Experiment-02 Preparation of a cement paste of

Standard Consistency.

Reference

O ASTM C 187

Objective/Theory

O Consistency is a measure of wetness or fluidity of a cement.

O The main purpose of the consistency test is to determine the

required quantity of water to obtain a standard or

homogeneous paste ,and water quantity is enough to

hydration process

O The standard consistency of a cement paste is defined as

that “consistency which will permit the vicat plunger to

penetrate to a point 10 ± 1 mm below the original surface in

30 s after being released”

Apparatus 1. VICAT APPARATUS

• The vicat apparatus consists of a frame having a movable

rod with a cap at one end and at the other end the

attachment, which are interchangeable.

2. PLUNGER FOR STANDARD CONSISTANCY

• It is of polished brass 10 ± 0.05mm in diameter with a

projection at the upper end for insertion into the movable

rod. The lower end is flat.

3. GRUADUATED SCALE

• Graduated scale is 40mm in length and the smallest

division of scale is 1mm

4. VICAT MOULD

The vicat mould is in the foam of a frustum of a cone having

an internal diameter of 60 ± 0.5mm at the top, 70 ± 0.5mm at

the bottom and height 40 ± 0.5mm.

Apparatus

Vicat’s Apparatus

With accessories

Procedure

1. Mix 650 g of cement with a measured quantity of water and

smooth the top, with a few light touches of the pointed end

of the trowel.

2. Quickly form the cement paste into the approximate shape

of a ball with gloved hands.

3. Then toss six times through a free path of about 150 mm (6

in.) from one hand to another so as to produce a nearly

spherical mass that may be easily inserted into the Vicat

ring with a minimum amount of additional manipulation.

4. Press the ball, resting in the palm of one hand, into the

larger end of the conical ring held in the other hand,

completely filling the ring with paste.

Procedure

5. Remove the excess at the larger end by a single

movement of the palm of the hand.

6. Place the ring on its larger end on the base plate and

slice off the excess paste at the smaller end at the top

of the ring and smooth the top.

7. During these operations of cutting and smoothing, take

care not to compress the paste.

8. Center the paste confined in the ring, resting on the

plate, under the rod, the plunger end of which shall be

brought in contact with the surface of the paste, and

tighten the set-screw .

Procedure 9. Then set the movable indicator to the upper zero mark of

the scale, or take an initial reading, and release the rod

immediately.

10. This must not exceed 30 s after completion of mixing.

11. The apparatus shall be free of all vibrations during the

test.

12. The paste shall be of normal consistency when the rod

settles to a point 10 ± 1 mm below the original surface in

30 s after being released.

13. Make trial pastes with varying percentages of water until

the normal consistency is obtained. Make each trial with

fresh cement.

OBSERVATIONS AND CALCULATIONS

Weight of cement taken (g) = _________

Sr. No

Weight OF WATER

ADDED

(g)

Amount of water

(%)

Depth of

penetration

(mm)

O Standard Consistency

=(Quantity of water for 10 ± 1 penetration from Top

Surface of mould /Weight of cement) X 100

Significance of Testing

O This method is intended to be used to determine the

amount of water required to prepare hydraulic cement

pastes for testing.