Structural health monitoring and concrete protection methods are needed to protect structures from environmental damage and corrosion. Concrete protection includes hydrophobic impregnation, painting, oils and sealers to prevent water and chemical ingress. Reinforcement can be protected through galvanization, corrosion-inhibiting admixtures, and cathodic protection. Self-regulating anodes provide galvanic protection to reinforced concrete through sacrificial corrosion of the anode material. Structural health monitoring assesses structural condition over time using automated methods to predict remaining lifespan.

1. UNIT 4
PROTECTION
METHODS &
STRUCTURAL
HEALTH
MONITORING
-BY KEERTHANA S,
M.E .STRUCTURAL ENGINEERING

2. AGENDA
• Introduction​,
• Concrete protection method,
• Reinforcement protection method,
• ​Self regulating anode,
• Conclusion.

3. .
INTRODUCTION
why protection method is needed in concrete?
Surface protection of concrete structural members is necessary to protect the structure from
damage due to environmental considerations.
Corrosion of reinforcement due to permeability of water / moisture, chemical attack on structural
members, structures nearby sea-coast etc
Structural health monitoring:
SHM can be defined as automated methods for determining adverse changes in the
integrity of mechanical systems
Structural health monitoring (SHM) is an area of growing interest and worthy of new
and innovative approaches.
Structural health monitoring has multiple applications.
Structural health monitoring assesses the state of structural health and, through
appropriate data processing and interpretation, may predict the remaining life of the
structure Structural health monitoring has multiple applications.
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4. CONCRETE PROTECTION
METHOD

5. METHODS OF PROTECTING CONCRETE SURFACES FROM
DAMAGES AND DETERIORATION
PRESENTATION TITLE 5
Following are the surface protection measures that may be taken to minimize or stop the damage to
concrete structures:
1.Hydrophobic Impregnation
2.Painting and oils
3.Sealers
Materials for concrete surface protection
The materials use for these methods for concrete surface protection are:
•Silicon organic solutions
•Resins
•Oils

6. HYDROPHOBIC
IMPREGNATION
Exposure to environmental elements can lead to the ingress of water, moisture, chlorides and
chemicals in concrete which can lead to corrosion of reinforcement and loss of structural
load-bearing capacity.
Therefore, it is necessary to protect concrete structures against the ingress of such elements-
and with hydrophobic impregnation, such damages can be prevented.
Hydrophobic impregnation is used to protect porous concrete surfaces from moisture
penetration, heavy weathering, and water ingress.
This in turn helps to produce a water-repellent surface, which not only keeps water out and
thereby prevents the ingress of aggressive water-soluble chlorides and sulphates, but also
minimizes the growth of algae and moss.
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7. PROPERTIES:
› Solvent-free, creamy hydrophobing agent based on silane
› Deep penetration into the concrete surface, water vapour-permeable and alkali-resistant
› Reduces the penetration of chlorides and other pollutants dissolved in water
› Compared to liquid media: a deeper penetration, a longer durability and a requirement of only one
instead of
two or three work steps
› Environmentally-friendly and frost and deicing salt resistant
› Prevents any moistening below surface protection coatings
› Easy to process, thixotropic, with only one work step extremely cost-effective
› Easily processable even in overhead areas
TITLE 7

8. PAINTS AND OILS:
New concrete surfaces after completion of the curing should be allowed to dry for 1 or 2 weeks
before waterproofing treatment is applied.
Such new surfaces are brushed with a solution of 40 gm of phosphoric acid and 16 gm of zinc
chloride to a liter of water.
This is done to prevent the saponification of linseed oil
This treatment is not necessary for old concrete surfaces.
Before adopting waterproofing measures the surface must be made clean & dry
After it apply two coats of linseed oil as mentioned below.
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9. APPLICATION:
A mixture of 50% raw linseed oil and 50% turpentine heated to a temperature of 800C is
applied with ordinary brush as first coat
Raw linseed oil heated to 800C is applied as a second coat with ordinary brush after 24 hours
of application of the first coat.
After the second coat waterproofing coat becomes thoroughly dry, the entire treated surface is
given two coats of standard white lead and oil paint.
The application of the paint is necessary otherwise the previously applied oil treatment will
deteriorate.
In order that the colour of oil paint should match with the colour of concrete surface, lamp
black or burnt sienna is added to the paint.
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10. SEALING COMPONENTS:
Concrete sealing compounds or concrete sealers are liquids applied on the hardened concrete
surface to prevent the penetration of deicing solutions, carbon-di-oxide, acids, water, etc. into
the concrete.
The penetration of such materials results in corrosion of reinforcing steel and cracks.
TYPES:
1.Topical Sealers
Example: Acrylic Sealers, Epoxy Concrete Coatings
2.Penetrating sealers.
Example: Silicates, siliconates, silanes, and siloxane.
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11. MAIN FEATURES OF SEALERS:
Concrete sealer compounds retard the penetration of harmful substances from the surrounding into the
concrete.
Concrete sealers are applied only after the concrete structure has gained 28 days of age and strength.
The concrete sealers can either block the pores of the concrete or act as an impermeable layer to
prevent the penetration of foreign materials.
Concrete sealers are essential where the deterioration of concrete due to chemical intrusion, corrosion
of steel reinforcement, and alkali-aggregate reaction is a problem. Its application is more in freezing
and thaw regions.
Chemical concrete sealers can last for ten years or longer. There are varied option of concrete sealers
in the market which serves the durability requirements of the concrete surfaces.
The sealers extend the useful life of the concrete. Hence, using concrete sealers is an environmentally
friendly decision. Among different types of sealers available in the market, water-based sealers are
found to be more environmentally friendly
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12. A GOOD COATING MATERIALS SHOULD
HAVE FOLLOWING PROPERTIES:
PRESENTATION TITLE 12
1. Resistance against chemical attacks,
2. Resistance against temperature changes
3. Good adhesion to the surface
4. Sufficient tensile strength and elasticity,
5. Sufficient abrasive resistance,
6. Capability to bridge cracks
7. Coefficient of thermal expansion comparable to that of concrete.

13. REINFORCEMENT
PROTECTION METHOD
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14. CAUSES FOR DAMAGES IN
REINFORCEMENT:
Aggregate expansion,
Salt weathering,
Carbonation, and
Leaching
PROTECTION METHOD:
Galvanization protection
Corrosion inhibiting admixture protection
Cathodic protection
PRESENTATION TITLE 14

15. CORROSION PROTECTION
METHODS FOR STEEL
REINFORCEMENT IN CONCRETE
Concrete protection methods for steel reinforcement in concrete is needed due to corrosion.
It is a natural process that converts a refined metal into a more chemically stable form such
as oxide, hydroxide, or sulfide.
It is the gradual destruction of materials (usually a metal) by chemical and/or
electrochemical reaction with their environment.
Corrosion in concrete steel reinforcement degrades the useful properties of materials and
structures including strength, appearance and permeability to liquids and gases.
Many structural alloys corrode merely from exposure to moisture in air, but the process can
be strongly affected by exposure to certain substances.
Corrosion can be concentrated locally to form a pit or crack, or it can extend across a wide
area more or less uniformly corroding the surface.
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16. THE TWO MOST COMMON CONTRIBUTING
FACTORS LEADING TO STEEL
REINFORCEMENT CORROSION ARE;
Chloride attack:
The passivity provided by the alkaline conditions can be destroyed by the presence of
chloride ions, even though a high level of alkalinity remains in the concrete.
The chloride ion can locally de-passivate the metal and promote active metal dissolution.
Chlorides react with the calcium aluminate and calcium aluminoferrite in the concrete to form
insoluble calcium chloroaluminate and calcium chloro ferrites in which the chloride is bound
in non-active form
However, the reaction is never complete and some active soluble chloride always remains in
equilibrium in the aqueous phase in the concrete.
PRESENTATION TITLE 16

17. CARBONATION:
Carbon dioxide, which is present in the air at around 0.3 percent by volume, dissolves in
water to form a mildly acidic solution.
This forms within the pores of the concrete, here it reacts with the alkaline calcium
hydroxide forming insoluble calcium carbonate.
The carbonation process moves as a front through the concrete, on reaching the reinforcing
steel, the passive layer decays when the pH value drops below 10.5.
If the carbonated front penetrates sufficiently deeply into the concrete to intersect with the
concrete reinforcement interface, protection is lost and, since both oxygen and moisture are
available, the steel is likely to corrode.
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18. CORROSION PROTECTION
METHODS FOR CONCRETE
REINFORCING STEEL:
Galvanization protection:
Galvanized reinforcing steel is used in concrete where unprotected reinforcement will not have
adequate durability.
The susceptibility of concrete structures to the intrusion of chlorides is the primary incentive for using
galvanized steel reinforcement.
Galvanized reinforcing steel is especially useful when the reinforcement will be exposed to the weather
before construction begins.
It provides visible assurance that the steel has not rusted and requires no on-site repair, unlike most
other coatings
Galvanized reinforcing steel can withstand exposure to chloride ion concentrations several times higher
than the chloride level that causes corrosion in black steel reinforcement.
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19. CORROSION-INHIBITING
ADMIXTURE PROTECTION
Inhibitors are the chemical substances which are added to the concrete in small
concentrations to inhibit the time to initiation of corrosion in concrete structures.
Corrosion-inhibiting admixtures increase the passivation of reinforcement and other
embedded steel.
This can inhibit corrosion when passivation would otherwise have been lost as a result of
chloride ingress or carbonation.
They are added to concrete during production and are referred to as ‘integral’ corrosion-
inhibitors.
These can significantly reduce maintenance costs of reinforced concrete structures.
Few of the most popular Corrosion Inhibiting Admixtures are, Amine Carboxylate, Amine-
ester Organic Emulsion, Calcium Nitrite, Organic Alkenyl Dicarboxylic Acid Salt, to name a
few.
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20. CATHODIC PROTECTION:
Cathodic protection is often used to mitigate corrosion damage to active metal surfaces.
It is used all over the globe to protect pipelines, water treatment plants, above and underwater
storage tanks, ship and boat hulls, offshore production platforms, reinforcement bars in
concrete structures and piers, and more.
Cathodic protection is often used to protect steel from corrosion. Corrosion is caused when
two dissimilar metals are submerged in an electrolytic substance such as water, soil, or
concrete.
This type of metal conducting path between the two dissimilar metals allows a pathway
through which free electrons move from the more active metal (anode) to the less active
metal (cathode).
If free electrons from the anode do not reach active sites on the cathode before the arrival of
oxygen, ions at the active sites can then recombine to produce ferrous hydroxide, i.e. rust.
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21. SELF
REGULATING
ANODE
PRESENTATION TITLE 21

22. SELF REGULATING ANODE :
Reinforced concrete is a versatile, economical, successful and commonly used material. It is
durable and strong, performing well throughout its service life.
Today, in India we are placing new concrete to the tune of approximately 1 m3 / person
nationally, which is a large quantity.
If we take stock of concrete placed in past years, then an educated guess is about 25 m3 /
person could be already in place
This is a huge inventory. A large quantity of this concrete is over 10 years old.
Most of this concrete was site mixed and without many controls and as a result more
susceptible to carbonation, chloride attack, loss of alkalinity and attack of other aggressive
chemicals.
PRESENTATION TITLE 22

23. PRESENTATION TITLE 23
In India, where approximately 80% of the rainfall takes place in the two monsoon
months, rusting related problems are very common, especially in industrial,
infrastructure and residential structures.
India has also a very long coastal line where marine conditions prevail. Typically, a
building requires major restoration within a decade approximately.
The present practice of repairs in India is focused towards the delaying of
rehabilitation/ restoration

24. GALVANIC PROTECTION:
Galvanic corrosion protection methods were originally developed in the 1820s.
Over the years, galvanic corrosion protection systems have been widely used to
protect underground steel structures, such as, pipelines and tanks.
Galvanic protection systems were first used inreinforced concrete structures around
1960.
Recent technological advancements in the developments of galvanic anodes have led
to a significant increase in their use for protecting reinforcing steel in concrete
structures
PRESENTATION TITLE 24

25. SACRIFICIAL PASSIVE PROTECTION
SYSTEMS:
The following are some of the sacrificial protective systems commonly used in the industry:
(1) Zinc sheet anodes, precoated with a conductive hydrogel adhesive, are applied to the
surface of the concrete. The formed anode is called zinc hydrogel anode and its
appearance is improved by coating with various paints.
(2) Zinc or zinc alloys are sprayed to the concrete using arc spray or flame spray
equipment.
(3) Embedded galvanic anodes are embedded within the repaired concrete and connected
with the reinforcing steel. The anodes are installed along the perimeter of concrete
patch repairs to protect adjacent areas from corrosion due to the anodic-ring effect
PRESENTATION TITLE 25

26. THANK YOU