Wire Mesh Services & Benefits
Looking to make your concrete projects more durable, more cost-effective with a quicker install and turn around? Look no further. Check out how reinforced wire mesh strengthens concrete and almost eliminates cracks!
ASTM A1064 defines welded wire reinforcement (WWR) as “a material composed of cold-worked steel wire with indented or raised rib deformations. The wire itself is cold-drawn 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.”
What is Wire Mesh
Also called reinforced wire mesh, welded wire mesh, welded wire reinforcement, wire mesh is easy to handle, move, lay in concrete, holds its shape, even when concrete is poured on top, and is a popular building material to reinforce roads and concrete structures. Available in a variety of sizes, strengths, and applications.
Known as an extremely strong, durable material, concrete’s strength lies in compression, but it doesn’t have a lot of tensile strength (the breaking or cracking point). However, steel has incredible tensile strength. Combining concrete with welded wire mesh creates an exceptionally strong construction material--reinforced concrete.
Why Use Wire Mesh
And while concrete shrinking or cracking can’t be totally avoided, using welded wire mesh in combination with proper concrete placing and finishing techniques, helps control where the cracks may happen and to what extent, as well as holding the concrete together, should cracks or shrinking happen. Plus, the welded wire mesh evenly distributes structural weight throughout.
Wire mesh is easily handled, quickly installed, stays in position when placed which means reduced labor hours, installation, and overall project costs. Contractors may be able to complete more jobs quickly, at competitive cost savings, while increasing structural capabilities when using reinforced concrete wire mesh.
Reinforced Wire Mesh Advantages:
• 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
Individual wire size designations, plain and deformed, are based on the cross-sectional area of a given wire. Gage numbers were used exclusively for many years until 1970. At this time, the industry changed over to a letter/number combination which uses the prefixes “W” and “D” in combination with a number. The letter “W” designates a plain wire, and the letter “D” denotes a deformed wire. The number following the letter gives the cross-sectional area in hundredths of a square inch.
Wire Size Designation
Reference the chart below for additional information on Wire Mesh Style Designations.
Wire Mesh Style Designation
*Exact W-number size for 8 gauge is W2.1
**Exact W-number size for 2 gauge is W5.4
Reinforced wire mesh offers many advantages, but you can only receive them when you properly install supports. Absent or improperly installed supports can be at fault for an under-performing slab-on-grade. Before placing concrete, be sure to install welded wire mesh supports as specified by the design professional. Properly spaced supports are crucial as they hold the reinforced wire mesh in place while the concrete is placed.
Installation Best Practices
When selecting supports, consider:
• size and weight of wire mesh
• base stiffness and strength
• position of reinforced wire mesh and number of layers
• concrete compatibility
• concrete construction process
There are a variety of commercial supports to choose from:
• Continuous support (used on firm subbase or mud mat)
• Slab bolster (one layer of reinforcement)
• Wire block (generally used on sloping grade)
• All plastic high chair (typically used with more stable base materials, such as compacted granular base)
• High chair with base plate (used with soft base materials, such as loose sand)
• Plain concrete block
• All plastic support (two layers)
Once supports have been selected, it is crucial to space supports appropriately to properly position the mesh so it remains in place during the construction process and achieves the amount of reinforcement required. Generally, vibration of the concrete is specified to obtain adequate consolidation. This helps encase the supports which in turn prevents voids.
Avoid “hooking” which is when the wire mesh reinforcement is placed on a slab surface and then pulled up and “walking-in" which is placing the wire mesh on top of a freshly placed concrete slab, then pressing the wire mesh into the concrete. Both of these methods are not recommended because the placement of the wire mesh is approximate causing issues during inspection.
Refer to the design to properly position the wire reinforcement. Here are a couple factors to consider in placement:
Welded Wire Reinforcement Placement
• One layer: locate above or at mid-depth of the slab. It may be required by architect or engineer to be 2” below top slab surface but never below mid-depth. Placement must always be low enough to not interfere with saw cutting.
• Two layers: upper layer should be placed at least 1” below the top slab surface. The lower layer, if the slab is on a well-constructed graded, compacted and porous base, must clear cover of at least 1 ½” below steel. Additional cover is not needed unless building codes specify otherwise.
• Store in racks or supports strong enough to prevent bowing.
Storage Best Practices
• Keep elevated off the ground to avoid contact with dust, dirt, and oil which can cling to the surface, reducing the ability to bond with concrete.
• If possible, store indoor or under cover as protection from weather and temperature fluctuations to reduce oxidation.
• Epoxy-coated mesh is susceptible to degradation from ultraviolet rays. Always store indoors or under tarps.
With a high-load capacity and strength for concrete or earthen constructions, epoxy-coated products have several advantages over steel wire products; they resist corrosion, rust, chemical, abrasions, temperature, age, UV, and weather. This ensures a longer wire mesh life span.
Epoxy-Coated Welded Wire Reinforcement
Starting with a certified multi-step epoxy coating process, the wire mesh is cleaned with a steel grit shot blasting process. Then, the metal surface is tested for backside contamination, chlorides and profile (etched depth of the steel). After passing these pre-coating CRSI Epoxy Coating requirements, and within 180 minutes of blasting, the welded wire reinforcement is preheated before the certified epoxy coating is applied, and then the wire mesh is cured. Post inspecting, handling, storage, and delivery to the jobsite is then completed per the CRSI Certified Epoxy Coating Standards to ensure the durability and protection of the epoxy coated welded wire reinforcement.
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