The standard consistency of cement is that consistency, which permit the vicat plunger to penetrate to a point 5 to 7mm from the bottom of the vicat mould when tested. Procedure to determine the quantity of water required to produce a cement paste of standard consistency is described below.

Determination of Standard Consistency of Cement

Apparatus for Standard Consistency

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 any one of the following attachment, which are interchangeable:

1. Needle for determining the initial setting time
2. Needle for determining the final setting time
3. Plunger for determining the standard consistency

2. Needles

Needle for Initial Setting Time

The needle is having a cross sectional area of 1mm2. The end of the needle is flat.

Needle for FInal Setting Time

The needle is circular having a cross sectional area of 1mm2. The needle is fitted with a metal attachment. The end of the needle projects beyond the cutting edge of the hollowed out metal attachment.

Plunger for Standard Consistency

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. Movable Rod

Movable rod carries an indicator which moves over a graduated scale attached to the frame (certain models have an additional attachment of dash pot, which facilitates lowering of movable rod slowly).

4. Graduated Scale

Graduated scale is 40mm in length and the smallest division of scale is 1mm.