What is Specific Gravity of Fine Aggregate (Sand)?
Specific gravity of fine aggregate(sand) is defined asthe ratio of theweightof a given volume ofaggregatestotheweightof equal volume of water. Thespecific gravityoffine aggregate(sand) is considered to be around 2.65 to 2.67.
Sandparticles composed of quartz have a specific gravity between2.65 to2.67. While inorganic clays generally range from2.70 to 2.80.Soils with large amounts of organic matter or porous particles (such asdiatomaceous earth) have specific gravity below 2.60 (Some range as lowas 2.00).
What is Specific Gravity of Aggregates?
Thespecific gravity of an aggregate is considered as the measure of strength orquality of the material. Specific gravity is defined as the ratio of weight of agiven volume ofaggregate to the weight of equal volume of water. Aggregateshaving low specific gravity are generally weaker than those with aggregateshaving high specific gravity. This property helps in a general identificationof aggregates.
Hifriends,you are welcomed in the world ofCivil Allied Gyan. Readhere definition, apparatus list, IS code, test procedure, formula and labreport about determination of specificgravity of fine aggregate.
Apparatus Required for Specific Gravity Test of Fine Aggregate:-
- Pycnometer bottle of 1000ml capacity
- Taping rod
IS Code of Test for Specific Gravity of Fine Aggregate:-
- IS:2386 (Part-3): 1963, Methods of test for aggregates for concrete (Determinationof Specific Gravity of aggregates)
Procedure for Specific Gravity Test of Fine Aggregate:-
- Take a clean, dry pycnometer and determine its empty weight(W₁g).
- Take a clean sample of fine aggregate (about 1kg) for whichspecific gravity is to be find out and transfer that to the pycnometer andweight (W₂ g).The aggregates finer than 6.3mm are taken.
- Pour distilled water in the pycnometer with aggregatesample at the temperature at 27 ºC, to just immerse sample.
- Immediately after immersion, remove the entrapped air fromthe sample by shaking or rotating the pycnometer, placing a finger on the holeat the top of the sealed pycnometer.
- Wipe out the outer surface of pycnometer. Now the pycnometeris completely filled up with water till the hole at the top, and afterconfirming that there is no more entrapped air in pycnometer, weight it (W₃ g).
- Transfer the aggregate of the pycnometer into a try carebeing taken to ensure that all the aggregate is transferred.Clean the pycnometer.
- Refill the pycnometer with distilled water up to the top ofthe pycnometer, without any entrapped air. It should be completely dry from outside andtake the weight (W₄ g).
- For mineral filler, specific gravity bottle is used and thematerial is filled up to one-third of the capacity of bottle. The rest of theprocess of determining specific gravity is similar to the one described above.
Table: Observation Table forSpecific Gravity of Fine Aggregate
Trail No. 2
Weight of pycnometer in air (W₁ g)
Weight of pycnometer+ Fine aggregate (W₂ g)
Weight of pycnometer + water + Fine aggregate (W₃ g)
Weight of pycnometer+ water in air (W₄ g)
Apparent Specific Gravity:
(W₂ – W₁) / (W₂ – W₁) – (W₃–W₄ )]
Formulafor specificgravity of fine aggregate:-
TheSpecific gravity of fine aggregate is =……………
- The specific gravity of aggregates normally used inconstruction ranges from around 2.5to 3.0 with an average value of about 2.68.
- Specific gravity of aggregates is considered as anindication of strength. Aggregates having higher specific gravity are generallyconsidered as having higher strength and aggregates having low specific gravityare generally considered as having weaker strength.
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