Learn to find Specific gravity of Fine Aggregates with detailed procedure, tabulation column.
THEORY:
Aggregates are divided into two categories based on consideration of size.
1) Aggregates whose size is greater than 4.75mm is considered as Coarse Aggregates.
2) Aggregates whose size is 4.75mm and less is considered as fine aggregate.
The specific gravity of an aggregate is defined as the ratio of the mass of a given volume of sample to the mass of an equal volume of water at the same temperature.
The specific gravity is generally required for calculations in connections with concrete mix design, for determination of moisture content and for the calculations of volume yield concrete. The specific gravity also gives information on the quality and properties of aggregates. If the specific gravity is above or below that normally assigned to a particular type of aggregate, it may indicate that shape and grading of aggregate has altered.
Water absorption influences the behavior of aggregates in concrete in several important aspects. A highly absorptive aggregate if used in dry condition will reduce effective water cement ratio to an appreciable extent and may even make the concrete unworkable unless a suitable allowance is made. Hence determination of absorption of aggregate is necessary to determine net water cement ratio.
APPARATUS:
1) Fine Aggregate
2) Pycnometer
3) Distilled Water
4) Tray
5) Weighing Balance
PROCEDURE:
1)Take 1/4th of sample and place it in the Pycnometer.
2) Pour distilled water into it until it is full.
3) Eliminate the entrapped air by rotating the Pycnometer on its side, the hole in the apex of the cone being covered with a finger.
4) Wipe out the outer surface of Pycnometer and weigh it.
5) Transfer the contents of the Pycnometer into a tray, care being taken to ensure that all the aggregate is transferred.
6) Refill the Pycnometer with distilled water to the same level and record the weight.
9) Calculate Specific Gravity with the formula
