Welded wire Fabric is a progression of parallel longitudinal wires welded to cross wires by electric combination strategy with exact dividing. The welding work is finished by apparatus which guarantees the exact measurements and results in extensive funds in time, work and cash.
In this article, we will consider the general detail, preferences, uses and correlation of welded wire fiber concrete.
General Specification of Welded Wire Fiber Concrete
The material utilized in assembling the wires for welded fiber is either treated steel rebar poles or aroused steel poles that have brilliant protection from erosion and can be utilized in wet conditions.
The wires comply with IS:432-Pt II/1982 which determines an extreme rigidity of 570 N/mm2 and a trademark quality of 480 N/mm
2. Shape and Size
The usually accessible states of the welded wire fiber are square shape and square. The texture can be produced for widths up to 3000mm with lengths restricted by transportation contemplations. At the point when provided in prepared to-lay level sheet structure the standard length is 5500mm. Something else, the texture can be provided in the moved structure in standard lengths of 15m,30m or 45m.
Wires utilized for the assembling of texture are commonly made in the scope of 2mm to 12mm width. It is fabricated fitting in with IS:1566-1982 with long and cross-wire spacings shifting from 25mm to 400mm
3. Cutting and Forming
Welded wire texture can be effectively cut with the assistance of wire cutters. On the off chance that the work is to be laid in a staircase, it very well may be effectively twisted into the required size and set down.
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.
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 Fabric
Reduction of permeability
Bond can deteriorate over time
Bonds effectively with concrete permanently
No surface protection provided
Improves surface durability
Minor resistance provided if properly placed
Improves impact, shatter and abrasion resistance
Difficult to install and expensive – high labor costs
Easy to use and cost effective – no labor costs
Difficult to place, especially if rolls – 1″ minimum cover required
Easy to place in concrete mix – No minimum cover
No effect on finish, but difficult to maintain placement in slab
Easy to finish with minor effect on workability of mix
Will deteriorate if not properly placed and protected
Will deteriorate if not properly placed and protected
Corrodes when exposed to water and chemicals
Increases tensile strength if properly placed
Increases tensile strength of plain non-reinforced concrete
Provides reinforcement in one plane
Provides three dimensional reinforcement
Increases ductility if properly placed
Permanent if visible with little remedy possible
No lasting aesthetics and can be easily remedied if necessary
Meets ASTM specifications if placed properly
Meets or exceeds ASTM specifications
Storage difficult and detrimental if stored outside
Can 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.
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
Structural flat slabs or in slabs with beam slab construction.
Large area floor slabs on ground, pavements, airport runways, aprons etc to achieve crack-free joint fewer surfaces.
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.
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.
Standard mass production precast R.C.C and prestressed elements like slab panels, wall panels.
As a bonding fabric during guniting or during re-plastering required for Repairs and rehabilitation of structures.
Unstressed shaping or form reinforcement used in Prestressed Concrete Girders of Box, I, T or Double T-section.
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.
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