To determine the final setting time of cement. This test is required to understand the rate of gain of strength of cement w.r.t. to time.
Vicat apparatus, needle for initial setting time, stop watch.
Take 400 gm of cement in a pan. Prepare a neat cement paste by adding 0.85 times the water required to give a paste of standard consistency by the previous test. Start a stop watch at the instant when water is added to the cement. 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.
Place the test block and the non porous plate under the rod bearing the needle with the annular attachment for final setting time. Lower the needle gently till the needle makes an impression there on, while the attachment fails to do so. In the beginning the needle will completely pierce the block. Repeat the procedure. The period elapsing between the time when water is added to the cement and the time at which the needle fails to make an impression on the surface of the test block shall be the final setting time.
The final setting time of the given sample of cement =……………..min