A residential subdivision is planned on a site underlain by highly expansive montmorillonite clay. The geotechnical report warns that the shrink-swell cycles will severely damage the shallow foundations and pavements. The engineer specifies lime stabilization to alter the clay's fundamental behavior.

While cation exchange occurs rapidly (within hours), the same lime-treated subgrade from Case Study 1 must also serve as a strong structural layer for the roadway base. The engineer must ensure long-term strength gain.

A contractor is building an access road over a deposit of non-plastic sandy silt. The material is too weak in its natural state to support heavy construction equipment. The contractor must decide whether to use lime or Portland cement for stabilization.

A large highway project requires the stabilization of miles of marginal clayey gravel subgrade. The budget is extremely tight, and traditional Portland cement is deemed too expensive for the required volume. A local coal-fired power plant produces large quantities of Class C fly ash.

A large liquid natural gas (LNG) storage tank is to be built on a coastal site underlain by 15 meters of loose, saturated silty sand. Dynamic compaction is ruled out due to nearby sensitive structures. The engineer specifies Wet Deep Soil Mixing to create a cellular grid of stabilized soil to prevent liquefaction.

A deep excavation for a subway station is required in a dense urban area. The site consists of very soft, highly sensitive clay with a high natural water content ($w_n > 80\%$). Traditional sheet piles would likely fail due to the extremely low shear strength of the clay. The engineer specifies Dry Deep Soil Mixing to create a gravity retaining wall.