Page 414 - Mechanics of Asphalt Microstructure and Micromechanics

T
406 Ch a p t e r w e l v e

25 psi is necessary to keep the membranes in good contact with the specimen. Stress
paths for IC, TC, TE, SS, CTC, and CTE tests were accomplished by simultaneous con-
trol of major, intermediate, and minor principal stresses as follows:
Isotropic compression (IC):
Δσ = Δσ = Δσ = Δσ
x y z

Triaxial compression (TC):
Δσ = Δσ, Δσ = Δσ =− 1 Δσ ; Δσ = Δσ, Δσ = Δσ =− 1 Δσ
x y z y x z
2 2
Δσ = Δσ, Δσ = Δσ = − 1 Δσ
z x y
2
Triaxial extension (TE):

Δσ =− Δσ, Δσ = Δσ = 1 Δσ ; Δσ =− Δσ, Δσ = Δσ = 1 Δσ
x y z y x z
2 2
Δσ =− Δσ, Δσ = Δσ = 1 Δσ
z x y
2

Simple shear (SS):
Δσ = 0, Δσ = Δσ, Δσ = − Δσ ; Δσ = 0, Δσ = − Δσ, Δσ = Δσ
x
x
y
z
y
z
Δσ = 0, Δσ = Δσ, Δσ = − Δσ ; Δσ = 0, Δσ = − Δσ, Δσ = Δσ
y x z y x z
Δσ = 0, Δσ = Δσ, Δσ = − Δσ ; Δσ = 0, Δσ = − Δσ, Δσ = Δσ
z y z z y z
Conventional triaxial compression (CTC):
Δσ = Δσ, Δσ = , Δσ = 0; Δσ = , Δσ = Δσ, Δσ = 0
0
0
x y z x y z
Δσ = 0, Δσ = 0, Δσ = Δσ
y x z
Conventional triaxial extension (CTE):
Δσ =− Δσ, Δσ = , Δσ = 0; Δσ = , Δσ =− Δσ, Δσ = 0
0
0
x y z x y z
Δσ = 0, Δσ = 0, Δσ = − Δσ
y x z
Cyclic conventional triaxial extension (CCTE):
The CTE test ran for a number of cycles.
Where Δs x , Δs y , Δs z are load increments and Δs > 0.
It should be noted that TC, TE, and SS tests are run at p = (σ +σ +σ )/3 = const or
x y z
on the π planes, planes that are normal to s x = s y = s z . The stress paths of these three tests
in the principal stress space are illustrated in Figure 12.10. There are three variations for
TC and TE stress paths respectively, and six variations for SS stress paths. Table 12.2 listed
all the stress paths that were followed in the test.