SUN7 is a fundamental research project, dedicated to Material Science. It aims at developing advanced experimental methods and characterization tools to monitor in-situ the phenomena occurring during setting and hardening of calcium phosphate cements for bone repair. This liquid-tosolid transition is indeed the key-point for successful biomedical applications, since it governs all functional properties, including the ease of handling by surgeons and mechanical and biological properties of set cements. In this framework, we intend to precisely characterize the setting process at different scales and with complementary quantitative methods. This global approach will permit to assess the chemical evolution and its reaction rate, the structuring of the paste, as well as the progression of its rheological and mechanical properties. Another important aspect of SUN7 is the 3D monitoring of microstructural features of a setting paste, using electron and X-ray tomography. This characterization in 4D (3 spatial + 1 time-related dimensions) will bring an unprecedented understanding of crystal growth and entanglements and of the formation of porosities during the setting process. Then, all results will be correlated to draw a global multiphysics and multiscale picture of setting and hardening processes. To do so, the impact of the different experimental methodologies on the setting process will be assessed; complementary in-situ approaches will be developed and, when possible, coupled. Finally, SUN7 will permit a thorough understanding of the whole process and of its kinetics. All experimental methods will first be developed and validated using gypsum plaster as a model material. Thus, this project will not only bring a comprehensive knowledge on setting of cements for bone repair, but will also be useful for a wide range of applications, including plaster and cements used in civil engineering. More generally, SUN7 will shed light on all studies related to the structuring of a mineral paste. Such a liquid-to-solid transition occurs, for instance, during the fabrication of ceramics or is sought for 3D impression. The development of advanced characterization methods in complex and specific environment (humidity, temperature) is another expected outcome of the project. Finally, the knowledge gained thanks to SUN7 will then have a strong impact to improve the biomaterials, which are currently commercialized.