Initial and Final setting time of cement test by vicat apparatus is required to find out when cement paste starts it’s chemical reaction and looses it’s plasticity simultaneously. We described full procedure of initial and final setting time test of cement by vicat apparatus as per IS Code 4031 part 5.
What is Initial setting time of Cement?
Initial setting time of a cement is, when chemical reaction starts between cement and water after mixing of both in required humidity and temperature.
What is Final setting time of Cement?
Final setting time of a cement is, when cement looses it’s plasticity and becomes hard after reaction with water.
Why setting time of cement test required ?
There are many reasons to test initial and final setting time of cement.
Some are listed below.
1. To know the start time of curing ( because of heat of hydration ).
2. To remove the shutter of any structure or concrete cube.
3. For concrete mix designs.
4. For better quality of cement.
Initial and final setting time IS Code
For test procedure of initial and final setting time of cement – IS code 4031 part 5.
Apparatus and Tools Required for Initial and Final Setting time of Cement
1. Vicat apparatus and it’s components ( confirming to IS 5513 – 1996 revision ) like plunger, movable rod, graduated scale and needles.
All dimensions of vicat apparatus components given in IS 5513
So now we assume that your all doubts are cleared about dimensions of vicat apparatus components.
2. Two numbers of Trowel ( for mixing cement with water ).
3. One non-porous plate on which cement and water shall be mixed.
4. Weighing balance with at least 0.1 gm accuracy because of permissible variation on 300 gm is +/- 0.3 gm, and for 500 gm is +/- 0.35.
5. Hand gloves for your safety.
Precautions before proceeding initial and final setting time of cement test
1. Vicat apparatus and its components shall be clean, mainly needles.
2. De-shuttering agent ( lubricant or grease ) shall be applied inner surface of vicat mould.
3. Non-porous plate and trowels shall be clean before test, we should not use trowels and non-porous plate in wet condition, this moisture may affect on the test result.
4. The temperature of room where initial and final setting test is going to be done shall be 27 +/- 2 degree centigrade, means between 25 to 29.
5. Like temperature, Humidity is also an important factor, humidity shall be 65 +/- 5 percent, means between 60 to 70.
Procedure of Initial and Final setting time test of cement
1. Take 400 gram of cement.
2. Water content percent will be 85 percent of consistency of cement.
if consistency is 28 percent
cement = 400 gm, water %= 28 * 85 % = 23.8
so water content = 400 * 23.8 % = 95.2 gram.
in a easy way, use 85 percent of water you used for consistency
cement = 400 gram, water = 112 * 85 % = 95.2 gram. ( If consistency is 28 percent, 400*28%=112 gram )
3. Mixing time is same like consistency test 3 to 5 minutes, it will start when you add water in cement and finish when cement paste shall be filled in vicat mould. ( important )
4. Start the stopwatch and add water in cement simultaneously.
5. Mix properly by using both trowels, it is very important.
6. After mixing well, vicat mould shall be filled by that cement paste by slightly shaking or slightly strucking the mould. Be ensure that no voids is in paste.
7. After filling mould with cement paste, vicat mould with paste shall be placed in vicat apparatus.
8. Already initial setting time needle ( which has 1.13 mm diameter ) shall be fixed in vicat apparatus.
How to test
9. As we described before initial setting time limit is minimum 30 minutes so we can test after 30 minutes, Lower the vicat plunger slowly untill the initial setting time needle bottom point touches the cement paste top surface filled in vicat mould.
10. Release the plunger quickly, let it sink in paste, when it stops sinking ( nearly 3 to 4 seconds ) note down the reading from graduated scale.
11. Wait until you get 5 +/- 0.5 mm means 4.5 to 5.5 mm reading on graduated scale.
12. Note down initial setting time in minutes from water adding time.
13. For final setting time wait until only needles spot comes on cement paste not circle from final setting needle.
In this image above you can significance of initial and final setting time of cement.
Report and Calculation of Initial and Final Setting time of Cement
cement (gm) water (%) initial setting time(min) final setting time(min)
400 23.8 142 265
INITIAL SETTING TIME OF CEMENT LIMIT
For ordinary portland cement , initial setting time limit is minimum 30 minutes.
FINAL SETTING TIME OF CEMENT LIMIT
For ordinary portland cement, final setting time limit is maximum 600 minutes.