Final setting time is that time period between the time water is added to cement and the time at which 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression. This is test is required to understand the rate of gain of strength of cement with respect to time.
Procedure to Find Final Setting Time of Cement
- Vicat’s apparatus
- Measuring cylinder
- Stop watch
- Glass plate
- Enamel tray
- Consistency test to be done before starting the test procedure to find out the water required to give the paste normal consistency (P).
- Take 400 g of cement and prepare a neat cement paste with 0.85P of water by weight of cement.
- Gauge time is kept between 3 to 5 minutes. Start the stop watch at the instant when the water is added to the cement. Record this time (T1).
- Fill the Vicat mould, resting on a glass plate, with the cement paste gauged as above. Fill the mould completely and smooth off the surface of the paste making it level with the top of the mould. The cement block thus prepared is called test block.
- For determining the final setting time, replace the needle of the Vicat’s apparatus by the needle with an annular attachment.
- The cement is considered finally set when upon applying the final setting needle gently to the surface of the test block; the needle makes an impression thereon, while the attachment fails to do so. Record this time (T2).
ObservationsWeight of cement taken (g) = _________ Quantity of water added to cement = =0.85 X Quantity of water required for standard consistency in ml = _____ Time at which water is first added to cement (T1) in sec = _____ Time when needle fails to makes an impression on the sample (T2) in sec = _____
Final Setting Time=T2-T1
ResultThe initial setting time of the given sample of cement= _____ min
PrecautionsSome necessary precaution taken while performing final setting time test are,
- Release the final setting time needles gently.
- The experiment should be performed away from vibration and other disturbances.
- Needle should be cleaned every time it is used.
- Position of the mould should be shifted slightly after each penetration to avoid penetration at the same place.
- Test should be performed at the specified environmental conditions.
Standard Specification of Setting Time for Different Type of CementDepending upon the admixtures added into the cement in the process of manufacture of cement, the setting time differs for different cement. Standard setting times are listed in the below table as per IS 4031, IS 269. Table-1: Final Setting Time for Different Type of Cement
|Cement Type||Final Setting Time, min (max.)|