Setting Time of Cement

SETTING TIME OF CEMENT

IS 8142 (1976): Method of test for determining setting time of concrete by penetration resistance [CED 2: Cement and Concrete]

Ref: http://www.iitk.ac.in/ce/test/IS-codes/is.8142.1976.pdf

Initial Setting Time - The elapsed time, after initial contact of cement and water, required for the mortar (sieved from the concrete) to reach a penetration resistance of 3.43 N/mm² ( 35 kgf/cm² )

Or

The time at which cement starts hardens and completely loses its plasticity is called Initial setting time of cement.

Or

The time available for mixing the cement and placing it in position is an Initial setting time of cement. If delayed further, cement loses its strength.

The initial setting time for OPC is 30 min

Final Setting Time - The elapsed time, after initial contact of cement and water, required for the mortar (sieved from the concrete) to reach a penetration resistance of 26.97 N/mm² ( 275 kgf/cm²)

Or

The time at which cement completely loses its plasticity and became hard is a final setting time of cement.

Or

The time taken by cement to gain its entire strength is a Final setting time of cement.

The final setting time for OPC is 600 min

Test for finding Initial and Final Setting time of Concrete

APPARATUS

Vicat apparatus conforming to IS: 5513-1976.

Balance of capacity 1kg and sensitivity 1 gram.

Gauging trowel conforming to IS: 10086-1982.

PROCEDURE

• Unless otherwise specified this test shall be conducted at a temperature of 27 +20 C and 65 + 5% of relative humidity of the Laboratory.

• Prepare a paste of 300 grams of cement with 0.85 times the water required to a give a paste of standard consistency IS: 4031 (Part 4) 1988.

• The time of gauging in any case shall not be less than 3 minutes not more than 5 minutes and the gauging shall be completed before any sign of setting occurs.

• Count the time of gauging from the time of adding water to the dry cement until commencing to fill the mould

• Fill the vicat mould with this paste making it level with the top of the mould.

• Slightly shake the mould to expel the air.

• In filling the mould the operator hands and the blade the gauging trowel shall only be used.

Initial Setting Time

• Immediately place the test block with the non-porous resting plate, under the rod bearing the initial setting needle.

• Lower the needle and quickly release allowing it to penetrate in to the mould.

• In the beginning the needle will completely pierce the mould

• Repeat this procedure until the needle fails to pierce the mould for 5 + 0.5mm.

• Record the period elapsed between the time of adding water to the cement to the time when needle fails to pierce the mould by 5 + 0.5mm as the initial setting time.

Final Setting Time

• Replace the needle of the vicat apparatus by the needle with an annular ring

• Lower the needle and quickly release.

• Repeat the process until the annular ring makes an impression on the mould.

• Record the period elapsed between the time of adding water to the cement to the time when the annular ring fails to make the impression on the mould as the final setting time.

REPORT

Report the initial setting time and final setting time in minutes.

PRECAUTION

The time of gauging in any case shall not be less than 3 minutes not more than

5minutes

The range of three results of properly conducted tests by the same operator with the same machine using similar materials on different days shall not exceed 4 minutes, and the average setting times for two sets

of tests each consisting of three similar batches shall not depart more than

20 minutes from the average of the two.