Self healing concrete •Introduction •necessity •advantages •disadvantages •Conclusion

1. PRESENT BY –
Akshaya R
Mohana priya R
SELF HEALING
CONCRETE

3. DEFINITION –
Self healing concrete is a
concrete which heals itself when it comes
in contact with air and water, it produces
lime on outer layer of concrete.
* In most of the traditional concrete
mixtures 20-30% of the cement is left
unhydrated.
* If cracking of the concrete occurs,
unreacted cement grains may become
exposed to moisture penetrating the
crack.
* In that case the hydration process may
start again and hydration products may
fill up and heal the crack.
INTRODUCTION

4. NECESSITY
FORCES ON CONCRETE -

5. Need of Self-healing
Concrete
1. It provides longer life to the structures.
2.Maintenance and repair are less required.
3. Improvement in compressive strength of concrete.
4. Reduction in permeability of reinforced concrete
5. Good resistance towards freeze-thaw attack reduction.

6. LIME FILLED IN CRACKS

7. Bacteria used for Self healing
The bacteria from the Bacillus family is considered for
self-healing in concrete. Following are those bacteria:
a. Bacillus Pastuerin
b. Bacillus Sphearicus
c. Bacillus Pseudofirmu
d. Bacillus Subtilia

8. Characteristics of Bacillus
• Spores are 1-1.2 microns in diameter, round, and terminal to subterminal.
• The colonies are generally circular and glossy, however, the size and opacity
increase from media to media.
• Urea-agar slant shows thin growth i.e. restricted and translucent.
• Urea-milk-agar streak plate shows variable hydrolysis of casein.

9. WORKING OF SELF HEALING
CONCRETE
1. Self-healing concrete is a substance that will biologically prepare
limestone to heal cracks that comes on the surface of concrete structures.
Ca(C3HSO2)2 + 702 → CaCO3 + 5CO2 + 5H20
(Calcium Lactate) (Lime)
2. Especially chose types of the bacteria genus Bacillus, with a calcium-
based nutrient given as calcium lactate, and nitrogen and phosphorus, are
added to the ingredients of the concrete when it is being mixed.

10. 1. Workability
2. Surface Crack healing
3. Compressive strength

11. TEST ON SELF HEALING
CONCRETE
HENK JONKERS
• In 2011, Jonkers and his team is doing testing
and case study on self healing concrete.
• A small structure or part of a structure will be
built with the self-healing material and observed
over three to five years.
• Structures will be fitted with some panels of self-
healing concrete and others with conventional
concrete so that the behaviour of the two can be
compared.
• Cracks will be made in the concrete that are
much larger than the ones that have healed up in
the laboratory to determine how well and fast
they heal over time.

12. COMPARISON BETWEEN SHC
AND ORDINARY CONCRETE

13. ADVANTAGES

14. Advantages of Self healing
Concrete
1. This concrete has comparatively much lower permeability, greater durability,
and stress carrying capacity than conventional concrete.
2. It can be applied to existing buildings in the form of spray which can reduce
the overall repair and maintenance costs of the buildings.
3. This is an environmentally friendly technique because the carbon dioxide
produced is prevented due to the low use of concrete.
4. SHC is a more effective shock absorber that protects during earthquakes
because it has a polymer membrane on its surface.
5. It can operate at internal levels which means that the smallest cracks can be
reached.

15. Disadvantages of Self healing
Concrete
1. Self-healing concrete cost price is almost 2 times compared to normal
concrete.
2. Growth bacteria can be affected by various environmental conditions.
3. The clay pallets mixed in concrete mostly cover 20 % volume of
concrete and This may result in a shear zone or fault zone in the concrete.

16. 1. Tunnel lining
2. Walls of the building
3. Highway bridges
4. Concrete floors
5. Structural Basement
6. Marines Structures
APPLICATIONS

17. Highlights of self healing
concrete
•MICP was used to repair concrete cracks with the width of
0.3–0.5 mm.
•Studied the basic and self-healing properties of two kinds of
self-healing concrete.
•Used sensors to monitor the generation of cracks through
strain and temperature.
•The concrete cracks in the engineering application site have
been well repaired.

18. CONCLUSION
• Hence, self healing concrete is crack resistant.
• Which protects the concrete and reinforcement
from cracks and from corrosion.
• By doing this, it prevents water to percolate into
reinforced steel concrete and hence it does not
comes in contact with reinforcements.
• Thus, it prevents reinforcement from corrosion.
• It is a research project.