The benefits of Jacketing and Collars for Concrete Structures
Jacketing is a process that is undertaken to repair the structural members. It's generally applied for columns while it is also utilized for other members like beam. Under this system, a jacket is arranged around the reinforcement and concrete is filled into the jacket. It raises the section of the member and as well as it's load bearing strength.
The purpose of Jacketing is to fortify weak RCC columns which are decayed over a period of time caused by harmful climatic conditions or poor maintenance.
Under this system, weak concrete as well as rusted rebars are fully eliminated. By arranging additional rebars, entire sectional area is extended to improve the compressive strength of columns. Additional rebars are arranged with stirrups and attached to old concrete with shear keys. Bond coat is provided on old concrete surface and polymer concrete is poured in form work.
Jacketing is provided from all sides or from three/two sides. It can also be provided from one side also.
Collars belong to jackets which encircle only for a part of a column or pier. These are normally used to give strong support to the slab or beam at the top of the column.
The form for the jacket comprises of timber, corrugated metal, precast concrete, rubber, fiberglass, or special fabric; and may be constant in some cases. The form should be supported with spacers to retain equivalent clearance among it and the existing member.
Materials, like traditional concrete and mortar, epoxy mortar, grout, and latex-modified mortar and concrete, are employed as encasement materials. For jacketing, the void among the form and the prevailing member is stuffed with pumping, tremie, or preplaced aggregate concrete.
Jacketing is mainly utilized for doing the repairing work of deteriorated columns, piers, and piles and easily be applied in underwater. The method is very effective for safeguarding the concrete, steel, and timber sections against further diminution and for strengthening.
Permanent forms should be used while providing protection against weathering, abrasion, and chemical pollution. The collar allows increased shear strength for the slab, and it reduces the effective length of the column.
Prior to apply jackets or collars, all decayed concrete should be eliminated, cracks should be patched, existing reinforcement must be cleansed, and surfaces should be developed. The surface preparation makes the bond better of the newly set materials with the prevailing structure, that is complicated for underwater repairs. For underwater conditions, a plastic shell should be used at the splash zone for the reduction of abrasion.
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