Reinforcement in existing concrete

1. the only reinforcement in the existing reinforced slab is within the upper 90 mm (measured to the top of the reinforcement from the top of the slab), and
2. the reinforcement is a mesh with a diameter of 12 mm or less and the distance between bar centres is 210 mm or less; and
3. the trench length to width ratio is below 3:2, i.e. length is greater than 1.5 times the width.

Tie ins

1. the only reinforcement in the existing reinforced slab is within the upper 90 mm (measured to the top of the reinforcement from the top of the slab), and
2. the reinforcement is a mesh with a diameter of 12 mm or less and the distance between bar centres is 210 mm or less.

1. The new reinforcement must be lapped and connected to the existing reinforcement. Reliable methods of connecting the bars include tied splices, mechanical fastening and welded splices.
2. A minimum of 150 mm of the existing reinforcement must be exposed to allow adequate connection of the new reinforcement.
3. Where 150 mm of the exposed reinforcement cannot be preserved during the excavation, the concrete road slab must be trimmed as necessary to expose additional reinforcement. This additional trimming does not supersede any requirement to provide dowel bars.
4. Where additional trimming extends beyond 300 mm and the reinforcement cannot be preserved, then the new reinforcement is not required to be connected or lapped.
5. For narrow trenches and small openings, the cut section of concrete may need to be widened to accommodate tie ins.