Structural rehabilitation of columns with reinforced concrete jacketing
Repairing of an RC member is an attempt to restore it is original strength and stiffness after being deteriorated or damaged due to different reasons, column jacket is one of these methods used to restore structural member strength, also it can be used to increase the member strength for certain events, the column jacketing can be used during constriction and service life due to different reasons, during construction the need for jacketing may arise due to design errors, poor workmanship, and deficient concrete production. Earthquake, change in structure functionality and accidents such as fire, collisions, explosions these are potential reasons during the service life of the structure.
Step of jacketing of RC column:
- Mechanical jacks and props should be used if required to reduce the loads temporarily on members undergoing the repairing process. if the purpose of jacketing is to resist additional load aside from load resisted by column then shoring and supporting of the structure may not be required.
- column reinforcement should be checked, if it is found corroded then the concrete cover should be removed and this steel should be cleaned properly using a wire brush or by sandblasting, after completion of removing steel rust, the reinforcement shall be coated properly to protect it against corrosion.
- holes shall be drilled to receive steel connector, spacing and depth of these holes shall be as per approved drawing, then holes should be clean properly by blowing air to remove all dust and other materials, then fill the holes with appropriate epoxy and insert the steel connector.
- vertical steel dowels should be add in column foundation and slab, adding of steel dowels is similar to adding steel connector
- vertical bar shall be installed and overlapped with vertical dowels, also stirrups should be added, spacing and diameter should be as per drawing.
- column surface shall be painted with a bonding agent to ensure good bonding between old and new concrete.
- then concrete shall be poured after installing shutters, concrete shall be non-shrinkable and consisting of small aggregates, normally aggregate size will be 2 mm maximum due to lack of space.