The presentation includes difference between repair, retrofitting and rehabilitation. methods of repairs, repair materials, various methods for retrofitting etc.

1. Prepared and Presented by
Nadeem Shobhani - 146510306051
Amit Mali - 146510306033
In-charge Faculty
Mr. Haresh R. Solanki
REPAIR, RETROFITTING
AND REHABILITATION
OF STRUCTURES

2. CONTENTS
 Definition
 Masonry Construction Aspect for
Earthquake Resistance
 Materials for Repairs of Crack
 Repair of Brick Masonry
 Repair of Stone Masonry
 Repair of Wall due to dampness
 Efflorescence in Walls
 Repair of RCC Slab
 Plate Bonding
 Fiber Wrap Technique
 Strengthening of interior reinforcing
 Rainwater Leakage from Terrace
 Damp Proofing of different parts of
building
 Anti-Termite Treatment
 Fungus Decay of Timber
 Cost Estimation of Repair and
Retrofitting

3. REPAIR
The main purpose of repair is to bring back the architectural shape of the
building so that all services start working and the functioning of building is resumed
quickly.
Repair does not pretend to improve the structural strength of the building .

4. The action will include the following:
 Patching up of defects such as cracks and fall of plaster.
 Repairing doors, windows, replacement of glass panes.
 Checking and repairing electric wiring.
 Rebuilding non-structural walls, compound walls, etc.
 Re-plastering of walls as required.
 Relaying cracked flooring at ground level.
 Decoration – white washing, painting, etc.
 Checking and repairing gas pipes, water pipes and plumbing services.

5. RESTORATION
It is the restitution of the strength of the building had before the damage occurred.
The main purpose of restoration is to carry out structural repairs to load bearing
elements.
Some of the approaches are stated below:
 Removal of portion of cracked masonry walls and piers and rebuilding them in richer
mortar
 Addition of reinforcing mesh on both face of the crack wall, holding it to the wall
through spikes or bolts and then covering it suitably
 Injecting epoxy like material, which is strong in tension into the cracks in walls,
column, beam and footing.

6. RETROFITTING
Retrofitting is the seismic strengthening of existing damaged or undamaged
buildings.
It is an improvement over the original strength when the evaluation of the
building indicates that the strength available before the damage was insufficient and
restoration alone will not be adequate in future quakes.

7. MASONRY CONSTRUCTION ASPECTS FOR
EARTHQUAKE RESISTANCE
A) PLAN OF A BUILDING
 The building as a whole or its various blocks should be kept symmetrical about
both the axes. Asymmetry leads to torsion earthquake and is dangerous.
 Simple and regular shapes behave better during earthquake than shapes with
many projections.
 If longer lengths are required two separate blocks with sufficient gap 25 to 40 mm
in between should be provided.
 The projection in plan shall not exceed L/3 or B/3 in length or width respectively.
 Length of block in plan should not exceed 3B.

9. MASONRY CONSTRUCTION ASPECTS FOR
EARTHQUAKE RESISTANCE
B) MASONRY MORTAR
 As per IS : 4326-1993, buildings are classified into A to E categories, According to
earthquake resistance, as under :
BUILDING CATEGORY DESIGN SEISMIC COEFFICIENT
A 0.04 to less than 0.05
B 0.05 to 0.06
C More than 0.06 and less than 0.08
D 0.08 to less than 0.12
E 0.12 and More

10. MASONRY CONSTRUCTION ASPECTS FOR
EARTHQUAKE RESISTANCE
 The proportion of masonry mortar shall not be poor than (1:6) cement-sand.
BUILDING CATEGORY MASONRY MORTAR
A
Cement-sand 1:6 or
Lime-Cinder 1:3 or richer
B, C
Cement-Lime-Sand 1:2:9 or
Cement-sand 1:6 or richer
D, E
Cement-sand 1:4 or
Cement-Lime-sand 1:1:6 or richer

11. MASONRY CONSTRUCTION ASPECTS FOR
EARTHQUAKE RESISTANCE
C) WALL DIMENSION AND BUILDING HEIGHT
 For single storey building, wall thickness shall not be less than 1 brick (190 MM)
 For Three storey building, wall thickness in ground storey shall not be less than
1
1
2
brick and in the upper floors wall thickness shall not be less than 1 brick.
 Wall thickness shall not the less than 1/16 of the distance between two cross
walls.
 The floor height shall not exceed 3.0 m.
BUILDING CATEGORY MAXIMUM NUMBER OF STOREYS
A, B, C 3
D 2

12. D) WALL OPENING
 In walls the size of opening shall be small and located in the middle of the wall.
 Opening Shall be located at minimum distance of ¼ into height of opening from
the inner corner. This distance shall not be less than 60cm.
 Total length of openings in a wall shall not exceed :
One Storey Building = 50% of the distance between two cross walls.
Two Storey building = 42% of the distance between two cross walls.
Three Storey building = 33% of the distance between two cross walls.
 The horizontal distance between two nearby openings shall not be less than 0.5 x
height of opening and not less than 60cm.
 The vertical distance between two openings shall not be less than 0.5 x Width of
opening and not less than 60cm.
 If above criteria are not satisfied, the opening shall protected by 2-8mm diameter
of bars.

13. E) MASONRY BOND
 For getting sufficient strength masonry work shall be carried out in proper bond
with vertical joints in one vertical line in the alternate courses. First of all wall
shall be constructed for 60cm height at the corners, than central portion of wall
shall be constructed. At the junction of two walls, toothed joint shall be
provided.

14. E) HORIZONTAL BANDS
 PLINTH BAND- Plinth bands are provided when soil is soft or uneven in their
properties. This band also acts as DPC
 LINTEL BAND- This is most important band and will in corporate in itself all doors
and window lintels. It must be provided in all storeys in buildings. The
reinforcement of lintels should be provided extra.
 ROOF BAND- This band will be required at eaves level of trussed roofs and also
below or in the level with such floors which consists of joists.
 GABLE BAND- Masonry gable ends must have the triangular portion of masonry
enclosed in a band, the horizontal part will be continuous with the eave level
band.

16. MATERIAL FOR REPAIR OF CRACKS
Material for Repair:-
1) Cement Slurry
2) Cement Mortar
3) Epoxy Resin
4) Polymer Modified Cementious Products (PMCC)
4.1) Polyvinyl Acetate
4.2) Styrene Butadiene Rubber
4.3) Acrylics

17. Requirements of and ideal Repair Materials:-
 An excellent bonding material.
 A very good repair mortar which provides excellent waterproofing and resistance to
carbon dioxide penetration apart from having bonding property.
 Temperature compatibility of the repair material with the material of existing
structure, which is being repaired.
 If distress is due to corrosion of reinforcement a proper surface cleaning and
application of a suitable corrosion inhibiting material is a requirement.
 If waterproofing treatment is necessary for rehabilitation, application of good
waterproofing system is required.

18. REPAIR OF BRICK MASONRY
1. Sealing of cracks by epoxy resin injections.
2. Repairing brick work with Epoxy mortar or Cement mortar.
3. Installing Ferro-cement plate at corner.
4. Rebuilding Portion of a wall.
5. Stitching Method of Repairing Cracks.

19. 1. Sealing of cracks by epoxy resin injections.
 If cracks are reasonably small the technique to restore the original tensile
strength of the cracked element is by pressure injection of epoxy.
The procedure for repair is as follows :
 The external surfaces are cleaned of non structural materials. Plastic injection
ports are place along the surface of the cracks on both sides of the member and
are secured in place with an epoxy sealant. The c/c spacing of these ports may be
approximately equal to the thickness of the element.
 After the sealant has cured, a low viscosity epoxy resin is injected into one port
at a time, beginning at the lowest part of the crack in case it is vertical or at one
end of the crack in case it is horizontal.
 The resin is injected till it is seen flowing from the opposite sides of the member
at the corresponding port. The injection port should be closed at this stage and
injection equipment move to the next port and so on.

21. 2. Repairing brick work with Epoxy mortar or Cement mortar.
 For cracks wider than about 6 mm or for region in which the concrete or masonry
is crushed a treatment other than the injection is indicated.
The procedure for repair is as follows :
 The loose material is removed and replace with any of the materials like
expansive cement mortar, quick setting cement or gypsum cement mortar.
 Where found necessary, additional or shear or flexural reinforcement
is provided in the region of repairs. This reinforcement could be covered by
mortar to give further strength as well as protection to the reinforcement.
 In areas of very sewer damage ,replacement of the member or the portion of the
member can be carried out.

23. 3. Installing Ferro-cement plate at corner.
 To repair the cracks at the corners of a wall, wire mesh G-14 (2mm wire, 25mm x
25mm mesh) is fixed with bearing of 500 to 600 mm on either side of crack. The
wire mesh is covered by rich mortar.

24. 4. Rebuilding Portion of Walls
 If the stone masonry is severely damaged due to earthquake, the portion of wall
or entire wall is dismantled and new masonry wall is constructed.
 At the time of repair, the roof must be supported temporarily.

25. 5. Stitching Method of Crack Repair
Stitching method is used for repairing wide cracks in masonry walls and slabs.
The Various steps are :
▪ Drill holes on either sides of the cracks.
▪ Chaze a groove between the holes drilled.
▪ Fix u-shaped M.S. bar in the holes and groove transverse to the cracks.
▪ Grout the holes using epoxy grout or other non-shrink grout.
▪ Finish the hole and groove with epoxy mortar.

27. REPAIR OF STONE MASONRY
1. Making ‘Through Bond’ in random rubble masonry
2. Connection between existing stone walls
3. Random Rubble Masonry Wall

28. 1. Making a through bond in random rubble masonry:
 First of all select the location in the rubble wall for placing through bond. The
location should be so selected that horizontal and vertical distance is 1 m.
 Remove the plaster at the selected location. Remove mortar around the stones
and open up the stones.
 Slowly remove the stone out of the wall.
 Create a hole of about 75 mm in the wall.
 Place 8 mm dia M.S. bar with hooks in the hole and fill the hole with around 1:2:4
concrete.
 Cure the surface for 10 days by sprinkling water.

31. 2. Connection between existing stone walls:
 Two stone walls can be strengthened by sewing at the corners. At the junction of
two walls 20 mm diameter holes are drilled into the masonry at 45° angle. The
depth of hole in the longitudinal wall should be up to 2 times the thickness of the
cross wall. 10 mm diameter steel bar is placed in the hole and it is cement
grouted.

33. 3. Repair of Random Rubble Masonry
 Random Rubble Masonry Walls are most vulnerable to a delamination and
complete collapse and must be strengthened by internal impregnation by rich
cement grout in the ratio of 1:1 or covered with steel mesh and mortar.
 In the method of grouting 2 to 4 holes are drilled per m² area. First of all holes
are cleaned by water injection. Then after cement-sand grouted at low pressure
of about 0.1 to 2.5 MPa into the holes. The grouting of holes is started from
bottom and proceeded towards up.
 When a wall contains many cracks and cracks are visible on both faces of walls, it
is strengthened by using wire mesh. Plaster is removed from the masonry surface.
Fix wire mesh 0f 50 mm x 50 mm size on both faces of wall and connect them
with steel rods at 300 mm to 400 mm distance. Apply cement mortar on the wire
mesh and finish the surface.
 In thick wall strengthening is done by placing ‘Through Stone’ or ‘Through Bond’
such through stone or through bond shall be placed at 1/3 points in the length
and height of the wall. Longer walls can be strengthened by buttress.

36. REPAIR OF WALLS FOR DAMPNESS
Plinth is the portion of the wall of a building immediately above ground level
to the ground floor level. This height is usually ranges from 45cm to 100cm.
In all buildings, nowadays, DPC is provided to prevent dampness going up
the walls from foundation due to capillary action of ground water the
thickness of DPC shall be 40mm to 50mm of 1:2:4 cement concrete with the
waterproofing compound. In some buildings 100mm thick plinth beam with
reinforcement bars is provided at the plinth level.
1) Providing new DPC layer
2) Chemical injection in plinth
3) Pressure injection of resin mortar in holes

37. 1. Providing new DPC Layer
 For providing new DPC layer in an old buildings, which has been built without
DPC, we cut the mortar bed of two brick courses above ground level in stages of
about one meter in length at a time.
 This method is very slow and may lead to structural settlement and cracking of
walls if the walls are weak. Therefore, this method is rarely used.
2. Chemical Injection at Plinth
 In this method, inclined holes are drilled in the walls in plinth portion.
Water soluble silicon is injected in to these holes. Silicon paints are used
for waterproofing of exterior wall portions, to prevent entry of rainwater
into the wall. There are two methods:
a) Pressure injection
b) Gravity feed

38. a. Pressure Injection
 In this method, plaster of walls up to 3-4 brick layer above ground level is removed.
Holes of 12mm diameter are bored into wall up to 2/3t, where = thickness of walls.
The c/c distance of holes is kept about 150mm. These holes should be slightly inclined
downwards. The chemical solution such as polyurethane injection resin or gel is
injected by a pressure pump until it extrudes from the masonry. We usually use high
pressure injection for solvent based solutions and low pressure injection for water
based solutions. The holes are finally finished with waterproof mortar.
b. Pressure Injection
 Rising dampness can also be prevented by simple gravity feed method. In this method,
inclined holes of 25mm diameter are drilled into holes up to 2/3t thickness. Feed
tubes are inserted into these holes and chemicals such as dilute silicon are transfused
from the containers under gravity. Liquid is allowed to flow till masonry gets
saturated.

39. 3. Pressure injection of resin mortar in holes
 In this method, 20mm to 30mm diameter holes are bored to a depth of 3/5t in a wall from
both the sides. The c/c spacing of holes is 30cm and inclined downwards at 20° to 30°.
Flush out the drill holes and inject the special mortar from base of hole to upwards using
hand operated caulking gun. This mortar is composed of special cement mortar containing
styrene butadiene resin or epoxy resin, mixed according to the instructions given by the
manufactures. This resin hardens to an impervious layer and prevents migration of moisture.

40. EFFLORESCENCE IN WALLS
Efflorescence is the formation of the white crystalline substances that appear on brick wall
surface due to salt in the brick or sand or the water used in its construction. Efflorescence is the
different from rising dampness. When the walls get wet and then dries out , the dissolved salts
come to the surface through the pores. The salts can also absorb water from atmosphere and
form ugly patches on the wall.

41. Measures to prevent efflorescence
1) Construction materials such as bricks, water, sand etc. Should not contain salts.
2) Provide DPC at plinth level.
3) Rainwater should not be allowed to moisten the walls.
For the repair of Efflorescence affected walls, first of all remove plaster from the wall.
Scrub the surface with a brush to clean the surface from salts. Now, clean the surface
with a solution of mild hydrochloric acid. The surface is then thoroughly cleaned with
wet brush and then, plastered and dried. No dampness due to rainwater or from storage
tank or drainage system should wet the wall again so that salts present inside are not
brought to the surface.

42. REPAIR OF RCC SLAB
1) Patch repair on top surface of slab.
2) Repair of RCC slab with bottom steel corroded.
3) Falling off of bottom plaster of new RC slab due to lack of bonding.

43. 1. Patch Repair on Top surface of slab
 Where there are localized depressions caused by wear, which may be either at the
middle of a slab or at a joint, these can be repaired as under :
Identify the patches to be repaired on the top surface of the slab. mark out perimeter
lines at least 100mm outside the worn area. the lines are then cut into the surface using
a concrete saw, making a groove 3mm wide and 6mm deep. Any rust on the surface of
the reinforcement cement bar is removed and cleaned off. Finally clean the repair area
by compressed air. The repair area is then thoroughly wetted and kept wet. All surplus
water must be removed from the area before attempting to place the filling material.

45. 2. Repair of RCC Slab with bottom steel corroded
 The corrosion of steel and cracking of the bottom of old RC roofs are very
common. Usually in case of the roof slab and the slab under the bathroom,
corrosion of steel takes place due to leakage and seepage of water.
 If corrosion of slab bars occurs in other intermediate floor slabs, find out the cause
of corrosion of steel whether it is due to carbonation or due to chloride corrosion .
if it is chloride corrosion, then it may happen again after repair.

46. Method:
1) Support the slab by props to relieve some load from the slab.
2) Remove all the defective concrete and expose the corroded reinforcement to its full
circumference. A clear gap of 15mm below the steel is recommended by CPWD.
3) If possible conduct a carbonation test to find the depth of carbonation and remove
concrete up to the depth.
4) Clean the reinforcement thoroughly and add extra bars, if required, welded to the old
bars. Modern hot rolled high strength steel posses higher resistance to corrosion.
5) Apply anti corrosive protective passivation coat to all the reinforcement . The
protective coating may be cement slurry or epoxy coating. Apply bonding coat on the
surface of concrete.
6) Now, apply polymer modified mortar before drying of the bond coat.
7) Cure the treated surface at least for 7 days using water.
8) Painting with cement paint or carbonation resistant paint, can be carried out after the
surface gets dry.

50. 3. Falling off of bottom plaster of new RC slab due to lack of bonding.
 The falling off of bottom plaster of new RC slab is mainly due to lack of bonding
between the concrete surface and the finishing plaster. Another main reason is the
lack of proper denting or hacking of the bottom of the slab, as per standard
practice. As the recent cements with large amount fly ash gives very smooth
surface on finishing, it is necessary to follow either the old practice of hacking or
use modern construction chemical for bonding concrete surface.
 The old specification is to hack with a pointed tool so that the depression should
not be less than 3mm deep and should be spaced not more than 50mm. The process
of hacking the concrete surface is difficult and time consuming.

52. STRENGTHENING OF RCC SLAB
The flexural performance of the slab can be improved by overlays or
underlays. The addition of overlays/underlays will also increase the
stiffness of the slabs and control the excessive deflection.
In the case of negative moment deficiency slab is strengthened by overlay
while in case of positive moment deficiency slab is strengthened by
underlays.

55. SLAB JACKING TECHNIQUE
The technique of pressure injection of grouts for the purpose of lifting or
raising or stabilizing faulty concrete pavement floors and other slab on
grade surfaces, is called slab jacking. It is referred to as slab jacking when
lifting of slab is involved or simply pressure grouting where void filling is
the main objective.
APPLICATION:
 Highway Maintenance
 Repair of expansion joints
 Repair of settlement damage in concrete slabs

57. CRACK REPAIRS IN CONCRETE
1. Epoxy Injection Grouting
2. Sealing of Cracks
3. Flexible Sealing
4. Repair by Addition Steel
5. Crack Repair by Prestressing Steel
6. Crack Repair by Prestressing Steel

58. Epoxy Injection Grouting

59. Sealing of cracks

60. SEALING OF CRACKS

62. ADDITION OF REINFORCEMENT

63. STITCHING METHOD

65. Drilling and Plugging

66. Pre-stressing

67. Pre-stressing

68. PLATE BONDING
Plat bonding is an inexpensive, versatile and advance technique for
rehabilitation MS plates are connected mechanically by bolting and gluing
to the surface of member with epoxy.
Plate Bond can increase
• Strength
• Stiffness
• Ductility
• Stability, of the RCC element

71. FIBRE WRAP TECHNIQUE
The fiber wrap technique, also know as composite fiber system is a non-
structural strengthening that technique increases load carrying capacity
(shear, flexural, compressive) and ductility of RCC member without
causing and distress or destruction To the existing concrete.

74. STRENGTHEING BY INTERIOR REINFORCING
A common method of providing additional reinforcement across cracked
surfaces is to install new dowels into holes drilled perpendicular to the cracked
surfaces. The entire length of the dowel is fixed to the concrete by the use of
bonding matrix.
The structure must be shored and jacked if it is desire to relieve the member’s
dead load stresses so that new reinforcing will resists the original dead load.
Several bonding materials may be used. Portland cement grout, epoxy, and other
chemicals adhesives have been successfully installed within the annular space
between the dowel and sides of the predrilled hole.

75. STRENGTHEING BY INTERIOR REINFORCING
The dowels may be deformed steel reinforcing bars, stainless steel rods or
bolts. Coating steel dowels with either zinc galvanizing or fused epoxy is
acceptable. If all components are chemically compatible with the bonding
material.
Dowels for providing shear transfer between adjoining sections of
pavements may be placed in slots cut from the top to mid depth of
adjoining sections. In one section dowel is bonded, in the other , the dowel
is unbounded using sleeve or deboning agent.

76. RAIN WATER LEAKAGE FROM TERRACE
 Various causes of leakage from terrace
1. Open tile joint
2. Improper slope of tile terracing
3. Improperly done construction practices
4. Depression to cause stagnation of water

81. DAMP PROOFING OF DIFFERENT PARTS OF BUILDING
DPC for Foundation
DPC for basements
DPC for flat roof
DPC for parapet
DPC for flooring
DPC for pitched roof

83. DPC for Foundation

84. DPC for Foundation

85. DPC for basement

86. DPC for parapet

87. DPC for pitched roof

88. ANTI TERMITE TREATMENT
The termites are popularly known as while ants and they are found in
abundance in tropical and sub-tropical countries. These insects live in a
and they are very fast in eating wood and other cellulosic materials as food.
The also damage non-cellulosic material like plastic leather, etc. The term
Termite-proofing is used to indicate the treatment which is given to a
building so as to prevent The growth of termite a building.
Categories:
 Pre Construction
 Post Construction

90. 1. Pre-Construction:
This treatment is started right at the initial stage of construction of
building. This treatment can be divided into three operations.
(1) Site preparation
(2) Soil treatment
(3) Structural barriers

92. 2. Post-Construction:
It is maintenance treatment for those building which are already under attack of
termite.
It is essential to carry out inspection to estimation the magnitude of spread of
termite in the building and to the points of entry of termite in the building. These
points may be in near vicinity of column, bathrooms, lavatories, leaking pipes,
drains etc.
Wherever these shelter tubes are detected, these should we destroyed after
injecting anti-termite emulsion through these. To Prevent the entry of termites
through voids in masonry. 12 mm dia. holes are drilled al 30 cm c/c al
downward angle of 45 from both the sides of walls at plinth level and chemical
emulsion is pumped into these holes under pressure. These holes are them sealed.

94. FUNGUS DECAY OF TIMBER
Timber is used is building for various purpose like. Doors and window,
furniture, flooring roof etc. These wooden item are also damaged by
fungus in a building.
There are two types of fungus :
 Dry rot
 Wet rot

99. THANK YOU !!!
FOR GIVING US YOUR PRECIOUS TIME.