PRESENTED BY:

RONAK MALPANI

RP15009

SELF-HEALING CONCRETE

SELF HEALING CONCRETE

“Bacillus” genus bacteria

Bacillus Pasteurii – a common soil bacterium

Bacteria converts nutrients to lime stone

In presence of water and nutrients bacteria feeds on soluble calcium lactate (CaCo3) in presence of oxygen

Converts to insoluble lime stone which solidifies.

Mineral producing concrete help mend micro- cracking in concrete.

Can seal cracks up to 0.5 mm

Survival of bacteria – even at depth more than 1KM within earth curst & desert.

Earlier mechanism - Enzymatic hydrolysis of urea

Presently Urea-mediated process wherein

urea (CO(NH2)2) + water = CO2 ammonia (NH3).

high pH value of the NH3/NH4+ system (about 9.2)

shift in the carbonate equilibrium

Precipitation of calcium carbonate (CaCO3)

Use of Scan Electron Microscope (SEM) for examination and analysis of micro structural characteristics of solids.• Increase in the compressive strength,

stiffness and modulus of rupture.

• Improved durability.

• Improvement in mechanical properties and permeability characteristics.

• Better resistance to freeze thaw attack reduction

• Bacterial Concrete failed at 5 % tensile strain while traditional concrete failed at 0.01% tensile strain.

Advantages:

• When bacterial concrete is fully developed, it may become yet another alternative method to replace OPC and its hazardous effect on environmental pollution.

• Reduction in permeability of concrete

• Reduction in corrosion of reinforced concrete.

1. Cost of bacterial concrete is double than conventional concrete.

2. Growth of Bacteria is not good in any Atmosphere & media.

3.Design of mix concrete with Bacteria there is no available any IS-code or other code.

4. Investigation of calcite precipitation is costly studied.

disadvantages:

Control (no bacteria, no ‘food’)

Bacterium C2C21A + CaLactate

Results of permeability testing

Crack formed Crack healing in presence of bacteria