Repairs of Rc Works Due to Corrosion of Steel
There are many types of repairs and the most common repair is the repair of spalling due to corrosion of steel which is discussed further.
We come across a large number of cause where the steel reinforcements corrode due to various causes such as lack of cover,leakage of roof ,etc.As steel rust occupies very much large volume (nore than 10 times) than steel, the surrounding concrete cracks and trends to get separated from steel and finally it falls down.This is particularly important in the ceiling plaster under leaking roofs.If we notice any disturbance in this plaster,it dhould be repaired as soon as possible.There are many causes in which the ceiling plaster has fa;;en down suddenly.
The repair for such causes is carried out as follows:-
- Hammer test the area for loose areas and remove all loose particles of mortar ,concrete , rust,.etc.from the spalled surface and clean it with a wire brush.
- Apply two coats of polymer modified active corrosion inhibitor to the remaining steel.(If additional steel is required,tie the new steel to the old steel by binding wires)Two coats of chromate paint can also be a substitute.
- Apply one coat of polymer bonding agent (latex based) over the entire area of steel and concrete to be treated.
- Apply polymer modified 1:3 cement mortar over the reinforcement and provide necessary cover.Addition of superplasticizer to reduce water and the incorporation of fires will help to produce strong mortar.If the area is large, guniting with assistive for quick setting can be used for better efficiency of the work.
- Cure the concrete.
- Apply a coat of waterproofing slurry coating for protection against environment, it necessary.
See more Cracking in Concrete and Types
Ebook to read Reinforced Concrete Analysis and Design
Important Characteristics of Repairs of Rc Works
This type of cracks occurs near to the supports of the beam.Generally the cracks occur in 45 degree or diagonal in manner.It is a serious structural active crack.
Cases & Reasons
Shear capacity of the beam is inadequate.Cross-Section or stirrups are insufficient.
Provide lateral ties/stirrups with adequate nos and spacing.
Chip the concrete and place the new stirrups with required spacing and apply fresh concrete.After concrete gets harden apply epoxy and paste carbon fiber sheets.