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,the
period of drying is depends to the sample, and visual experience, some time it may dry at 18 hours but
often the best result will get in 24 hours.Absorption: the increase of the mass of aggregate due to water in the pores if the material, but not including water adhering to the outside surface of the particle. when aggregate called dry which be in temperature of 110 0 (with tolerance of 5 degree) at sufficient time.
specific gravity :the ratio of the mass ( or weight0 of a unit volume of of a material to the mass of the same volume of water at stated temperature, value is dimensionless.
Apparent specific Gravity : the ratio of the weight in air of a unit volume of aggregate( included the permeable and impermeable voids in the particles, but not including the voids between the particles) at stated temperature to the weight in air of an equal volume of gas-free distilled water at a stated temperature. ((it uses for very fine aggregates and some where use for liquid materials))
Bulk Specific Gravity : the ratio of the weight in air of a unit volume of aggregate, including the mass of water within the void filled to the extend achieved by submerged in water for approximately 15 hours ,at stated temperature, compared to the weight in air of an equal volume of gas-free distilled water at stated temperature. ((It uses for dry aggregate conditions or assumed dry aggregate)).
Balance 2. Sample Container 3. Water Tank 4. Suspended Basket 5.Seives
Sampling for this test is as described in the ((Sampling)) page ,and or use the ((T2)) classification in AASHTO guide book. After sampling be sure to take such amount which represents the whole sample, for this ,it can be use the Splitter or Divider . After that pass the sample form sieve No 4( 4.75mm),to avoid the final error in mass of the sample.
1. Dry the sample at standard temperature
,the
period of drying is depends to the sample, and visual experience, some time it may dry at 18 hours but
often the best result will get in 24 hours.
2. After drying it must be cooled in room temperature (about 25),until the sample be suitable to carry in hand (about 50°). record the mass of the aggregate and then immerse the sample to water which its temperature is normal(25 degree) for a period of 14-19 hours .
3.After mentioned time take out the sample from water and put them on a cotton cloth, and roll them on cloth until its shiny reflect be removed from the surface of the aggregate ,for bigger aggregate individually wipe them ,but avoid the aggregate to evaporate the inner water in aggregate ,try to just dry the surfaces (which it called saturated surface dry (SSD) ) ,A normal cooling machine (like fun) can help dry the aggregates faster.
4.Record the mass of the sample (SSD) ,and immediately place the sample, in Basket which is suspended in the water and Record the mass of the sample in water. It is important that density of the water be natural water density(997 kg/m3), water temperature must be about 23-25°.
5.Take out the sample from basket and dry the sample in Standard
temperature,and
cool in room air temperature. and determine the mass of the sample.
for more pictures and Procedure about S.G Please Click Here
before getting Start be sure to sieve the sample by No 4 (4.75 mm) in order to avoiding the error in determination of S.G
during immersing the sample in water be sure to exert all air voids between the aggregates by shaking the basket in water
1. Bulk Specific Gravity: ( For Detail sample Calculation (Fine agg. ) click Here )
using the following formula to find the Bulk specific gravity
where : A = Mass of oven-dry test sample in air
B = Mass of saturated -surface-Dry test sample in air
C = Mass of saturated test sample in water
2.Apparent Specific Gravity:
3. Absorption:
1. Report the S.G to the nearest 0.01 digit, and indicate the type of the S.G ( whether is Bulk, SSD ,or Apparent).
2.Report the absorption result to the nearest 0.1 percent.
3. If S.G and absorption values were determined without first drying the aggregate, it shall be noted in the report.