Trimming Reinforcement

Summary

Trimming Reinforcement - Whilst trimming reinforcement doesn’t increase the structural capacity of the concrete, it can help to mitigate cracking near a re-entrant corner. It prevents the cracks opening far enough that they would become a problem and it stops them propagating further into the slab.

Technical Information

Whilst trimming reinforcement doesn’t increase the structural capacity of the concrete, it can help to mitigate cracking near a re-entrant corner. It prevents the cracks opening far enough that they would become a problem and it stops them propagating further into the slab.
According to Technical Report 34, the bars should be placed at 45° to the corner and at least 300mm2 of reinforcement should be provided within a 0.5m zone adjacent to the corner.

It must be installed near the surface of the slab as that is where control of the cracks is most important. In the past, it has been common practice to simply push the trimming reinforcement down through the surface of the concrete after it has been placed. However, it is best practice to support the trimming reinforcement using spacers and cast the concrete around it.

If concrete cover is not controlled, it renders the trimming reinforcement redundant and cracking will not be controlled.