Civil Engineering - Building Materials - Discussion

INITIAL AND FINAL SETTING TIME.

We need to calculate the initial and final setting time as per IS: 4031 (Part 5) - 1988. To do so we need Vicat apparatus conforming to IS: 5513 - 1976, Balance, whose permissible variation at a load of 1000g should be +1.0g, Gauging trowel conforming to IS: 10086- 1982.

Procedure to determine initial and final setting time of cement.

i) Prepare a cement paste by gauging the cement with 0.85 times the water required to give a paste of standard consistency.

ii) Start a stop-watch, the moment water is added to the cement.

iii) Fill the Vicat mould completely with the cement paste gauged as above, the mould resting on a non-porous plate and smooth off the surface of the paste making it level with the top of the mould. The cement block thus prepared in the mould is the test block.

Before commencing setting time test, do the consistency test to obtain the water required to give the paste normal consistency (P).

Take 400 g of cement and prepare a neat cement paste with 0.85 P of water by weight of cement.

Gauge time is kept between 3 to 5 minutes. Start the stopwatch 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.

A neat cement paste is prepared by adding 0.85 times the water required to give a paste of standard consistency.

The Quantity of water added to cement = 0.85 X Quantity of water required for standard consistency.

Why we are taking the water 0.85 * P for initial setting of cement. What is digit of 0.85 in intial setting time?

What is the amount of water required to give the paste normal consistency for consistency test?

Why used in cement setting time mould 85 percent water addition & Le chart. 78 percent.

It is not 400 gm, 500 is right, if anyone have doubt means refer concrete tech text book.

Why only 0.85 water is required in the initial setting time?

Anyone explain me.

Soundness test the value is 0.78p and the consistency test 0.85p.

.85p is the right answer for initial setting time test.