Self-healing concrete, also known as bio concrete, incorporates bacteria that can mend cracks by producing limestone when activated by water and oxygen, significantly increasing the durability of concrete structures. This innovative material can repair itself within three weeks and has the potential to extend a structure's lifespan by up to 200 years, although it comes with a higher cost and reduced strength. It aims to address common issues with conventional concrete, such as corrosion and expensive repairs due to crack deterioration.

1. SELF-HEALING CONCRETE
(bio concrete)
By shekhar chapagain

2. Concrete
• main materials used in the construction industry, from the foundation of
buildings to the structure of bridges and underground parking lots
concrete Stress
weather conditions = breaking
• tends to crack when subjected to tension
• it is possible to repair cracks, but this takes time and money, especially when the
construction has to be closed down while the reparations take place

3. Once damaged, cracks in concrete will rapidly
become worse if it is not repaired
• Water will enter the cracks
• in winter, there are chances that it freezes, causing the cracks to
grow.
• When these cracks are deep enough to reach the steel reinforcement,
this can corrode, causing serious damage.
• Repairs can be particularly time consuming and expensive because it
is often very difficult to gain access to the structure to make repairs,
especially if they are underground or at a great height.

4. Why to solve this problem?
• Concrete will continue to be the most important building material for
infrastructure but most concrete structures are prone to cracking
• water seeps in to degrade the concrete and corrode the steel
reinforcement, greatly reducing the lifespan of a structure
• tensile forces can lead to cracks and these can occur relatively soon after
the structure is built.
• Repair of conventional concrete structures usually involves applying a
concrete mortar which is bonded to the damaged surface
• Repairs can be particularly time consuming and expensive because it is
often very difficult to gain access to the structure to make repairs,
especially if they are underground or at a great height.

5. What can we do?
• Mineral-producing bacteria have been found that could help mend
micro-cracking in concrete.
• self-healing concrete that can repair itself within three weeks and
makes manual repairs superfluous
mixing genus Bacillus with healing agent
• capable of surviving in an extreme alkaline environment
• Cement and water have a pH value of up to 13

6. genus Bacillus
• A healing agent that works when bacteria embedded in the concrete
convert nutrients into limestone
• These bacteria are enclosed in pellets and can be dormant for 200
years.
• when they come into contact with water and oxygen, they wake
up(This can only happen when the concrete is cracked or
deconstructed)
• Fed by nutrients in the pellets, the bacteria will multiply and start to
produce calcium carbonate (limestone), filling the cracks

8. What is bio concrete
• It is the special type of concrete invented by a group og 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

9. How does bioconcretework?
• A healing agent that works when bacteria embedded in the
concrete convert nutrients into limestone
• These bacteria are enclosed in pellets and can be dormant for
200 years.
• when they come into contact with water and oxygen, they wake
up(This can only happen when the concrete is cracked or
deconstructed)
• Fed by nutrients in the pellets, the bacteria will multiply and start
to produce calcium carbonate (limestone), filling the cracks

10. How does bioconcretework?
• consumption of oxygen during the bacterial conversion of calcium
lactate to limestone
• Oxygen is an essential element in the process of corrosion of steel
and when the bacterial activity has consumed it all it increases the
durability of steel reinforced concrete constructions
• when water seeps into the concrete, the bacteria germinate and
multiply quickly.

11. How does bioconcretework?
• biologically produce limestone to heal cracks that appear on the surface of
concrete structures
• genus Bacillus, along with a calcium-based nutrient known as calcium
lactate, and nitrogen and phosphorus, are added to the ingredients of the
concrete when it is being mixed.
• genus Bacillus + water and nutrients activated
• activated bacteria feeds (calcium lactate) oxygen is consumed
• calcium lactate insoluble limestone
• The limestone solidifies on the cracked surface

12. Benefits of using bio-concrete
• It increases the life span by 4 times(200 years)
• The length of the cracks does not matter, only the breadth
• At the moment, the bacteria can fill cracks up to 0.8 mm
• The material is repaired within 3 weeks, no matter the length of the
crack
• Basilisk has also developed a liquid containing the bacteria that can
make ordinary concrete self-healing.

13. Disadvantage
• clay pellets holding the selfhealing agent comprise 20% of the volume
of the concrete.
That 20% would normally comprise harder aggregate such as
gravel. The clay is much weaker than normal aggregate and this
weakens the concrete by 25% and significantly reduces its compressive
strength.
• cost of self-healing concrete is about double that of conventional
concrete(€80 euros per cubic metre)
• If the life of the structure can be extended by 30%, the doubling in
the cost of the actual concrete would still save a lot of money in the
longer term