Objective: To determine the final setting time of cement.
This test is required to understand the rate of gain of strength of cement with respect to time.
Apparatus
Vicat apparatus, needle for initial setting time, stop watch.
Theory
Final setting time is the time when the cement paste completely loses its plasticity. It is the time taken for the cement paste or cement concrete to harden sufficiently and attain the shape of the mould in which it is cast. After the final setting, 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression.
Procedure
First of all take 400 gm of cement and put it in a pan. Now blend it into a clean and neat cement paste by incorporating 0.85 times the water needed to give a paste of average constancy by the preceding test. Keep a stop watch on at the right moment when water is blended into the cement. Keep the vicat mould/cast on a non absorbent plate and put cement paste in it. After entirely filling up the mould, we should shake it gently to discarhe the air. Even off the facade of the paste and make it even level with the top of the mould/cast.
Now put the test block and the non absorbent plate below the rod holding the needle with the annular connection for last setting time. Lower the needle slowly till the needle penetrates through, while the attachment does not succeed to do so. At first, the needle will entirely penetrate through the block. Complete the procedure as per the need again and again. The period spent between the time-frame when water is incorporated to the cement and the time at which the needle does not succeed to create an impression on the facade of the test block will be known as the final setting time.
Outcome
The final setting time of the given sample of cement =……………..min