⏱️ Initial and Final Setting Time Test of Cement

📘 Aim

To determine the initial and final setting time of cement using the Vicat Apparatus as per IS: 4031 (Part 5) – 1988.

⚙️ Apparatus Required

• Vicat Apparatus with needle and movable rod
• Stopwatch
• Measuring cylinder
• Glass plate
• Trowel
• Balance (accuracy 1 g)
• Water (clean and potable)

📏 Theory

The setting time of cement refers to the time interval between the addition of water to the cement and the point when it loses its plasticity and becomes hard. This test ensures that cement remains workable for sufficient time and develops strength properly.

Two important times are measured:

• Initial Setting Time — The time taken for the cement paste to start losing its plasticity (when the Vicat needle penetrates up to 33–35 mm from the top).
• Final Setting Time — The time when the paste has completely lost its plasticity and the needle fails to make an impression on the surface.

🧪 Procedure

1. Prepare a cement paste by adding water equal to 0.85 × P, where P = percentage of water for standard consistency.
2. Start the stopwatch immediately when water is added to the cement.
3. Fill the Vicat mould with the paste and smooth the surface.
4. Place the mould under the Vicat needle (1 mm square section needle) and lower it gently to touch the surface.
5. Release the needle and note the depth of penetration at regular intervals (every 2–5 minutes).
6. The time at which the needle penetrates up to 33–35 mm from the top of the mould is the Initial Setting Time.
7. For final setting time, replace the needle with the annular attachment and repeat the test.
8. The time when the needle makes only a faint impression while the annular collar does not mark the surface is the Final Setting Time.

📊 Observation Table

🧮 Calculations

Initial Setting Time = Time from adding water to the time when penetration = 33–35 mm.

Final Setting Time = Time from adding water to the time when the needle fails to make an impression on the surface.

✅ Result

• Initial Setting Time = 30 minutes
• Final Setting Time = 5 hours (300 minutes)

📋 Permissible Limits (as per IS 4031:1988)

• Initial Setting Time ≥ 30 minutes
• Final Setting Time ≤ 600 minutes (10 hours)

🧩 Significance

• Ensures sufficient working time for mixing, placing, and compaction.
• Helps control setting behavior in different environmental conditions.
• Indicates the quality and soundness of cement.

⚠️ Precautions

• Conduct the test at a temperature of 27°C ± 2°C and 65% ± 5% humidity.
• Use freshly prepared cement paste and clean apparatus.
• Start the stopwatch immediately when water is added.
• Avoid vibration and external disturbance to the apparatus during testing.

📘 Conclusion

The initial and final setting times of cement are 30 minutes and 5 hours respectively, which are within the permissible limits specified by IS 4031:1988. Hence, the cement sample is suitable for construction use.