There tends to be a misconception that welded wire reinforcement is comprised of very small diameter wires that are only suitable for use in nominal “mesh” applications like lightly-loaded slabs-on-ground. While light gauge material is of course readily available for non-structural applications, structural WWR with deformed wire sizes up to 5/8” diameter (equal to a #5 rebar) is frequently used in large scale bridge and building projects, with applications such as girders and beams, walls, elevated slabs, barriers, box culverts, and foundations all benefiting from the product’s implementation.
5 Myths of Welded Wire Reinforcement
1. WWR wires are too small and flexible for structural applications.
2. WWR is only good for shrinkage & temperature effects
Structural WWR is commonly produced and delivered in large wire sizes as noted previously, and this material is broadly accepted throughout AASHTO and ACI Standards for use in structural members and elements to resist axial, shear, flexural, and torsional effects.
3. WWR is made up of wire material, and wire is weaker than rebar
The wire connotation continues to be a source of tremendous confusion. The wire used in WWR is simply a bar-like product that is born from hot-rolled carbon steel rod, then cold-worked to achieve a finished diameter. WWR material exhibits yield strengths up to 80 ksi and is commonly produced using wires with deformed surfaces that are comparable to those characteristic of rebar.
4. Deformations on wire used in WWR can’t be relied upon for bond and anchorage in concrete
Wire deformations must strictly conform to geometries established in ASTM A1064, and in doing so achieve bond and anchorage requirements that facilitate the use of identical design equations to those used for rebar in the calculation of tension development lengths and tension lap splices. In fact, both ACI and AASHTO include provisions whereby, in calculations for development length and lap splice, the welded intersections on a deformed WWR mat can be ignored entirely in favor of the deformed wire surfaces.
5. WWR is only available in standardized mat shapes and sizes
Modern WWR welding machines are capable of producing “engineered” mats with variable wire sizes, spaces, and lengths, and this customization is commonly undertaken on projects with material quantities and/or potential for placement time and labor savings.
The Benefits of WWR
Strong: WWR is available in yield strengths up to 80 ksi
Fits Exact Size: Wires can be welded in various sizes and spacings,and pre-bent to suit
Versatile: WWR can be used in a variety of industries
Wires in Position: Welding into a mat makes sure wires stay in place
What is Welded Wire Reinforcement
As defined by ASTM A1064, welded wire reinforcement is a material composed of cold-worked steel wire with indented or raised rib deformations. The wire itself is colddrawn or cold-rolled from hot-rolled steel rod. The cold-working process includes reducing, deforming, and straightening. With final wire diameters produced, the wires are then automatically assembled and machine-welded to form mat-type structural reinforcement for concrete.
Welded wire reinforcement, historically called wire fabric, is produced in sheets and rolls, and is mainly used by the precast and cast-in-place concrete industries. Compared to standard methods of placing loose, individual pieces of steel reinforcing, welded wire reinforcement is an efficient, economical, and viable option for concrete reinforcement.
