Scope:

ASTM C329 is used to determine the specific gravity or relative density of Ceramic Whiteware Materials. Specific gravity is useful in quality control of Ceramic Whiteware Materials. If a substance’s relative density is less than 1 then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal.

Test Procedure:

The powdered sample is placed in a glass weighing bottle and dried to constant weight at 105 to 110°C. The bottle is closed with a glass stopper immediately after removing it from the oven.

The pycnometer and stopper are dried at 105 to 110°C, cooled to room temperature, weighed on an analytical balance, and their weight is recorded as p. The pycnometer bottle is filled with distilled water at room temperature, t1. A stopper is inserted, and excess water is removed on the tip of the capillary using filter paper. The pycnometer and its contents are weighed and their weight is recorded as W1. Next, the Pycnometer is emptied and dried.

Inside the dried pycnometer, 8 to 12 g of the dried specimen are placed; pycnometer, stopper, and specimen are weighed and their weight is recorded as W. Distilled water is added to the pycnometer until the bottle is half full. To remove entrapped air, the specimen and water are thoroughly stirred with a glass rod. Then the glass rod is removed. The specimen and water are then subjected to reduced air pressure. After evacuation with distilled water at room temperature, t2, the bottle is filled, the stopper is inserted, and the excess water on the tip of the capillary is removed using filter paper. Pycnometer and contents are weighed and their weight is recorded as W2.

 Specimen size:

Two pieces, totaling 100 to 150g, should be removed from different portions of the material in such a way as to exclude skin surfaces as much as possible. The pieces are crushed, if necessary, between two steel surfaces. A quarter of the sample, 25 to 50g will be isolated and any magnetic material introduced during crushing will be removed. The sample is then ground in a suitable mortar so that it will pass a 150-µm (No. 100) sieve.

Data:

The specific gravity with respect to water is calculated as follows:

Specific gravity = d2d1 (W – p)/
0.999973 [d2 (W1 – p) – d1(W2- W)

Where,
d1 = absolute density of water at temperature t1.
d2 = absolute density of water at temperature t2.
p = weight of the stoppered pycnometer.
W= weight of the stoppered pycnometer and specimen.
W1 = weight of the stoppered pycnometer filled with water.
W2 = weight of the stoppered pycnometer, specimen, and water.