SPECIFIC GRAVITY OF CEMENT
To determine the specific gravity is normally defined as the ratio between the weight of a given volume of material and weight of an equal volume of water.To determine the specific gravity of cement, kerosene which doe snot recent with cement is used.
Le Chaterlier”s flask, weighing balance, kerosene (free from water).
Le Chaterlier”s flask, is made of thin glass having a bulb at the bottom. The capacity of the bulb is nearly 250 ml. The bulb is 7.8 cm in mean diameter. The stem is graduated in millimeters. The zero graduation is at a distance of 8.8 cm from the top of the bulb. At 2 cm from the zero, there is another bulb is of length 3.5cm and capacity 17 ml. At 1 cm from bulb, the stem is marked with 18 ml and is grated up to 24 ml. The portion above 24ml mark is in the form of a funnel of diameter 5cm.
(I) Dry the flask carefully and fill with kerosene or naphtha to a point on the stem between zero and 1 ml.
(II) Record the level of the liquid in the flask as initial reading.
(III) Put a weighted quantity of cement (about 60 gm) into the flask so that level of kerosene rise to about 22 ml mark, care being taken to avoid splashing and to see that cement does not adhere to the sides of the above the liquid.
(IV) After putting all the cement to the flask, roll the flask gently in an inclined position to expel air until no further air bubble rise3s to the surface of the liquid.
(V) Note down the new liquid level as final reading.
OBSERVATION AND CALCULATIONS
(I) Weight of cement used =W gm
(ii)Initial reading of flask =V1 ml
(iii)Final reading of flask =V2 ml
(iv)Volume of cement particle= V2-V1 ml
(v)weight of equal of water= ( V2-V1) x specific weight of water.
Specific gravity of cement = (Weight of cement/ Weight of equal volume of water)
(I) Duplicate determination of specific gravity should agree within 0.01.
(II) To get more accurate result, the flask should be held in a constant temperature before each reading is taken.
Specific gravity of a sample of cement =