LimsPulse
Construction materials testing

Vicat Apparatus

A weighted sliding rod with interchangeable plunger and needles used to find the standard consistency of cement paste and its initial and final setting times.

  • Cement manufacturing
  • Construction materials testing
  • Ready-mix concrete
  • Admixture manufacturers
  • Academic labs
Photo of a Vicat Apparatus
Photo: Habib M’henni, CC BY-SA 3.0 (cropped), via Wikimedia Commons
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1

Before you start

  1. 1Check the room temperature and humidity are within the standard's limits and record them.
  2. 2Check the moving part slides freely and the pointer reads zero with the plunger resting on the base plate.
  3. 3Check the needle and plunger dimension check is in date; replace a bent needle.
  4. 4Lightly oil the inside of the mould and the base plate.
  • Use distilled or potable water at room temperature; warm water shortens setting time.
STAGE 2

Standard consistency

  1. 1Weigh the cement and gauge it with a trial amount of water (for example 26% by mass), starting the stopwatch when water is added.
  2. 2Fill the mould within the gauging time, shake off air and strike the surface level.
  3. 3Lower the plunger gently to touch the paste, tighten, then release quickly.
  4. 4Read the penetration; repeat with fresh paste and different water until the plunger stops 5–7 mm from the bottom of the mould (IS 4031 Part 4).
  • Do not reuse paste from a failed trial; it has started to hydrate.
STAGE 3

Setting times

  1. 1Prepare paste with 0.85 P water and fill the mould; note the time water was added.
  2. 2Fit the initial needle and release it at regular intervals (e.g. every few minutes), moving to a fresh spot each time.
  3. 3Record initial setting time when the needle stops about 5 ± 0.5 mm from the bottom.
  4. 4Change to the final-setting needle and record final setting time when only the needle, not the collar, marks the surface.
  • Clean the needle after every penetration; paste on the needle reduces penetration.
  • Keep the specimen in a humid cabinet between readings.
STAGE 4

After testing

  1. 1Remove and discard the paste before it hardens in the mould.
  2. 2Wash and dry the mould, plunger and needles.
  3. 3Record P, initial and final setting times with room conditions.
In LimsPulse · Calibration Management

Keep every Vicat in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how