Straightening and rebending reinforcement
The requirement to bend or rebend reinforcement partly cast into concrete falls into two broad categories: planned situations and correcting errors. Practical guidance is given in Concrete Advice No. 03.
For planned situations (for example when a vertical member is cast and a slab is subsequently joined to the vertical face) the preferred solution is to use a properly designed proprietary continuity system for bar sizes up to 12 mm. These systems comprise pre-bent reinforcement housed in a carrier case. After the first section of concrete has reach sufficient strength, the bars are straightened using a special tool. Alternatively, cast-in couplers may be used. Couplers should be used for all bars larger that 16 mm.
When errors occur, it may be necessary to bend or rebend projecting bars. Small bars can be bent cold, taking care to avoid damage to the cover concrete, using a suitable tool. Alternatively bars can be heated to 800 or 900oC, but this is difficult to control and can cause damage to the concrete.
Further information may be found in Concrete Advice No. 03, Straightening and rebending reinforcement on site.