Table 5. Modified testing sequence for VAOT base/subbase
material.
Confining Maximum Cyclic
Contact Number of
Sequence
pressure axial stress stress
stress
load
no.
(kPa)
(kPa)
(kPa)
(kPa)
applications
0
103.4
103.4
93.1
10.3
5001000
1
68.9
68.9
62.0
6.9
100
2
68.9
137.9
124.1
13.8
100
3
68.9
206.8
186.1
20.7
100
4
103.4
68.9
52.0
6.9
100
5
103.4
103.4
93.1
10.3
100
6
103.4
206.8
186.1
20.7
100
7
137.9
103.4
93.1
10.3
100
8
137.9
137.9
124.1
13.8
100
9
137.9
275.8
248.2
27.6
100
10
34.5
34.5
31.0
3.5
100
11
34.5
68.9
62.0
6.9
100
12
34.5
103.4
93.1
10.3
100
larger than 19 mm was removed and replaced with an
Ws
Vs =
(7)
Gsγ w
equal amount of material passing the 19-mm sieve and
retained on the 4.75-mm sieve. The sample was prepared
in 150-mm lifts at the prescribed moisture content and
where Ws = weight of solids (dry weight of sample)
γw = density of water
compacted in accordance with AASHTO TP-46. The test-
ing sequence was as prescribed in Table 2 of AASHTO
Gs = specific gravity of solids (aggregate mix-
TP-46 and is reproduced here as Table 6. The sample
ture).
conditioning, data acquisition, and post testing were sim-
The void ratio (e) can be rewritten as
ilar to the large-scale samples.
Ws
Ws
Ws
-
Vt -
Results
γ
Gsγ w
Gsγ w
Vv
e=
=
= d
The resilient modulus is defined as
Ws
Ws
Ws
Gsγ w
Gsγ w
Gsγ w
σd
Mr =
(5)
εr
Ws
Ws
1
1
where Mr = resilient modulus
-
-
γ
Gsγ w
γ
Gsγ w
σd = deviator stress
= d
= d
εr = resilient strain.
Ws
1
Gsγ w
Gsγ w
(8)
The resilient modulus was determined as an average of
the last five measurements of the deviator stress and resil-
where Vt = total volume and γd = dry density.
ient strains as shown in Figures 12 and 13. In addition to
The optimum and test densities, void ratios, and tar-
dry density and moisture content, the void ratio (e) was
get moisture contents for the test samples are presented
calculated for each test specimen prior to testing, as fol-
in Table 7. Relative densities ranged from 0.95 to 1.05,
lows:
with most around 0.98. This provided an opportunity
to quantify the effect of density on the resilient and shear
Vv
e=
Air
(6)
properties. Target moisture contents ranged from 4.6 to
Vs
Vv
5.4%. At the end of the test, some standing water was
Water
found at the bottom of some of the test samples.
VT
Average resilient modulus results from the individ-
ual tests are presented in Appendix A. In a triaxial test,
Ws
Solid
Vs
bulk stress or the first stress invariant (θ) is defined as
θ = σ1 + 2σ3
where Vv = volume of voids and Vs = volume of solids.
= σd + 3σ3
(9)
9
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