This research investigates the shear strength characteristic of lime and flyash
stabilized clay. Research consists of two processes: identifying soil properties
and observing shear strength characteristic of soil. Observing shear strength
characteristic had done by doing direct shear test. Initially, the optimum values of
lime mixture were observed, samples were the soil mixture with 4%, 6%, and 8%
of lime content. The optimum percentage of lime was used to create other
variation by mix it with certain amount of fly-ash: 10%, 15%, and 20%. Research
found that that all samples with 4%, 6%, or 8% of lime content have increasing
cohesion value (c) along the time curing periods. In the other hands samples that
mixed with 6% Lime and 10% Fly-ash; 6% Lime and 15% Fly-ash; 6% Lime and
20% Fly-ash shows that the cohesion value is decreasing along the time curing
periods. Soil samples that mixed with lime only additive have decreasing friction
angle value (ɸ) along curing periods but, all samples that added with lime and flyash
show the increasing value of friction angle along the time curing. The result of
direct shear test shows that sample booth lime only also lime and fly-ash sample
indicates the improvement of shear strength (τ). The shear strength of clay which
is added by lime mixed with fly ash is provides better result than lime only
additive. Result of direct shear concludes that clay with 6% Lime and 15% Flyash
content provides optimum value of shear strength (τ) which is reaching 0,629
kg/cm2.