this is a small litarature study over formation of differernt types of cracks formed in a building and its rectification

1. LITERATURE
STUDY
ON
CRACKS
by
V.Chiranjeevi
13061AA011
v

2. INTRODUCTION.
 Majority of cracks occur when
the building or its components
or the material of which the
building is made up of its
subjected to forces which are
greaterthan those which it can
withstand.
 Cracks may also occur if the
material used in the building
is of poor quality and the
construction is not carried out
in accordance with relevant

3. Cracks can be divided into
two categories
 STRUCTURAL CRACKS
 NON STRUCTURAL CRACKS

4. STRUCTURAL CRACKS.
 These cracks may arise due to
various reasons such as
incorrect design, overloading
of the structural components,
overloading of soil on which
the following building is
constructed or other similar
factors.
 Structural cracks endanger the
stability of the building and
maybe difficult to be
rectified.

5. NON-STRUCTURAL
CRACKS.
 These cracks are generally due
to internal forces developed in
the building on account of
changes in the size of building
components due to moisture
variation, temperature
variation, the effect of gases,
liquids and solids on the
building components.
 The non-structural cracks can
be repaired provided the
reasons for cracks are

6. CAUSES OF OCCURANCE OF
CRACKS.
 CRACKS DUE TO MOISTURE CHANGES.
 CRACKS DUE TO TEMPERATURE.
 CRACKS DUE TO VEGETATION.
 CRACKS DUE TO MOVEMENTS OF
GROUND.
 CRACKS DUE TO EFFECT OF
CHEMICAL REACTION.
 CRACKS DUE TO ELASTIC
DEFORMATION AND CREEP.

7. TYPES OF CRACKS.
HORIZONTAL CRACK.
VERTICAL CRACK.
DIAGONAL CRACK.
TOOTHED CRACK.
IRREGULAR OR RANDOM CRACKS.


8. EPOXY INJECTION
 Cracks are generally about
0.05mm width
 These can be generally over
come by epoxy injection
process
 In this process is established
by entry and venting ports at
close intervals along the
cracks,sealing the crack on
exposed surfaces,and injecting
the epoxy under pressure
 Epoxy injection has been
successfully used in repair of

9.  If the cause of the crack cannot
be removed then 2 options are
available
 One is to route and seal the crack
,thus treating it as a joint
 And the other is to establish a
joint that will accommodate the
movement and then inject the crack
with epoxy or other suitable
materials
o epoxy injection requires a high
degree of skill for satisfactory
excruciation of technique

10. CLEAN THE CRACKS
 This is to clean the cracks that
have been contaminated
 In the contaminants such as oil,
grease ,dirt, fine particles of
concrete will prevent epoxy
penetration and bonding and reduce
the effectiveness of the repairs
 These can be removed by vacuuming
are flushing with water or other
special effective cleaning
solutions

11. sealing of surfaces
 A surface can be sealed applying
an epoxy ,polyester, or other
appropriate sealing materials to
the surface of the crack and
allowing it to harden.
 A strippable plastic surface
sealer can be stripped away to
expose the gloss-free surface.
 For an extremely high injection
pressure are needed , the crack
can be cut out to a depth of ½
inch to 13mm and width of about ¾
inch or 20mm in a V shape , filled

12. GENERAL METHODS IN
INSTALLING ENTRY AND
VENTING PORTS
 Fittings inserted into drilled holes: This
method was the first to be used,
and is often used in conjunction
with V-grooving of the cracks. The
method entails drilling a hole
into the crack, approximately 3/4
in. (20 mm) in diameter and 1/2 to
1 in. (13 to 25 mm) below the apex
of the V grooved section.


13.  Bonded flush fitting: When the cracks
are not V grooved , a method
frequently used to provide an
entry port is to bond a fitting
flush with the concrete face over
the crack. The flush fitting has
an opening at the top for the
adhesive to enter and a flange at
the bottom that is bonded to the
concrete.

14.  Interruption in seal: Another system of
providing entry is to omit the
seal from a portion of the crack.
This method can be used when
special gasket devices are
available that cover the unsealed
portion of the crack and allow
injection of the adhesive directly
into the crack without leaking.

15.  Inject the epoxy: Hydraulic pumps,
paint pressure pots, or air-
actuated caulking guns may be
used. The pressure used for
injection must be selected
carefully
 If the pressure can not be
maintained, the epoxy is still
flowing into unfilled portions or
leaking out of the crack

16.  Alternative procedure: For massive
structures, an alternate procedure
consists of drilling a series of
holes [usually 7/8 to 4-in. (20 to
100-mm) diameter] that intercepts
the crack at a number of
locations. Typically, holes are
spaced at 5-ft (1.5-m) intervals.

17. ROUTING AND
SEALING
 The procedure consists of
preparing a groove at the surface
ranging in depth, typically, from
1/4 to 1 in. (6 to 25 mm). A
concrete saw, hand tools or
pneumatic tools may be used. The
groove is then cleaned by air
blasting, sandblasting, or water
blasting, and dried. A sealant is
placed into the dry groove and
allowed to cure. A bond breaker
may be provided at the bottom of

18. How to refill crack

19. 

20. CRACK IN BEAMS


21. Pre-stressing steel
 Post-tensioning 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 .
This technique uses pre stressing
strands or bars to apply a
compressive force. Adequate
anchorage must be provided for the
pre stressing steel, and care is
needed so that the problem will
not merely migrate to another part

22. 

23. Slab failre due to improper
treatment and rain water
de[position

24. CRACKS IN SLABS
 CAUSES
 DUE TO THE IMPROPER MAINTANENCE OF
CURING
 DUE TO SALTS THAT CORRODE THE
STEEL IN SLAB
PREVENTION
Adding joints maybe necessary
to reduce further slab
cracking if the joints are
omited in the original

25. CRACKS IN COLUMNS

26. REASONS
 MANY OF THE TIMES IT BECOMES
NECESSARY TO INTRODUCE RCC COLUMNS
IN A LOAD BEARING WALLS FOR
SUPPORTING HEAVIER LOADS WITH
PASSAGE OF TIME.
 RCC COLUMS UNDERGO SOME SHORTENING
DUE TO ELASTIC DEFORMATION AND
CREEP RESULTING IN VERTICAL
CRACKS.
 THESE CAN BE APPEARED AT THE
JUNCTION OF COLUMN WITH MASONRY

27. PREVENTION
 These types of cracks can be
prevented by ensuring adequate
curing of R.C.C columns and by
providing air gap between the
masonry and column.
 Besides this a groove in the
plaster at the joints between the
column and the masonry also helps
in restricting crack within the
groove.

28. Brick wall cracks.
 These are the some of the reasons
for the brick wall cracks.
Cold weather.
Bad foundation.
Too much weight.
Structural problem.
Too much moisture.

29. Preventative steps
Remove protrusions or loose
debris.
Tape holes and cracks.
Fill voids and cover tape.
Smooth the area.
Finish the area.

30. Cracks in walls.

31. CRACKS ABOVE WINDOWS AND
DOOR OPENINGS
 These are common structural
defects that show signs of
movement which will need to be
rectified
 Diagonal stepped cracking often
indicates that the lintel and
supports the masonry above the
openings has failed
 Lintel failure often occurs upon
the removal of hard wood windows
that are originally designed to
bear a substantial load with out
distorting and are replaced with

32.  Prevention
 Lintels can now be repaired using the
twist fix helical system by using
their bed joint reinforcement
which is effectively creates a new
lintel within the existing masonry by
removing the mortar within two bed
joints above the lintel and inserting
helical rods composed in grout to
create a load bearing lintel which
spreads the structural loads across
the length of bars preventing further
sagging of a lintel with the
patented twist fix 9mm CD helical tie

33. Cracks above arches


34. Window seal level crack