SELF HEALING BACTERIAL CONCRETE

PRESENTATION BY noella rhea bernard guided by Dr.Nagraj sitaram

INTRODUCTIONCracking of Concrete is an inevitable phenomenon.It cracks and suffers serious wear and tear over the decades of its expected term of service.Self-healing concrete in general seeks to rectify these flaws in order to extend the service life of any given concrete structure. self-healing concrete. Self-healing concrete consists of a mix with bacteria incorporated into the concrete and calcium lactate food to support those bacteria when they become active. The bacteria, feeding on the provided food source, heal the damage done and can also reduce the amount of damage

SELF HEALING BACTERIAL CONCRETEMainly micro cracks with widths typically in the range of 0.05 to 0.1 mm have been observed to become completely seale.bacteria were externally and manually applied on the concrete surface, while for autogenously repair an intrinsic healing agent is needed. The development of a self-healing mechanism in concrete that is based on a potentially cheaper and more sustainable material then cement could thus be beneficial for both economy and environment

BACTERIAS USED Bacillus cohnii Bacillus filla Bacillus parturii

ADVANTAGES & DISADVANTAGESThe self healing bacterial concrete helps in reduced maintenance and repair costs of steel reinforced concrete structures.Oxygen is an agent that can induce corrosion, as bacteria feeds on oxygen tendency for the corrosion of reinforcement can be reduced.Formation of crack will be healed in the initial stage itself thereby increasing the service life of the structure than expected life.the strength of the concrete is reduced.Hence preparation of self healing concrete costs double than conventional concrete.

APPLICATIONS

TESTING OF BACTERIAL CONCRETE

Concrete disks are prepared containing the porous aggregates filled with food only and with food and bacteria. The specimens are cured for 56 days and then tested in a deformation controlled tensile splitting loading to crack them partially. After this cracking the specimens are placed in a permeability test setup in which water is applied at one side of the specimen for 24 hours. After the healing the cracks are examined under the microscope and the results were observed.

Test samples Test setup

XRD ANALYSISXRD provides most definitive structural information.It uses monochromatic beam for sample analysis.Single crystal differaction mechanism is adopted in XRD.XRD is based on the indexing the patterns.Most effective in cubic specimens.

MICROSTRUCTURE EXAMINATIONSIt is based on the micrograph obtained by scanning electron microscopic analysis.From the micrograph it was investigated the growth of rod shaped fabulous deposition in concrete with bacteria.It also reveals the calcifying power of the different bacterial micro-organisms and their interaction with concrete.

BIOCONCRETE MECHANISM

STRENGTH STUDIES

28 days strengthControlled concrete

M20 M40Bio concrete

M20 M40compressive strength (Mpa) 28.2 52.0132.74 61.06Split tensile strength(Mpa)3.3 4.513.73 5.13Flexural strength(Mpa)4.7 6.116.11 7.73

COMPRESSIVE STRENGTH COMPARISION

BacteriaSpecimen Compressive StrengthB. Pasturii30 B. Subtiles33B. Sphaericus28B. Cohnii29

CELL CONCENTRATION

DURABILITY COMPARISON

CONCLUSIONB . Subtiles is found to be most effective microbiome for the crack remediation as it remediates the crack easily and helps in development of strength in early age.

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