Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

Login

Register Now

Welded wire fabric is a series of parallel longitudinal wires welded to cross wires by electric fusion method with accurate spacing. The welding work is done by machinery which ensures the precise dimensions and results in considerable savings in time, labour and money.

Fig 1: Use of Welded Wire Fibre is embankment concreting.

In this article, we will study the general specification, advantages, uses and comparison of welded wire fibre concrete.

General Specification of Welded Wire Fibre Concrete

1. Material

The material used in manufacturing the wires for welded fibre is either stainless steel rebar rods or galvanized steel rods that have excellent resistance to corrosion and can be used in wet conditions.

The wires conform to IS:432-Pt II/1982 which specifies an ultimate tensile strength of 570 N/mm2 and a characteristic strength of 480 N/mm2.

2. Shape and Size

The commonly available shapes of the welded wire fibre are rectangle and square. The fabric can be manufactured for widths up to 3000mm with lengths limited by transportation considerations. When supplied in ready-to-lay flat sheet form the standard length is 5500mm. Otherwise, the fabric can be supplied in the rolled form in standard lengths of 15m,30m or 45m.

Wires used for the manufacture of fabric are generally manufactured in the range of 2mm to 12mm diameter. It is manufactured conforming to IS:1566-1982 with long and cross-wire spacings varying from 25mm to 400mm.

3. Cutting and Forming

Welded wire fabric can be easily cut with the help of wire cutters. If the mesh is to be laid in a staircase, it can be easily bent into the required size and laid down.

Fig 2: Welded Wire Fibre in floor slab.

4. Lapping and Clearance

As the wire fibres are available in any sizes required, lapping is not usually required, but in the case, if lapping is required, a minimum of 6 inches of lapping is recommended.

As a standard practice, 1 to 3 inches of clearance is given between the wire fabric and formwork.

5. Vibrating

Vibrating plastic concrete reinforced with welded fibre mesh is recommended in order to ensure the mix is distributed completely and the fabric is properly embedded all around to reduce the cracking.

Comparison between Welded Wire Fibre and Conventional Reinforcement

Welded Wire FabricConventional Reinforcement
Increased permeability.Reduction of permeability
Bond can deteriorate over timeBonds effectively with concrete permanently
No surface protection providedImproves surface durability
Minor resistance provided if properly placedImproves impact, shatter and abrasion resistance
Difficult to install and expensive – high labor costsEasy to use and cost effective – no labor costs
Difficult to place, especially if rolls – 1″ minimum cover requiredEasy to place in concrete mix – No minimum cover
No effect on finish, but difficult to maintain placement in slabEasy to finish with minor effect on workability of mix
Will deteriorate if not properly placed and protectedAlkali resistant
Will deteriorate if not properly placed and protectedAcid resistant
Corrodes when exposed to water and chemicalsCorrosion resistant
Increases tensile strength if properly placedIncreases tensile strength of plain non-reinforced concrete
Provides reinforcement in one planeProvides three dimensional reinforcement
Increases ductility if properly placedIncreases ductility
Permanent if visible with little remedy possibleNo lasting aesthetics and can be easily remedied if necessary
Meets ASTM specifications if placed properlyMeets or exceeds ASTM specifications
Storage difficult and detrimental if stored outsideCan be stored for long periods of time

Advantages of Welded Wire Fabric in Concrete

1. Higher Design Strength

The structural behaviour of welded wire fabric is the same as that of HYSD bars or plain mild steel bars. The higher strength is due to the characteristic strength of welded wires.

2. Better Bonding

The main factor responsible for the bonding of concrete is the peripheral surface area. The rigid mechanical interconnections by means of welds to cross-wires are primarily responsible for stress transfer from concrete to steel and vice-versa in the case of welded wire fabric.

Each of the rigid welds capable of resisting up to 210 N/mm2 ensure quick and complete stress transfer within 2 welded joints from the critical section.

3. Effective Crack Resistance

The two major properties of welded wire fibre which help in reduction of cracks in the concrete are the strong mechanical anchorage of the welds at each intersection and the close spacing of thinner wires.

The close spacing of wires serves as most effective in countering the non-load phenomena or strain induced stresses due to shrinkage and temperature changes. This property of the welded wire fibre preserves the structural integrity of the slab.

4. Economical

The most obvious and clinching advantage in the use of welded wire fabric is the immediate and positive savings in labour and time. There is no cutting of bars, no marking and spacing them out, and above all no laborious tying of binding wires.

5. Flexible in Handing and Placing

The usage of thinner wires lends the fabric as extremely flexible in handling. Coupled with the availability in long lengths in roll form, welded wire fabric provides the ideal and convenient solution for all kinds of repair work by Re-plastering or Guniting.

Uses of Welded Wire Fabric in Concrete

  1. Structural flat slabs or in slabs with beam slab construction.
  2. Large area floor slabs on ground, pavements, airport runways, aprons etc to achieve crack-free joint fewer surfaces.
  3. Concrete elements of curved or difficult shapes such as arches, domes, lotus petals etc. where the flexibility of welded wire fabric and its ready to use nature aids all the way.
  4. Precast elements which are thin or are difficult to reinforce such as curved arch flat members, Hyperbolic Paraboloid Shells, folded plate roof girders, fins, thin pardis or chajja drops.
  5. Standard mass production precast R.C.C and prestressed elements like slab panels, wall panels.
  6. As a bonding fabric during guniting or during re-plastering required for Repairs and rehabilitation of structures.
  7. Unstressed shaping or form reinforcement used in Prestressed Concrete Girders of Box, I, T or Double T-section.
  8. Ferrocement or Ferrocrete works where welded wire fabric is the only solution for forming the reinforcing matrix for precast elements such as water tanks, fins, shelves etc.

About Fasi Ur RahmanVerified

Fasi is a Civil Engineer associated with Tumkur Smart City Project. He is the author, editor and partner at theconstructor.org