Bacterial self-healing concrete contains special bacteria and a chemical precursor that allow it to self-heal cracks. The bacteria are added to the concrete mixture along with a precursor like calcium lactate. When cracks form and water enters, the precursor activates the bacteria which metabolize it to produce calcium carbonate, filling the cracks. This extends the concrete's lifespan by autonomously repairing damage from cracking or corrosion.

2. INTRODUCTION
Crack formation is a typical phenomenon
related to durability.
Percolation of cracks may lead to leakage problems, causing
deterioration of the concrete matrix or corrosion of
embedded steel reinforcement.
In recent years a bacteria-based self-healing concrete is
being developed in order to extend the service life.
A two component healing agent is added to the concrete
mixture.
The agent consists of bacteria and an organic mineral
precursor compound.

3. WHAT IS BIO CONCRETE
Its is a special type of concrete invented by a group of microbiology
researchers under the head of Henk Jonkers.
Bio concrete is also called as BACTERIAL CONCRETE or self healing
concrete.
Its specially made to increase
the lifespan or the durability
of concrete structure by
the self healing action
of that concrete.

4. WHAT SPECIAL PRESENT IN BIO
CONCRETE
There are two thing present in bio concrete.
1) The special bacteria that has to resist the alkalinity and the
mechanical stress of concrete.
2) The chemical precursor to activate the bacteria.

5. WHAT BACTERIA IS USED
Most of the bacteria belongs to genus bacillus are fulfilling
the required criteria discussed above. some of the list of
bacteria are
B. Pseudofirmus ,
B. Cohnii B. Filla B.
Pasteurii…etc
The suitable chemical precursor found to be most suitable
is “calcium lactate” Ca(C3H5O2)2

6. WHAT IS HAPPENING INSIDE BIO
CONCRETE(MECHANISM)
The cracks are formed on the surface of concrete due to
many reasons like shrinkage, Inadequate water for hydration
…ect,
The water is deliberately forced into the crack and the
precursor is activated

7. Ca(C3H5O2)2 + 7O2 → CaCO3 + 5CO2 + 5H2O
CO2 + Ca(OH)2 → CaCO3 + H2O
(carbonation)
The activated precursor intern induces the bacteria to react
with that precursor and form a base of calcium carbonate
called as limestone, the chemical equation is given above.

9. BEFORE
HEALING
AFTER
HRALING

10. 20x

11. 40x

13. HOW THE HEALING AGENTS ARE
APPLIED
1)BY DIRECT APPLICATION
The bacteria and the chemical precursor(calcium lactate)
are added directly while making the concrete.
2) ENCAPSULATION LWA
a) The part of the coarse aggregate is replaced by the light
light weight aggregate(LWA) , which is impregnated with
twice the calcium lactate solution and the spores of
bacteria.
b) After impregnation the clay particles with 6% healing
agents and the concrete is made .

14. EVALUATION
 The Concrete properties should not be
negatively affected by addition of a healing
agent to the concrete mixture.
 a large amount of bacteria and certain mineral
precursor compounds like calcium lactate do
substantially influence concrete compressive
and tensile strength
 when the healing agent is added, Optimization
of healing agent is necessary so that it wont
affect the characteristics of concrete

15. CONCLUSION
The spores would be crushed by smaller holes.
No strong spores were detected in a 135-day old specimen,
implying the majority of spores in the cured cement mixture
were available for less than 4 months.
Further research is needed to increase the time period that
the bacterial spores remain in the concrete. It could be
possible.