Water leaching of high and ultra high performance concrete: a nuclear magnetic resonance study

The consequences in terms of microstructure and texture of a prolonged contact between concrete and a continuous flow of mineral water have been investigated here by Nuclear Magnetic Resonance (NMR) because of its non-invasiveness and sensitivity to local environment. In particular, we evidence the dissolution of residual anhydrous cement, which leads to the further precipitation of hydrates occurring over 12 months of leaching tests in High Performance Concrete (HPC) and Ultra High Performance Concrete (UHPC). The study of the longitudinal relaxation of proton magnetization shows that the difference of pore size distribution between these two types of concrete remains mostly in the number of capillary pores. Its evolution with the time of water leaching up to the end of our experiment is not significant.