Skip to main content

Consistency test of cement

Short answer

Weigh 400 g cement, mix with trial water, fill Vicat mould, release 10 mm plunger. Standard consistency is when plunger penetrates to 5–7 mm from mould bottom (33–35 mm from top). If not, repeat with adjusted water. P = (water mass/cement mass)×100, typically 26–33%.

Describe the procedure for performing the consistency test of cement in the lab.

The consistency test finds the water percentage (P) that gives cement paste of standard consistency (IS 4031 Part 4), using the Vicat apparatus with a 10 mm diameter, 50 mm long plunger.

Procedure

  1. Take 400 g of cement and mix with a trial water percentage (for example 26% by weight of cement), gauging for 3-5 minutes.
  2. Fill the Vicat mould (resting on a glass plate) with paste, then smooth the top surface level.
  3. Place the mould under the plunger, lower it until it just touches the paste surface and tighten the clamp; set the pointer to zero.
  4. Release the plunger quickly, letting it sink into the paste.
  5. Read the depth of penetration. If the plunger stops 5-7 mm from the bottom of the mould (that is 33-35 mm from the top), the paste has standard consistency.
  6. Otherwise repeat with a fresh sample and a different amount of water (increase by 1% each time) until this penetration is obtained.
  7. Consistency P = (weight of water / weight of cement) x 100, typically 26-33%.

P is then used for the setting time, soundness and strength tests.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Civil Engineering Materials chapter 5 questions →