Palm oil fuel ash (POFA) in both cost-effective and environmentally friendly ways has
potential applications in soft soil stabilization. This study investigates the possible uses
of POFA (individually and in combination with cement) on several basic characteristics
of clayey soil behavior, such as proctor compaction, Atterberg limit, and unconfined compression
strength (UCS). These properties are compared with those of unstabilized clay and
stabilized clay with cement. Scanning electron microscopy with X-ray microanalysis is
conducted on untreated and treated soil to elucidate their strength development, and
the observed test results are then explained. Findings show that POFA and POFA/cement
mixture treatments result in significant reductions in the soil plasticity index (PI). The
results of the compaction test indicate that the utilization of POFA and POFA/cement mixture
in soft soil stabilization decreases the optimum moisture content and increases the
maximum dry density across selected binder dosages. The results show that using POFA
alone to stabilize clayey soil results in a slight increase in the UCS of the specimens until
the 28 days of curing, whereas combining POFA with cement results in a sharp increase
in the UCS of the samples in the same curing time. The results demonstrate the environmental,
technological, and economic advantages of utilizing this well known agricultural
waste as a partial substitute for cement in stabilizing soils, particularly soft soils that usually
demand high quantities of stabilizer to reach satisfactory results