Determination of Specific Gravity of Coarse and Fine Aggregates
Determination of Specific Gravity of Coarse and Fine Aggregates
Determination of Specific Gravity of Coarse and Fine Aggregates
JOB NO: 6
Determination of the Specific Gravity of the Coarse & Fine Aggregate
(ASTM C 127)
(ASTM C 128)
6.1 Objective:
To determine the property of aggregate
To determine the specific gravity of aggregate
To determine the water absorption of aggregate
Coarse Aggregates
Fine Aggregates
The aggregate which is retained on ASTM sieve # 4 (4.75 mm) is known as coarse
aggregate.
The aggregate which is passing ASTM sieve # 4 (4.75 mm) is known as fine aggregate.
6.2.4 Absorption:
It is the increase of the mass of aggregate due to the addition of the water into the aggregate
is called absorption. The term absorption does not include the amount of water adhering to the
surface of the particles. Water absorption is expressed as percentage of the dry mass.
6.2.5 Saturated surface dry condition:
It is the condition of the aggregate particles in which the permeable pores of the aggregate
particles are filled with water but there is no water on the surface of the particles.
It is the mass of the saturated surface dry aggregate per unit volume of the aggregate particles.
The term volume includes the volume of the permeable and the impermeable pores which are filled
with water and does not include the volume of the voids between the particles.
It is the mass of the oven dry aggregate per unit volume of the solid portion of the aggregate.
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It is the ratio of the density of the aggregate to the density of the water at the 4 0 C is called as
relative density.
It is the ratio of the saturated surface dry density of the aggregate to the density of the water at
a standard temperature (i.e. 40 C).
It is the ratio of the oven dried density of the aggregate to the density of the gas free distilled
water at a standard temperature (i.e. 4o C).
It is the ratio of the apparent density of the aggregate to the density of the gas free distilled
water at a standard temperature (i.e. 40 C).
6.3 Apparatus:
6.3.1 Coarse:
Container to soak aggregate
Weighing balance
Wire mash Bucket
Water container
Oven
6.3.2 Fine:
Container to soak aggregate
Weighing balance
Oven
Stove
Pycnometer
6.4 Procedure:
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Then put the same aggregate on wire mesh and dip the bucket into the water.
Take the weight of aggregate in water.
C = weight of aggregate in water
Now take the aggregate out of water and oven dry it and weight it.
B
S.G SSD = BC
A
S.G app = AC
( B A)100
% age Absorption = A
6.4.2 Fine aggregate:
First of all take about 500 g of aggregate, including equal quantities of all fractions.
Dry to a constant weight at a temperature of 100 to 110C.
Allow to cool and cover with water for about 30 min.
Remove excess water and spread on a flat surface. Expose to a gentle moving flame until
test sample approaches a free-flowing condition.
Place a portion of the fine aggregate sample loosely into the mold. Tamp lightly 25 times and
lift the mold vertically. If surface moisture is present, the fine aggregate will maintain its
molded shape. Continue drying and testing until upon removal of the mold, the aggregate
slumps slightly. This indicates that the saturated, surface-dry condition has been reached.
Immediately introduce into the pycnometer 500 g of the fine aggregate. Fill the pycnometer
almost to capacity and eliminate the air bubbles by agitation. Add water until the bottom of
the meniscus is at the 500 cm3 line, reach on the pycnometer. Determine the total weight of
the flask, including the sample, and the water.
Carefully remove the fine aggregate and dry to a constant weight of 100 to 110C and cool
for at least 30 min. and weight it.
A
S.G oven dry = B+500C
500
S.G SSD = B+500C
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A
S.G app = BC+ A
% age Absorption =
(500 A)100
A
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6.6Precaution:-
Weight the sample carefully.
Avoid loss of sample.
Experiment should be performed according to requirement
6.7Comments:-
From experiment it is noted that the percentage absorption of fine
aggregate is more than coarse aggregate.
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