prentation use sp25 as reference

1. SUBMITTED BY
TUFAIL UN NABI
ENROLL 2805

2. CONTENTS…
• INTRODUCTION
• CLASSIFICATION
• CAUSES OF CRACKS
• CONTROL OF CRACKING
• CONCLUSION

3. INTRODUCTION
3
Cracks in buildings are of common occurrence and are
developed whenever stress in the component exceeds its
strength. This stress may be caused by external forces such
as dead, live, wind, seismic loads and foundation settlement;
or may be induced internally due to thermal movements,
moisture changes, chemical actions, resulting in shrinkage or
expansion of the bricks, mortar, concrete or due to corrosion
of reinforcement etc. render the structure unsafe. The other
causes may be due to fault of structural design.

4. CLASSIFCATION OF CRACKS
# These result from incorrect
design, faulty construction
or overloading and these
may endanger the safety of
a building and their
habitants.
# These may endanger the
safety of a building.
STRUCTURAL CRAKS
# Occur mostly due to internally
induced stresses in building
materials.
# These cracks normally do not
endanger the safety but may
look unsightly, create an
impression of faulty work or
give a feeling of instability.
NON-STRUCTURAL CRAKS

5. CAUSES OF CRACKS
• Thermal variation
• Chemical reaction
• Moisture movement
• Elastic deformation
• Foundation movement & settlement of soil
• Vegetation

6. THERMAL MOVEMENTS
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• Refers to the expansion and contraction
caused due to temperature changes
• FACTORS AFFECTING
• Temperature variation
• Physical properties of the materials
• Dimensions
• Coefficient of thermal expansion
• CURE : insulation layer, color with
high reflecting characteristics,
using slip and expansion joints

7. LONG SPAN EFFECT IN LOAD
BEARING WALLS
 When a beam or slab of
large span undergoes
excessive deflection and
there is not much
vertical load above the
supports, ends of
beam/slab curl up
causing cracks in
supporting masonry;

8. LONG SPAN EFFECT IN FRAMED BUILDINGS

9. OPENINGS IN LAOD BEARING WALLS
portions of wall marked ‘A’ act
as pillars and are stressed
much more than the portions
marked ‘B’ below the windows.
Thus, as a result of differential
stress, vertical shear cracks
occur in the wall as shown
HEAVY LOADHEAVY LOAD

10. FOUNDATION MOVEMENT &
SETTLEMENT
10
• Shear cracks in buildings occur
when there is large differential -
settlement of foundation either
due to unequal bearing pressure
under different parts of the
structure
• shrinkable clays (also sometimes
called expansive soils) which
swell on absorbing moisture and
shrink on Drying as a result of
change in moisture content of the
soil, are extremely crack-prone
• Cracks that occur due to
foundation movement of a corner
on an end of a building are usually
diagonal

11. VEGETATION
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 Existence of vegetation, such
as fast growing trees in the
vicinity of compound walls can
sometimes cause cracks in
walls due to expansive action
of roots growing under the
foundation.
They also cause dehydration of
soil allowing soil to shrink thus
allowing settlement

12. SOME PRECAUTIONS
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 For shrinkage Indian Standard Code recommends a
minimum reinforcement of 0.25/0.20 percent in the horizontal
direction and 0.15/0 .12 in the vertical direction when using
plain/deformed bars

13. EXPOXY INJECTION

14. STITCHING
• Quick, simple, effective
and permanent.
• The grout combination
provides an excellent
bond within the substrate.
• Masonry remains flexible
enough to accommodate
natural building
movement.
• Non-disruptive structural
stabilization with no
additional stress

15. CONCLUSION…
This work concludes that though it is impossible to guarantee
against cracking yet attempts can be made to minimize
development of crack. And also, not all type of crack requires
same level of attention. The potential causes of crack can be
controlled if proper consideration is given to construction
material and technique to be used. In case of existing cracks,
after detail study and analysis of crack parameters, most
appropriate method of correction should be adopted for
effective and efficient repair of crack