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DETERMINATIONOF DENSITY OF HYDRAULIC CEMENT

SIGNIFICANCE:

The value of specific gravity of cement is used in the design and control of concrete

mixture.

APPARATUS:

1. Le Chatelier flask 

2. Kerosene free of water or naphta, having a gravity not lighter than 62 API shall beused in the density determination.

3. Balance and Weights

PROCEDURE:

1. Fill Le Chatelier flask with kerosene, free of water or naphta to a point on the stem between zero and 1-ml mark.

2. Immerse the flask in a water bath of constant temperature maintained at ambienttemperature, for a sufficient time before making any reading.

3. Take initial reading.

4. Introduce into the flask the cement sample, at least 64 grams.

5. Remove air bubbles by gently rolling the flask with stopper and swirlingoccasionally.

CALCULATIONS:

1. The difference between the first and the final reading represents the volume of liquid

displaced by the mass of cement used in the test.

2. Calculate the cement density, p, in g/cm3 as follows:

 NOTE 1:

The density in g/cm3 is numerically equal to specific gravity.

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DETERMINATION OF FINENESS OF HYDRAULIC CEMENT

BY THE NO. 200 (0.075 mm) SIEVES

APPARATUS:

1. Sieves, Standard No. 100 (150-um) or No. 200 (75-um) sieves conforming to the

requirements of the AASHTO M – 92, for Wire Cloth Sieves for Testing

Purposes. Wire cloth for standard sieves for cement shall be woven (not twilled)from brass, bronze or other suitable wire and mounted without distortion on a

frame about 2 in. (50mm) below the top of the frame. The joint between the cloth

and frame shall be smoothly filled with solder to prevent lodging of the cement.The sieve frame shall be circular, 8 in. (203 mm) in diameter and provided with a

 pan and cover.

2. Balance – the analytical balance used in fineness determinations shall conform to

the requirements of 4.1 of AASHTO T – 105, for Chemical Analysis of HydraulicCement.

3. Brush – a 1 or 1 ½ in. (25 or 38 – mm) brush with a 10 in. (250 mm) handle is a

convenient size.

4. Weights

PROCEDURE:

1. Place at least 50 grams cement sample on the clean, dry No. 0.075 mm sieve with the

 pan attached.

2. Start sieving with a gentle wrist motion until most of the fine material has passed

through the sieve and the residue appears fairly clean for a period of 4 minutes.

3. Place the cover on the sieve and remove the pan. Then gentle top the side of the sieve

to dislodge dust adhering to the sieve. Brush also the underside of the sieve.

4. Empty the pan and wipe it. Then replace the sieve on the pan, and carefully remove

the cover. Return any coarse material that has been caught in the cover during the

tapping to the sieve.

5. Continuous the sieving without the cover as described in procedure #2 for 5 to 10

minutes depending on the condition of the cement. The gentle wrist motion involves

no danger in spilling the residue, which shall be kept well spread out on the sieve.Continuously rotate the sieve throughout the sieving. This open sieving may usually

 be continued safely for 9 minutes or more but take care that it is not continued too

long. Then, replace the cover and clean, following the same process as described in

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 procedure #2. If the cement is in proper condition, there should now be no

appreciable dust neither remaining in the residue nor adhering to the sieve or pan.

6. Make 1 minute tests as follows: Hold the sieve, with pan and cover attached, in one

hand in a slightly inclined position and move it forward and backward in the plane of 

inclination; at the same time gently strike the side about 150 times/minute against the palm of the other hand on the upstroke. Perform the sieving over a white paper.

Return any material escaping from the sieve or pan and collecting on the paper to the

sieve. After every 25 strokes, turn the sieve about one-sixth of a revolution, in thesame direction. Continue the sieving operation until not more than 0.05 gram of the

material passes through in 1 minute of continuous sieving. Then, transfer the residue

on the sieve to the balance pan, taking care to brush the sieve cloth thoroughly from

 both sides to ensure the removal of all the residue from the sieve.

7. Then transfer the residue on the sieve to the balance pan. Brush the sieve cloth

thoroughly from both sides to ensure the removal of all residues from the sieve.

COMPUTATION: