Jacketing of concrete columns

1. JACKETING
Er. SHAIKH ARSHAD
VJTI MTECH CM

2. INTRODUCTION
• It is a part of retrofitting i.e. repair, renovation, strengthening.
• Retrofitting is the modification of existing structures to make
them more resistant.
• Jacketing is the most popularly used method for strengthening of
building columns.
• Jacketing consists of added concrete with longitudinal and
transverse reinforcement around the existing column.
• It improves axial and shear strength of column and major
strengthening of foundation may be avoided.

3. NECESSITY OF JACKETING
• The load carried by column is increased.
• When there is error in design.
• Deterioration of column due to weathering action.
• Dilapidation of column.
• Heavy damage due to other causes like earthquake, fire etc.

4. ADVANTAGES OF JACKETING
• It increases the seismic capacity of column.
• Amount of work is less as foundation strengthening does not
required.
• It increases the shear strength of column.
• It also increases confinement of concrete in circular columns.
• Steel jacketing does not increase significant weight of column and
also saves construction time (curing).

5. TYPES OF JACKETING
• Reinforced concrete jacketing
• Steel jacketing
• Fiber reinforced polymer composite jacket
• Jacket with high tension materials like carbon fiber, glass fiber
etc.

6. PROCEDURE OF RC JACKETING
• It can be employed as a repair
or strengthening scheme.
• First prepare the surface of
existing structural member.
• Provide shear key and
reinforcement around the
existing column.
• Bonding agent is applied over
prepared surface of existing
column and concrete is casted.

7. SHEAR KEY
• Drill holes of specified
diameter and depth to receive
shear key.
• Clean the drilled holes by
blowing air.
• Inject epoxy bonding paste in
drilled holes to fill it from
ends to half of the holes.
• Insert “L” shaped shear key
and allow epoxy to cure.

8. FUNCTIONS OF SHEAR KEY
• Bond properly new concrete and old concrete
• It holds the main reinforcement in position
• Treat a monolithic column
• Whole section is effective
• Resist shear failure
• Improve shear resistance
• Reduce the sliding effect between new and hollow column

9. REINFORCEMENT
• The longitudinal and
transverse reinforcement as
per design are fixed around
the existing column.
• Reinforcement is properly tied
with shear key using binding
wire.

11. REINFORCEMENT
JACKETING
REINFORCEMENT
AT KALPATRU
BUYER SITE
KOLSHETH ROAD
THANE WEST

12. BONDING AGENT
• It is needed to properly bond new concrete with old concrete.
• So a bonding agent should be applied to surface of old concrete
before casting of new concrete.
• Generally epoxy bonding paste is used as bonding agent.
• FUNCTIONS:
I. Bond properly new concret & old concrete
II. Treat a monolithic column
III. Whole section is effective

13. ADMIXTURE
• A hyper plasticizer admixture is used with new concrete to
increase the strength & workability.
• FUNCTIONS:
I. It creates the concrete flowable
II. Eliminates the difficulty of vibration
III. Increses the strength of new concrete

14. CASTING OF CONCRETE
• Formwork is installed around
the existing column and proper
support is provided to
withstand the newly poured
concrete.
• Finally concrete is poured and
curing is done.

16. STEEL JACKETING
• Addition of steel often applied
in the form of plates and
jackets.
• Main advantage is it does not
add significant weight to
structure in comparison with
concrete and also it saves
curing time.
• Disadvantage is it requires
heavy equipments to handle
and maintenance is more
difficult.

17. FRP JACKETING
• It is a fiber reinforced polymer composite jacket used for
strengthening.
• very effective for confinement & shear strengthening
• FRP composites present advantages over a traditional
confinement technique.
• The cross section dimension of column does not increase, which
permits compliance with architecture restraints.
• Due to light weight of FRP material, the installation procedure is
faster and easier.

18. FRP JACKETING

19. REFERENCES
• Ravishankar.K., Krishnamoorthy.T.S, " Structural Health Monitoring,
Repair and Rehabilitation of Concrete Structures", Allied
Publishers, 2004
• CPWD and Indian Buildings Congress, Hand book on Seismic
Retrofit of Buildings, Narosa Publishers, 2008.
• https://theconstructor.org/practical-guide/jacketing-collars-
structure-retrofit-repair-strengthening/5829/
• http://www.iitk.ac.in/nicee/wcee/article/11_504.PDF
• https://www.youtube.com/watch?v=B6Ubl5W9WVE

20. REFERENCES
• https://www.google.co.in/search?q=column+jacketing&dcr=0&sou
rce=lnms&tbm=isch&sa=X&ved=0ahUKEwiPtuDig7vWAhVCRY8KHYpo
AVYQ_AUICigB&biw=1280&bih=645#imgrc=NTZ47bWybVuUMM:
• https://www.youtube.com/watch?v=aXP4oNzi6YM
• http://www.iosrjournals.org/iosr-jmce/papers/Conf15010/Vol-
1/7.%2040-46.pdf

21. THANK YOU