Study of the porous structure of hardened gypsum by pulsed nuclear magnetic resonance

Probing Microstructure Evolution during the Hardening of Gypsum by Proton NMR Relaxometry

“…Second, we used the water fraction values obtained by a bi-exponential fit of the measured transverse relaxation decay, to follow the hydration kinetics and to provide some details of the evolving porous structure during the setting of plaster pastes prepared with several formulation parameters. We show that there are two evolution modes of organization of the microstructure in the range (0.4 ≤ w / p ≤ 0.6) and (0.7 ≤ w / p ≤ 1) in agreement with pulsed field gradient experiments. − Then, we developed saturation (water re-impregnation) and desaturation (drying) experiments in order to obtain some information about water dynamics in pores of hardened gypsum. Finally, we proposed a detailed original model explaining the slow exchange mode that can exist between water populations saturating the material.…”

“…We show that there are two evolution modes of organization of the microstructure in the range (0.4 e w/p e 0.6) and (0.7 e w/p e 1) in agreement with pulsed field gradient experiments. [8][9][10] Then, we developed saturation (water reimpregnation) and desaturation (drying) experiments in order to obtain some information about water dynamics in pores of hardened gypsum. Finally, we proposed a detailed original model explaining the slow exchange mode that can exist between water populations saturating the material.…”

Study of fracture toughness and weakening mechanisms in gypsum interlayers in corrosive environments

“…4 and 5 and Table 2, the fracture toughness of gypsum in the dry state decreases slightly with increasing temperature. This is because the dehydration of calcium sulfate can occur even at 60 C. Then, the gypsum interlayers begin to contain small amounts of hemihydrate and anhydrite (Yu et al, 2012;Filippov et al, 1996;Paulik et al, 1992). The dehydration reaction is expressed as…”