CARBON NMR USED IN PROBING THE EXCHANGE OF ETHANOL WITH WATER IN WATER-SATURATED CEMENT PASTES

The exchange of water by ethanol in two water-saturated cement pastes has been investigated by carbon NMR, The two cement pastes differed on ly in their thermal history. The diffusion of ethanol into the cement paste was shown to be described by Fickian diffusion, assuming one-dim ensional diffusion under perfect sink boundary conditions, The diffusi on coefficients were calculated to be (1.28 +/- 0.14)10(-7) cm(2)/s fo r the virgin cement sample and (4.38 +/- 0.57)10(-7) m(2)/s for the pr eheated cement sample (preheated at 105 degrees C for 12 h), respectiv ely, The measurements indicate an extensive exchange between water and ethanol. Copyright (C) 1996 Elsevier Science Inc.