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HOW TO DETERMINE OF CONSISTENCY OF STANDARD CEMENT PASTE

HOW TO DETERMINE OF CONSISTENCY OF STANDARD CEMENT PASTE

IN THIS ARTICLE WE WILL LEARN ABOUT TEST METHOD TO FIND CONSISTENCY OF STANDARD CEMENT PASTE AS PER IS 4031(PART-4)- 1988

DETERMINATION OF CONSISTENCY OF STANDARD CEMENT PASTE 


WHAT DO YOU MEAN BY STANDARD CONSISTENCY OF CEMENT 

SCOPE - This standard covers the procedure for determining the quantity of water required to produce a cement paste of standard consistency.

SAMPLING AND SELECTION OF TEST SPECIMENThe samples of the cement shall be taken in accordance with the requirements of IS 3535-1986 and the relevant standard specification for the type of cement being tested. The representative sample of the cement selected as above shall be thoroughly mixed before testing.

TEMPERATURE AND HUMIDITY -  The temperature of moulding room, dry materials and water shall be maintained at 27±2 °C.
The relevant humidity of the laboratory shall be 65±5 percent.

APPARATUS -  

1. Vicat Apparatus - Vicat Apparatus conforming to IS 5513 - 1976
2. Balance - The balance shall confirming to the following requirements. On a balance in use, the permissible variation at a load of 1000g shall be plus or minus 1.0g. The permissible variation on new balance shall be one half of the value. The sensibility reciprocal shall not be greater than twice the permissible variation.
3. Standard Weights 
4. Gauging Trowel - Gauging Trowel conforming to IS 10086: 1982.



PROCEDURE - The standard consistency of a cement paste is defined as that consistency which will permit the Vicat plunger G to penetrate to a point 5 to 7 mm from the bottom of the Vicat mould when the cement paste is tested as described 

1. Prepare a paste of weighed quantity of cement with a weighed quantity of potable or distilled water, taking care that the time of gauging is not less than 3 minutes not more than 5 minutes, and the gauging shall be completed before any sign of setting occurs.
2. The gauging time shall be counted from the time of adding water to the dry cement until commencing to fill the mould.
3. Fill the Vicat mould E with this paste, the mould resting upon a non-porous plate.
4.After completely filling the mould, smoothen the surface of the paste, making at level with the top of the mould. 
5.The mould may be slightly shaken to expel the air.
6.Clean appliances shall be used for gauging. In filling the mould, the operator's hand and the blade of the gauging trowel shall alone be used.
7.Place the test block in the mould, together with the non-porous resting plate, under the rod bearing the plunger, lower the plunger gently to touch the surface of the test block, and quickly release, allowing it to sink the paste. This operation shall be carried out immediately after filling the mould.
8. Prepare trial pastes with varying percentages of water and test as described above until the amount of water necessary for making up the standard consistency.



CALCULATION -  Express the amount of water as a percentage by mass of the dry cement to the first place of decimal.

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