MARINE CONCRETE

ADVANCED CONCRETE TECHNOLOGYBY :KARAN SHAH

SUBMITTED TO : DR. NEERAJA MADAM

SMBS, VIT UNIVERSITY

INTRODUCTION

• By the year 2025 more than 5500 million

people will live in cities. The growth of these

giant urban agglomerations is a new

experiment for life on Earth.

• What most of the times go unnoticed are the

basics. And what are the basics ?? Earth

comprises of roughly 29% of land and the rest

which in turn is the major chunk is 71% water.

• Earth is said to sustain life for atleast 1.75

billion years!! From the present date.Just

imagine the amount of human population.

• Hence with this backdrop there is a strong urge

to develop structures which will be able to

sustain life off shore . SMBS, VIT UNIVERSITY

MARINE STRUCTURES

• Typical wiki definition of a marine structure would be structures that

have application in petroleum industry for extracting oil and natural gas

and nowadays for wind turbines. But here we are talking about

sustaining life on marine environment.

• ‘Marine Spaces’ as I would like to mention them will be exploiting 70%

of the earth’s space.

• Concrete the most robust material in construction industry till date

would definitely need some see through changes to tackle an

completely different environment.

SMBS, VIT UNIVERSITY

SMBS, VIT UNIVERSITY

DEVELOPMENT OF AIRPORT , JAPAN

THE PALM ISLANDS , DUBAI

AUTOPIA AMPERE ,

ARTIST’S IMPRESSION

LILYPAD, ARTIST’S

IMPRESSION

CONCRETE IN MARINE

ENVIRONMENTPROS

• REDUCED DOWNTIME DUE TO INSPECTION

• REDUCED MAINTENANCE COSTS

• ECONOMIES OF SCALE

• GOD IMPACT RESISTANCE

• LOW CENTRE OF GRAVITY / GOOD STATION KEEPING

• REDUCED MOTIONS

• EXCELLENT FATIGUE

• HIGH MASS MOMENT OF INERTIA

• SLOWER THERMAL RESPONSE

• BETTER INSULATION

• RESISTANCE TO FATIGUE AND CRACK

• PROPAGATION

• RESISTANCE O BUCKLING

CONS• SALINITY RESISTANCE

• MICROCRACK DEVELOPMENT

• CRYSTALLIZATION OF SALTS

WITHIN CONCRETE

• ALKALI-AGGREGATE

EXPANSION

• CHLORIDE INGRESS

• PERMEABILITY

• HIGH COVER REQUIREMENT

• CRACKING AND SPALLING OF

COVER CONCRETE

• FORMATION OF EXPANSIVE

CORROSION PRODUCTS AT

THE REINFORCEMENT

SMBS, VIT UNIVERSITY

GLOBAL SALINITY SCENARIO

SMBS, VIT UNIVERSITY

SMBS, VIT UNIVERSITY

SALT WATER INGRESSION AND CORROSION

Olympus BXiS microscope

analysis of salt water intrusion

using Olympus STREAM

software

SMBS, VIT UNIVERSITY

SMBS, VIT UNIVERSITY

MICROCRACKS AND HEALING• Crack formation is a commonly observed phenomenon in concrete structures.

Although micro crack formation hardly affects structural properties of constructions,

increased permeability due to micro crack networking may substantially reduce the

durability of concrete structures due to risk of ingress of aggressive substances

particularly in marine environments.

• In order to increase the often observed autogenous crack-healing potential of

concrete, specific healing agents can be incorporated in the concrete matrix.

• The aim is to quantify the crack-healing potential of a specific and novel two-

component bio-chemical self-healing agent embedded in porous expanded clay

particles, which act as reservoir particles and replace part of regular concrete

aggregates

• a number of published studies the potential of calcite precipitating bacteria for

concrete or limestone surface remediation or durability improvement was

investigated. The mechanism of bacterially mediated calcite precipitation in latter

studies was primarily based on the enzymatic hydrolysis of urea. A potential

drawback of this reaction mechanism is that for each carbonate ion two ammonium

ions are simultaneously produced which may result in excessive environmental

nitrogen loading. Moreover, in these studies bacteria or derived ureolytic enzymes

were externally applied on cracked concrete structures or test specimens. Thus the

remediation mechanism in those studies cannot be defined as self-healing

SMBS, VIT UNIVERSITY

MICROCRACKS AND HEALING

• applied two-component bio-chemical self-healing agent, consisting of a

mixture of bacterial spores and calcium lactate, can be successfully

applied to promote and enhance the self-healing capacity of concrete

as the maximum healable crack width more than doubled

• The microbial enhanced crack-healing ability is presumably due to

combined direct and indirect calcium carbonate formation: (i) direct

CaCO3 precipitation through metabolic conversion of calcium lactate (ii)

indirect formation due to reaction of metabolically produced

CO2 molecules with Ca(OH)2 minerals present in the concrete matrix

leading to additional CaCO3 precipitation.

• In addition, as the metabolically active bacteria consume oxygen, the

healing agent may act as an oxygen diffusion barrier protecting the

steel reinforcement against corrosion.

SMBS, VIT UNIVERSITY

FINDINGS• Fig shows direct stereomicroscopic observation of cracks from control

and bacteria-based specimens before and after 28 days of immersion in

water. Width of completely healed cracks was significantly larger in

bacteria-based specimens (0.46 mm) compared to control specimens

(0.18 mm).

SMBS, VIT UNIVERSITY

Stereomicroscopic images of crack-

healing process

1. control mortar specimen

(a)before healing

(c) after 28 days healing

2. bio-chemical agent-based specimen

(b) before healing

(d) after 100 days healing .

FINDINGS• Element composition analysis using energy dispersive spectroscopy

(EDAX) revealed that the massively formed precipitate on crack

surfaces of bacterial specimens was essentially an association of

calcium, oxygen and carbon atoms, what suggests that mineral

precipitates were calcium carbonate (CaCO3) based.

SMBS, VIT UNIVERSITY

lamellar rhombohedra and

needle-like clusters assembled in

dumbbell shapes, possibly

polymorphs of CaCO3

CONCLUSIONS

• Concrete the second most used materials on earth has a major

drawback of carbon emissions and hence not environment friendly.

• Marine structures would use more concrete in comparison with the

lithosperic structure , but by self healing matrix we can reduce the

cover required for concrete structures for safeguarding the

reinforcements.

• Moreover it will lead to formation of a completely non permeable

material which would avoid salt water ingression through the

microcracks and hence reinforcements wouldn't be prone to

corrosion

• A major financial breakthrough can be made using this technology

because a repetitive sum of money can be saved which has to be

used in maintenance of these structures .

• Design life of marine structures can be drastically increased looking

into the future needs.SMBS, VIT UNIVERSITY

ACKNOWLEDGEMENTS

SMBS, VIT UNIVERSITY