Initial setting time of cement test

Initial setting time 

 Aim :-  

To determine the initial strength of cement paste .

Objective :-

Initial setting time gives an idea about how fast cement can start losing its plasticity and gain some strength to resist pressure.

Apparatus:- 

1. Balance :-The permissible variation at a load of 1000 g shall be ± 1.0 g.
2. Vicat Apparatus – Vicat apparatus should confirm to IS : 5513-1976.
3. Stop Watch
4. Gauging or Mixing Trowel
5. Glass Plate
6.  Enamel tray
7. Needle for initial setting time
8. mould

References :-

As Per  IS: 4031 (Part 5) – 1988.  The initial and final setting time of cement is calculated using the VICAT apparatus conforming to IS: 5513 – 1976.

Procedure :-

• Procedure for preparation of cement paste

1. Consistency of cement shall be tested before conducting a test to find out % of the water required by the weight of cement as normal consistency of cement (P).

2. Take about 400 gm of cement and add water about 0.85x P (P is % water required for normal consistency of cement)

3. Mix water with cement quickly in a short time about 3 min to 5 min. Start the stopwatch at the instance when water added to the cement. Record this time (T1).

4. Now, fill this prepared cement paste in Vicat apparatus mould having a diameter of 80 mm and a height of 50 mm resting on non –porous glass plate. Properly fill and smooth off the top surface of mould and level it.

• Procedure of Initial Setting Time of Cement

1. For determining the initial setting time of cement, place this mould filled with cement paste below the vicat apparatus and fit needle used for testing initial setting time.

2. Lower the bottom of needle such that it touches the top of cement paste filled  in mould.

3. Remove locking pin from top and quick release the needle, allowing it to penetrate into the cement paste.

4. At the beginning, the needle penetrates and touches the bottom of mould. Repeat this process, like quickly releasing the needle after every 2 minutes till the needle fails to penetrate the cement paste for about 5 mm measured from the bottom of the mould.

5.  Note Time (T2) when needle fail to penetrate 5 mm from the bottom of mould.

Conclusion:-

when needle fail to penetrate 5 mm form the bottom of mould then required time is called initial setting time .