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Technical Data Sheets |
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Gabions
SANS 1580:2005 (Figure 1 and Table
1). Gabions are filled with rock at the project site to fo
rm flexible, permeable, monolithic structures such as retaining walls, channel linings and weirs for
erosion control projects.
The steel wire used in the manufacture of the gabion is heavily
zinc coated Class A as per SANS
675:1997 (Table 2). If required,
a PVC coating is extruded over the galvanised wire to provide
added protection for use in aggressive environments such as
acidic soils and water, in salt water, in water carrying a high
abrasive sediment load or wher
ever the risk of corrosion is The tolerances of mesh and wire are shown in Tables 1 and
2.
In order to reinforce the structure, all mesh panel edges are
selvedged with a wire having a greater diameter than the mesh
wire. The gabion is divided into cells by means of diaphragms
positioned at approximately 1m centres (Figure 1). Dimensions
and sizes of galvanised and PVC coated gabions are shown in
Table 3. When specifying Gabions in the tender documents or bill
of quantities, please refer to Table 4.
Filling and Lacing
The Gabions must be filled with rock ranging between 100 mm and
250 mm. The range in sizes may allow for a variation of 5%
oversize and / or 5% undersize rock, provided it is not placed at
the exposed surface. In all cases, oversize rock shall not be larger
than 300 mm and the undersize rock shall not be smaller than 100
mm. Rocks shall be hard, angular toround, durable and of such quality that they shall not disintegrate on exposure to water or
weathering during the life of the structure. Care should be taken
when placing the stone to ensure that the PVC coating on gabions
is not damaged. All visible faces should be carefully hand placed
for appearance purposes. For further information on the installation
of gabions please refer to the Installation Guidelines for Gabions.
In place of lacing wire, lacing operations can be made by using a
Spenax tool (Figure 4) available from our offices together with
stainless steel rings (Figure 3A) having the following specifications:
diameter: 3mm -
tensile strength: 156-178 kg/mm2
Spacing of the rings or loops must not exceed that shown in
Figure 3B.
Wire
All tests on wire are performed prior to manufacturing the mesh.
1. Tensile strengthThe wire used for the manufacture of the gabions has a tensile strength between 350-575 N/mm2 according to SANS 675:1997.
2. Elongation Elongation is not less than 10% in accordance with
EN 10223-3. Tests are carried out on a sample at least 25 cm
long.
3. Adhesion of zinc The adhesion of the zinc coating to the wire is
such that, when the wire is wrapped six turns around a mandrel
having four times the diameter of the wire, it does not flake or
crack when rubbed with the bare fingers, in accordance with
SANS 675:1997.
4. Ductility The ductility of the zinc-coated wire is such that when
the wire is wrapped at least eight times around a wire having the
same diameter of the test specimen at a rate not exceeding
15 turns per minute and then unwrapped at the same rate, it
does not show any sign of fracture of the underlying steel wire in
accordance with SANS 675:1997. |
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