INITIAL AND FINAL SETTING TIME OF CEMENT TEST (IS: 4031-(PART-5)-1988)

INITIAL AND FINAL SETTING TIME  CEMENT TEST

The initial setting time may be defined as the time taken by the paste to stiffen or solidify to such an extent that the Vicat’s needle is not permitted to move down through the paste to within 5 to 7 mm measured from the bottom of the mould. 

The final setting time is the time after which the paste becomes so hard that the angular attachment to the needle, under standard weight, fails to leave any mark on the hardened concrete.

Factors Affecting Initial And Final Setting Time Of Cement :

The factors influencing the setting properties of cement are : 

• Its composition, The effect of gypsum is to increase the setting time of freshly ground cement. 

• The percentage of retardant. 

• Degree of calcination. 

• Fineness of grinding.

• Aeration subsequent to grinding clinker. 

• Percentage of water used to make cement paste. 

• The temperature of the mixing water. 

• Cement and the atmosphere where the cement paste is placed.

OBJECTIVE 

To determine the initial and final setting time of cement paste of normal consistency.

APPARATUS

• Vicat’s Apparatus :

SAMPLE/SPECIMEN 

300 gm of cement is taken and then mix it with the required water percentage mentioned  in the consistency test of cement.

PROCEDURE FOR INITIAL SETTING TIME

• The prepared cement paste is filled in the vicat mould.
• The square needle of cross-section 1 mm x 1 mm is attached to the movable rod of the Vicat apparatus.

• Then the needle is allowed to quickly release to penetrate in the cement paste. during initial stage, the needle penetrates completely. It is then taken out and dropped at a fresh place. The test procedure is repeated at regular intervals till the needle does not penetrate completely. The needle should penetrate upto about 5 mm measured from bottom.

• The initial setting time is found out by taking  the interval between the addition of water to cement and the stage when needle stops to penetrate completely. The time should be less than 30 minutes for ordinary cement.

PROCEDURE FOR FINAL SETTING TIME :

• 300 gm of cement is taken and then mix it with the required water percentage mentioned  in the consistency test of cement.

• The prepared cement paste is then fill in the vicat mould.

• Instead of square needle, annular collar is used. The annular collar is attached to the movable rod of vicat apparatus.

• The annular rod is gently released. The time at which the annular rod makes an impression on test block and the collar fails to do so is noted.

• The final setting time is found out by taking the difference between the time at which water is added to cement and time as recorded in.

• The final setting time for ordinary cement should be 10 hours.

Initial And Final Setting Time Of Various Types Of Cement :

• Ordinary Portland Cement : The initial setting time of OPC should not be less than 30 minutes and the final setting time of this type of cement should not be greater than 10 hours or 600 minutes.

• Rapid Hardening Cement : for this type of cement, initial and final setting time is same as OPC cement.

• Portland Pozzolana Cement :  For this type of cement, initial and final setting time is same as OPC cement.

• Low Heat Portland Cement : For this type of cement, initial and final setting time is not less than 30 min and not greater than 600 minutes.

• Portland Blast Furnace Slag Cement : For this type of cement, initial and final setting time is same as OPC cement.