Table 12. Specific setups for coarse fractions
for the pouring test. (After Ishai and Tons
Supports
1977.)
Dimensions
Coarse fractions
(cm)
12.7 to 15.9 mm
#3 to #4
Bin
c
Bin diameter
16.0
16.0
Funnel orifice diameter
3.0
1.44
Aggregate head
12.0
12.0
Pouring height
21.0
21.0
D
b
Container diameter
12.2
10.3
Funnel
Container height
15.2
11.8
a
Bead diameter (avg.)
16.0
6.0
volves allowing the fine aggregates to freely fall
Bin Shutter
into a calibrated cylinder from a specified height.
Large Pan for
The exception here is that the aggregates are not
Particle Collection
H
separated into various sieve sizes, as is done with
the other index tests. The test for fine aggregates
is designated by ASTM as Test Method C 1252.
φ
The weight of aggregate and the bulk specific
Container
h
gravity are used to calculate the uncompacted
void content:
H = Pouring Height
D
=
Bin Diameter
M
φ = Container Diameter
a
=
Funnel Office Diameter
Vcyl -
h = Container Height
c
=
Bin Height
Gsb
b
=
Aggregate Head
UVC =
100
Vcyl
Figure 14. Schematic description of the pouring device.
(After Ishai and Tons 1977.)
where UCV = uncompacted void content (%)
Vcyl = volume of cylinder (cm3)
angular and rougher. Also shown in the figure is
M = mass of aggregate in cylinder (g)
the effect of aggregate size on the specific rugos-
Gsb = bulk specific gravity of aggregates.
ity. The value of the specific rugosity increases as
the size of the material decreases.
UCV increases with increasing angularity and
roughness of the aggregates. Aldrich (1996) mod-
Uncompacted voids in aggregates
ified this test for coarse aggregates. A schematic
This test method is similar to the specific rug-
of his test apparatus is shown in Figure 16. The
osity test. Initially developed for fine aggregates
coarse aggregate for the test passed the 19-mm
by the National Aggregate Association, it in-
sieve and was retained on the #4 sieve. The test
25
Natural Gravel (#3 to #4)
Crushed Gravel (#3 to #4)
20
Limestone (#3 to #4)
Beach Pebbles (#3 to #4)
15
10
Natural Gravel (1/2 to 3/8 in.)
Crushed Gravel (1/2 to 3/8 in.)
5
Limestone (1/2 to 3/8 in.)
Beach Pebbles (1/2 to 3/8 in.)
0
2.1
2.2
2.5
2.6
2
2.3
2.4
2.7
2.8
Packing Specific Gravity (Pouring), Gpx
Figure 15. Packing specific gravity and rugosity for different aggregates.
14
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