Initial and Final Setting Time of Cement Test as per Indian Standard (IS 4031: Part 5)

Initial and Final Setting Time of Cement Test

The aim of this test is to determine the initial and final setting time of cement using the Vicat apparatus. These times are critical in understanding the workability and usability of cement during construction activities. The initial setting time indicates the time available for mixing and placing the cement, while the final setting time shows when the cement has completely hardened.

Apparatus

1. Vicat Apparatus with Needle (Initial Setting Needle: 1 mm² cross-sectional area and Final Setting Needle: 5 mm diameter)
2. Weighing Balance
3. Measuring Jar
4. Stopwatch
5. Glass or Non-Absorbent Plate
6. Trowel
7. Cement Sample (about 500g)
8. Water

Theory
The setting time of cement refers to the duration during which the cement paste undergoes the transition from a fluid to a solid state. The initial setting time is defined as the time interval between the moment water is added to the cement and the moment when the cement paste begins to lose its plasticity. The final setting time is the time when the cement paste has completely lost its plasticity and can bear load.

The initial setting time ensures that the concrete mixture remains workable for an adequate period after mixing. The final setting time ensures that the cement gains sufficient strength to support structures.

The test is performed using the Vicat apparatus, where the setting time is determined by observing the penetration of the needle into the cement paste.

Procedure

1. Prepare the Cement Paste: Weigh 400g of cement and mix it with the water content corresponding to standard consistency (usually between 0.85 to 0.9 times the standard consistency).
2. Fill the Mould: Fill the Vicat mould resting on a glass plate with the prepared cement paste.
3. Start the Timer: As soon as water is added to the cement, start the stopwatch.
4. Test for Initial Setting Time: Place the initial setting needle (1 mm²) on the surface of the paste and release it to observe its penetration. The initial setting time is noted when the needle penetrates the paste to a depth of 5–7 mm from the bottom of the mould.
5. Test for Final Setting Time: Replace the needle with the final setting needle (5 mm diameter) and repeat the process. The final setting time is recorded when the needle fails to make an impression on the surface of the paste.
6. Repeat Penetration Test: Keep testing at regular intervals until the cement reaches both the initial and final setting stages.

Observation Table

Trial No.	Time After Mixing (Minutes)	Depth of Penetration (mm)	Setting Stage (Initial/Final)
1	20	25	Initial Setting
2	40	7	Initial Setting
3	50	5	Initial Setting
4	120	Needle Does Not Penetrate	Final Setting

Sample Readings

• Initial Setting Time: If the needle penetrates 5 mm at 50 minutes, then the initial setting time is reported as 50 minutes.
• Final Setting Time: If the needle fails to penetrate the surface at 120 minutes, the final setting time is reported as 120 minutes.

Reporting the Results

• Initial Setting Time: The time taken from the moment water is added to the cement until the needle penetrates to a depth of 5–7 mm is noted as the initial setting time.
• Final Setting Time: The time taken from the moment water is added to the cement until the needle fails to penetrate or make an impression on the surface is noted as the final setting time.

Example of Reporting:

• Initial Setting Time: 50 minutes
• Final Setting Time: 120 minutes

Conclusion
The initial and final setting times are important parameters in cement. The initial setting time gives an idea of the working time available to place the concrete. The final setting time gives the time when the cement has hardened sufficiently to resist external load. IS 4031: Part 5 specifies that the initial setting time of Ordinary Portland Cement (OPC) should not be less than 30 minutes, and the final setting time should not be more than 600 minutes (10 hours). These values may vary depending on the type of cement used. The test results help in selecting suitable cement for specific construction conditions.