This technical seminar provides basic information about the various types of cracks in concrete and their potential effect on the long-term performance of concrete structures.

2. Simple answer is…
…
…
“Cracks can be treated as Cancer in R.C.
Structures”

3.  Various types of cracks;
 Their causes; and
 Their effect on long-term performance of
structure.

4. Structural crack Non structural crack
Improper design
Faulty construction
Overloading
Internal induced stress
in building material

5. Type Width
Thin
Medium
Wide
< 1 mm
1-2 mm
> 2 mm

6. A. FLEXURAL CRACKS:
when tension exceeds tensile strength of
concrete(@ soffit), a transverse or flexural
crack is formed.

7.  Acc. to ASCC
“R.C Structures normally crack when carrying
service loads”

8.  Better described as “Diagonal Tension
Cracks”
 occur because of comb. effect of bending
and shear due to structural loading.
 Generally Beams and Columns are prone to
such type of cracking.

9. • OCCURS DUE TO SHEAR STEEL DEFICIENCY
• OCCURS IN MAXIMUM SHEAR REGION

10.  Pre-hardening Cracks;
 In Hardened concrete; and
 Due to Chemical effects.

11. a. Moisture changes;
b. Thermal variations;
c. Elastic deformations;
d. Creep;
e. Chemical reaction;
f. Foundation movement;
g. Settlement of soil; and
h. Vegetation.

12.  Upward movement of water when
concrete settle downs

14.  Concrete surface loses water faster than the
bleeding action brings it to top
 Quick drying of concrete at the surface results
in shrinkage
 Concrete at the plastic state can not resist
tension
 Shallow cracks of 5 to 10 cm, width 3 mm @
surface
 Once developed difficult to rectify
 If not minimized initially , can be severe due to

15.  Moisture the sub grade and form work
 Erect the temporary wind breaker
 Erect the temporary roof to protect green
concrete from hot sun
 Reduce the time between placing & finishing
 In case of delay in finishing cover the
concrete with polythene

17.  If concrete is free to settle uniformly, no
crack occurs
 Due to excessive bleeding
 Obstruction to uniform settlement creates
voids/cracks
(Reinforcement/Aggregate/Formwork)
 Settlement crack (common in deep beam)

19.  Pouring of concrete in layers with proper
compaction
 Concrete Vibration (and Re-vibration, if
possible)
 An increase in concrete cover

20.  Movement of concrete during stiffening of
concrete
 Can’t support self wt. ,until it gains enough
strength.
 Don’t remove formwork until concrete gains
sufficient strength.

21.  Surface has more water cont. than interior
concrete.
 Due to use of wet concrete (high w/c )
 Inadequate curing
 Series of shallow, closely spaced, fine
cracks.

22.  Due to reduce in volume as a result of
moisture losses into the atmosphere in its
hardened state.
 Sufficient restraint produces tensile stresses,
and this leads to crack development.
 Generally appear after several weeks or
even months after casting

23.  Increasing amount of agg’s (particularly
coarse agg’s)
 Reducing total water content
 Adequately and correctly positioned steel
reinforcement

24.  Usually in case of high quality special class
concrete
 Due to temp. rise from heat of hydration of
the cementitious material
 Appear b/w 1day and 2 weeks after casting.

25.  Due to chemical reaction b/w alkali
hydroxide in concrete and reactive
aggregates
 Causes map cracking
 These may eventually result in complete
deterioration of structure.

26.  Cracks due to Corrosion of Steel
Reinforcement
• Shallow cover, usually seen at corners of
beams & columns with signs of rust
• Avoided by using coated reinf.

28. 1. Resin Injection (epoxy polymer)
2. Routing and Sealing (joint sealant)
3. Gravity Feed (low viscosity resins)
4. Coating over cracks, etc.

29.  Cracking of concrete structures can never be
totally eliminated, but the practitioners
should be aware of causes, evaluation
techniques and the methods of repair.
Thank you..