EXPERIMENT NO-5

OBJECT: To determine the final and initial setting time of cement.

APPARATUS REQUIRED: 1. Vicat Apparatus

                                                 2. Initial setting needle

                                                 3. Final setting needle

                                                 4. Stop watch

MATERIAL REQUIRED:  1. Cement

                                                2. Water

PROCEDURE:

1. Prepare a cement paste by gauging the cement with 0.85 times the water required to give a paste of standard consistency.
2. Start a stop-watch, the moment water is added to the cement
3. Keep the vicat mould on a non porous plate and fill the cement paste in it. After completely filling the mould, it should be shaken slightly to expel the air. Smooth off the surface of the paste making it level with the top of the mould. The test block is ready.

INITIAL SETTING TIME:

Place the block under the rod bearing the needle. Lower the needle gently in order to make contact with the surface of the cement paste and release quickly, allowing it to penetrate the test block. Repeat the procedure till the needle fails to pierce the test block to a point 5.0 ± 0.5mm measured from the bottom of the mould.The time period elapsing between the time, water is added to the cement and the time, the needle fails to pierce the test block by 5.0 ± 0.5mm measured from the bottom of the mould, is the initial setting time.

FINAL SETTING TIME:

Replace the above needle by the one with an annular attachment. The cement should be considered as finally set when, upon applying the needle gently to the surface of the test block, the needle makes an impression therein, while the attachment fails to do so. The period elapsing between the time, water is added to the cement and the time, the needle makes an impression on the surface of the test block, while the attachment fails to do so, is the final setting time.

OBSERVATION AND RESULT:
Weight of cement taken (g) = _________
Quantity of water added to cement = 0.85 X Quantity of water required for standard consistency = _______
The initial setting time of the given sample of cement=……………..min
The final setting time of the given sample of cement =……………..min