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Noel Le CE 221LArevik Sargsyan Date assigned: October 9thSasha
Kornilova Date completed: October 16thCesar Flores
Weekly Progress Report #3 (Lab #7,9)
Objective
Part 1:To determine the specific gravity and absorption of a
coarse aggregate
sample. The specific gravity may be expressed as bulk specific
gravity (Gsb), bulk
specific gravity SSD (Gsb SSD), or apparent specific gravity
(Gsa).
Part 2: To determine the bulk unit weight and voids in aggregate
in either a
compacted or loose condition.
Background:
A. Bulk Specific Gravity (Gsb) (also known as Bulk Dry Specific
Gravity):
The ratio of the weight in air of a unit volume of aggregate at
a stated
temperature to the weight in air of an equal volume of gas-free
distilled water at a
stated temperature (Fig. 1). This unit volume of aggregates is
composed of the
solid particle, permeable voids, and impermeable voids.
; where:
Figure 1: Diagram of Bulk Specific Gavity
A = Oven dry weight.B = SSD weight.C = Weight in water.
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B. Bulk SSD Specific Gavity (GsbSSD):
The ratio of the weight in air of a unit volume of aggregate,
INCLUDING the
weight of water within the voids filled to the extent achieved
by submerging in
water for approximately 24 hours, to the weight in air of an
equal volume of gas-
free distilled water at room temperature (Fig. 2).
; where:
Figure 2: Diagram of Bulk SSD Specific Gravity
C. Apparent Specific Gravity (Gsa):
This ratio of the weight in air of a unit volume of the
IMPERMEABLE portion of
aggregate (does not include the permeable pores in aggregate) to
the weight in
air of an equal volume of gas-free distilled water at a stated
temperature (Fig. 3).
; where:
Figure 3: Diagram of Apparent Specific Gravity
B = SSD weight.C = Weight in water.
A = Oven Dry weight.C = Weight in water.
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D. Absorption (%Abs):
The increase in weight of aggregate due to water in the pores of
the material, but
not including water adhering to the outside surface of the
particles (Figure 4).
; where:
Figure 4: Increase in Mass Due to Absorption of Water
E. Bulk Unit Weight of Aggregate:
The bulk density of aggregate is needed for the proportioning of
portland cement
concrete mixtures. The bulk density may also be used to
determine the
mass/volume relationships for conversions in purchase
agreements.
where:F. Percentage of Voids Within Aggregate Sample:
The percentage of voids between the aggregate particles
can also be determined, on the basis of the obtained bulk
density.
whereTest procedure:
1. Immerse the aggregate in water at room temperature for a
period of 24 hrs.
2. Remove the test specimen from water and roll it in a large
absorbent cloth until
all visible films of water are removed. Wipe the larger
particles individually.
A = Oven Dry weight.B = SSD Weight
M = Bulk Unit Weight of Aggregate kg/m3(lb/ft
3)
T = Weight of Measure kg (lb)V = Volume of Measure m
3 ft
3
M = Bulk Unit Weight of Aggregate kg/m3(lb/ft
3)
S = Bulk Specific Gravity (dry basis)W= Unit Weight of Water 998
kg/m
3(62.3 lb/ft
3)
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3. Weigh the test sample in saturated surfacedry condition, and
record it as B
using lab scale (Fig. 5). Record this weight and all subsequent
weights to the
nearest 0.5 g or 0.05% of the sample weight, whichever is
greater.
4. Place the specimen in the wire basket and determine its
weight while it is
submerged in water and record it as C. Take care to remove all
entrapped air
before weighing it by shaking the container while it is
immersed.
5. Dry the test sample to a constant weight (oven dry), record
this weight as A
using coarse aggregate gravity apparatus (Fig. 6).
Figure 5: Lab Scale Figure 6: Coarse Aggregate Gravity
Apparatus
Data:
Part 1:
Trial A [kg] B [kg] C [kg]
1 2.650 2.675 1.660
Part 2:
Trial Height of
Measure [in]
Diameter
Measure [in]
T [kg] G [kg]
1 6-1/8 6-1/16 1.560 6.050
A = Weight of Oven Dry Specimen in AirB = Weight of SSD Specimen
in AirC = Weight of SSD Specimen in Water
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Calculations:
Part 1:
Bulk Specific Gravity: Bulk SSD Specific Gravity: Apparent
Specific Gravity: Absorption:
Part 2:
Volume of Measure:
[
]
Bulk Unit Weight:
() *
+*
+* +
Results:
Bulk Specific Gravity (Gsb) 2.611
Bulk SSD Specific Gravity (GsbSSD) 2.635Apparent Specific
Gravity (Gsa) 2.677
Absorption () 0.943%Volume of Measure (V) 0.102 [ft ]
Bulk Unit Weight (M) 25.52[lb/ft3]
% Voids 85.45%
Conclusion:
These calculations demonstrate the relationship between Gsb,
GsbSSD, and Gsa.
The Gsb(bulk specific gravity) will always be the lowest value
since the volume
calculated includes voids permeable to water. The GsbSSD (bulk
specific gravity
at SSD) will always be the intermediate value, and the
Gsa(apparent specific
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gravity) will always be the highest, since the volume calculated
includes only the
"solid" aggregate particle (does not include those voids
permeable to water).
