The amount of water content that brings the cement paste to a standard condition of wetness is called normal consistency. It has a marked effect upon the time of set as well as upon other properties of cement. The paste at normal consistency is fairly stiff and is used only for the determination of time of set and soundness of cement. It is necessary to fix the quantity of water to be mixed in cement while experimenting on it.
The normal consistency of a cement paste is defined as that consistency (% of water) which will permit the vicat plunger to penetrate to a point 10 mm from the top of the vicatmould. The usual range of values being between 22 to 30 percent by weight of dry cement. Normal consistency is also called standard consistency.
1.3 Reference Standard:
This test method conforms to the ASTM standard requirements of specification C187.
This test method is intended to be used to determine the amount of water (by % weight of dry cement) required to prepare hydraulic cement pastes for testing.
Necessity and Use of Normal Consistency:
Cement produced by different factories may not have same properties and so it is necessary to standardize the consistency using standard equipment.
The knowledge of normal consistency is required while performing other important tests such as setting time, soundness etc. as these tests are performed on cement paste using a certain percentage of water required for standard consistency.