Normal Consistency of Cement

Normal consistency of hydraulic cement lab

Objectives :
Determine normal consistency of hydraulic Portland cement in accordance with standard specifications.

Materials Used :
A provided sample of dry Portland Type II Cement was used. 
Distilled water was also used.

Apparatus Used :
      1. Vicat Apparatus .
      2. Graduated Cylinders.
      3. Mixers .

Procedure :
a) Place all the mixing water in the mixing bowl.
   b) Add the cement to the water and allow 30 s for the absorption of water.
   c) Start the mixer and mix at slow speed (140 rpm) for 30 s.
   d) Stop the mixer for 15 s; during this rest period scrap down into the batch any paste that may have collected on the sides of the bowl.
   e) Start the mixer at medium speed (285 rpm) and mix for 1 minute.
Note: Approximately 170 g of mixing water is a good starting point to determine the normal consistency of the cement.
2. Quickly form the cement paste prepared above into the approximate shape of a ball with gloved hands. Then toss six times through a free path of about 6 inches from one hand to the other producing a nearly spherical ball shaped mass.
3. 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. Remove the excess at the larger end by a single movement of the palm of the hand. Place the ring on its larger end on the glass plate, and slice off the excess paste on the smaller end at the top of the ring by a single oblique stroke of a sharp edge trowel. Smooth the top if necessary.
4. Center the paste specimen under the 10 mm end of the Vicat apparatus. Lower the movable rod until the 10 mm end makes contact with the paste. Zero the indicator. Release the movable rod. A “normal consistency” is obtained when the penetration, below the original surface after 30 seconds, is 10 mm +/- 1 mm.
5. Repeat this process, using fresh cement, with varying percentages of water until the normal...