Mesh now available for reinforcing concrete slabs-on-ground

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Grade 500E reinforcing mesh, specified in the Department of Building and Housing’s latest version of Acceptable Solution B1/AS1 for the reinforcement of concrete slabs-on-ground, is now widely available.

Designers should be now specifying Grade 500E reinforcing mesh when designing to B1/AS1.
B1/AS1 now requires that concrete slabs-on-ground, constructed to NZS 3604:2011 on good ground, be reinforced with a minimum of 2.27 kg/sq m of Grade 500E reinforcing mesh. The mesh must conform to AS/NZS 4671.

The change to require a minimum of Grade 500E mesh was made because of the poor ductile performance of reinforcing mesh in the Canterbury earthquake sequence.
Grade 500E reinforcing mesh allows better ductile performance to reduce damage during earthquake shaking and ground movement.
As Grade 500E reinforcing mesh was not initially available, the Department issued two satisfactory solutions of equivalent capacity. One was based on a lower-strength ductile reinforcing mesh, and the other on lower Grade (300E) ductile reinforcing bars.

Since then, the Department has worked with the industry to ensure Grade 500E reinforcing mesh is available. In particular, the Department liaised with Pacific Steel Ltd, which manufactures the wire for the mesh, and members of the Welded Wire Reinforcing Market Development Alliance (WWRMDA), which manufactures the mesh.
Grade 500E reinforcing mesh is now widely available, and designers who follow Acceptable Solution B1/AS1 should be specifying it.

However, the Department’s guidance (www.dbh.govt.nz/earthquake-concrete-slabs-guidance) still offers the alternatives above if needed.

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