Direct investigation of the fate of NAPL contaminations in a hydrating cement matrix by means of magnetic resonance techniques.

The behavior of nonwatery solvent phases in hydrating cement pastes is of great interest in the context of solidification of wastes containing such phases. In a recent study, the influence of various solvents on the hydration kinetics of cement was studied. In this paper, we present results on the changes in the behavior of the solvent phases themselves during setting of the cement pastes. The methods used in the studies were NMR relaxometry and pulsed field gradient (PFG) NMR diffusometry. To study selectively the behavior of the non-aqueous-phase liquid (NAPL) phases, heavy water was used in the preparation of the cement pastes. The experimental results are in good agreement with the observations from earlier studies concerning the behavior of toluene in hydrating cement. For aliphatic solvents (cyclooctane, n-hexanol), indications for surprisingly large networks of connected droplets in the cement matrices are found.