Egypt has witnessed tremendous development in its
infrastructure over the last decades. The problems of expansive
soils seem to be overlooked during the design and construction of
some of the projects. As a result, some houses and roads were
demolished. In this study, soil samples were taken from New
Sohag City (town in Upper Egypt). The physical and mechanical
properties of the natural soil were obtained. Then the soil was
treated with chemical additives (Addicrete P) 0.5%, 1% and 2% by
dry weight of soil. After treatment of soil the properties of samples
were investigated at different times. The main results show that
with increase of Addicrete P Plastic limit increases and liquid limit
decreases, hence decreases plasticity index. As the amount of
additives is increased, there are apparent reductions in optimum
moisture content, unconfined compressive strength, and free
swell, swelling potential and swelling pressure, and a
corresponding increase in maximum dry density and continue to
increase or decrease over time. This study established optimum
dosage levels for each of the treated additives. Based on the results
obtained, it can be concluded that the expansive soil can be
successfully improved by Addicrete P