Soil collapse occurs when increased moisture causes chemical or physical bonds between the soil particles to weaken, which allows the structure of the soil to collapse. Collapsible soils are generally low-density, fine-grained combinations of clay and sand left by mudflows that have dried, leaving tiny air pockets. When the soil is dry, the clay is strong enough to bond the sand particles together. When the clay becomes wet, moisture alters the cementation structure and the soil's strength is compromised, causing collapse or subsidence. Based on soil type and density, the potential for encountering collapsible soils throughout most of the project alignment is low.Conditions in arid and semi‐arid climates like Borg El Arag, near Alexandria Egypt favor the formation of the most problematic collapsible soils.The behavior and performance of compacted sand replacement over treated collapsible soil by pre-wetting and compaction is investigated in the current study. Field investigation was performed in the form of plate loading tests conducted on compacted sand replacement over improved collapsible soil. Field plate load tests program was developed to explore effect of compacted sand replacement thickness on collapsibility potential. Treated collapsible soil was replaced with imported cohesion-less soil with variable thickness up to footing width. Results proved that improvement of collapsible soils by sand / crushed stone replacement is possible to control /mitigate their risk potentials against sudden settlement when exposed to a source of water.