Table 1. Classification properties of test soils.
Silt, some fine sand.
Some coarse to fine
gravel, trace coarse to
medium sand (glacial till).
Fine sand, some silt.
Coarse to fine gravelly,
coarse to medium sand,
trace fine sand.
Coarse to medium sand,
little fine sand.
Clayey silt (marine
except for the marine clay. Tests at 20C were dis-
tended dwell times at peak pressure, and a vari-
continued for all materials, with the exception of
ety of predetermined totals of compaction counts.
the marine clay. A minimum of two tests were con-
It has been used at our laboratory for asphalt speci-
ducted at each temperature.
mens, and was retrofitted to make the 2.8-in.-diam.
and 6-in. soil samples. A procedure was developed
(see App. A) to reproduce uniform density and
moisture samples. The test specimens were fabri-
cated at optimum moisture and density. This was
accomplished by applying a known kneading
pressure to the specimen through a tamping foot
by means of a controlled dynamic force. As the
kneading pressure was applied, the sample rotated
on the compactor's rotating table. The rotation was
electronically timed to the tamper foot.
A brief summary of the test method is presented
here. Details on the sample preparation and test-
ing method can be found in Appendix B. Vertical
and radial deformations, confining pressure, de-
viator stresses and temperatures were measured
during the test. Vertical deformations were mea-
sured using linear variable displacement transduc-
ers (LVDTs). Radial deformations were measured
ers (VITs). Three multi-VITs were used for the
measurements. Temperature was measured using
thermistors in dummy samples located in the en-
vironmental chamber. A typical setup is shown in
Figure 4. For the resilient modulus tests, the tem-
peratures used for testing ranged from room tem-
perature +20, +0.5, 0.5, 2, 5, and 10 C.
The 0.5 C test temperatures were of particular
interest for the thawing process. Several tests were
conducted at 20C, and we found that the resil-
Figure 3. Kneading compactor used for fabricating test
ient modulus was similar to that obtained at 10C,