Since 2000, the use of soil mix walls for the construction of retaining structures has become increasingly popular in Belgium and in the Netherlands. In practice, however, each supplier of these walls had its own approach for the design and execution. There was a lack of generally accepted requirements and criteria regarding the soil mix walls. For this reason, designers and contractors have been asked to pool knowledge and experience with such structures. The result was published in 2018 under the form of the BBRI/SBRCURnet Handbook Soil mix walls, referred as the handbook in the present paper. Nevertheless, if this handbook provides a lot of information regarding the durability of the soil mix material and requirements for the permanent soil mix walls, the readers find in this publication few information regarding the mix design that is generally considered by the practice as a trade secret. In the present paper, the authors still provide some practical thoughts regarding the compliancy rules for the mixing water and the types of cement/binder which can be used for permanent soil mix walls considering the potential degradation phenomena which can arise with time due to the nature of the concept.