Deep mixing technique to reinforce Loire levees are currently used. The techniques were implemented with dedicated trench-cutting equipment rotating so that cut-off wall could be continuous in the levee structure and its foundation. It resulted in a mixture between the soil in place, a hydraulic binder and water. Several formulations are tested for the soils of the levees and their foundation. Indeed, hardening issues appeared locally, on part of Orleans levee, linked to the presence of organic soils. It led to experiment several lime-cement formulations in the laboratory. Subsequently, the best soil-fitted formulation was tested in the lab and applied on site to validate the implementation. This included testing new control timeframes in terms of permeability and mechanical resistance. The properties of the deep mixing material were assessed by testing clay-cement materials, treated at different cement and water contents. Permeability and strength parameters were confronted to their physico-chemical and microstructural characteristics in order to explain the variations of the mechanical properties and better understand the behaviour of natural soils treated with this technique. In addition, differences appear between mixture built on site and in the laboratory in terms of hydraulic and mechanical properties but also in terms of soil inclusions.