Table 5. Compressive strength of CFG ice held in a thermal gradient. The distances given are
measured from the ice surface to the bottom of the brick.
Distance from ice
Distance from ice
Average
Uniaxial
surface at the start
surface at the end
temperature of
compressive strength
the layer (C)
(cm)
(cm)
(MPa)
0
5
0.9
2.65
5
0
0.9
7.26
10
5
3.5
4.71
15
10
3.5
4.22
20
15
6.6
4.61
25
20
6.6
4.71
30
25
10.2
4.51
recrystallization, but crystal sizes remain relatively
consistently lower strength values than any of the other
small (less than 1 mm) even at the warm temperatures
CFG ice samples, except the embedded and partially
at this level.
recrystallized sample. Further investigation of these
The compressive strength was measured for the
observations would be useful to try to identify the cause
seven lowest bricks, and the values are given in Table
of this apparent anomaly.
5 along with the approximate average temperatures
over the last 14 days of the test period. The results are
PART 3. MICROSTRUCTURE
inconclusive. The measured strength of the bottommost
brick, embedded in newly formed snow ice, is roughly
the same as that of the snow ice cut from the ice cover
Solid state sintering has received considerable
as shown in Table 2. The brick immediately above it
attention in recent years because of its importance in
gave a measured strength nearly that of the other CFG
the manufacture of metals, ceramics, and cements. The
ice measured in this study, while the remaining bricks,
ideal raw material is fine-grained (to increase the speed
up to about 25 cm above the final ice surface, gave
of sintering or lower the temperature for effective
0.6
0.4
0.2
0
0.01
0.1
1
5
10
20 30
50
70 80
90 95
99
99.9
99.99
Percent
Figure 15. Grain size distribution of CFG ice. Dimensions were obtained using the linear
intercept method.
11
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