Nestle N, Zimmermann C, Dakkouri M, Niessner R
Institut für Wasserchemie, TU München, Germany.
Environ Sci Technol. 2001 Dec 15;35(24):4953-6. doi: 10.1021/es015528y.
Cementitious materials are widely used as binders both in construction and in environmental technology (e.g., for stabilization and solidification). When dealing with materials contaminated with organic solvents, it is important to have an idea about the interaction between the solvents and the hydrating cement. Here, we introduce nuclear magnetic resonance relaxometry experiments as a way to study both the influence of organic model contaminants on the hydration kinetics of cement and the distribution of the contaminant in the cement matrix during the first hours and days of hydration. All solvents were found to lead to some delay in the hydration kinetics. While nonpolar compounds only lead to a minor delay and qualitatively to the same hydrating kinetics as in an uncontaminated cement mixture, the polar solvents lead to much more pronounced delays in the hydration kinetics. For toluene contents in the low percent range, there was no indication for the formation of macroscopic liquid pockets in the hydrating cement paste. The findings are consistent with recent results on the distribution of toluene in fully hydrated concrete samples.
