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Flow table test

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Equipment; flow table, Abrams cone, waterbucket and broom.
The cone filled with concrete, prior to lifting.
The diameter of the resulting flow is measured.

The flow table test or flow test is a method to determine the consistence of fresh concrete.

Application When fresh concrete is delivered to a site by a truck mixer it is sometimes necessary to check its consistence before pouring it into formwork.

If the consistence is not correct, the concrete will not have the desired qualities once it has set, particularly the desired strength. If the concrete is too pasty, it may result in cavities within the concrete which leads to corrosion of the rebar, eventually leading to the formation of cracks (as the rebar expands as it corrodes) which will accelerate the whole process, rather like insufficient concrete cover. Cavities will also lower the stress the concrete is able to support.

Equipment

  • Flow table with a grip and a hinge, 70 centimetres (28 in) square.
  • Abrams cone, open at the top and at the bottom - 30 centimetres (12 in) high, 17 centimetres (6.7 in) top diameter, 25 centimetres (9.8 in) base diameter.
  • Water bucket and broom for wetting the flow table.
  • Tamping rod, 60 centimetres (24 in) long

Conducting the test

  • The flowtable is wetted.
  • The cone is placed in the center of the flowtable and filled with fresh concrete in two layers. Each layer is tamped 25 times with tamping rod.
  • The cone is lifted, allowing the concrete to flow.
  • The flowtable is then lifted up several centimeters and then dropped, causing the concrete flow a little bit further.
  • After this the diameter of the concrete is measured.

See also

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