CORROSION- DAMAGED RC COLUMNS REPAIRED BY CFRP SHEETS

1. CORROSION- DAMAGED RC
COLUMNS REPAIRED BY CFRP
SHEETS
Er. B.D.KANWADE
B.E. Civil, M.E. Structure
.

2. INTRODUCTION
■ Premature failure of RC structure due to
corrosion of steel reinforcement is a significant
problem.
■ Removing the corrosion damaged concrete
covers causes load redistribution and the
exposed steel reinforcement may buckle and
loose its capacity.
■ Thus we provide CFRP sheets for repair.

3. Causes of corrosion
■ Reactivity of metal
■ Presence of impurities
■ Presence of air, moisture, gases like SO2 and
CO2
■ Presence of electrolytes

4. Damages because of corrosion

5. Damages because of corrosion

6. Failure mode analysis
■ The failure of all the repaired samples was due
to the tensile failure of the FRP layers.
■ The failure initiated from about one-eighth to
the middle along the height of the columns.
■ Once the crack was initiated, it propagated
along the axial direction towards the ends of
the sample.

7. Materials used in repairs
■ Polymer modified concrete
■ Fibre reinforced plastic
■ Epoxy resins
■ Polymer based material
■ High performance cement
■ Fibre reinforced polymer of tubes or
pile/column
■ Epoxide resin latex

8. Repairs of damaged RC column

9. Repairs of damaged RC column
■ For the epoxy resin and the UV curing resin,
the wet lay-up technique was used. This
technique started with applying a layer of resin
(about 300 g/m2 for epoxy and about 200 g/m2
for UV curing resin) to the surface of the
concrete column.

10. Steps for CFRP sheets wrapping
■ Removing plaster, loose concrete, clean the
surface
■ Applying epoxy primer surface concavity
■ Applying saturant epoxy
■ stretch unidirectional E-glass fibre cloth
b-directional E-glass + Aramide fibers over the
surface

11. Properties of CFRP
■ CFRP – Carbon Fibre Reinforced Polymer
■ High strength,
■ Resistant to chemicals,
■ Good fatigue strength,
■ Non magnetic,
■ Non corrosive,
■ Non conductive.

12. Cost/Benefit analysis
■ the heat activated curing prepreg and the UV
curing resin would become even more
economically desirable
■ prepreg repaired samples showed the
maximum strength and stiffness, UV curing
resin is a more preferable choice.

13. Case study
■ Retrofitting of earthquake damaged building at
GUJRAT:
■ The Bhuj 2001 earthquake provide eye opening
information on state of construction practice
followed in India. It is notified that majority of
building in India are not design as per I.S. code
practice; especially for seismic design and are
highly vulnerable to strong seismic ground
motion. In this case study we have taken some of
columns 11 floor of manasi Apartment.

14. CFRP using technique

15. Disadvantages
■ Lack of codes of practice and design standards.
■ Limitation in application to certain geometrical
shapes.
■ Necessity of personal skilled in polymer.
■ Fire and ultraviolet (UV) radiation protection
required.

16. Conclusion
■ CFRP is the most important technique in the
structure like beams and columns.
■ Because of CFRP life of structure is increase.
■ Proper use of I.S. code is important.