Mitigation of collapse of marshes soil by nano silica fume

Abstract

Marshes are water areas in the south of Iraq and cover about (35000) Km2. Because of its strategical and economic importance in addition to tourism, this study is important. In recent years, many of problems had been observed in many structures constructed on marshes soils due to complex collapsible behavior of such soils. The soils of the marshes are considered as weak soil. This fact comes along because of water table being near the ground level or above it which is usually a fine sand and silty sand. The objective of this study is to investigate the effect of silica fume as Nano-materials on the collapsibility of disturbed marshes soils brought up from Alchibayish area (Thi-Qar) Governorate and Alhalfaiya area (Messan) Governorate collected at depth (1.0) m below the natural ground surface. All fundamental tests were performed on these soils. The effect of adding Nano silica fume on collapsibility of marshes soil by using three different percentages by weight of the dry marshes soil (1, 2, and 3) % were studied. The results of single collapse tests marked (3) % of Nano silica fume decreases the collapsibility sharply; more than 50 % of improvement in collapse potential has been achieved at these optimum percent of silica fume as Nano-material. Where considerable reduction is observed in compressibility by (45-50) % for marshes soil. In laboratory tests, results showed that these soils have high collapsibility and that the shear parameters increase when treated with Nano silica fume.