2. 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.
3. 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.
4. 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
5. MECHANISM
The cracks are formed on the surface of concrete due to many
reasons like shrinkage, Inadequate water for hydration …etc
The water is deliberately forced into the crack and the precursor is
activated
.
6. 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
8. 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 weight
aggregate(LWA) , which is impregnated with twice the calcium
lactate solution and the spores of bacteria.
b) b) After impregnation the clay particles with 6% healing agents
and the concrete is made .
9. TESTING ON BACTERIAL CONCRETE
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
behavior 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.
11. ADVANTAGES AND DISADVANTAGES OF
BACTERIAL CONCRETE:
ADVANTAGES
Improvement in compressive strength of concrete
Reduction in permeability of concrete
Reduction in corrosion of reinforcement
12. DISADVANTAGES
Cost of bacterial concrete is double than
conventional concrete
Growth of bacteria is not good in every
atmosphere
No IS Code or any other code is available for
design of mix concrete with bacteria
13. APPLICATION OF BACTERIAL CONCRETE
For constructing underground retainers for hazardous waste
For high rise building
Water retaining structures.
Concrete floors, Tunnel linings, basement walls
14. Current research
To find alternative precursor
Ability of bacteria to resist sulphate attack
To develop spray able version
