Self – Levelling Underlayment (SLU) is one of the high-performance new materials used in the construction industry. Besides the strength, other characteristics of SLU such as workability, rapid drying, rapid hardening, shrinkage compensation, smooth nature, etc. are required depending on the application. The aim of this study is to evaluate the structuration with the time of SLU through some important characteristics such as the evolution of rheological properties, ettringite, and gibbsite phase development. To this purpose, a rheometer with rotation mode and oscillation mode was used to determine the yield stress, plastic viscosity, rheological dynamic modulus (storage modulus and loss modulus). The use of these techniques is considered to be a method for monitoring structuration development in cement materials. The result shows that during the hydration process, increased plastic viscosity, yield stress, and dynamic modulus of the SLU were identified from just 5 minutes after mixing until the setting period when the transition from a fluid state to a solid-state of SLU takes place. By using a rheometer in oscillation mode, the beginning of the transition process from the liquid-state to the solid-state of SLU was identified, this method is more precise when compared to traditional Vicat method.