The specific gravity of fine aggregate, which is commonly known as sand, refers to the measurement of the weight of a certain volume of the aggregate compared to the weight of an equal volume of water. The specific gravity of sand is typically considered to be around 2.65.
Apparatus for Specific Gravity Test
The equipment required for this task includes a balance with a minimum capacity of 3kg, which is able to provide a reading accuracy of 0.5 gm. This balance should be suitable for weighing the vessel containing both the aggregate and water. In addition, a well-ventilated oven capable of maintaining a temperature range between 100ºC and 110ºC is necessary.
A pycnometer with a capacity of around 1 litre is also required for this task. The pycnometer should have a metal conical screw top, which features a 6mm hole at its apex, and must be watertight. A means of providing a current of warm air is also necessary, as well as a tray with a minimum area of 32cm².
To carry out this task, an airtight container, which is large enough to take the sample, is also required. Filter papers and a funnel are also necessary components of the equipment needed for this task.
Standard Pycnometer Apparatus
Procedure of Test
To determine the density of a sample, take about 500g of it and put it in a pycnometer. Fill the pycnometer with distilled water until it is completely full. Eliminate any trapped air by rotating the pycnometer on its side while covering the hole in the apex of the cone with a finger. Wipe the outer surface of the pycnometer clean and weigh it, which we’ll call W.
Transfer the entire sample from the pycnometer to a tray, being careful to ensure that all of the aggregate is transferred. Refill the pycnometer with distilled water to the same level as before. Find out the weight of the pycnometer with the water in it, which we’ll call W1.
Drain the water from the sample by filtering it through a filter paper. Then, place the sample in an oven in a tray and set the temperature to between 100ºC to 110ºC for approximately 24 hours, stirring occasionally to facilitate drying. Once the sample has dried, allow it to cool and then weigh it again, which we’ll call W2.
Calculations
The apparent specific gravity is a measure of the density of a substance relative to the density of water. It is calculated by dividing the weight of a dry sample of the substance by the weight of an equal volume of water. Mathematically, this can be expressed as the ratio of W2 (weight of dry sample) to (W2 – (W – W2)), where W is the weight of water required to fill a container to a certain volume.
By using this formula, we can determine the apparent specific gravity of a substance without directly measuring its density. The weight of the dry sample is divided by the weight of the water displaced by the sample, which provides an indirect measure of the sample’s density. This calculation assumes that the volume of the sample is equal to the volume of water displaced by the sample.
The apparent specific gravity is an important property that can be used to identify and characterize different substances. It is commonly used in industries such as oil and gas, pharmaceuticals, and cosmetics, where accurate measurements of density are essential for quality control and product development. The apparent specific gravity is also used in various scientific and engineering applications, such as in the design of materials and structures.
Question :
What is the unit of Specific gravity of Fine Aggregate ? Comment your answers below.