Wp. Halperin et al., APPLICATION OF SPIN-SPIN RELAXATION TO MEASUREMENT OF SURFACE-AREA AND PORE-SIZE DISTRIBUTIONS IN A HYDRATING CEMENT PASTE, Magnetic resonance imaging, 12(2), 1994, pp. 169-173
Nuclear magnetic resonance (NMR) relaxation analysis has been applied
to interpret the evolution of microstructure in a cement paste during
hydration. Measurements of transverse magnetic relaxation were made in
fully and partially filled white cement pastes for hydration times be
tween 1 h and 6 mo. It was found that only the evaporable water molecu
les contributed to the echo amplitude in the NMR measurement, while bo
th the evaporable and the hydrated water contribute to the amplitude o
f the free induction decay. The spin-spin relaxation rate was found to
increase markedly during hydration and can be directly related to the
total surface area of the CSH gel accessible to evaporable water. The
amount of water consumed during the hydration process was determined
independently from the amplitude of the NMR echo signal extrapolated t
o the beginning of the pulse sequence. A numerical inversion of the fu
ll spin-spin relaxation profile, determined with a CPMG pulse sequence
, was interpreted as a pore volume distribution function. The measurem
ents of total surface area, amount of water consumed, and pore distrib
utions were performed in situ nondestructively, throughout the hydrati
on period for a single sample of cement paste.