Treatment of collapsible soils by mixing with iron powder

Collapsible soils are meta-stable soils which present a potential for a large deformation and a complete change to the whole particle structure after wetting, with or without loading. Such soils can show high apparent strength in its natural state but collapse takes place as the bonds between grains break down when the soil is wetted or loaded. There are several techniques for treatment of collapsible soils such as chemical stabilization and dry mixing the soil with other material/materials which improve the soil's mechanical properties. This paper discusses a new proposed technique for treating the collapsible soils by dry mixing with iron powder in a specified percentage proportional to the weight (Ad). Experimental tests program was performed on collapsible soils with/without the addition of iron powder. The analysis of results showed the effect of the initial unit weight of soil γd, and the percentage of the weight-related additives on collapse potential (CP). The testing program also presents the effects of the amount of induced rainfall water (Qw), the applied stress on footing model (q), the ratio between depth of improved soils and the footing width (di/B), as well as the degree of compaction (Rc) of the improved portion of collapsible soils. This study presents the obtained results and shows in detail the positive effect of using iron powder for treating the collapsible soils and subsequently reducing the expected collapse settlement. Keywords: Treatment of collapsible soils, Experimental study, Iron powder, Reduction ratio, Soils suctio