Comparison between T1 relaxation and capacitive method used for studying cement paste structuration evolution

Abstract : A better understanding of cement hydration evolution and development of cementitious materials microstructure (pore size distribution) at an early age is very important for improving concrete durability. The originality of the study is to compare T1 relaxation (inversion–recuperation sequence) along with capacitive method to characterize cement porosity (Fig. 1). The capacitive method (close to thermoporometry principle), developed in the laboratory, allows to study a cylindrical sample saturated in water (Fig. 2). The samples are less damaged (no preliminary drying), and the measured parameter by the capacitive method is closer to NMR than that by common techniques used in pore size distribution determination (pore size and not pore entry size). With this approach, freezing/thawing technique is used to identify porosity observed by NMR and also provides validation of NMR as a tool to investigate cement hydration. So, it allows to study by NMR cement pastes hydration at a very early age to old age.