---
title: "Consistency test of cement"
subject: "Civil Engineering Materials"
chapter: 5
key: "semester_3/civil_engineering_materials:cement-consistency-test"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/cement-consistency-test
site: BCT Engineering
---

# Consistency test of cement

Civil Engineering Materials · Chapter 5: Cement

- Asked in: 2081 Baisakh (new course), 2 marks
- Video: [Standard Consistency Test of Cement](https://www.youtube.com/watch?v=jbogeG4D02c) — Concrete Engineers
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/cement-consistency-test
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-5

## Question

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

## 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%.

## Answer

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.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Standard consistency is reached when the plunger stops:
   A. 5-7 mm from the bottom of the mould
   B. 10 mm from the top
   C. At the bottom
   D. Immediately at surface
   Answer: A. That is 33-35 mm from the top. (Key point: Plunger penetration)

2. If penetration is not correct, what do you do?
   A. Add water to same paste
   B. Repeat with fresh sample and change water by 1%
   C. Reduce cement
   D. Stop
   Answer: B. Fresh sample and different water. (Key point: Trial)

3. P from this test is used for:
   A. Colour test
   B. Specific gravity only
   C. Setting time, soundness and strength tests
   D. Fineness
   Answer: C. P = water/cement x 100, usually 26-33%. (Key point: Use of P)

## Related in Civil Engineering Materials

- [Soundness test of cement and procedure](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acement-soundness-test-procedure) — Civil Engineering Materials, chapter 5
- [Compressive strength test of cement](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acement-compressive-strength-test) — Civil Engineering Materials, chapter 5, asked 3×
- [Why soundness test of cement](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Awhy-soundness-test-cement) — Civil Engineering Materials, chapter 5
- [Stepwise preparation of cement mortar](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Astepwise-preparing-cement-mortar) — Civil Engineering Materials, chapter 6, asked 4×

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