Initial and Final setting of Cement

Aim
To determine the initial and final setting time of a given sample of cement.

Apparatus
Vicat apparatus conforming to IS : 5513-1976, Balance, Gauging Trowel, Stop Watch

Theory
For convenience, initial setting time is regarded as the time elapsed between the moments that the water isadded to the cement, to the time that the paste starts losing its plasticity. The final setting time is the timeelapsed between the moment the water is added to the cement, and the time when the paste has completely lost its plasticity and has attained sufficient firmness to resist certain definite pressure

Procedure 

1. Preparation of Test Block - Prepare a neat 300 gms cement paste by gauging the cement with 0.85 times the water required to give a paste of standard consistency. Potable or distilled water shall be used in preparing the paste.

2. Start a stop-watch at the instant when water is added to the cement. Fill the Vicat
mould with a cement paste gauged as above, the mould resting on a nonporous plate. Fill
the mould completely and smooth off the surface of the paste making it level with the top
of the mould.

3. Immediately after moulding, place the test block in the moist closet or moist room
and allow it to remain there except when determinations of time of setting are being made.

4. Determination of Initial Setting Time - Place the test block confined in the mould
and resting on the non-porous plate, under the rod bearing the needle ( C ); lower the
needle gently until it comes in contact with the surface of the test block and quickly
release, allowing it to penetrate into the test block

5. Repeat this procedure until the needle, when brought in contact with the test block
and released as described above, fails to pierce the block beyond 5.0 ± 0.5 mm measured
from the bottom of the mould shall be the initial setting time.

6. Determination of Final Setting Time - Replace the needle (C) of the Vicat
apparatus by the needle with an annular attachment (F).

7. The cement shall be considered as finally set when, upon applying the needle gently
to the surface of the test block, the needle makes an impression thereon, while the attachment fails to do so.

8. The period elapsing between the time when water is added to the cement and the
time at which the needle makes an impression on the surface of test block while the
attachment fails to do so shall be the final setting time


Observation
1. Weight of given sample of cement is _ _ _ _ gms
2. The normal consistency of a given sample of cement is _ _ _ _ %
3. Volume of water addend (0.85 times the water required to give a paste of standard consistency) for preparation of test block _ _ _ _ ml

Sl. No.

Setting time
(Sec)

Penetration
(mm)

Remark

 

 

 

 

 

 

 

 

 

 

 

 

 


Result

i) The initial setting time of the cement sample is found to be …..
ii) The final setting time of the cement sample is found to be …..

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