محمود حامد عليمحمد

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Abstract : The purpose of this experiment is to determine the normal consistency of standard

paste cement using Vicat apparatus.

That means this test is intended to be used to determine the amount of water required

to prepare hydraulic cement pastes for testing .

Introduction :

The principle of doing this test is : standard consistency of cement is that consistency

at which the Vicat plunger penetrates to a point 5-7mm from the bottom of Vicat

mould.

We will use that device to determine the consistency of the our cement sample in order

to know how much percent of water is required to make the right standard cement .

Some definitions :

- Consistency of cement :

It refers to the ability of cement to flow & it means amount of water needed to

prepare a plastic mix of cement .

- consistency test :

This test is used to find the amount of water to be mixed with cement . It is

necessary to find the consistency because amount of water present in the cement paste

may affect the setting time.

- Vicat apparatus :

A penetration device used to determine the setting characteristics of hydraulic

cements.

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Materials & Equipment :

- Cement .

- A sensitive scale to take a specific amount of cement .

- Water ( distilled ) .

- A graduated cylinder to take a specific amount of water.

- Vicat apparatus :

It consists of a Release pin & Hard rubber mould . Figure 1. Shows the standard

Vicat device that is required in the BS standard ( EN 196-3: 1994) .

Figure 1. Vicat device

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Series of the Procedures That We Have Done in the Lab :

- We have prepared a paste of weighed quantity of cement ( 400gm ) with

weighed quantity of patable or distilled water. ( starting with 27% of water)

- We have added the water & counted from the time of adding water to the dry

cement until commencing to fill the mould & the paste started to form . we have

checked that it’s less than 3 minutes ( we did it in 4 minutes ).

- We have filled the Vicat mould with this paste resting upon a non-porous plate.

- We have Smoothened the surface of the paste, making it level with the top of

the mould .

- We have slightly shaken the mould to expel the air .

- After that, We have Immediately placed the test block with the non-porous

testing plate, under the rod bearing the plunger of the vicat device .

- We have lower the plunger gently to touch the surface of the test block and

quickly release, allowing it sink into the paste .

- We have recorded the depth of penetration.

- We have cleaned the plunger after finishing .

- We have repeated the test using varying percentages of water ( 29% & 31% )

and continued the test as described above until the plunger is 5 mm to 7 mm

from the bottom of the Vicat mould .

Data recorded : Table.1 readings

Water percentage Water amount ( ml ) Depth of penetration (mm)

27 % 108 33

29 % 116 22

31 % 124 6.5

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Notes after reading the standards :

- In the BS standard , The test should be done at a temperature of (20 2)

& the humidity is less than 65 % . Our test condition was far away from these

numbers .

- In order to not losing any amount of water, BS standards required that the

adding-water time should be between 5 seconds & 10 seconds .We didn’t do

that in the lab . We spilled the water in a less time .

- BS standards required a ( Distilled or deionized water ) to use in the test ,

unfortunately we didn’t have that , so we did the experiment with a normal

water .

Discussion :

Our test result is not so far from the true value, although errors were made in the

procedure by not following our standard requirements.

Conclusion:

31% of water is the required amount of water to have a consistence cement paste , the

reason for that is we get a 6.5 mm (which is between 5 & 7 mm) in that percent of

water-adding.

& Refernces : tandards S

- BS EN 196-3 : 1994 [ Methods of testing cement ]

- ASTM ( C 187 – 98 ) [ Standard Test method for Normal Consistency of cement ]

- Definitions : Wikipedia .