NORMAL CONSISTENCY OF CEMENT
(IS: 269 - 1989 and IS: 4031 - 1988 (Part 4))
AIM: To determine the quantity of water required to produce a cement paste of standard
APPARATUS: Vicat apparatus (conforming to IS: 5513 - 1976) with plunger (10 mm in
diameter) balance, weights, gauging trowel.
INTRODUCTION: The standard consistency of a cement paste is defined as that consistency
which will permit the vicat plunger to penetrate to a point 5 to 7 mm from the bottom of the vicat
mould. For finding out initial setting time, final setting time, soundness of cement and
compressive strength of cement, it is necessary to fix the quantity of water to be mixed in cement
in each case. This experiment is intended to find out the quantity of water to be mixed for a given
cement to give a cement paste of normal consistency and can be done with the help of vicat
1. Prepare a paste of weighed quantity of cement (300 grams) with a weighed quantity of
potable or distilled water, starting with 26% water of 300g of cement.
2. Take care that the time of gauging is not less than 3 minutes, not more than 5 minutes and
the gauging shall be completed before setting occurs.
3. The gauging time shall be counted from the time of adding the water to the dry cement
until commencing to fill the mould.
4. Fill the vicat mould with this paste, the mould resting upon a non porous plate.
5. After completely filling the mould, trim off the surface of the paste, making it in level
with the top of the mould. The mould may slightly be shaken to expel the air.
6. Place the test block with the mould, together with the non-porous resting plate, under the
rod bearing the plunger (10mm diameter), lower the plunger gently to touch the surface
of the test block and quickly release, allowing it to penetrate into the paste.
7. 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 the standard consistency as defined above is
9. Express the amount of water as a percentage by weight of the dry cement.
PRECAUTIONS: Clean appliances shall be used for gauging. In filling the mould the operator
hands and the blade of the gauging trowel shall alone be used. The temperature of cement, water
and that of test room, at the time when the above operations are being performed, shall be 27 + 2
C. For each repetition of the experiment fresh cement is to be taken.