Visualization and quantification of water movement in porous cement-based materials by real time thermal neutron radiography: Theoretical analysis and experimental study

Water movement in porous cement-based materials is of great importance when studying their deterioration processes and durability. Many traditional methods based on mass changes, electricity or nuclear magnetic resonances are available for studying water transport in cement-based materials. In this research, an advanced technique i.e. thermal neutron radiography was utilized to achieve visualization and quantification of time dependent water movement including water penetration and moisture vapor in porous cement-based materials through theoretical analysis and experimental study. Because thermal neutrons experience a strong attenuation by hydrogen, neutron radiography exhibits high sensitivity to small amounts of water. A neutron transmission analysis for quantitative evaluation of raw radiographic measurements was developed and optimized based on point scattered functions (PScF). The determinations of the real time and space dependent water penetration into uncracked and cracked mortar samples, as well as the drying process have been presented in this paper. It is illustrated that thermal neutron radiography can be a useful research tool for visualization and quantification of water movement in porous building materials. The obtained results will help us to better understand deteriorating processes of cement-based materials and to find ways to improve their durability.