1000
25%
75%
0%
100%
50%
100% Crushed, e = 0.268
75% Crushed, e = 0.231
50% Crushed, e = 0.231
Figure 17. Resilient modulus as
25% Crushed, e = 0.221
a function of bulk stress and
0% Crushed, e = 0.187
aggregate angularity, 150-mm-
100
diameter samples.
1000
100
Bulk Stress, θ (kPa)
tests were conducted at a constant strain rate of 1% per
1000
minute. Typical stress and strain results are shown in
Figure 19. Tests were conducted at approximately 35
kPa or 70 kPa confining pressure. The measured σ3f
and τmax are presented in Table 12. The angle of inter-
100
nal friction and cohesion was obtained from Mohr
circles; examples are shown in Figures 20 and 21. As
seen in Table 12, the angle of internal fricton (φ) varied
150-mm, e = 0.27
between 31 and 51, with the 100% natural material
300-mm, e = 0.16
100% Crushed
having the lowest value. We were unable to calculate
10
shear properties for the 0% natural (100% crushed) and
75% natural (25% crushed) material from the tests
because of the large difference in void ratios between
1000
the two samples. Based on the other test results, we
estimated the angle of internal friction for the 100%
crushed material with a void ratio of 0.16 to be about
51 or higher. There is some apparent cohesion of mater-
ial and this cohesion was the highest for the 100% natu-
100
ral material (Table 12).
A similar set of results from the 150-mm-diameter
specimens are presented in Table 13. The angle of inter-
150-mm, e = 0.23
nal friction varied between 41 and 46 for void ratios
50% Crushed
300-mm, e = 0.19
around 0.22. For the 100% natural material (void ratio
10
of 0.18), the angle was 53. Note that for the 300-mm-
diameter samples, φ was smallest when the percentage
1000
of crushed material was zero. In this case, φ is highest
when the percentage of crushed material is zero.
The maximum shear stress (τmax) and the angle of
internal friction are more a function of void ratio and
less a function of percentage of crushed material as
100
shown by the results plotted in Figures 22 and 23. In
Figures 22 and 23, the values next to the figures indi-
150-mm, e = 0.18
cate the percentage of crushed material in the aggre-
300-mm, e = 0.14
gate mixture. Clearly, from these results the percent-
0% Crushed
age of crushed material has no direct correlation to the
10
maximum shear stress. Another observation made with
10
100
1000
Bulk Stress (kPa)
the 300-mm-diameter samples tests (Fig. 22) is that the
effect of the higher confining pressure (70 kPa) tends
Figure 18. Effect of specimen size on resilient modulus.
15
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