Experiment #1 Standard Or Normal Consistency Of Cememt 666t6v

EXPERIMENT NO. 1 Determination of standard or normal consistency of hydraulic cement 1.1 Purpose 

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The objective of this experiment is to determine the required amount of water to be added to a certain amount of cement to achieve a cement paste of normal or standard consistency, which refers to the amount of water for obtaining plastic cement paste. Cement paste of standard consistency is to be used for the determination of cement initial and final setting times; soundness; and tensile and compressive tests.

1.2 Reference The reference standards for this test are  

B.S 12 ASTM C-187-04

1.3 Apparatus        

Vicat apparatus having moveable plunger of 10mm diameter Spatula Steel plate Scraper Glass graduated cylinder Trowel Stopwatch Thermometer

1.4 Materials  

Amount of cement = 500 g (BS 12) Clean water

1.5 Test Specifications 

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The cement paste must be properly mixed and placed in the test specimen within a maximum time of 4±1/4 min from the instant when cement and water were initially brought in . The temperature of the air in the vicinity should be between 20-27.5 °C. The temperature of the mixing water should be 23±2 °C. The relative humidity of the laboratory should not be less than 50%.

1.6 Related Theory 1.6.1 Cement In BS 12-1996, cement is defined as cement is a hydraulic binder, i.e. it is a finely ground inorganic material which, when mixed with water, forms a paste which sets and hardens by

means of hydration reactions and processes and which after hardening, retains its strength and stability even under water. Cement conforming to this standard shall, when appropriately mixed with aggregate and water, be capable of producing mortar or concrete which retains workability for a sufficient time and shall after defined periods attain specified strength levels and also possess long-term volume stability. 1.6.2 Normal/Standard Consistency of Cement It is defined as the percentage of water by weight of cement, required to produce cement paste showing the penetration of plunger with dia 10mm by a value of 10mm ± 1mm below the original surface in 30 seconds after being released. 1.6.3 Vicat Apparatus It consists of the following: 1. 2. 3. 4.

Ruler starting from 0 to 40mm which is the height of the mould Mould Non-porous plate Plunger

Inside dia of the ring at bottom = 70mm ± 3mm Inside dia of the ring at top = 60mm ± 3mm Height of the ring = 40mm ± 1mm

Fig 1.1 Vicat Apparatus

1.7 Procedure   

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   

Mix 500g of cement with a measured quantity of water and make a cement paste as per the standard procedure. Put the cement paste in the ring of the Vicat apparatus and remove the excess paste with the help of a trowel. Center the paste confined in the ring, resting on the plate, under the rod B, Fig. 1, the plunger end C of which shall be brought in with the surface of the paste, and tighten the set-screw E. Then set the movable indicator F to the upper zero mark of the scale, or take an initial reading, and release the rod immediately. This must not exceed 30 s after completion of mixing. The apparatus shall be free of all vibrations during the test. The paste shall be of normal consistency when the rod settles to a point 10mm ± 1 mm below the original surface in 30 s after being released. Make trial pastes with varying percentages of water until the normal consistency is obtained. Make each trial with fresh cement. Experiments have found that the %age of water added to obtain normal consistency is about 22% to 30% of the amount of cement

1.8 Observations & Calculations Type of cement: Ordinary Portland Cement Manufacturer: Maple leaf Room temperature = 20°C Water temperature = 23°C Relative Humidity = 52.54%

Sr. No.

Weight of Cement W1

Weight/ Volume of water W2

%age of water= (W2/W1)*100

Penetration of plunger

1 2 3

g 500 500 500

1g = 1mL 120 130 135

% 24 26 27

mm 9 11 12

1.8.1 Interpolation for 10mm Penetration 14

Penetration (mm)

12 10 8 6 4 2 0 23.5

24

24.5

25

25.5

26

26.5

27

27.5

%age of water

Fig 1.2 From the interpolation of the data we get the standard consistency of cement against 10mm penetration of plunger as 25% 1.9 Precautions 

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 

The cement paste must be properly mixed and placed in the test specimen within a maximum time of 4±1/4 min from the instant when cement and water were initially brought in . The temperature of the air in the vicinity should be between 20-27.5 °C. The temperature of the mixing water should be 23±2 °C. The relative humidity of the laboratory should not be less than 50%. There should be no vibration on the working table. The plunger should be cleaned during every repetition

1.10 Comments  

The test conditions i.e. temperature and relative humidity were close to the standard conditions. The obtained normal consistency of cement is 25% which is in the range 22 to 30%