SEMINARON

BACTERIAL CONCRETING -A self repairing bio-material

Guided by, Presented by,

Ms. SMITHA M S ABHIJITH SURESH

Assistant Professor S7 CE

Civil Department Roll No: 01

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INTRODUCTION Cracking of concrete is an inevitable phenomenon related to

durability.

repairing of existing cracks has been a subject of research for

many years.

In recent years, a bacteria based self healing concrete is being

developed to extend the service life.

Synthetic polymers such as epoxy treatment etc. are currently

being used as filling agents.

They are neither eco-friendly nor safe for human health.

Hence the use of a biological repair technique or micro-

biologically induced calcite precipitation technique[MICP] in

concrete is focused,

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OBJECTIVES

For studying the strength and regaing capacity of concrete with

different bacterial class.

To study the durability of bacterial concrete.

It’s resistance towards freeze thaw attack and sulphate attack.

To study advantages and dis-advantages and possibilities of

application of MICP (Microorganism used for Calcium Carbonate

Precipitation in Concrete) in construction area.

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WHATIS

“ BACTERIAL CONCRETE ?”

It is a special type of concreting.

by a group of micro-biologically researchers under the head of

henk jonkers.

It is also called as “ bio-concrete” or “self healing concrete.”

It is mainly invented to increase the durability or lifespan of the

concrete.

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WHAT IS “MICP- TECHNIQUE?”

It is a novel technique in remediating cracks and fissures in

concrete.

It is done by utilizing micro-biologically induced calcite[CaCo3]

in normal concrete.

It is pollution free and natural.

It will acts as a microbial sealant through out the concrete.

It comes under a broader category of science called “bio-

mineralization”.

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BIO-MINERALISATION

It is a process by which living organisms form inorganic solids.

“Bacillus pasteruii” is a common soil bacterium can induce the

precipitation of concrete.

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HOW DOES BACTERIA REMEDIATE

CRACKS?

-the chemical reaction process

The cell surface is negative in charge.

It draws cations including Ca2+ from the atmosphere to

deposit on the surface.

Thus the calcite is precipitated and eventually plug in the pores of

the concrete.

Ca2++ cell = cell- Ca2+

Cell - Ca2++Co32- = cell-CaCo3

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WHAT HAPPENING IN THE BACTERIAL

CONCRETE?

- mechanism of bacterial concrete

The cracks are formed on the surface of concrete due to manyreasons like shrinkage,inadequate water for hydration etc.

The water is deliberately forced into the crack and the precursoris activated.

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The activated precursor intern induces the bacteria to react with

that precursor and form a base of calcium carbonate called as

lime stone,

Ca2++ cell = cell- Ca2+

Cell - Ca2++Co32- = cell-CaCo3

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40X

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some Pictures about bacterial concreting,

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TYPES OF BACTERIA USED

They are classified as the following ;

Bacillus pasturii.

Bacillus Subtiles.

Bacillus Sphaericus.

Bacillus Cohnii.

These can lie dormant within the concrete for several years.

B.Cohnii. B.pasturii. B.Sphaericus B.Subtiles.

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PRACTICAL USE

The use of Self healing concrete has been very limited world

wide .

The concept is still in developing stage & on the way to large

scale use.

In India no use of this has been done.

A group of professors in JNTU are researching on bacterial

concrete.

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FUTURE SCOPE

Can be used in the construction of aircraft runways, bridges and

dams reducing the maintenance cost.

Retaining wall construction.

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SCANNING ELECTRON MICROSCOPY

INVESTIGATION

To give a visual documentation of the extent of mineral

precipitation in various regions with in the cement mortar.

To characterize the micro-structure relationship relationship of the

precipitates and the filling materials.

To confirm the elemental composition of the mineral precipitates.

To identify the microscopic evidence supporting the participation

of bacteria in mineral precipitation.

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XRD ANALYSIS-xray diffraction analysis method

XRD provides most definitive structural information.

It use monochromatic beam for sample analysis.

Single crystal diffraction mechanism is adopted in XRD analysis.

XRD is based on indexing the patterns.

Most effective in cubic specimens.

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MICRO-STRUCTURE EXAMINATIONS

It is based on the micrograph obtained by scanning electron

microscopic analysis.

From the micrograph, it is was investigated the growth of rod

shaped fabulous

deposition in concrete with bacteria.

It also reveals the calcifying power of the different micro-

organisms and their interaction with concrete.

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Magnified image of full grown calcite crystals with distinct and

sharp edges, found in the interior surface of the crack.

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ROAD SHAPED DEPOSITION ON

CONCRETE SURFACE

Road shaped impressions, consistent with the dimensions of

B.pasteurii are spread around the calcite crystals, formed on the

surface of the specimens subjected to sulphate attack.

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DEVELOPING CALCITE CRYSTALS

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MAGNIFIED IMAGE OF CALCITE

CRYSTALS

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DURABILITY COMPARISON

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COMPRESSIVE STRENGTH

COMPARISON

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ADVANTAGES

Perpetual and expected cracking that occurs in everyconcrete structure due to its brittle nature can be controlled.

Repairs without a human work crew.

Self-healing concrete also prevents the exposure of theinternal reinforcements.

It has made to extend the life span of a concrete structureof any size, shape.

Material consumption reduced in form of cement.

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CONCLUSION

It was found that all specimens with bacteria formed a layer of

calcite at the surface.

There were improvements in impermeability and its resistance to

alkaline environment,sulphate attack, freeze and thaw etc.

SEM method was used to document the role of bacteria in

improving the durability of concrete.

B.subtiles was most effective microbiome for the crack

remediation as remediates easily and helps in gaining early

strength.

Thus it can be concluded that presence of bacteria in concrete can

improve the strength and durability of concrete structure.

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REFERENCE

Vijeth N Kashyap and Radhakrishna,a study on the effects of

bacteria on cement composites,356-360,2013

M.V. Seshagiri Rao, V. Srinivasa Reddy, M. Hafsa, P. Veena and P.

Anusha,Bioengineered Concrete - A Sustainable Self-Healing

Construction Material,45-51,2013.

Mayur Shantilal Vekariya, Prof. Jayeshkumar Pitroda, Bacterial

Concrete: New Era For Construction Industry, Volume 4 Issue 9-

Sep 2013

www.Google.com

www.ijret.org

www.Wikipedia.org27/28

THANK YOU.. FOR LISTENING….

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