all engineering techniques of structure repairing are added in this presentation

1. REPAIRS AND REHABILITATION OF
STRUCTURES
Prepared by:-
Brijlata sharma
Assistant professor
JECRC Jaipur

2. CONCRETE REPAIR
REPAIR REFERS TO MODIFICATION OF
STRUCTURE,
DAMAGED IN ITS APPEARANCE OR
SERVICEABILITY, TO
RESTORE, PARTLY OR WHOLLY, THE PRE-EXISTING
CHARACTERISTICS OF SERVICEABILITY, LOAD-
BEARING
CAPACITY AND IF NECESSARY, TO IMPROVE ITS
DURABILITY.

3. NEED FOR REPAIR AND REHABILITATION OF
CONCRETE STRUCTURE
•Faulty design of the structure
•Improper execution and bad
workmanship
•Extreme weathering and
environmental conditions
•High degree of chemical attack
•Ageing of the structure

4. CONCRETE DETERIORATION

5. PENETRABILITY OF CONCRETE - PERMEABILITY,
SORPTIVITY, DIFFUSION.Physical processes - abrasion, erosion.
Chemical process - carbonation, chloride and sulfate
attack. Alkali –Aggregate reaction. Corrosion –
mechanism.

6. WHAT IS PERMEABILITY OF CONCRETE?
IS THE PROPERTY OF CONCRETE TO ABSORB WATER
What is Sorptivity of concrete?
Sorptivity is materials ability to
absorb and transmit water through
it by capillary suction.

7. DIFFUSION
THE CHLORIDE PENETRATION IS
A DIFFUSION PROCESS, WHEN THE CONCRETE IS
SATURATED WITH WATER AND WHEN CEMENT DOES
NOT REACT TOO MUCH WITH THESE SALTS. ANY
REINFORCEMENT IS IN A CONCRETE PRACTICALLY
SATURATED WITH WATER, WHEN ITS COVER IS
RATHER THICK AND IS NOT TOO DRY

8. CONCRETE DETERIORATION CAN OCCUR
THROUGH
 Scaling
 Dis-integration
 Erosion
 Spalling
 De-lamination
 Corrosion Of Reinforcement
 Alkali-aggregate Reactions, And
 Cracking of concrete

9. SCALING DIS-INTEGRATION

10. EROSION

11. Corrosion Of Reinforcement,
.

13. Alkali-aggregate Reactions

14. Spalling De-lamination

15. CRACKING OF CONCRETE

16. WHY CONCRETE CRACKS?
DUE TO
1. EXCESS WATER IN THE MIX
2. CONCRETE DRYING TOO FAST
3. IMPROPER STRENGTH CONCRETE POURED ON
THE JOB
4. LACK OF CONTROL JOINTS (IN CONCRETE
SLAB).
5. FOUNDATIONS POURED IN THE WINTER

17. PATTERNS OF CRACKS IN MASONRY/ CONCRETE
BUILDINGS

18. SIX COMMON TYPES OF CRACKS IN YOUR
CONCRETE
1. Plastic shrinkage concrete cracks
2. Expansion concrete cracks
3. Heaving concrete cracks
4. Settling concrete cracks
5. Concrete cracks caused by overloading the slab
6. Concrete cracks caused by premature drying

19. 1 CRACKS IN BRICK MORTAR JOINT 2 MAIN WALL AND CROSS
WALLS JOINT CRACKS
3 CRACK FORMATION BELOW THE LOAD BEARING
WALLS

20. 4 CRACKS FOUND IN R.C.C COLUMNS AND MASONRY

21. 5 CRACKS IN ROOF SLAB

22. 5 THE HORIZONTAL CRACKS BETWEEN R.C.C
SLAB AND THE BRICK PARAPET

23. Crack Depth Measurement in Concrete
I. Visual Examination of Concrete Cores
II – Impact Echo
III – Ultrasonic Pulse Velocity

24. ASSESSMENT OF RISK/DAMAGING STRUCTURE
1 PRELIMINARY INVESTIGATION:-VISUAL, HISTORY
COLLECTION..
2 DETAILED INVESTIGATION:- CORE CUTTING, REBAR
LOCATOR, CORROSION METER, PENETRATION RESISTANCE,
PULL OUT TESTS, HALF-CELL POTENTIAL, CONCRETE
RESISTIVITY ETC.

25. CORE CUTTING

26. REBAR LOCATOR
Concrete Cover Meter, Steel Bar Position Detector

27. CORROSION METER

28. PENETRATION RESISTANCE
Purpose
 Determine the uniformity of concrete
 Specify exact locations of poor quality or
deteriorated concrete zones
 Assess in-place strength of concrete
Application
Penetration resistance test is conducted to estimate the
strength of concrete on-site for early form removal or to
investigate the strength of concrete in place because of
low cylinder test results

29.  Apparatus

30. Purpose of Penetration Resistance Test
1. Determine the uniformity of concrete
2. Specify exact locations of poor quality or deteriorated
concrete zones
3. Assess in-place strength of concrete
Application of Penetration Resistance Test
Penetration resistance test is conducted to estimate the
strength of concrete on-site for early form removal or to
investigate the strength of concrete in place because of
low cylinder test results.

31. TESTING PROCEDURE
1. Place the positioning device on the surface of the concrete
at the location to be tested.
2. Mount a probe in the driver unit
3. Position the driver in the positioning device
4. Fire the probe into the concrete.
5. Remove the positioning device and tap the probe on the
exposed end with a small hammer to ensure that it has not
rebounded and to confirm that it is firmly embedded.
6. Place the measuring base plate over the probe and
position it so that it bears firmly on the surface of the
concrete without rocking or other movement.

33. WHAT IS PULLOUT TESTS ON HARDENED CONCRETE?
The fundamental principle behind pull out testing is that
the test equipment designed to a specific geometry will
produce results (pull-out forces) that closely correlate
to the compressive strength of concrete. This
correlation is achieved by measuring the force required
to pull a steel disc or ring, embedded in fresh concrete,
against a circular counter pressure placed on the
concrete surface concentric with the disc/ring.

34. TYPES OF PULL OUT TESTS:
1. LOK test
2. CAPO test (Cut and Pull out Test)
LOK Test:
The LOK-TEST system is used to obtain a reliable estimate
of the in-place strength of concrete in newly cast structures
in accordance with the pullout test method described in
ASTM C900, BS 1881:207, or EN 12504-3

35. LOK Test Process. H indicated the highest pullout
force.
LOK Test

36. HALF-CELL POTENTIAL TEST
is the only corrosion monitoring technique
standardized
 Identify rebar location
 Make a connection with the reinforcement (more
than one connection can be required if there is a
discontinuity between reinforcements)
 Prepare concrete surface through wetting

37. CONCRETE RESISTIVITY TEST
Conduct by Concrete Resistivity Meter
Resistivity is one of the key controlling factors once
corrosion begins. Corrosion requires a flow of ions
between anodic and cathodic sites on the reinforcement
of concrete; the resistivity controls the rate of this flow of
ions and therefore directly controls the rate of concrete
corrosion

38. CHAPTER-5
MATERIALS FOR REPAIR
1. Cement based and polymer modified Mortars or
Grout
2 self Curing Compound:- internal curing refers to the
process by which the hydration of cement occurs
because of the availability of additional internal water that
is not part of the mixing Water.
3 Resin and a polymers
4 FRP (Fibre-reinforced plastic)
5 Ferro-cement

39. WHAT IS THE DIFFERENCE BETWEEN RESIN AND A
POLYMER?
Polymer is a large molecule consisting of many
repeating subunits. Resin is a solid or viscous
material which gives a polymer after curing.
Resins can be synthetic or natural and generally
are mixtures of organic compounds. After
polymerizarion or curing, resins form polymers.
Commercially available adhesives and sealants
generally come in two parts- resin and hardener.
When both parts are mixed, polymerization starts,
the resin gets cured and the product we get is a
polymer.

40. WHAT IS FRP ?
Also called fiber-reinforced polymer, or fiber-
reinforced plastic) is a composite
material made of a polymer matrix
reinforced with fibres.
The fibres are
usually glass (in fibreglass), carbon (in carbon fiber
reinforced polymer), aramid, or basalt. Rarely, other
fibres such as paper, wood, or asbestos have been
used. The polymer is usually an epoxy, vinyl ester,
or polyester thermosetting plastic, though phenol
formaldehyde resins are still in use.

41. WHAT IS FERRO CEMENT?
Ferro cement is a type of thin wall reinforced concrete,
commonly constructed of hydraulic cement mortar,
reinforced with closely spaced layers of continuous and
relatively small size wire mesh. The mesh may be made
of metallic or other suitable materials

42. CHAPTER-6
REPAIR TECHNIQUES
1 Grouting
2 Jacketing
3 External bond plates-process
And its Limitations, design computations

43. GROUTING
filling voids, and sealing joints such as those between tiles.

44. JACKETING
Jacketing is a technique used to increase the strength of
existing structural members (e.g. Columns, Beams etc.)
by providing a “Jacket” of additional material around the
existing member.

45. EXTERNAL BOND PLATES-PROCESS
 Recent developments in material technology have seen the
introduction of carbon fibre plates, which are significantly
lighter and easier to install than steel plates of similar capacity.
 Carbon fibre fabric is now also used to strengthen columns
and beams using a wrapping technique. Single or multiple
layers of uni or bi-directional fabric are impregnated with resin
adhesive and applied to sections such as beams and columns
to improve strength.
 The technique is used to provide additional resistance to
bending, improve load capacity or reduce deflections, and is
particularly useful as a retrospective method when changes in
use in a building, or perhaps increased vehicle loadings on a
bridge structure need to be addressed or bursting or impact
resistance for columns on bridge structures.

47. UNDERWATER REPAIR OF CONCRETE
STRUCTURES
 Underwater concrete structures are prone to damage due to many
reasons. There are some methods which are specially adapted to
repair these damages. Care should be taken to ensure that the
damaged area is not contaminated before the application of the
repair material. The material used for the repair should be
compatible with its underwater usage while placing as well
as curing.
 The different methods which are used to repair the
underwater structures are as follows:
1 Surface spalling repair
2 Large scale repair
3 Preplaced aggregate concrete
4 Injection technique
5 Guniting or shotcrete method
6 Steel sleeve repairing technique

48. SURFACE SPALLING REPAIR
The cover provided for the concrete structures can spall
off due to the accidental damages. To prevent the
future corrosion of the reinforcement in the concrete, the
damaged area must be repaired or replaced. The areas
which are already slightly deteriorated with time, will be
prone to severe and dangerous damage in a short
period of time, especially in the splash zones. Before
starting the repairing procedures, the damaged area
must be cleared off of the marine growth and the loose
concrete.

49. Formwork for surface spalling repair

50. LARGE SCALE REPAIR
 This type of repair is used when the damages is caused by:
• Structural overloading,
• Fire,
• Ship impact, or
• Reinforcement corrosion especially in the splash zone
 The repair method and the material selection should be
done carefully when a large area of damage has to be
restored because the shrinkage and bleeding may lead to a
leakage path at the top of parent concrete and the repair
material surface.

51. PREPLACED AGGREGATE CONCRETE
 In this type of repair, formwork is installed in the area to
be repaired and a well graded aggregate is compacted in
it. Before placing the grout in the aggregate, it is ensured
that the aggregate is cleaned with the help of freshwater.
Then, specific grout is injected into the base of the well
compacted aggregate in the formwork.
 The water and voids which are present in the aggregate
are expelled out by the grout. The formwork which is
placed at the damaged area, should be grout proof to
avoid the leakage. Furthermore, there should be proper
venting so as to help the voids and sir to escape.

52. Preplaced aggregate concrete method

53. INJECTION TECHNIQUE
 This type of repair is similar to the procedure used for
repairing the dry structures where injection of cementitious
grout or resin can be employed to repair cracks and or voids.
The selection for the material depends on the void or crack
size and also on the possibility of the predicted displacement
of the member in the future.
 • Epoxy resin is employed for a crack width of 0.1mm
• Cement grout is used when the crack width is greater than
few millimeters.
• If the crack width is less than 0.1mm, injection is not
necessary.
 There are two methods of injection that include:
• Pressure injection
• Gravity feed.
 If there is evidence of corrosion in the reinforcement,
complete repairing should be recommended instead of
injection methods.

54. GUNITING OR SHOTCRETE METHOD
 This type of repair is used when large surface area or
beams or columns are encased. Dry processing is
employed in this method where dry mix is transferred by a
hose and water is added to the dry mix at the nozzle.
 Guniting method is actually not suitable for the repair of
underwater concrete structures but it can be utilized in
slash zones or tidal zones, if rapid setting additives are
employed. The maximum thickness of shotcrete is limited to
50mm but in case of thick layer, a second layer can be
placed.
 The success of this technique depends on skill of the man
handling the nozzle and experience in
• Adjusting addition of water
• Pressure of water
• Thickness uniformity

55. Guniting method done on land

56. STEEL SLEEVE REPAIRING TECHNIQUE
 This type of repair employs a steel sleeve which is used
around a pile or column. Then the space between the
sleeve and pile or column is filled with mortar or concrete.
The steel sleeve should be designed such that there should
be enough space for further reinforcement corrosion.
 The sleeve should extend and exceed the damaged length
of the pile/column from both top and bottom and should
bear the respective forces if the bars are ineffective due to
corrosion

57. Steel Sleeve Repairing Technique