Selvedge Wire

The selvedge wire acts as the structural frame for woven gabion and Reno mattress units. Mechanically integrated into the mesh during the weaving process, it forms the longitudinal edges of the mesh sheet. Its primary function is to provide edge rigidity, preventing the mesh from “necking down” or unraveling under tension.

In civil engineering applications, the selvedge wire is the critical anchor point for connection. When adjacent gabion units are laced together or fastened with spacing rings, the connection force is applied directly to this wire. Adherence to ISO and ASTM standards ensures that the selvedge wire possesses sufficient tensile capacity to withstand the bursting forces exerted by the stone fill and external hydrostatic pressures without deformation.

Technical Principles

The mechanical superiority of the selvedge wire is derived from increased diameter and continuous integration. Unlike welded mesh where edges may be trimmed or welded post-production (creating potential corrosion points), woven selvedge wire is continuous with the mesh production.

• Dimensional Requirement: To maintain structural integrity, the selvedge wire must have a larger diameter than the body mesh wire. ASTM A975 and EN 10223-3 dictate that the selvedge wire must be of a heavier gauge to accommodate the stress concentrations at the panel edges.
• Tensile Strength: The wire typically utilizes low-carbon steel with a tensile strength between 350 and 500 MPa, allowing for flexibility without fracture.
• Coating Continuity: Because the selvedge is woven, not welded, the corrosion-resistant coating (Zinc-Aluminum/Galfan or PVC/Polymer) remains unbroken. This prevents the “edge effect” corrosion often seen in lower-grade welded wire mesh products.

Standard Wire Diameter Combinations (ASTM A975 / EN 10223-3)

Specification Notes (Advisor Note)

Advisor Note: Avoiding Structural Connection Failures

A common failure point in gabion retaining walls arises from underspecified edge wires. To reduce raw material costs, some manufacturers may supply mesh where the selvedge wire is the same diameter as the mesh wire (e.g., using 2.7mm for both).

Why this fails:
When the selvedge wire lacks the required additional thickness, it cannot sustain the point-load stresses applied by pneumatic lacing tools (hog rings) or helical binders. This leads to edge deformation, bulging faces, and potential connection rupture during the stone-filling process.

How to specify:
To ensure project compliance and longevity, include the following in your technical specifications:

1. Mandatory Diameter Differential: “The selvedge wire diameter must be strictly greater than the mesh wire diameter, adhering to ASTM A975 Table 1 standards.”
2. Verification: “Material Test Certificates (MTC) must clearly list the selvedge wire diameter separately from the mesh wire diameter for verification prior to shipment.”