The document discusses different methods for repairing concrete members: grouting, guniting/shotcreting, epoxy injection, and jacketing. Grouting involves placing cementitious materials into cavities using pressure to fill voids and increase load capacity. Guniting uses a cement-sand mixture applied pneumatically to restore damaged surfaces. Epoxy injection establishes entry points to inject epoxy under pressure into cracks. Jacketing increases member size and stiffness by adding new concrete to encase the existing member, improving load capacity through composite action.

1. REPAIR OF
CONCRETE MEMBERS
Gohel Prithviraj K.

2. What is repair?What is repair?
The main purpose of repair is to bring back the architectural shape of the
building so that all services start working and the functioning of building is
resumed quickly.
◦The repairing of concrete members done by following methods:
1. Grouting
2. Guniting or Shotcrete
3. Epoxy injection
4. Jacketing

3. Grouting
Topic – 1

4. What is Grouting?What is Grouting?
◦ Grouting is the process of placing a material into cavities in concrete or masonry
structure for the purpose of increasing the load bearing capacity of a structure,
restoring the monolithic nature of a structural member, filling voids around pre
cast connections steel base plates, providing fire stops, stopping leakages, placing
adhesives and soil stabilization.
◦ Grout is a mixture of water, cement and optional material like sand, water
reducing admixtures, expansion agents and pozzolans. The water to cement ratio
is around 0.5. Fine sand is used to avoid segregation.

6. Procedure of groutingProcedure of grouting
◦ A 1:2 cement-sand grout with a water-cement ratio between 0.6 and 0.8 is
prepared using a mechanical mixer.
◦ The mixture is then sent down under pressure (of about 120kg/cm²) through a
30-50 mm diameter pipe terminating into steel cages.
◦ As the grouting proceeds the pipe is raised gradually upto a height of not more
than 60 cm above its starting level after which it is withdrawn and placed into the
next cage for further grouting by the same procedure.
◦ After grouting the whole area for a height of about 60 cm , the same operation is
repeated, if necessary , for the next layer of 60cm and so on.

7. Grout mixer:

8. Guniting
Topic – 2

9. What is Guniting?What is Guniting?
◦ Gunite is also known as shotcrete or pneumatically applied mortar.
◦ It can be used on vertical and overhead, as well as on horizontal surfaces and is
particularly useful for restoring surfaces spalled due to corrosion of reinforcement
.
◦ Gunite is a mixture of Portland cement, sand and water, shot into the place by
compressed air .
◦ The gunite is a mixture of cement and sand, the usual proportion being 1:3. A
cement gun is used to deposit this mixture on the concrete surface under a
pressure of about 20 to 30 N/cm2
.

10. Conti….Conti….
◦ Guniting is extensively used to rehabilitate concrete bridges, dams, spillways,
buildings, marine structures, swimming pool, tanks, etc.
◦ There are two different methods of spraying:
◦ Dry process spraying
◦ Wet process spraying

11. Gunite Mixer:Gunite Mixer:

12. Use of guniting:Use of guniting:

13. Use of guniting:

14. A well furnished guniting:A well furnished guniting:

15. Epoxy injection
Topic – 3

16. Epoxy-Injection:Epoxy-Injection:
◦ Epoxy compounds are having very good compressive, tensile and bond strength. They
can be used for preparing repair mortars but if used as a bonding/binding material for
concrete, the cost is prohibitic.
◦ Due to bad temperature compatibility, they can not be used on concrete specially for
external application. The use of epoxies on wet structures require special grade of
epoxies, which are much costlier than the normal epoxy compounds.
◦ The technique generally consists of establishing entry and venting ports and close
intervals along the cracks, sealing the crack on exposed surfaces, and injecting the epoxy
under pressure.
◦ Epoxy injection has been successfully used in the repair of cracks in buildings, bridges,
dam and other types of concrete structures.

18. Jacketing
Topic – 4

19. Concept of Jacketing:Concept of Jacketing:
◦ Jacketing of RCC members increase its size significantly. This has advantage of increasing
the member stuffiness and is useful where deformations are to be controlled.
◦ Jacketing of slender RCC column in a building provides a better solution for avoiding
buckling problems.
◦ Design for strengthening is based on composite action between the old and new work.
◦ As the new jacket is to behave compositely with the parent member, the new jacket can
take additional load only with the increase in the stresses and strains in the old concrete.
◦ Jacketing is done to improve the load carrying capacity of the member.

21. Thank You.....