repair , retrofitting and strengthening of concrete structures
mohammearif63
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May 18, 2024
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About This Presentation
repairing
Slide Content
STRUCTURAL
FAILURES
AND
REHABILITATION
REPAIR AND
RETROFITTING OF RCC
STRUCTURES
School of Building Science and
Technology, CEPT University, Ahmedabad
1
FAILURES
AND
REHABILITATION
REPAIR AND
RETROFITTING OF RCC
STRUCTURES
School of Building Science and
Technology, CEPT University, Ahmedabad
1
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
2
AN OVERVIEW OF PRESENT REPAIR PRACTICES
Since 1950s, the construction activity in India has been increasing
geometrically without matching increase in the availability of quality
inputs, in terms of materials and skilled workmen.
The gap between the quality planned and the quality achieved
continues to become wider.
The engineers responsible for maintaining buildings often begin repair
activity without adequate understanding of the factors responsible for
the defects.
Many engineers unintentionally attempt treating the symptoms,
instead of dealing with the cause and effect phenomenon.
REPAIR AND RETROFITTING OF RCC STRUCTURES
2
AN OVERVIEW OF PRESENT REPAIR PRACTICES
Since 1950s, the construction activity in India has been increasing
geometrically without matching increase in the availability of quality
inputs, in terms of materials and skilled workmen.
The gap between the quality planned and the quality achieved
continues to become wider.
The engineers responsible for maintaining buildings often begin repair
activity without adequate understanding of the factors responsible for
the defects.
Many engineers unintentionally attempt treating the symptoms,
instead of dealing with the cause and effect phenomenon.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
3
AN OVERVIEW OF PRESENT REPAIR PRACTICES
Structural defects are dealt with in this fashion, it remains only as
defects camouflaged beneath finishes, which gives a false sense of
safety to the occupants allowing the problem to continue without
getting treated.
REPAIR AND RETROFITTING OF RCC STRUCTURES
3
AN OVERVIEW OF PRESENT REPAIR PRACTICES
Structural defects are dealt with in this fashion, it remains only as
defects camouflaged beneath finishes, which gives a false sense of
safety to the occupants allowing the problem to continue without
getting treated.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
4
INTRODUCTION TO CONCRETE REPAIRS
Concrete construction is generally expected to give trouble free
service through out its intended design life.
However, these expectations are not realized in many constructions
because of
structural deficiency
material deterioration
unanticipated over loadings or physical damage
Premature material deterioration can arise from a number of causes,
the most common being when the construction specifications are
violated or when the facility is exposed to harsher service
environment than those expected during the planning and design
stages.
REPAIR AND RETROFITTING OF RCC STRUCTURES
4
INTRODUCTION TO CONCRETE REPAIRS
Concrete construction is generally expected to give trouble free
service through out its intended design life.
However, these expectations are not realized in many constructions
because of
structural deficiency
material deterioration
unanticipated over loadings or physical damage
Premature material deterioration can arise from a number of causes,
the most common being when the construction specifications are
violated or when the facility is exposed to harsher service
environment than those expected during the planning and design
stages.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
5
Premature material deterioration can arise from a number of causes,
the most common being when the construction specifications are
violated or when the facility is exposed to harsher service environment
than those expected during the planning and design stages.
Physical damage can also arise from fire, explosion – as well as from
restraints, both internal and external, against structural movement.
Except in extreme cases, most of the structures require restoration to
meet its functional requirements by appropriate repair techniques.
REPAIR AND RETROFITTING OF RCC STRUCTURES
5
Premature material deterioration can arise from a number of causes,
the most common being when the construction specifications are
violated or when the facility is exposed to harsher service environment
than those expected during the planning and design stages.
Physical damage can also arise from fire, explosion – as well as from
restraints, both internal and external, against structural movement.
Except in extreme cases, most of the structures require restoration to
meet its functional requirements by appropriate repair techniques.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND REHABILTATION OF RCC STRUCTURES
6
CONDITION SURVEY
Definition :
Condition Survey is an examination of concrete for the purpose of
identifying and defining area of distress.
Objectives :
• To identify -causes of distress and -their sources;
• To assess -the extent of distress occurred the residual
strength of the structure and –its rehabilitability
•To prioritise the distressed elements according to seriousness
for repairs
•To select and plan the effective remedy. “Find the cause, the
remedy will suggest itself
Stages :
a)Preliminary Inspection.
b)Planning.
c)Visual Inspection.
d)Field and Laboratory testing.
REPAIR AND REHABILTATION OF RCC STRUCTURES
6
CONDITION SURVEY
Definition :
Condition Survey is an examination of concrete for the purpose of
identifying and defining area of distress.
Objectives :
• To identify -causes of distress and -their sources;
• To assess -the extent of distress occurred the residual
strength of the structure and –its rehabilitability
•To prioritise the distressed elements according to seriousness
for repairs
•To select and plan the effective remedy. “Find the cause, the
remedy will suggest itself
Stages :
a)Preliminary Inspection.
b)Planning.
c)Visual Inspection.
d)Field and Laboratory testing.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND REHABILTATION OF RCC STRUCTURES
7
NON-DESTRUCTIVE TEST EVALUATION
•In-situ Concrete Strength
Rebound Hammer Test
Ultrasonic Pulse Velocity
Windsor Probe
Capo/Pullout Test
Load Test
Lab Testing
•Core Cutting/Sampling
•Chemical Attack
Carbonation Test
Chloride Test
Sulphate Test
REPAIR AND REHABILTATION OF RCC STRUCTURES
7
NON-DESTRUCTIVE TEST EVALUATION
•In-situ Concrete Strength
Rebound Hammer Test
Ultrasonic Pulse Velocity
Windsor Probe
Capo/Pullout Test
Load Test
Lab Testing
•Core Cutting/Sampling
•Chemical Attack
Carbonation Test
Chloride Test
Sulphate Test
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND REHABILTATION OF RCC STRUCTURES
8
NON-DESTRUCTIVE TEST EVALUATION
•Corrosion Test
Covermeter/Profometer
Half Cell Method
Resistivity Meter
Permeability
Water
Air
•Fire Damage Assessment
Thermo-Gravimetric Analysis
Differential Thermal Analysis
X-ray Diffraction
•Structural Integrity/Soundness Assessment
Ultrasonic Pulse Velocity
Radiography
Impact Echo Test
REPAIR AND REHABILTATION OF RCC STRUCTURES
8
NON-DESTRUCTIVE TEST EVALUATION
•Corrosion Test
Covermeter/Profometer
Half Cell Method
Resistivity Meter
Permeability
Water
Air
•Fire Damage Assessment
Thermo-Gravimetric Analysis
Differential Thermal Analysis
X-ray Diffraction
•Structural Integrity/Soundness Assessment
Ultrasonic Pulse Velocity
Radiography
Impact Echo Test
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
9
CONCRETE DETERIORATION FROM ENVIRONMENTAL EFFECTS
REPAIR AND RETROFITTING OF RCC STRUCTURES
9
CONCRETE DETERIORATION FROM ENVIRONMENTAL EFFECTS
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
10
CAUSES OF DISTRESS AND DETERIORATION OF
CONCRETE
•Accidental Loadings
•Chemical Reactions
•Acid attack
•Aggressive-water attack
•Alkali-carbonate rock reaction
•Alkali-silica reaction
•Miscellaneous chemical attack
•Sulphate attack
•Construction Errors
•Corrosion of Embedded Metals
REPAIR AND RETROFITTING OF RCC STRUCTURES
10
CAUSES OF DISTRESS AND DETERIORATION OF
CONCRETE
•Accidental Loadings
•Chemical Reactions
•Acid attack
•Aggressive-water attack
•Alkali-carbonate rock reaction
•Alkali-silica reaction
•Miscellaneous chemical attack
•Sulphate attack
•Construction Errors
•Corrosion of Embedded Metals
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
11
CAUSES OF DISTRESS AND DETERIORATION OF
CONCRETE
•Design Errors
•Inadequate structural design
•Poor design details
•Erosion
•Abrasion
•Cavitations
•Freezing and Thawing
•Settlement and Movement
•Shrinkage
•Plastic
•Drying
REPAIR AND RETROFITTING OF RCC STRUCTURES
11
CAUSES OF DISTRESS AND DETERIORATION OF
CONCRETE
•Design Errors
•Inadequate structural design
•Poor design details
•Erosion
•Abrasion
•Cavitations
•Freezing and Thawing
•Settlement and Movement
•Shrinkage
•Plastic
•Drying
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
12
CAUSES OF DISTRESS AND DETERIORATION OF
CONCRETE
•Temperature Changes
•Internally generated
•Externally generated
•Fire
•Weathering.
REPAIR AND RETROFITTING OF RCC STRUCTURES
12
CAUSES OF DISTRESS AND DETERIORATION OF
CONCRETE
•Temperature Changes
•Internally generated
•Externally generated
•Fire
•Weathering.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
13
RELATING SYMPTOMS TO CAUSES OF DISTRESS AND
DETERIORATION OF CONCRETE
REPAIR AND RETROFITTING OF RCC STRUCTURES
13
RELATING SYMPTOMS TO CAUSES OF DISTRESS AND
DETERIORATION OF CONCRETE
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
14
RELATING SYMPTOMS TO CAUSES OF DISTRESS AND
DETERIORATION OF CONCRETE
REPAIR AND RETROFITTING OF RCC STRUCTURES
14
RELATING SYMPTOMS TO CAUSES OF DISTRESS AND
DETERIORATION OF CONCRETE
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
15
CLASSES OF DAMAGE AND REPAIR CLASSIFICATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
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CLASSES OF DAMAGE AND REPAIR CLASSIFICATION
16
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
CLASSES OF DAMAGE AND REPAIR CLASSIFICATION
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
CLASSES OF DAMAGE AND REPAIR CLASSIFICATION
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
17
CONSIDERATIONS FOR REPAIR STRATEGY
1.Identification of the cause of problem and its source is the
fundamental to the success or failure of the repair. A lack of
attention at this point can put at risk the whole job.
2.For arriving at an effective and economical solution, systematic
documentation of all observations is essential, which will greatly
facilitate in diagnosing and making assessment of the extent of
damage.
3.Available space and accessibility will determine the selection of
repair method and repair strategy.
4.Accessibility to the areas identified for repairs needs consideration
REPAIR AND RETROFITTING OF RCC STRUCTURES
17
CONSIDERATIONS FOR REPAIR STRATEGY
1.Identification of the cause of problem and its source is the
fundamental to the success or failure of the repair. A lack of
attention at this point can put at risk the whole job.
2.For arriving at an effective and economical solution, systematic
documentation of all observations is essential, which will greatly
facilitate in diagnosing and making assessment of the extent of
damage.
3.Available space and accessibility will determine the selection of
repair method and repair strategy.
4.Accessibility to the areas identified for repairs needs consideration
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
18
CONSIDERATIONS FOR REPAIR STRATEGY
4.Depending upon the scope and scale of repairs, the repair strategy
has to suit and dovetail the on-going activities in the building.
5.The prioritization of repairs and their sequencing are important
components for deciding the repair strategy.
6.Major repair procedure may demand propping the structural
members to relieve a part or full component of the load acting on
the member. If the building requires extensive
7.Propping, vacating the building may become the pre-requisite.
8.Safety measures to prevent any immediate major mishap shall be
prescribed without loosing further time
REPAIR AND RETROFITTING OF RCC STRUCTURES
18
CONSIDERATIONS FOR REPAIR STRATEGY
4.Depending upon the scope and scale of repairs, the repair strategy
has to suit and dovetail the on-going activities in the building.
5.The prioritization of repairs and their sequencing are important
components for deciding the repair strategy.
6.Major repair procedure may demand propping the structural
members to relieve a part or full component of the load acting on
the member. If the building requires extensive
7.Propping, vacating the building may become the pre-requisite.
8.Safety measures to prevent any immediate major mishap shall be
prescribed without loosing further time
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
19
SELECTION OF REPAIR METHOD FOR ACTIVE CRACKS
REPAIR AND RETROFITTING OF RCC STRUCTURES
19
SELECTION OF REPAIR METHOD FOR ACTIVE CRACKS
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
20
SELECTION OF REPAIR METHOD FOR ACTIVE CRACKS
SELECTION OF REPAIR METHOD FOR PASSIVE CRACKS
REPAIR AND RETROFITTING OF RCC STRUCTURES
20
SELECTION OF REPAIR METHOD FOR ACTIVE CRACKS
SELECTION OF REPAIR METHOD FOR PASSIVE CRACKS
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
21
REPAIR..
REPAIR AND RETROFITTING OF RCC STRUCTURES
21
REPAIR..
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
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Removing the concrete
REPAIR AND RETROFITTING OF RCC STRUCTURES
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Removing the concrete
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
23
Boom-mounted concrete crusher
Diamond-blade saw
Diamond-wire saw
Boom-mounted breaker
REPAIR AND RETROFITTING OF RCC STRUCTURES
23
Boom-mounted concrete crusher
Diamond-blade saw
Diamond-wire saw
Boom-mounted breaker
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
24
Presplitting using chemical-expansive
agent
Piston-jack splitter
Blasting operations in or adjacent to buildings, structures, or other facilities should be
carefully planned with full consideration of all forces and conditions involved.
Appropriate vibration and damage control should be done accordingly.
REPAIR AND RETROFITTING OF RCC STRUCTURES
24
Presplitting using chemical-expansive
agent
Piston-jack splitter
Blasting operations in or adjacent to buildings, structures, or other facilities should be
carefully planned with full consideration of all forces and conditions involved.
Appropriate vibration and damage control should be done accordingly.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
25
SURFACE PREPARARTION
For reinforced concrete, repairs must include proper preparation of
the reinforcing steel to develop bond with the replacement concrete
to ensure desired behavior in the structure.
A)CONCRETE
1.Chemical cleaning : In cases in which concrete is contaminated
with oil, gsrease, or dirt, these contaminants must be removed
prior to placement of repair materials
2.Mechanical cleaning : Mechanical devices include scabblers,
scarifiers, and impact tools. Depending upon the hammer heads
used or the nature of the abrasive material, a variety of degrees
of surface preparation may be achieved
3.Shot blasting : Steel shot blasting produces a nearly uniform
profile that is ideally suited for thin overlay repairs.
4.Blast cleaning. : Blast cleaning includes wet and dry and blasting,
and water jetting.
REPAIR AND RETROFITTING OF RCC STRUCTURES
25
SURFACE PREPARARTION
For reinforced concrete, repairs must include proper preparation of
the reinforcing steel to develop bond with the replacement concrete
to ensure desired behavior in the structure.
A)CONCRETE
1.Chemical cleaning : In cases in which concrete is contaminated
with oil, gsrease, or dirt, these contaminants must be removed
prior to placement of repair materials
2.Mechanical cleaning : Mechanical devices include scabblers,
scarifiers, and impact tools. Depending upon the hammer heads
used or the nature of the abrasive material, a variety of degrees
of surface preparation may be achieved
3.Shot blasting : Steel shot blasting produces a nearly uniform
profile that is ideally suited for thin overlay repairs.
4.Blast cleaning. : Blast cleaning includes wet and dry and blasting,
and water jetting.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
26
5.Acid etching : Acid etching of concrete surfaces has long been
used to remove laitance and normal amounts of dirt. The acid
will remove enough cement paste to provide a roughened
surface which will improve the bond of replacement
materials.
6.Bonding agents: The general guidance is that small thin
patches (less than 50 mm (2 in.) thick) should receive a
bonding coat while thicker replacements probably do not
require any bonding agent.
B) REINFORCING STEEL
1.In limited areas, wire brushing or other hand methods of
cleaning are acceptable. For larger areas, dry sandblasting is
the preferred method.
2.Alternative methods of cleaning the steel are wet
sandblasting or water-jet blasting.
REPAIR AND RETROFITTING OF RCC STRUCTURES
26
5.Acid etching : Acid etching of concrete surfaces has long been
used to remove laitance and normal amounts of dirt. The acid
will remove enough cement paste to provide a roughened
surface which will improve the bond of replacement
materials.
6.Bonding agents: The general guidance is that small thin
patches (less than 50 mm (2 in.) thick) should receive a
bonding coat while thicker replacements probably do not
require any bonding agent.
B) REINFORCING STEEL
1.In limited areas, wire brushing or other hand methods of
cleaning are acceptable. For larger areas, dry sandblasting is
the preferred method.
2.Alternative methods of cleaning the steel are wet
sandblasting or water-jet blasting.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
27
Methods and materials for repair
Each project for concrete rehabilitation and repair is unique. We cant use
same method for each project.
Method 01: Additional Reinforcement
It is the provision of additional reinforcing steel, either conventional
reinforcement or prestressing steel, to repair a cracked concrete section. In
either case, the steel that is added is to carry the tensile forces that have
caused cracking in the concrete.
Cracked reinforced concrete bridge girders have been successfully repaired by
use of additional conventional reinforcement. Posttensioning is often the
desirable solution when a major portion of a member must be strengthened
or when the cracks that have formed must be closed. For the posttensioning
method, some form of abutment is needed for anchorage, such as a
strongback bolted to the face of the concrete, or the tendons can be passed
through and anchored in connecting framing.
REPAIR AND RETROFITTING OF RCC STRUCTURES
27
Methods and materials for repair
Each project for concrete rehabilitation and repair is unique. We cant use
same method for each project.
Method 01: Additional Reinforcement
It is the provision of additional reinforcing steel, either conventional
reinforcement or prestressing steel, to repair a cracked concrete section. In
either case, the steel that is added is to carry the tensile forces that have
caused cracking in the concrete.
Cracked reinforced concrete bridge girders have been successfully repaired by
use of additional conventional reinforcement. Posttensioning is often the
desirable solution when a major portion of a member must be strengthened
or when the cracks that have formed must be closed. For the posttensioning
method, some form of abutment is needed for anchorage, such as a
strongback bolted to the face of the concrete, or the tendons can be passed
through and anchored in connecting framing.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
28
Conventional reinforcement
This technique consists of sealing the crack, drilling holes 19 mm (3/4 in.) in
at 90 degree to the crack plane, cleaning the hole of dust, filling the hole and
crack plane with an adhesive (typically epoxy) pumped under low pressure
344 to 552 KPa (50 to 80 psi), and placing a reinforcing bar into the drilled
hole. 4 or 5 bars are used, extending at least 0.5 m (1.6 ft) on each side of the
crack. The adhesive bonds the bar to the walls of the hole, fills the crack
plane, bonds the cracked concrete surfaces together in one monolithic form,
and thus reinforces the section.
REPAIR AND RETROFITTING OF RCC STRUCTURES
28
Conventional reinforcement
This technique consists of sealing the crack, drilling holes 19 mm (3/4 in.) in
at 90 degree to the crack plane, cleaning the hole of dust, filling the hole and
crack plane with an adhesive (typically epoxy) pumped under low pressure
344 to 552 KPa (50 to 80 psi), and placing a reinforcing bar into the drilled
hole. 4 or 5 bars are used, extending at least 0.5 m (1.6 ft) on each side of the
crack. The adhesive bonds the bar to the walls of the hole, fills the crack
plane, bonds the cracked concrete surfaces together in one monolithic form,
and thus reinforces the section.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
29
Prestressing steel.
This technique uses prestressing strands or bars to apply a
compressive force. Adequate anchorage must be provided for the
prestressing steel, and care is needed so that the problem will not
merely migrate to another part of the structure. The effects of the
tensioning force (including eccentricity) on the stress within the
structure should be carefully analyzed.
REPAIR AND RETROFITTING OF RCC STRUCTURES
29
Prestressing steel.
This technique uses prestressing strands or bars to apply a
compressive force. Adequate anchorage must be provided for the
prestressing steel, and care is needed so that the problem will not
merely migrate to another part of the structure. The effects of the
tensioning force (including eccentricity) on the stress within the
structure should be carefully analyzed.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
30
REPAIR AND RETROFITTING OF RCC STRUCTURES
30
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
31
Method 02: Autogenous Healing
Autogenous healing is a natural process of crack repair that can occur in the
presence of moisture and the absence of tensile stress.
Autogenous healing has practical application for closing cracks in a moist
environment. Healing will not occur if the crack is active and is subjected to
movement during the healing period. Healing will also not occur if there is a
positive flow of water through the crack which dissolves and washes away
the lime deposit. A partial exception is a situation in which the flow of water
is so slow that complete evaporation occurs at the exposed face causing
redeposition of the dissolved salts.
Healing occurs through the carbonation of calcium hydroxide in the cement
paste by carbon dioxide, which is present in the surrounding air and water.
Calcium carbonate and calcium hydroxide crystals precipitate, accumulate,
and grow within the cracks. As a result, some of the tensile strength of the
concrete is restored across the cracked section, and the crack may become
sealed.
REPAIR AND RETROFITTING OF RCC STRUCTURES
31
Method 02: Autogenous Healing
Autogenous healing is a natural process of crack repair that can occur in the
presence of moisture and the absence of tensile stress.
Autogenous healing has practical application for closing cracks in a moist
environment. Healing will not occur if the crack is active and is subjected to
movement during the healing period. Healing will also not occur if there is a
positive flow of water through the crack which dissolves and washes away
the lime deposit. A partial exception is a situation in which the flow of water
is so slow that complete evaporation occurs at the exposed face causing
redeposition of the dissolved salts.
Healing occurs through the carbonation of calcium hydroxide in the cement
paste by carbon dioxide, which is present in the surrounding air and water.
Calcium carbonate and calcium hydroxide crystals precipitate, accumulate,
and grow within the cracks. As a result, some of the tensile strength of the
concrete is restored across the cracked section, and the crack may become
sealed.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
32
Method 03: Conventional Concrete Placement
This method consists of replacing defective concrete with a new conventional
concrete mixture of suitable proportions that will become an integral part of
the base concrete. The concrete mixture proportions must provide for good
workability, strength, and durability. The repair concrete should have a low
w/c and a high percentage of coarse aggregate to minimize shrinkage
cracking.
If the defects in the structure go entirely through a wall or if the defects go
beyond the reinforcement and if the defective area is large, then concrete
replacement is the desired method. Replacement is sometimes necessary to
repair large areas of honeycomb in new construction.
Conventional concrete should not be used for replacement in areas where an
aggressive factor which has caused the deterioration of the concrete being
replaced still exists.
REPAIR AND RETROFITTING OF RCC STRUCTURES
32
Method 03: Conventional Concrete Placement
This method consists of replacing defective concrete with a new conventional
concrete mixture of suitable proportions that will become an integral part of
the base concrete. The concrete mixture proportions must provide for good
workability, strength, and durability. The repair concrete should have a low
w/c and a high percentage of coarse aggregate to minimize shrinkage
cracking.
If the defects in the structure go entirely through a wall or if the defects go
beyond the reinforcement and if the defective area is large, then concrete
replacement is the desired method. Replacement is sometimes necessary to
repair large areas of honeycomb in new construction.
Conventional concrete should not be used for replacement in areas where an
aggressive factor which has caused the deterioration of the concrete being
replaced still exists.
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
33
Concrete removal
Surfaces cleaning
Formwork
Concreting
External vibration
Curing of concrete
REPAIR AND RETROFITTING OF RCC STRUCTURES
33
Concrete removal
Surfaces cleaning
Formwork
Concreting
External vibration
Curing of concrete
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
34
Method 04: Crack Arrest Techniques
Crack arrest techniques are those procedures that may be used during
the construction of a massive concrete structure to stop crack
propagation into subsequent concrete lifts.
These techniques should be used only for cracking caused by
restrained volume change of the concrete. They should not be used
for cracking caused by excessive loading.
The simplest technique is to place a grid of reinforcing steel over the
cracked area.
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Method 04: Crack Arrest Techniques
Crack arrest techniques are those procedures that may be used during
the construction of a massive concrete structure to stop crack
propagation into subsequent concrete lifts.
These techniques should be used only for cracking caused by
restrained volume change of the concrete. They should not be used
for cracking caused by excessive loading.
The simplest technique is to place a grid of reinforcing steel over the
cracked area.
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The semicircular pipe is made by splitting a 200-mm (8-in.)-dia piece of 16-
gauge pipe and bending it to a semicircular shape with about a 76-mm- (3-in.-
) flange on each side. Then, the area surrounding the crack should be well
cleaned and the pipe should be centered on the crack. Once in place, the
sections of the pipe should be welded together. Holes should be cut into the
pipe to receive grout pipes. Finally, the pipe section should be covered with
concrete placed concentrically by hand methods. The grout pipes may be
used for grouting at a later date to attempt to restore structural integrity of
the cracked section.
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The semicircular pipe is made by splitting a 200-mm (8-in.)-dia piece of 16-
gauge pipe and bending it to a semicircular shape with about a 76-mm- (3-in.-
) flange on each side. Then, the area surrounding the crack should be well
cleaned and the pipe should be centered on the crack. Once in place, the
sections of the pipe should be welded together. Holes should be cut into the
pipe to receive grout pipes. Finally, the pipe section should be covered with
concrete placed concentrically by hand methods. The grout pipes may be
used for grouting at a later date to attempt to restore structural integrity of
the cracked section.
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Method 05: Drilling and Plugging
Drilling and plugging a crack consists of drilling down the length of the crack
and grouting it to form a key.
This technique is applicable only where cracks run in reasonably straight lines
and are accessible at one end. This method is most often used to repair
vertical cracks in walls.
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Method 05: Drilling and Plugging
Drilling and plugging a crack consists of drilling down the length of the crack
and grouting it to form a key.
This technique is applicable only where cracks run in reasonably straight lines
and are accessible at one end. This method is most often used to repair
vertical cracks in walls.
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Method 06: Drypacking
Drypacking is a process of ramming or tamping into a confined area a low
water-content mortar. Because of the low w/c material, there is little
shrinkage, and the patch remains tight and is of good quality with respect to
durability, strength, and water-tightness. This technique has an advantage in
that no special equipment is required. However, the method does require
that the craftsman making the repair be skilled in this particular type of work.
Drypacking can be used for patching rock pockets, form tie holes, and small
holes with a relatively high ratio of depth to area. It should not be used for
patching shallow depressions where lateral restraint cannot be obtained, for
patching areas requiring filling in back of exposed reinforcement, nor for
patching holes extending entirely through concrete sections. Drypacking can
also be used for filling narrow slots cut for the repair of dormant cracks. The
use of drypack is not recommended for filling or repairing active cracks.
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Method 06: Drypacking
Drypacking is a process of ramming or tamping into a confined area a low
water-content mortar. Because of the low w/c material, there is little
shrinkage, and the patch remains tight and is of good quality with respect to
durability, strength, and water-tightness. This technique has an advantage in
that no special equipment is required. However, the method does require
that the craftsman making the repair be skilled in this particular type of work.
Drypacking can be used for patching rock pockets, form tie holes, and small
holes with a relatively high ratio of depth to area. It should not be used for
patching shallow depressions where lateral restraint cannot be obtained, for
patching areas requiring filling in back of exposed reinforcement, nor for
patching holes extending entirely through concrete sections. Drypacking can
also be used for filling narrow slots cut for the repair of dormant cracks. The
use of drypack is not recommended for filling or repairing active cracks.
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Method 07: Fiber-Reinforced Concrete
Fiber-reinforced concrete is composed of conventional portland-cement
concrete containing discontinuous discrete fibers. The fibers are added to the
concrete in the mixer. Fibers are made from steel, plastic, glass, and other
natural materials.
Fiber-reinforced concrete has been used extensively for pavement repair.
Fiber-reinforced concrete has been used to repair erosion of hydraulic
structures caused by cavitation or high velocity flow and impact of large
debris. The slump of a concrete mixture is significantly reduced by the
addition of fibers. Use of the inverted slump cone test for workability is
recommended.
A fiber mixture will generally require more vibration to consolidate the
concrete.
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Method 07: Fiber-Reinforced Concrete
Fiber-reinforced concrete is composed of conventional portland-cement
concrete containing discontinuous discrete fibers. The fibers are added to the
concrete in the mixer. Fibers are made from steel, plastic, glass, and other
natural materials.
Fiber-reinforced concrete has been used extensively for pavement repair.
Fiber-reinforced concrete has been used to repair erosion of hydraulic
structures caused by cavitation or high velocity flow and impact of large
debris. The slump of a concrete mixture is significantly reduced by the
addition of fibers. Use of the inverted slump cone test for workability is
recommended.
A fiber mixture will generally require more vibration to consolidate the
concrete.
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Preparation of the area to be repaired, mixing, transporting, placing, and
finishing fiber-reinforced concrete follows the procedures for and generally
uses the same equipment as plain concrete.
Pumping of steel fiber-reinforced concrete with up to 1.5 percent fibers by
volume has been done successfully.
Mixture design and especially the amount of fibers used are critical so that
design parameters for strength and durability are met and the mixture will
still be workable.
About 2 percent by volume is considered a practical upper limit for field
placement with the necessary workability.
Steel fiber-reinforced shotcrete, with up to 2.0 percent fibers by volume,
generally mixed with the dry-mixture process has been successfully used to
repair concrete.
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Preparation of the area to be repaired, mixing, transporting, placing, and
finishing fiber-reinforced concrete follows the procedures for and generally
uses the same equipment as plain concrete.
Pumping of steel fiber-reinforced concrete with up to 1.5 percent fibers by
volume has been done successfully.
Mixture design and especially the amount of fibers used are critical so that
design parameters for strength and durability are met and the mixture will
still be workable.
About 2 percent by volume is considered a practical upper limit for field
placement with the necessary workability.
Steel fiber-reinforced shotcrete, with up to 2.0 percent fibers by volume,
generally mixed with the dry-mixture process has been successfully used to
repair concrete.
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Method 08: Flexible Sealing
Flexible sealing involves routing and cleaning the crack and filling it with a
suitable field molded flexible sealant. This technique differs from routing and
sealing in that, in this case, an actual joint is constructed, rather than a crack
simply being filled.
Flexible sealing may be used to repair major, active cracks. It has been
successfully used in situations in which there is a limited water head on the
crack. This repair technique does not increase the structural capacity of the
cracked section. Chemical grouting is a more complicated and expensive
procedure, but it can be used in conditions of flowing water.
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Method 08: Flexible Sealing
Flexible sealing involves routing and cleaning the crack and filling it with a
suitable field molded flexible sealant. This technique differs from routing and
sealing in that, in this case, an actual joint is constructed, rather than a crack
simply being filled.
Flexible sealing may be used to repair major, active cracks. It has been
successfully used in situations in which there is a limited water head on the
crack. This repair technique does not increase the structural capacity of the
cracked section. Chemical grouting is a more complicated and expensive
procedure, but it can be used in conditions of flowing water.
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Method 09: Gravity Soak
High molecular weight methacrylate (HMWM) is poured or sprayed onto any
horizontal concrete surface and spread by broom. The material penetrates
very small cracks by gravity and capillary action, polymerizing to form a “plug”
which closes off access to the reinforcing steel.
Repairing cracks with the gravity soak method and HMWM has become a
proven and cost-effective method. Gravity soak can be an effective repair
method for horizontal concrete surfaces that contain excessive, closely spaced
shrinkage cracking. This would include bridge decks, parking decks, industrial
floors, pavements etc.
New concrete must be cured for a week and air dried and cleaned. The
mononmer is mixed with the catalyst and quickly poured on the concrete
surface. The material is spread by a broom . After about 30 min of penetration
time a light broadcast of sand is usually recommended. The excess sand is
removed. The surface is ready in 3 to 24 hours.
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Method 09: Gravity Soak
High molecular weight methacrylate (HMWM) is poured or sprayed onto any
horizontal concrete surface and spread by broom. The material penetrates
very small cracks by gravity and capillary action, polymerizing to form a “plug”
which closes off access to the reinforcing steel.
Repairing cracks with the gravity soak method and HMWM has become a
proven and cost-effective method. Gravity soak can be an effective repair
method for horizontal concrete surfaces that contain excessive, closely spaced
shrinkage cracking. This would include bridge decks, parking decks, industrial
floors, pavements etc.
New concrete must be cured for a week and air dried and cleaned. The
mononmer is mixed with the catalyst and quickly poured on the concrete
surface. The material is spread by a broom . After about 30 min of penetration
time a light broadcast of sand is usually recommended. The excess sand is
removed. The surface is ready in 3 to 24 hours.
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Method 10: Grouting (Chemical)
Chemical grouts consist of solutions of two or more chemicals that react to
form a gel or solid precipitate as opposed to cement grouts that consist of
suspensions of solid particles in a fluid. The reaction in the solution may be
either chemical or physicochemical and may involve only the constituents of
the solution or may include the interaction of the constituents of the solution
with other substances encountered in the use of the grout. The reaction
causes a decrease in fluidity and a tendency to solidify and fill voids in the
material into which the grout has been injected.
Cracks in concrete as narrow as 0.05 mm (0.002 in.) have been filled with
chemical grout. The advantages of chemical grouts include their applicability
in moist environments, wide limits of control of gel time, and their application
in very fine fractures. Disadvantages are the high degree of skill needed for
satisfactory use, their lack of strength, and, for some grouts, the requirement
that the grout not dry out in service. Also some grouts are highly inflammable
and cannot be used in enclosed spaces.
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Method 10: Grouting (Chemical)
Chemical grouts consist of solutions of two or more chemicals that react to
form a gel or solid precipitate as opposed to cement grouts that consist of
suspensions of solid particles in a fluid. The reaction in the solution may be
either chemical or physicochemical and may involve only the constituents of
the solution or may include the interaction of the constituents of the solution
with other substances encountered in the use of the grout. The reaction
causes a decrease in fluidity and a tendency to solidify and fill voids in the
material into which the grout has been injected.
Cracks in concrete as narrow as 0.05 mm (0.002 in.) have been filled with
chemical grout. The advantages of chemical grouts include their applicability
in moist environments, wide limits of control of gel time, and their application
in very fine fractures. Disadvantages are the high degree of skill needed for
satisfactory use, their lack of strength, and, for some grouts, the requirement
that the grout not dry out in service. Also some grouts are highly inflammable
and cannot be used in enclosed spaces.
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Method 11: Jacketing
Jacketing consists of restoring or increasing the section of an existing member
(principally a compression member) by encasing it in new concrete. The
original member need not be concrete; steel and timber sections can be
jacketed.
The most frequent use of jacketing is in the repair of piling that has been
damaged by impact or is disintegrating because of environmental conditions.
It is especially useful where all or a portion of the section to be repaired is
underwater. When properly applied, jacketing will strengthen the repaired
member as well as provide some degree of protection against further
deterioration. However, if a concrete pile is deteriorating because of exposure
to acidic water, for example, jacketing with conventional portland-cement
concrete will not ensure against future disintegration.
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Method 11: Jacketing
Jacketing consists of restoring or increasing the section of an existing member
(principally a compression member) by encasing it in new concrete. The
original member need not be concrete; steel and timber sections can be
jacketed.
The most frequent use of jacketing is in the repair of piling that has been
damaged by impact or is disintegrating because of environmental conditions.
It is especially useful where all or a portion of the section to be repaired is
underwater. When properly applied, jacketing will strengthen the repaired
member as well as provide some degree of protection against further
deterioration. However, if a concrete pile is deteriorating because of exposure
to acidic water, for example, jacketing with conventional portland-cement
concrete will not ensure against future disintegration.
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The removal of existing damage is necessary to ensure that repair
material bond well with the original material. If a significant amount
of removal is necessary then temporary support is required.
A steel reinforcement cage may be constructed around the damaged
section. Once the form is in place, it may be filled with any suitable
material. Choice of the filling material should be based upon the
environment in which it will serve as well as a knowledge of what
caused the original material to fail. Filling may be accomplished by
pumping, by tremie placement, by preplaced aggregate techniques,
or by conventional concrete placement if the site can be dewatered.
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The removal of existing damage is necessary to ensure that repair
material bond well with the original material. If a significant amount
of removal is necessary then temporary support is required.
A steel reinforcement cage may be constructed around the damaged
section. Once the form is in place, it may be filled with any suitable
material. Choice of the filling material should be based upon the
environment in which it will serve as well as a knowledge of what
caused the original material to fail. Filling may be accomplished by
pumping, by tremie placement, by preplaced aggregate techniques,
or by conventional concrete placement if the site can be dewatered.
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METHOD 12 : JUDICIOUS NEGLECT
As the name implies, judicious neglect is the repair method of
taking no action. After a careful (i.e., “judicious”) review of the
circumstances the most appropriate action may be to take no action
at all.
Judicious neglect would be suitable for those cases of deterioration
in which the damage to the concrete is causing no current
operational problems for the structure and which will not
contribute to future deterioration of the concrete.
Dormant cracks, such as those caused by shrinkage or some other
one-time occurrence, may be self-sealing. That the cracks clog with
dirt, grease, or oil, or perhaps a little recrystallization occurs. The
result is that the cracks are plugged, particularly if leakage is the
result of some intermittent cause than a continuing pressure head,
will disappear without doing any repair.
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METHOD 12 : JUDICIOUS NEGLECT
As the name implies, judicious neglect is the repair method of
taking no action. After a careful (i.e., “judicious”) review of the
circumstances the most appropriate action may be to take no action
at all.
Judicious neglect would be suitable for those cases of deterioration
in which the damage to the concrete is causing no current
operational problems for the structure and which will not
contribute to future deterioration of the concrete.
Dormant cracks, such as those caused by shrinkage or some other
one-time occurrence, may be self-sealing. That the cracks clog with
dirt, grease, or oil, or perhaps a little recrystallization occurs. The
result is that the cracks are plugged, particularly if leakage is the
result of some intermittent cause than a continuing pressure head,
will disappear without doing any repair.
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METHOD 13 : OVERLAYS (POLYMER)
Polymer overlays generally consist of latex-modified concrete,
epoxy-modified concrete and epoxy mortar and concrete.
They are known as polymer portland-cement concretes (PPCC).
These materials may be formulated to provide improved bonding
characteristics, higher strengths, and lower water and chloride
permeabilities compared to conventional concrete.
Overlays composed of epoxy mortars or concretes are best suited
for use in areas where concrete is being attacked by an aggressive
substance such as acidic water or some other chemical in the water.
These overlays may also be used in some instances to repair surface
cracking, provided that the cause of the cracking is wellunderstood
and no movement of the concrete is expected in the future
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METHOD 13 : OVERLAYS (POLYMER)
Polymer overlays generally consist of latex-modified concrete,
epoxy-modified concrete and epoxy mortar and concrete.
They are known as polymer portland-cement concretes (PPCC).
These materials may be formulated to provide improved bonding
characteristics, higher strengths, and lower water and chloride
permeabilities compared to conventional concrete.
Overlays composed of epoxy mortars or concretes are best suited
for use in areas where concrete is being attacked by an aggressive
substance such as acidic water or some other chemical in the water.
These overlays may also be used in some instances to repair surface
cracking, provided that the cause of the cracking is wellunderstood
and no movement of the concrete is expected in the future
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METHOD 14 : OVERLAYS (PORTLAND-CEMENT)
Overlays are simply layers of concrete (usually horizontal) placed
over a properly prepared existing concrete surface to restore a
spalled or disintegrated surface or increase the load-carrying
capacity of the underlying concrete.
A portland-cement-concrete overlay may be suitable for a wide
variety of applications, such as resurfacing spalled or cracked
concrete surfaces on bridge decks or lock walls, increasing cover
over reinforcing steel, or leveling floors or slabs.
Other applications of overlays include repair of concrete surfaces
which are damaged by abrasion-erosion and the repair of
deteriorated pavements
Overlays should not be used in applications in which the original
damage was caused by aggressive chemical attack that would be
expected to act against the portland cement in the overlay
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METHOD 14 : OVERLAYS (PORTLAND-CEMENT)
Overlays are simply layers of concrete (usually horizontal) placed
over a properly prepared existing concrete surface to restore a
spalled or disintegrated surface or increase the load-carrying
capacity of the underlying concrete.
A portland-cement-concrete overlay may be suitable for a wide
variety of applications, such as resurfacing spalled or cracked
concrete surfaces on bridge decks or lock walls, increasing cover
over reinforcing steel, or leveling floors or slabs.
Other applications of overlays include repair of concrete surfaces
which are damaged by abrasion-erosion and the repair of
deteriorated pavements
Overlays should not be used in applications in which the original
damage was caused by aggressive chemical attack that would be
expected to act against the portland cement in the overlay
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METHOD 15 : POLYMER COATINGS
Polymer coatings, if the right material for the job condition is
selected and properly applied, can be an effective protective
coating to help protect the concrete from abrasion, chemical attack,
or freeze and thaw damage.
Epoxy resin is used as a protective coating because of its
impermeability to water and resistance to chemical attack.
Mixing and applying polymers should be cariied out between 16 °C
(60 °F) and above 32 °C (89 °F) .
Special sharp sand must be broadcast on the fresh surface if foot
traffic is expected on the finished surface. Because of their high
exotherm and higher shrinkage values, a neat epoxy in thicker
sections is likely to crack.
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METHOD 15 : POLYMER COATINGS
Polymer coatings, if the right material for the job condition is
selected and properly applied, can be an effective protective
coating to help protect the concrete from abrasion, chemical attack,
or freeze and thaw damage.
Epoxy resin is used as a protective coating because of its
impermeability to water and resistance to chemical attack.
Mixing and applying polymers should be cariied out between 16 °C
(60 °F) and above 32 °C (89 °F) .
Special sharp sand must be broadcast on the fresh surface if foot
traffic is expected on the finished surface. Because of their high
exotherm and higher shrinkage values, a neat epoxy in thicker
sections is likely to crack.
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METHOD 16 : POLYMER IMPREGNATION
Polymer impregnated concrete (PIC) is a portland-cement concrete
that is subsequently polymerized
This technique requires use of a monomer system, which is a liquid
that consists of small organic molecules capable of combining to
form a solid plastic.Monomer systems used for impregnation
contain a catalyst or initiator and the basic monomer (or different
isomers of the same monomer)
When heated, the monomers join together, or polymerize to
become a tough, strong, durable plastic, which in concrete greatly
enhances a number of the properties of the concrete.
If a cracked concrete surface is dried, flooded with the monomer,
and polymerized in place, the cracks will be filled and structurally
repaired
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METHOD 16 : POLYMER IMPREGNATION
Polymer impregnated concrete (PIC) is a portland-cement concrete
that is subsequently polymerized
This technique requires use of a monomer system, which is a liquid
that consists of small organic molecules capable of combining to
form a solid plastic.Monomer systems used for impregnation
contain a catalyst or initiator and the basic monomer (or different
isomers of the same monomer)
When heated, the monomers join together, or polymerize to
become a tough, strong, durable plastic, which in concrete greatly
enhances a number of the properties of the concrete.
If a cracked concrete surface is dried, flooded with the monomer,
and polymerized in place, the cracks will be filled and structurally
repaired
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Polymer impregnation has not been used successfully to repair fine
cracks.
Badly fractured beams have been repaired with polymer
impregnation by drying the fracture, temporarily encasing it in a
watertight (monomer proof) band of sheet metal, soaking the
fractures with a monomer, and polymerizing the monomer. Large
voids or broken areas in compression zones can be filled with fine
and coarse aggregate before flooding them with the monomer,
providing a polymer-concrete repair.
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Polymer impregnation has not been used successfully to repair fine
cracks.
Badly fractured beams have been repaired with polymer
impregnation by drying the fracture, temporarily encasing it in a
watertight (monomer proof) band of sheet metal, soaking the
fractures with a monomer, and polymerizing the monomer. Large
voids or broken areas in compression zones can be filled with fine
and coarse aggregate before flooding them with the monomer,
providing a polymer-concrete repair.
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METHOD 17 : PRECAST CONCRETE
Precast concrete is concrete cast elsewhere than its final position.
The use of precast concrete in repair and replacement of structures
has increased significantly in recent years and the trend is expected
to continue.
Typical applications of precast concrete in repair or replacement of
civil works structures include navigation locks, dams, channels,
floodwalls, levees, coastal structures, marine structures, bridges,
culverts, tunnels, retaining walls, noise barriers, and highway
pavement.
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METHOD 17 : PRECAST CONCRETE
Precast concrete is concrete cast elsewhere than its final position.
The use of precast concrete in repair and replacement of structures
has increased significantly in recent years and the trend is expected
to continue.
Typical applications of precast concrete in repair or replacement of
civil works structures include navigation locks, dams, channels,
floodwalls, levees, coastal structures, marine structures, bridges,
culverts, tunnels, retaining walls, noise barriers, and highway
pavement.
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METHOD 18: PREPLACED-AGGREGATE CONCRETE
Preplaced-aggregate concrete is produced by placing coarse aggregate
in a form and then later injecting a portland-cement-sand grout,
usually with admixtures, to fill the voids. As the grout is pumped into
the forms, it will fill the voids, displacing any water, and form a
concrete mass.
Preplaced-aggregate concrete is used on large repair projects,
particularly where underwater concrete placement is required or
when conventional placing of concrete would be difficult.
Typical applications have included underwater repair of stilling basins,
bridge piers, abutments, and footings.
The advantages of using preplaced-aggregate concrete include low
shrinkage because of the point-to point aggregate contact & ability to
displace water from forms as the grout is being placed.
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METHOD 18: PREPLACED-AGGREGATE CONCRETE
Preplaced-aggregate concrete is produced by placing coarse aggregate
in a form and then later injecting a portland-cement-sand grout,
usually with admixtures, to fill the voids. As the grout is pumped into
the forms, it will fill the voids, displacing any water, and form a
concrete mass.
Preplaced-aggregate concrete is used on large repair projects,
particularly where underwater concrete placement is required or
when conventional placing of concrete would be difficult.
Typical applications have included underwater repair of stilling basins,
bridge piers, abutments, and footings.
The advantages of using preplaced-aggregate concrete include low
shrinkage because of the point-to point aggregate contact & ability to
displace water from forms as the grout is being placed.
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METHOD 18 : PREPLACED-AGGREGATE CONCRETE
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METHOD 18 : PREPLACED-AGGREGATE CONCRETE
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METHOD 19 : ROLLER-COMPACTED CONCRETE
Roller-compacted concrete (RCC) is defined as “concrete compacted
by roller compaction; concrete that, in its unhardened state, will
support a roller while being compacted”
RCC should be considered where no-slump concrete can be
transported, placed, and compacted with earth and rock-fill
construction equipment. Ideal RCC projects will involve large
placement areas, little or no reinforcement or embedded metals, or
other discontinuities such as piles.
RCC has been so successful for repair of non-Corps dams that the
number of dam repair projects now exceeds the number of new
RCC dams. The primary advantages of RCC are low cost (25 to 50
percent less than conventionally placed concrete) and rapid
construction.
RCC has been used to strengthen and improve the stability of
existing dams, to repair damaged overflow structures, to protect
embankment dams during overtopping, and to raise the crest on
existing dams.
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METHOD 19 : ROLLER-COMPACTED CONCRETE
Roller-compacted concrete (RCC) is defined as “concrete compacted
by roller compaction; concrete that, in its unhardened state, will
support a roller while being compacted”
RCC should be considered where no-slump concrete can be
transported, placed, and compacted with earth and rock-fill
construction equipment. Ideal RCC projects will involve large
placement areas, little or no reinforcement or embedded metals, or
other discontinuities such as piles.
RCC has been so successful for repair of non-Corps dams that the
number of dam repair projects now exceeds the number of new
RCC dams. The primary advantages of RCC are low cost (25 to 50
percent less than conventionally placed concrete) and rapid
construction.
RCC has been used to strengthen and improve the stability of
existing dams, to repair damaged overflow structures, to protect
embankment dams during overtopping, and to raise the crest on
existing dams.
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METHOD 20 : SLABJACKING
Slabjacking is a repair process in which holes are drilled in an
existing concrete slab and a cementitious grout is injected to fill any
voids and raise the slab as necessary. This process is also known as
mudjacking.
Slabjacking is applicable to any situation in which a slab or other
concrete section or grade needs to be repositioned. Slabjacking
should be considered as an alternative to removal and replacement
with conventional concrete.
Applications include sidewalks, pavement slabs, water tanks, and
swimming pools. This process has also been used to fill voids behind
and under concrete structures; in such applications, it is simply a
variation of portland-cement grouting.
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METHOD 20 : SLABJACKING
Slabjacking is a repair process in which holes are drilled in an
existing concrete slab and a cementitious grout is injected to fill any
voids and raise the slab as necessary. This process is also known as
mudjacking.
Slabjacking is applicable to any situation in which a slab or other
concrete section or grade needs to be repositioned. Slabjacking
should be considered as an alternative to removal and replacement
with conventional concrete.
Applications include sidewalks, pavement slabs, water tanks, and
swimming pools. This process has also been used to fill voids behind
and under concrete structures; in such applications, it is simply a
variation of portland-cement grouting.
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METHOD 21 : STITCHING
This min stitching dogs (U-shaped metal units with short legs) that
span the crack.
Stitching may be used when tensile strength must be reestablished
across major cracks. Stitching a crack tends to stiffen the structure,
and the stiffening may accentuate the overall structural restraint,
causing the concrete to crack elsewhere.
Therefore, it may be necessary to strengthen the adjacent section
with external reinforcement embedded in a suitable overlay.
ethod involves drilling holes on both sides of the crack and grouting
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METHOD 21 : STITCHING
This min stitching dogs (U-shaped metal units with short legs) that
span the crack.
Stitching may be used when tensile strength must be reestablished
across major cracks. Stitching a crack tends to stiffen the structure,
and the stiffening may accentuate the overall structural restraint,
causing the concrete to crack elsewhere.
Therefore, it may be necessary to strengthen the adjacent section
with external reinforcement embedded in a suitable overlay.
ethod involves drilling holes on both sides of the crack and grouting
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Procedure:
The stitching procedure consists of drilling holes on both sides of
the crack, cleaning the holes, and anchoring the legs of the dogs in
the holes, with either a no shrink grout or an epoxy-resin-based
bonding system.
Spacing of the stitching dogs should be reduced at the end of cracks
and consideration should be given to drilling a hole at each end of
the crack to blunt it and relieve the concentration of stress.
Both sides of the concrete section shall be stitched so that further
movement of the structure will not bend the dogs. Stitching shall be
done on the tension face, where movement is occurring.
The crack shall be made watertight as well as stitched to protect the
dogs from corrosion. If there is a tendency for the crack to close as
well as to open, the dogs must be stiffened and strengthened.
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Procedure:
The stitching procedure consists of drilling holes on both sides of
the crack, cleaning the holes, and anchoring the legs of the dogs in
the holes, with either a no shrink grout or an epoxy-resin-based
bonding system.
Spacing of the stitching dogs should be reduced at the end of cracks
and consideration should be given to drilling a hole at each end of
the crack to blunt it and relieve the concentration of stress.
Both sides of the concrete section shall be stitched so that further
movement of the structure will not bend the dogs. Stitching shall be
done on the tension face, where movement is occurring.
The crack shall be made watertight as well as stitched to protect the
dogs from corrosion. If there is a tendency for the crack to close as
well as to open, the dogs must be stiffened and strengthened.
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Method 22: Shotcrete
Shotcrete is defined as pneumatically applied concrete or mortar placed
directly on to a surface. The shotcrete shall be placed by either the dry mix or
wet mix process.
The dry mix process shall consist of:
Thoroughly mixing the dry materials,
Feeding of these materials into mechanical feeder or gun,
Carrying the materials by compressed air through a hose to a special nozzle,
Introducing water at nozzle point and intimately mixing it with other
ngredients at the nozzle;
Jetting the mixture from the nozzle at high velocity on to the surface to
receive the shotcrete.
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Method 22: Shotcrete
Shotcrete is defined as pneumatically applied concrete or mortar placed
directly on to a surface. The shotcrete shall be placed by either the dry mix or
wet mix process.
The dry mix process shall consist of:
Thoroughly mixing the dry materials,
Feeding of these materials into mechanical feeder or gun,
Carrying the materials by compressed air through a hose to a special nozzle,
Introducing water at nozzle point and intimately mixing it with other
ngredients at the nozzle;
Jetting the mixture from the nozzle at high velocity on to the surface to
receive the shotcrete.
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The wet-mix process shall consist of:
Thoroughly mixing all the ingredients with the exception of the
accelerating admixture,
Feeding the mixture into the delivery equipment;
Delivering the mixture by positive displacement or compressed air to
the nozzle;
Jetting the mixture from the nozzle at high velocity on to the surface
to receive the shotcrete.
Procedure: The gun is easily assembled from readily available
material, has only a few critical dimensions, and can be operated by
personnel
without extensive training.
The gun is used for application of mortar in small, shallow repairs on
vertical and overhead surfaces.
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The wet-mix process shall consist of:
Thoroughly mixing all the ingredients with the exception of the
accelerating admixture,
Feeding the mixture into the delivery equipment;
Delivering the mixture by positive displacement or compressed air to
the nozzle;
Jetting the mixture from the nozzle at high velocity on to the surface
to receive the shotcrete.
Procedure: The gun is easily assembled from readily available
material, has only a few critical dimensions, and can be operated by
personnel
without extensive training.
The gun is used for application of mortar in small, shallow repairs on
vertical and overhead surfaces.
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Method 23: Plate bonding
Plate bonding is an inexpensive, versatile and advanced technique for
rehabilitation, up gradation of concrete structures by mechanically
connecting MS plates by bolting and gluing to their surfaces with epoxy. Plate
bonding can substantially increase strength, stiffness, ductility and stability of
the reinforced concrete elements and can be used effectively for seismic
retrofitting.
In this method the bolts, which are first used to hold the plates in position
during construction, act as permanent shear connectors and integral
restraints. The bolts are also designed to resist interface forces assuming the
epoxy glue used as non-existent assuming it as destroyed by fire, chemical
break down, rusting or simply bad workmanship. Since epoxy is prone to
premature debonding, use of mechanical anchorage along with epoxy
bonding is considered more reliable. Since the steel plates are unobtrusive,
with this technique original sizes of the structural members are not increased
significantly. This method is preferred where enlargement of the members
is going to affect the headroom, existing windows, doors and other fixtures.
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Method 23: Plate bonding
Plate bonding is an inexpensive, versatile and advanced technique for
rehabilitation, up gradation of concrete structures by mechanically
connecting MS plates by bolting and gluing to their surfaces with epoxy. Plate
bonding can substantially increase strength, stiffness, ductility and stability of
the reinforced concrete elements and can be used effectively for seismic
retrofitting.
In this method the bolts, which are first used to hold the plates in position
during construction, act as permanent shear connectors and integral
restraints. The bolts are also designed to resist interface forces assuming the
epoxy glue used as non-existent assuming it as destroyed by fire, chemical
break down, rusting or simply bad workmanship. Since epoxy is prone to
premature debonding, use of mechanical anchorage along with epoxy
bonding is considered more reliable. Since the steel plates are unobtrusive,
with this technique original sizes of the structural members are not increased
significantly. This method is preferred where enlargement of the members
is going to affect the headroom, existing windows, doors and other fixtures.
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METHOD 24 : FOUNDATION REHABILITATION METHODS
A.Shoring
1.Raking shores with the angle of shores generally 60
o
to 75
o
are
usually used where external support is necessary. In case, the feet of
raking shores are to be kept free, then flying shores can be provided
which strut against another structure or wall.
2. Flying shores merely provide a restraint against building or tilting.
3. Dead shores are verified struts bearing on the ground at the
required distance & supporting the vertical load of a wall wherever
required in conjunction with flying shores or horizontal ties
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METHOD 24 : FOUNDATION REHABILITATION METHODS
A.Shoring
1.Raking shores with the angle of shores generally 60
o
to 75
o
are
usually used where external support is necessary. In case, the feet of
raking shores are to be kept free, then flying shores can be provided
which strut against another structure or wall.
2. Flying shores merely provide a restraint against building or tilting.
3. Dead shores are verified struts bearing on the ground at the
required distance & supporting the vertical load of a wall wherever
required in conjunction with flying shores or horizontal ties
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B. UNDERPINNING
Underpinning piles are normally provided in pairs, one on each side
of the load bearing walls or in groups around the sides of columns.
Micro-piles are a useful means of underpinning.
They can be installed from the ground surface without deep
excavation and the equipment in installing the piles is suitable for
working in confined spaces.
The rotary drilling results in less damage & loss of ground, as
compared to the percussion method.
Proprietary jacked piles with pre-cast segments are another means
of underpinning. In the proprietary ‘pretest’ methods of
underpinning the underlying ground is preloaded before the load
of the structure is finally transferred by means of jacking between
the tilted existing structure & the new underpinning.
There are various patented systems of jacking, involving
interconnection of jacks with centralised pumping plant etc.
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B. UNDERPINNING
Underpinning piles are normally provided in pairs, one on each side
of the load bearing walls or in groups around the sides of columns.
Micro-piles are a useful means of underpinning.
They can be installed from the ground surface without deep
excavation and the equipment in installing the piles is suitable for
working in confined spaces.
The rotary drilling results in less damage & loss of ground, as
compared to the percussion method.
Proprietary jacked piles with pre-cast segments are another means
of underpinning. In the proprietary ‘pretest’ methods of
underpinning the underlying ground is preloaded before the load
of the structure is finally transferred by means of jacking between
the tilted existing structure & the new underpinning.
There are various patented systems of jacking, involving
interconnection of jacks with centralised pumping plant etc.
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RETROFITTING ….
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RETROFITTING ….
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RETROFITTING
In retrofitting, the structure must be designed so it is in keeping with
its purpose of use and is both safe and durable, with consideration
given to the ease of retrofitting construction and post-retrofitting
maintenance, as well as overall economy and environment-
friendliness.
Retrofitting is an important element of home improvement,
especially when it comes to protecting older homes from damage,
especially damage caused by the elements and weather events. The
term "retro" generally refers to things of the past, so combined with
the term "fitting" we can establish that it refers to fitting things in
with items from the past. When it comes to home improvement, it
essentially means adding new equipment or technology to previously
built structures.
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RETROFITTING
In retrofitting, the structure must be designed so it is in keeping with
its purpose of use and is both safe and durable, with consideration
given to the ease of retrofitting construction and post-retrofitting
maintenance, as well as overall economy and environment-
friendliness.
Retrofitting is an important element of home improvement,
especially when it comes to protecting older homes from damage,
especially damage caused by the elements and weather events. The
term "retro" generally refers to things of the past, so combined with
the term "fitting" we can establish that it refers to fitting things in
with items from the past. When it comes to home improvement, it
essentially means adding new equipment or technology to previously
built structures.
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CASES WHEN RETROFITTING IS DONE
1.The performance requirements are the same as those of the
structure when it was first built, but because the performance of
the structure has declined due to load action and environmental
action over time, the structure did not fulfill performance
requirements at the time of the inspection; through retrofitting,
the performance that would satisfy performance requirements is
added.
2.The design load has been changed or the structure otherwise
requires a higher level of performance than when initially
constructed, and therefore it does not fulfill performance
requirements; through retrofitting, the performance that would
satisfy performance requirements is added.
3.At the time of the inspection, the structure fulfilled performance
requirements but is predicted to not do so in the future due to a
decline in performance due to load action and environmental
action over time; performance improvements are conducted to
prevent this in advance.
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CASES WHEN RETROFITTING IS DONE
1.The performance requirements are the same as those of the
structure when it was first built, but because the performance of
the structure has declined due to load action and environmental
action over time, the structure did not fulfill performance
requirements at the time of the inspection; through retrofitting,
the performance that would satisfy performance requirements is
added.
2.The design load has been changed or the structure otherwise
requires a higher level of performance than when initially
constructed, and therefore it does not fulfill performance
requirements; through retrofitting, the performance that would
satisfy performance requirements is added.
3.At the time of the inspection, the structure fulfilled performance
requirements but is predicted to not do so in the future due to a
decline in performance due to load action and environmental
action over time; performance improvements are conducted to
prevent this in advance.
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FLOW OF RETROFITTING PROCESS
Retrofitting of structures shall proceed as follows:
(1) Identify the performance requirements for the existing Structure
to be retrofitted and draft an overall plan from inspection through
selection of retrofitting method, design of retrofitting structure and
implementation of retrofitting work.
(2) Inspect the existing structure to be retrofitted.
(3) Based on the results of the inspection, evaluate the performance
of the structure and verify that it fulfills performance requirements.
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FLOW OF RETROFITTING PROCESS
Retrofitting of structures shall proceed as follows:
(1) Identify the performance requirements for the existing Structure
to be retrofitted and draft an overall plan from inspection through
selection of retrofitting method, design of retrofitting structure and
implementation of retrofitting work.
(2) Inspect the existing structure to be retrofitted.
(3) Based on the results of the inspection, evaluate the performance
of the structure and verify that it fulfills performance requirements.
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(4) If the structure does not fulfill performance requirements, and
if continued use of the structure through retrofitting is desired,
proceed with design of the retrofitting structure.
(5) Select an appropriate retrofitting method and establish the
materials to be used, structural specifications and construction
method.
(6) Evaluate the performance of the structure after retrofitting and
verify that it will fulfill performance requirements.
(7) If it is determined that the retrofitting structure will be capable
of fulfilling performance requirements with the selected
retrofitting and construction methods, implement the retrofitting
work.
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(4) If the structure does not fulfill performance requirements, and
if continued use of the structure through retrofitting is desired,
proceed with design of the retrofitting structure.
(5) Select an appropriate retrofitting method and establish the
materials to be used, structural specifications and construction
method.
(6) Evaluate the performance of the structure after retrofitting and
verify that it will fulfill performance requirements.
(7) If it is determined that the retrofitting structure will be capable
of fulfilling performance requirements with the selected
retrofitting and construction methods, implement the retrofitting
work.
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RETROFFITING STRATEGIES
A number of options are available for giving a relief to a distressed
structure, which could cover any of the following:
1.Reduction of dead/live loads
2.Repair/strengthening of Columns, beams and slabs
3.Improving the compressive strength of concrete.
4.Attending to Cracks and joints
5.Improving the masonry structure to be able to resist earthquake
forces
6.Providing protective cover against the aggressive deteriorating
chemicals.
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RETROFFITING STRATEGIES
A number of options are available for giving a relief to a distressed
structure, which could cover any of the following:
1.Reduction of dead/live loads
2.Repair/strengthening of Columns, beams and slabs
3.Improving the compressive strength of concrete.
4.Attending to Cracks and joints
5.Improving the masonry structure to be able to resist earthquake
forces
6.Providing protective cover against the aggressive deteriorating
chemicals.
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STRESS REDUCTION
This can be achieved by
1.Reducing dead load and live loads;
2.Replacing heavy solid partitions with lightweight partitions;
3.Enlarging openings by removing filler walls;
4.Reducing numbers of stories;
5.Changing the building use to a lower classification of loading;
6.Span reduction of beams by providing struts etc;
7.Installation of shear movement joints in a continuous spans at points of
zero moment.
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STRESS REDUCTION
This can be achieved by
1.Reducing dead load and live loads;
2.Replacing heavy solid partitions with lightweight partitions;
3.Enlarging openings by removing filler walls;
4.Reducing numbers of stories;
5.Changing the building use to a lower classification of loading;
6.Span reduction of beams by providing struts etc;
7.Installation of shear movement joints in a continuous spans at points of
zero moment.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
•COLUMNS
The strengthening of columns may be required for the following
a. CAPACITY: The load carrying capacity of the column can be enhanced
by section enlargement. Different types of arrangement for section
enlargement are shown below
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STRENGTHENING COLUMNS, BEAMS AND SLABS
•COLUMNS
The strengthening of columns may be required for the following
a. CAPACITY: The load carrying capacity of the column can be enhanced
by section enlargement. Different types of arrangement for section
enlargement are shown below
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Column Compressive
Strengthening by
Section Enlargement
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Column Compressive
Strengthening by
Section Enlargement
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STRENGTHENING COLUMNS, BEAMS AND SLABS
b. DUCTILITY/CONFINEMENT: The ductility of the column can be
enhanced by providing additional tiles, steel plate bonding, and fibre
wrap.
c. JOINTS: The joints play crucial for resisting earthquake forces. The
joints can be strengthening by enlargement, jacketing by steel collar and
fibre wrap.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
b. DUCTILITY/CONFINEMENT: The ductility of the column can be
enhanced by providing additional tiles, steel plate bonding, and fibre
wrap.
c. JOINTS: The joints play crucial for resisting earthquake forces. The
joints can be strengthening by enlargement, jacketing by steel collar and
fibre wrap.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
•BEAMS
The strengthening of beams may be required for the following
a. FLEXURAL STRENGTH: The flexural strength of the beam can be
enhanced by
i. Section enlargement in compression,
ii. Additional reinforcement in the tension. Caution shall be exercised to
ensure that section is not over reinforced while providing additional
reinforcement to compensate loss of reinforcement due to corrosion
etc.
iii. The provisioning for enhanced tensile strength if being undertaken,
this should be accompanied with corresponding increase in
compression
as well .Due to such increased flexural capacities extra shear capacities
required to ensure ductile behaviour during earthquake shall also
considered for provision.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
•BEAMS
The strengthening of beams may be required for the following
a. FLEXURAL STRENGTH: The flexural strength of the beam can be
enhanced by
i. Section enlargement in compression,
ii. Additional reinforcement in the tension. Caution shall be exercised to
ensure that section is not over reinforced while providing additional
reinforcement to compensate loss of reinforcement due to corrosion
etc.
iii. The provisioning for enhanced tensile strength if being undertaken,
this should be accompanied with corresponding increase in
compression
as well .Due to such increased flexural capacities extra shear capacities
required to ensure ductile behaviour during earthquake shall also
considered for provision.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
iv. MS plate bonding
v. High Strength Fibre Fabric Wrap Technique (without section
enlargement)
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STRENGTHENING COLUMNS, BEAMS AND SLABS
iv. MS plate bonding
v. High Strength Fibre Fabric Wrap Technique (without section
enlargement)
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Beam Strengthening : Concrete Overlay And Section Enlargement
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Beam Strengthening : Concrete Overlay And Section Enlargement
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STRENGTHENING COLUMNS, BEAMS AND SLABS
•SLAB
The performance of the slab can be improved by providing overlays (in
case of negative moment deficiency) or underlay (in case of positive
moment deficiency).
The addition of overlay/underlay will also increase the stiffness of the
slabs and control the excessive deflections problems.
The slabs are generally safe in shear and as such no need is likely to
occur for shear strengthening except flat slabs near column capital.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
•SLAB
The performance of the slab can be improved by providing overlays (in
case of negative moment deficiency) or underlay (in case of positive
moment deficiency).
The addition of overlay/underlay will also increase the stiffness of the
slabs and control the excessive deflections problems.
The slabs are generally safe in shear and as such no need is likely to
occur for shear strengthening except flat slabs near column capital.
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Slab Strengthening : Concrete Overlay
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Slab Strengthening : Concrete Overlay
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STRENGTHENING COLUMNS, BEAMS AND SLABS
CRACKS/JOINTS
The concrete and masonry are weak in tension.
The cracks indicate the tensile failure of the material.
The cause of cracking should be examined in detail and remedial
measures taken accordingly. Inactive (i.e. non-moving) cracks in
masonry can be repaired by stitching. Grouting with non-shrink
grouts also repairs these types of cracks.
The active cracks required for accommodating thermal movements
shall be repaired by suitably locating the expansion joints and filling
them with flexible materials like poly-sulphides, bituminous fillers
etc.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
CRACKS/JOINTS
The concrete and masonry are weak in tension.
The cracks indicate the tensile failure of the material.
The cause of cracking should be examined in detail and remedial
measures taken accordingly. Inactive (i.e. non-moving) cracks in
masonry can be repaired by stitching. Grouting with non-shrink
grouts also repairs these types of cracks.
The active cracks required for accommodating thermal movements
shall be repaired by suitably locating the expansion joints and filling
them with flexible materials like poly-sulphides, bituminous fillers
etc.
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STRENGTHENING COLUMNS, BEAMS AND SLABS
PROTECTION
Protective measures for preservation and extending the service life of
the structure. They are given below:
Water Proofing
Depressed Floor Treatment
Terrace Treatment
Sun Shade
Surface Treatment
Creation of Barrier
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STRENGTHENING COLUMNS, BEAMS AND SLABS
PROTECTION
Protective measures for preservation and extending the service life of
the structure. They are given below:
Water Proofing
Depressed Floor Treatment
Terrace Treatment
Sun Shade
Surface Treatment
Creation of Barrier
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SEISMIC REHABILITATION
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SEISMIC REHABILITATION
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
88
Seismic Rehabilitation
REPAIR AND RETROFITTING OF RCC STRUCTURES
88
Seismic Rehabilitation
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
89
REPAIR AND RETROFITTING OF RCC STRUCTURES
89
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
90
Choice of a Seismic Strengthening Scheme
The strengthening solution
• Must correct known seismic deficiencies of the system
• Must be structurally compatible with the existing system
• Must be functionally and aesthetically compatible
• Must meet the expected performance goal such as life safety or
limited damage.
• Must minimize the disruption to occupants
• Must be cost-effective and use available materials and
Equipment
REPAIR AND RETROFITTING OF RCC STRUCTURES
90
Choice of a Seismic Strengthening Scheme
The strengthening solution
• Must correct known seismic deficiencies of the system
• Must be structurally compatible with the existing system
• Must be functionally and aesthetically compatible
• Must meet the expected performance goal such as life safety or
limited damage.
• Must minimize the disruption to occupants
• Must be cost-effective and use available materials and
Equipment
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
91
Adding New Shear Walls
Filling Openings
REPAIR AND RETROFITTING OF RCC STRUCTURES
91
Adding New Shear Walls
Filling Openings
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
92
Adding Shotcrete to Existing Masonry
Adding Jackets to RC Frame Members
REPAIR AND RETROFITTING OF RCC STRUCTURES
92
Adding Shotcrete to Existing Masonry
Adding Jackets to RC Frame Members
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
93
Adding Wing (Side) Walls
Adding Buttresses
REPAIR AND RETROFITTING OF RCC STRUCTURES
93
Adding Wing (Side) Walls
Adding Buttresses
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
94
Adding Braces
REPAIR AND RETROFITTING OF RCC STRUCTURES
94
Adding Braces
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
95
Underpinning the Footing
REPAIR AND RETROFITTING OF RCC STRUCTURES
95
Underpinning the Footing
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
96
CASE STUDY : Ten Storied RCC Framed Office
Building at Delhi
REPAIR AND RETROFITTING OF RCC STRUCTURES
96
CASE STUDY : Ten Storied RCC Framed Office
Building at Delhi
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
97
SALIENT FEATUERS
REPAIR AND RETROFITTING OF RCC STRUCTURES
97
SALIENT FEATUERS
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
98
VISUAL OBSERVATIONS
REPAIR AND RETROFITTING OF RCC STRUCTURES
98
VISUAL OBSERVATIONS
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
99
REPAIR AND RETROFITTING OF RCC STRUCTURES
99
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
100
REPAIR AND RETROFITTING OF RCC STRUCTURES
100
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
101
REPAIR AND RETROFITTING OF RCC STRUCTURES
101
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
102
REPAIR AND RETROFITTING OF RCC STRUCTURES
102
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
103
REPAIR AND RETROFITTING OF RCC STRUCTURES
103
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
104
REPAIR AND RETROFITTING OF RCC STRUCTURES
104
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
105
REPAIR AND RETROFITTING OF RCC STRUCTURES
105
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
106
REPAIR AND RETROFITTING OF RCC STRUCTURES
106
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
107
REPAIR AND RETROFITTING OF RCC STRUCTURES
107
STRUCTURAL REPAIR AND REHABILITATION
REPAIR AND RETROFITTING OF RCC STRUCTURES
108
REPAIR AND RETROFITTING OF RCC STRUCTURES
108
School of Building Science and
Technology, CEPT University, Ahmedabad
THANK YOU
0806
0606
1206 2306
109
Technology, CEPT University, Ahmedabad
THANK YOU
0806
0606
1206 2306
109
School of Building Science and
Technology, CEPT University, Ahmedabad
Question
What is Seismic Rehabilitation ?
110
Technology, CEPT University, Ahmedabad
Question
What is Seismic Rehabilitation ?
110
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