Salt crystallization can cause major damage to building materials. This project will focus on the dynamics of in-pore salt crystallization using two complementary imaging techniques: X-ray microtomography and micro-particle image velocimetry. Crystallization processes will be studied in natural building stones and in model porous structures by time-lapse imaging. X-ray microtomography allows to study crystal growth or dissolution and crystal distributions in porous systems of building materials and model structures. Micro-particle image velocimetry allows to investigate the fluid dynamics in the saline fluid surrounding a growing or dissolving crystal in model porous structures. The particular focus will lie on the correct prediction of the crystal distribution within the pore space, on the growth kinetics and on the influence of the fluid dynamics on these kinetics. These factors are decisive for the correct prediction of the risk for crystallization damage. This project will allow to assess how these factors depend on the specific topology of the pore space of a building material. For the first time, it will be possible to predict these factors based on the physics of crystallization at the pore-scale level. This will improve salt damage risk assessment and can help practitioners working in the field of civil constructions and cultural heritage to choose the best suited building material for a specific environmental setting in order to avoid crystallization damage.