Theory:

Standard consistency of cement pest is defined as that consistency  which permits vicate plunger to penetrate a point 5 to 7 mm from the bottom of the vicate mould. In this test standard consistency is also called normal consistency. Certain or minimum quantity of water to be mix with cement so as to complete chemical reaction between water and cement. Less water than its quantity couldn’t complete chemical reaction. Thus, resulting is reduction of strain and more water would increased water cement ratio and so would reduce its strength.

Application:

The knowledge of standard consistency is require while performing other test such as setting time, soundness, compressive strain etc. As this test are perform on cement test using percentage of water require for standard consistency.
Item Required:
  1. Vicat apparatus with plunger 10 mm diameter.
  2. Weighing balance with weight box.
  3. Trawel.
  4. Measuring glass 200 ml
  5. Clean platform to make cement paste.
  6. Cement sample 3-4 kg.
  7. water.

Procedure:

The vicate mould was placed on the porous plate, filled mould with cement paste. Smooth the surface of the plate making thick level with the top of the mould. Shake the mould slightly to remove the air gaging time between 3 to 5 min. The paste block in the masid together with non-porous plate was placed under the required plunger of 10 mm diameter. The plunger was gently touched the surface of the paste block and quickly released allowing it sink into the cement paste. The penetration of the needle from the bottom of the mould indicate on the scale was plated. Same procedure was repeated until the amount of water necessary for making standard consistency (which permits plunger to penetrate to a point 5 mm to 7 mm from bottom of the mould) was determined.

Precaution:

  1. Clean the apparatus will be used.
  2. Mixing of cement to water should be within 3 to 5 mm.
  3. Vicat plunger released without jerk.
  4. Vicat mould with cement paste must be kept on the non-porous plate or tile.

       Diagram:


      


Calculation:

1.     Percentage of water = Volume of water/quantity of water X 100
                                     = 75/300 X 100 = 25 %

2.     Percentage of water = Volume of water/quantity of water X 100
                                     = 90/300 X 100 = 30 %

3.     Percentage of water = Volume of water/quantity of water X 100
                                     = 105/300 X 100 = 35 %

4.     Percentage of water = Volume of water/quantity of water X 100
                                     = 107/300 X 100 = 35.66 %

5.     Percentage of water = Volume of water/quantity of water X 100
                                     = 110/300 X 100 = 36.66 %

Observation :

Sr. No.
Quantity of cement
Volume of water
Penetration of plunger from bottom
% percent of water
1
300 gm
75   ml
28 mm
25 %
2
300 gm
90   ml
23 mm
30 %
3
300 gm
105 ml
13 mm
35 %
4
300 gm
107 ml
11 mm
35.66 %
5
300 gm
110 ml
7   mm
36.66 %


Conclusion:

For given sample of cement the standard consistency is achived with water percentage.

Result:

The percentage by weight of water with respect to cement to produce standard consistency is 36.66 %