SEMINAR ON

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: 011/28

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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WHAT IS “ 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 many reasons like shrinkage,inadequate water for hydration etc.

The water is deliberately forced into the crack and the precursor is 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.. 13/28

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 every concrete structure due to its brittle nature can be controlled.

Repairs without a human work crew. Self-healing concrete also prevents the exposure of the

internal reinforcements. It has made to extend the life span of a concrete

structure of 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.org

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THANK YOU.. FOR LISTENING….

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