Wire
All wire used for making the gabions and for tying during the construction of the gabions shall comply with the requirements of BS 1052 for mild-steel wire.
PVC-coated Wire
Where gabions with PVC-coated wire are specified, the wire used for gabion mesh and for tying the gabions during their construction shall be galvanized wire as specified in Clause 6.2.2.2 (d) supplied with an extruded polyvinyl chloride coating (PVC coating). The average thickness of the PVC coating shall be not less than 0.55 mm, and the minimum thickness of the coating shall be 0.4 mm. It shall also be resistant to the harmful effect of normal weather and to being exposed to salt water.
Galvanizing
All wire used in the making of gabions shall be galvanized in accordance with the provisions of the agreed standards. The minimum mass per unit area of the zinc coating shall be in accordance with the figures
The adhesion of the zinc coating to the wire shall be such that, when the wire is wrapped six turns around a mandrel of four times the diameter of the wire, it shall neither flake nor crack to such an extent that any zinc can be removed by rubbing the wire with bare fingers.
Wire Mesh
Wire mesh shall be hexagonally woven mesh in which the joints are formed by each pair of wire being twisted through three half-turns. The tightness of the twists shall be such that a force of not less than 1.7 kN is required for pulling on one wire in order to separate it from the other wire, provided that both wires are prevented from turning and the applied forces and the wire are all kept in the same plane.
Filter Fabric Below Gabions
Where indicated on the Drawings or ordered by the Engineer, one layer of filter fabric of at least 200 g/m2 shall be placed on the prepared surface prior to the gabions being placed. The material shall be placed, in accordance with the instructions, in strips with a minimum overlap of 300 mm at the joints, and shall be properly fastened to prevent any movement or slipping while the gabions are being placed.