Abstract:
Clay shale is a type of soil found in the
construction of several roads in the northern and southern
regions of Thailand. This study is part of a long-term
project of the Deparment of Highways dealing with the
properties and stabilization of clay shale for use as a
materials for low volume road in the remote area.
The clay shale sample used in this study is from Km.
115+475 to Km. 115+687 on the right side of Chiengmai-Chieng
Dao-Fang Highway in the northern region of Thailand. Lime
used in the study is quicklime.
The relationship between the UCS and Unsoaked CBR
of lime-stabilized clay shale at 2 3 4 5 and 6 percent
lime tended to be a face-down parabola curve for all curing
periods. This indicates that at lime content greater than
an appropriate amount the UCS values tend to be reduced while
the CBR values shows the trend of increasing for all lime
contents, curing periods, and energies of compaction. The
vertex of this face-down parabola curve indicated that at
lime content of approximately 4 percent, the value of UCS
tends to be maximum.
The relationship between UCS and Unsoaked CBR of
lime-stabilized clay shale for the age of curing of 3 7 14
and 28 days for all lime contents tends to be a face-up
parabola curve. It is shown that at a curing age less than
14 days, the value of UCS would be fluctuated, and for the
curing age greater than 14 days the UCS value would change
significantly, while the unsoaked CBR value would increase
steadily for all ages of curing for both standard Proctor
and modified Proctor compactions.
The reason for this phenomenon is probably due to
the pozzolanic reaction which is regarded as a long-term
reaction begins to arise at the curing age of 14 days. So
in considering using lime-stabilized clay shale as a road
construction material, the CBR value should be a major
factor to be considered associated with the value of the UCS.
This is due to the fact the samples for the unconfined
compressive test could be easily made both during and after
construction as compared to those for The CBR test.
The parabola curve showing the relationship between
an UCS and an unsoaked CBR for the modified compaction test
had a higher slope value than the standard compaction test,
showing that an increase in compaction energy will give
greater effect to the value of UCS than the unsoaked CBR.