Shotcrete of Yuleba Minerals

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Shotcrete of Yuleba Minerals
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Shot Crete

• Shotcrete is, in effect, a version of a
  cast-in-place concrete wall. Rather than placing
  concrete into forms, however, a fresh mix is
  sprayed onto wall, roof or other panels.

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• A nozzle man applies concrete from a pressurized
  hose to encompass the reinforcement and build up
  the wall thickness, forming structural shapes
  that include walls, floors, roofs, and other
  assemblies.

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• This material has also been called gunite in
  reference to the nozzle or gun used to shoot
  material at the form face. Any surface suitable
  for accepting fresh concrete can be used wood,
  steel, and polystyrene are common. Finishes are
  often applied directly to the concrete while it
  is still wet.

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Advantages

• Shotcrete structures have advantages, they are
  strong, durable, resistant to disasters, fires,
  mould, insects and vermin, and have low
  permeability, good thermal mass, and create tight
  envelopes.

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• Although the hardened properties of shotcrete are
  similar to conventional cast-in-place concrete,
  the nature of the placement process provides
  additional benefits, such as very fast erection,
  particularly on complex forms or shapes,
  including curved walls and arches.

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• Shotcrete is a cost effective building method due
  to the speed of construction and minimal
  equipment requirements.

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Installation

• One reason that shotcrete systems are installed
  so quickly is that the formwork is often
  lightweight. They are easy to handle and make
  erecting the shape simple. It may be possible to
  do this primarily with manual labour and very
  limited equipment.

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• In most shotcrete systems, dowels from the floor
  slab provide attachment at the base of the walls.
  For insulated panels, each segment is attached to
  at least two dowels. At the top edges, the panels
  are connected to ones on either side of them.

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• For the plain mesh systems (no polystyrene core),
  rebar is attached to the floor dowels and then
  wire mesh is hung off the rebar. One proprietary
  system uses a top beam to position and brace the
  rebar and form a clean edge at the roofline. 

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• All shotcrete methods involve spraying material
  onto the forms. There are two ways to do this a
  wet mix and a dry mix. The end result is the same
  on the wall, but the mixing equipment is slightly
  different.

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• Wet Mix - All ingredients, including water, are
  thoroughly mixed and introduced into the delivery
  equipment. Wet material is pumped to the nozzle
  where compressed air is added to provide high
  velocity for placement and consolidation of the
  material onto the receiving surface.

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• Dry Mix - Pre-blended dry or damp materials are
  placed into the delivery equipment. Compressed
  air conveys material through a hose at high
  velocity to the nozzle, where water is added.
  Material is consolidated on the receiving surface
  by the high-impact velocity.

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• The basic concrete mix contains cement,
  aggregates, and water. Natural aggregates and
  sand are easy to pump and form the basis of
  Yuleba Minerals SP2, SP3 and SP4 shotcrete
  product range and According to the American
  Shotcrete Association, properties of both wet and
  dry process shotcrete can be further enhanced
  through the addition of other ingredients, such
  as

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• Silica Fume - Provides reduced permeability,
  increased compressive and flexural strength,
  increased resistance to alkali and chemical
  attack, improved resistance to water washout,
  reduced rebound levels, and allows for thicker
  single pass applications.

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• Air-Entraining Admixtures - Improve pump
  ability and adhesion in wet-process shotcrete and
  freeze-thaw durability in both wet and dry
  processes.

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• Fibres - Control cracking, increase toughness
  values and improve impact resistance and energy
  absorption. Accelerators - Improve placement
  characteristics in adverse conditions, allow for
  thicker single pass applications, increase
  production capabilities and reduce the occurrence
  of fallouts on structures subjected to vibration.

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• Yuleba Minerals (www.yulebaminerals.com.au )
  manufactures its products at its quarry in the
  Surat Basin around the Roma and Miles townships
  and distribute shotcrete throughout the Emerald,
  Mackay, Blackwater (Bowen Basin) and the NSW
  mining areas including the Gunnedah and Hunter
  Valley.