Figure 23. Effect of percent crushed aggregate, sample size, and void ratio on the maximum shear stress

300

0

250

300-mm, Sigma 3 = 36 kPa

300-mm, Sigma 3 = 71 kPa

50

150-mm, Sigma 3 = 36 kPa

150-mm, Sigma 3 = 70 kPa

Figure 23. Effect of percent crushed aggregate, sample size, and void ratio on the maximum shear stress.

Table 14. Shear strength as a function of

Table 13. Shear strength material properties from

percent crushed aggregates, void ratio, and

150-mm sample tests.

specimen size.

Test

Void

Void

Sample

ratio

(kPa)

crushed

ratio

(kPa)

The effect of void ratio on the angle of internal fric-

tion for the 150-mm-diameter samples is that, with

increasing void ratio, the angle of internal friction

decreases (Fig. 24). This is in line with results for sands

ials and shear strength. The angle of internal friction

in the literature. However, with the 300-mm samples,

for base course materials is not significantly affected

it appears from the limited data that the effect on the

angle of internal friction (φ) is at most small when there

when there is at least 50% crushed aggregate. There is

significant difference between 100% natural material

is at least 50% crushed material present in the mixture.

and material with at least 50% crushed aggregate.

There is a significant difference between the 100% natu-

ral material and mixtures containing at least 50%

crushed aggregates.

PARTICLE INDEX TESTS

In summary, based on large-scale triaxial tests, the

The particle index (PI) test is based on the idea that

void ratio of the mixture has a significant effect on the

void ratio and rate of void change are affected by the

shear strength of base course aggregates. There is no

aggregates' shape, angularity, and surface texture. The

direct correlation between the percent of crushed mater-

18

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