Wednesday, April 20, 2016

Consistency of cement

 Consistency means amount of water needed to prepare a plastic mix. “Normal or Standard Consistency” value of a cement sample is used for preparing the pastes for the determination of the setting time, unsoundness, compressive and tensile strength of the cement. Normal or Standard consistency of cement is determined using the Vicat’s Apparatus. It is defined as that percentage of water added to form the paste which allows a penetration of 10 ± 1 mm of the Vicat plunger
Procedure to determine consistency of cement
i) Weigh approximately 400g of cement and mix it with a weighed quantity of water. The time of gauging should be between 3 to 5 minutes.
ii) Fill the Vicat mould with paste and level it with a trowel.
iii) Lower the plunger gently till it touches the cement surface.
iv) Release the plunger allowing it to sink into the paste.
v) Note the reading on the gauge.
vi) Repeat the above procedure taking fresh samples of cement and different quantities of water until the reading on the gauge is 5 to 7mm.

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