CRACKS IN BUILDINGS
For cracks occur in building when the building or its
components subjected to external forces higher than those which can withstand. Also
cracks appear low quality construction materials used in structure and improper
construction techniques etc
Cracks can be divide into following
1. Structural cracks
2. Non structural cracks
STRUCTURAL CRACKS
NON STRUCTURAL CRACKS
non structural cracks
may occur due to some variations like temperature variations moisture
variations and the effect of gases ad liquid cam cause internal forces
developed in the building this force can make cracks non structural cracks is
easily recoverable and remedial measures are taken to prevent they re occur
Non structural cracks classified as horizontal cracks
vertical cracks , diagonal cracks and irregular cracks
HORIZONTAL CRACKS IN MASONRY AND PLASTER
For load bearing wall the roof slab is to be expensed in day
time due to heat of sun and alternative contraction in knight time this process
can make pushing out the top coarse of masonry and its cause horizontal cracks
in masonry structure.
PREVENTION METHOD
Causes of cracks due to temperature variation can be
minimized providing expansion and contraction joints in specified locations.
Painting top or roof with reflective finish can minimize
cracks
VERTICAL CRACKS
If the building has large openings in the external walls it
can be seen that portion of wall immediately below the sill is subjected to
much lesser loads as compared to the portion of the wall on either side of the
window openings this results in uneven loading of the wall which may cause
vertical cracks .
TRANSVERSE CRACKS
Continuous structure like sunshade, long open verandah slab
can expansion in day time due to heat of sun alternatively contraction in
knight time it will cause transverse cracks
CRACKS IN CONCRETE
There are six type of cracks appear in concrete. They are
follow as
1.thermal contraction
cracks
2.structural cracks
3.sulphate attack cracks
4.alkali aggregate reaction cracks
5.shrinkage cracks
6. Plastic cracks
THERMAL CONTRACTION
CRACKS
For horizontal cracks near window ,sunshade and sill level
due to pull exerted on the wall by roof slab. Because expansion of slab in day time and shrinkage in knight
time due to climatic condition changing . This pull result in bending of wall
which cause crack in weak section that is at the near of sunshade and large
span rooms.
STRUCTURAL CRACKS
Cracks occur where the applied forces on the members are
greater than what they could withstand the imbalance in the load causes serious
strains in the structural and ultimately the sign of distress appear as cracks
.
SULPHATE ATTACK CRACKS
Sulphate attack on cement i concrete and mortar of masonry
in foundation and plinth would weaken these components and in course o time
cause unequal settlement of foundation and cracks in the super structure if
brick aggregates used in base concrete of flooring contains too much of soluble
sulphates and water table is high so as to make it in damp condition the base
concrete will swell and cause cracking for the concrete floor.
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