Research about stabilization of clay with many kind of stabilizers such as
cement, lime soil, cane pulp ash are commonly done. However, study of clay
stabilization soil is still interesting subject to be investigated. This research
investigates the shear strength of fly ash stabilized clay which is due to cohesive
value (c) and friction angle value (Ф).
The research divided into 2 steps of test, for the initial test in order to find
the OMC (Optimum Moisture Content) condition of clay, this step covers clay
characteristics test (water content test) and standard proctor test (compaction
method). The second step is triaxial test, in order to find the shear strength of clay
stabilized with fly ash. The percentage of fly ash which is added is: 0%; 15%,
20%, 25%, and 30%. By using Mohr circle, the cohesive value (c) and friction
angle value (Ф) can be found.
The results of the research are: clay reach the optimum moisture content
when added with 901.54 ml of water, and reach the maximum shear strength when
added fly ash as much as 30% with 2 kg/cm2 pressure given. Exchange of positive
ion between clay and fly ash results the change of friction angle value (Ф),
whereas hydration reaction get the increment of cohesive value (c). Friction angle
value reach the optimum value on 7th day of curing time, and cohesive value
increment determined by fly ash addition and curing time period. By fly ash
addition, the shear strength of clay increases.