Chapter 19: Applications of Field-cycling NMR Relaxometry to Cement Materials
Published:11 Oct 2018
In this chapter, some applications of fast field-cycling (FFC) NMR relaxometry to cement-based materials are described. The effects on the hydration process of the curing temperature, the addition of silica fume and the addition of a superplasticizer to the cement mixture are discussed. The interpretation of the relaxation dispersion curves relies on the assumption that the interaction of water protons with paramagnetic centers located on the surface of cement grains dominates the relaxation process. This allowed us, in the frame of a two-phase exchange model, to monitor the evolution of the surface-to-volume ratio of capillary pores during the early stages of hydration. Further, the transverse diffusional correlation time at the surface of cement grains and the corresponding surface diffusion coefficients were extracted. The results show a small decrease of the transverse diffusional correlation time by increasing the temperature and an increase in the presence of a superplasticizer. No influence of the addition of silica fume on the transverse diffusional correlation time was detected. A continuous growth in the surface-to-volume ratio of capillary pores during the early stages of hydration was also demonstrated for all the samples studied.