| Abstract | The strength and deformation characteristics and the time dependent behaviour of the
cement treated Bangkok clay were studied through comprehensive series of unconfined
compression and oedometer tests. The base clay used were lightly overconsolidated soft
Bangkok clay, at a depth of 3 to 4 m from AIT campus. Type I Portland cement powder was
used to stabilize the soft clay and cement content of 150 and 200 kg/m3
were used. Both dry
and slurry mixing were used for Unconfined Compression Test and Oedometer Tests. For
Unconfined Compression Tests, curing period of 3, 7, 14, 28, 60, 90 and 120 days, w/c ratio
of 0.5, 0.6, 0.8, 1.0, 1.2 were used. For oedometer tests, curing period of 7, 28, 60 and 90 days
with w/c ratio of 1.0 were used.
The unconfined compressive strength of cement treated sam~les were found to increase
with curing time. For dry mixing, cement content of 150 kg/m could be regarded as an
optimum cement content for long term curing period. Strength increment of sluny mixed
samples reduce with increase in w/c ratio. Oedometer tests revealed that the cement treatment
caused substantial improvement of consolidation properties, apparent preconsolidation
pressure, reduction of compression index (Cc), increase the value of coefficient of
consolidation (Cv)ยท. Coefficient of permeability of cement treated soil is smaller than the
untreated soil, and hence it is not suitable as material for vertical drain.
As compared with previous research from AIT, laborato1y studies on the use of various
additive to soft Bangkok clay indicated that cement is the most superior additive in achieving
higher strength within the optimum specific time of curing.The improved strength of treated
samples are dependent on strength and physical prope1ties of untreated clay, mixing method,
sample preparation, sample curing method, curing time, w/c ratio and cement content.
Unconfined compressive strength of treated samples from the same location can differ a lot
depending on sample preparation and curing method |