Usage of internal magnetic fields to study the early hydration process of cement paste by MGSE method.
Internal magnetic field gradients, arising within the porous media due to susceptibility differences at the interfaces of solid and liquid as well as due to the contained magnetic impurities, can be employed by the method of modulated gradient spin echo to get insight into the velocity autocorrelation spectrum of liquid confined in the porous structure. New theoretical treatment of spin interaction with the radio-frequency field and the simultaneously applied static non-uniform magnetic field provides the formula that match well with the measurement of restricted diffusion of water in pores of cement paste. Its fitting to the experimental data gives the changes in the mean size of capillary pores, the spin relaxation and the magnitude of mean internal magnetic field gradients during the induction period and early acceleration stage of hydration processes at different temperatures.
University of Ljubljana, Faculty of Mathematics and Physics, Physics Department, Jadranska 19, 1000 Ljubljana, Slovenia; Institute Jožef Stefan, Jamova 39, 1000 Ljubljana, Slovenia. Electronic address: Janez.Stepisnik@fmf.uni-lj.si.
Janez
J
Stepišnik
Physics Department, Faculty of Materials Science and Engineering, Technical University of Cluj-Napoca, Romania.
Ioan
I
Ardelean
CPMG; Cement; Diffusion; Hydration process; Magnetic resonance; Magnetic susceptibility; Modulated gradient spin echo; Structure of porous media; Velocity correlation function