Sand Testing WasherNKW

Dry the sand to be tested by keeping at 105 deg.C ± 5 deg. for 1 to 2 hours, or by using a quick moisture tester. After drying, keep the sand in a desiccator for until cooling. Take a sample of 50 g by weighing with a balance of sensitivity of 1/100 g. Put it in a beaker and add 475 ml of distilled water at 20 to 25 deg.C and 25 ml of caustic soda solution (30 g of caustic soda diluted in 970 ml of water). Place the motor carefully above the beaker and stir well the solution for approximately 10 minutes. Pour water into the beaker to wash down all the sand adhering to the wall and adjust the volume of the total solution to be about 15 cm deep. After stirring well, keep still the solution for 10 minutes. Then pump out the top layer of solution until the level becomes 2.5 cm above the bottom.

Again add water of 20 to 25 deg.C up to the depth of 15 cm, stir well, hold for 10 minutes, and pump out the top water to the depth of 2.5 cm. Repeat the same process, whereas now pumping may be done after 5 minutes of holding, until the top water becomes clear. Then the sand remained on the bottom is filtered using a Buchner funnel and a filtering paper of about 9 cm in diameter. Transfer the filtered sand in a dish together with the filtering paper for thorough drying at 105 deg.C ±5 deg. and cooling in a desiccator . After cooling to room temperature, weigh the sand. The difference of weight before and after washing is doubled to obtain the percentage of clay content in the sand.