Mitigation of Collapse of Gypseous Soil by Nano-Materials

The objective of this study is to investigate the effect of fly ash and silica fume as nano-materials on the collapsibilityof disturbed gypseous soilbrought up from Salah El-Deen Governorate with gypsumcontent (58 %) collected at depth (1.0) m below the natural ground surface. Gypseous soil is a problematic soil due to its high-water sensitivity. In dry state, this soil shows relatively high apparent strength, however, when water flows through it or saturated by rainwater, the gypsum in these soils are leached out, so there are many problems can be occurred to the structures that built on making them prone to subsidence. Since permeability and chemical composition of these soils are varying in time due to the solubility and leaching of gypsum. Therefore, the properties of this type of soils must be studied and improved. The effect of adding fly ash and silica fume on collapsibility of gypseous soil using three crushed percentages (1, 2, and 4) % by weight of the dry gypseous soil were studied. The results of single collapse tests marked that (2) % of fly ash and (4) % of silica fume decreases the collapsibility sharply, more than 83 % of improvement in collapse potential has been achieved at these optimum percent of fly ash as nano-material.