Bulking of sand – The increase in volume of sand due to presence of surface moisture up to certain extent is known as Bulking of sand. Bulking is caused due to the formation of thin film of surface moisture around the sand particles which tends to push the particles apart due to surface tension. Fine sand bulks much more than the coarse sand. It is observed that with the moisture content of 5 to 10 % by weight, the increase in the volume of sand varies from 25% to 50% depending upon the fineness of sand. Normally beyond this percentage of moisture content, bulking of sand tends to decrease.
