Problematic soils such as expansive soil are those clay soils which exhibited
significant volume changes as results of soil moisture variation, when a dry mass of
clay is allowed to absorb water, the effective size of particles increases and therefore
the clay mass swells. This type of soil, upon wetting and drying, causes sever damage
to structures built on such soil.
A treatment of swelling/shrinkage using silica fume was studied in this work. The
soil selected for the present investigation classified as (CH) according to unified soil
classification system with liquid limit = 51% and plastic limit = 27%. Soil specimens
were mixed with various percentages of silica fume contents (10%, 20%, 25%, 30%
and 50%) to determine their effects on geotechnical properties such as Atterberge’s
limits, compaction, unconfined compression and swelling properties.
The results show that the silica fume played an important role in improving the
problem of swelling behavior in expansive soil. The silica fume decrease liquid limit
and changed compaction parameters of expansive soils the moisture content values
increased and the maximum dry unit weight values decrease. Also the silica fume
increased unconfined compressive strength, decreased the compressibility and the
vertical swelling percentages of clayey soil-silica fume mixtures.