2
Answer
Dormant spores require water and oxygen from cracks to germinate.
15
Question
What visual change occurs in the diagram of bioconcrete healing?
Page 2
Answer
Cracks fill with precipitated \(CaCO_3\) crystals, sealing them.
16
Question
What are Bacillus spores mixed into for self-healing concrete?
Page 3
Answer
Fresh concrete, often encapsulated in lightweight aggregates, silica gel, or other carriers.
17
Question
Name examples of Bacillus species used in self-healing concrete.
Page 3
Answer
B. subtilis, B. cohnii, Sporosarcina/Bacillus pasteurii.
18
Question
Why are Bacillus spores encapsulated in carriers like lightweight aggregates or silica gel?
Page 3
Answer
To protect them during hydration.
19
Question
How long can Bacillus spores remain dormant in concrete?
Page 3
Answer
For decades.
20
Question
What activates dormant Bacillus spores in concrete cracks?
Page 3
Answer
Water penetration into the crack.
21
Question
What is the role of calcium lactate in self-healing concrete?
Page 3
Answer
Added as a biocompatible calcium and carbon source for bacteria.
22
Question
What do germinated bacteria do to calcium lactate?
Page 3
Answer
Oxidize lactate.
23
Question
Besides oxidizing lactate, what else do bacteria consume during the process?
Page 3
Answer
Oxygen.
24
Question
What do bacteria generate from lactate oxidation that aids in calcite formation?
Page 3
Answer
Carbonate species.
25
Question
What reacts with carbonate species produced by bacteria to form crystals?
Page 3
Answer
Available \( \ce{Ca^2+} \).
26
Question
What type of bacteria oxidize lactate in self-healing concrete?
Page 3
Answer
Heterotrophic bacteria.
27
Question
What is the product of lactate oxidation by heterotrophic bacteria?
Page 3
Answer
\( \ce{CH3COO^- + 2O2 -> 2CO2 + H2O} \)
28
Question
What reaction occurs between CO2 and hydroxide in the healing process?
Page 3
Answer
\( \ce{2CO2 + OH^- -> CO2 + HCO3^-} \)
29
Question
What is the final precipitation reaction forming calcite?
Page 3
Answer
\( \ce{2HCO3^- + Ca^2+ -> CaCO3 + CO2 + H2O} \)
30
Question
Where does precipitated calcite deposit in self-healing concrete?
Page 3
Answer
On cell surfaces and surrounding matrix.