THE EFFECT OF NONIONIC SURFACTANTS ON THE STATE OF WATER IN CEMENT SYSTEMS (BY NMR RELAXATION DATA) - 1 - THE STATE OF WATER IN THE COURSE OF STRUCTURE FORMATION

The state of water in bound-disperse structures formed in the course o f cement hardening and the effect of surfactants [polyethylene glycol (PEG), polypropylene glycol (PPG), and hexanol] on this state and also the state of water in freely-disperse structures in hydrated cements in the presence of the same surfactants at different extents of their adsorption were studied by the NMR relaxation technique. It is establi shed that, in the semilog scale, the envelope of spin-echo signals fro m protons in the samples with a water-to-cement-ratio of 0.3 can be de composed into three components (for samples containing PPG or hexanol additives, into four components) corresponding to protons of different water fractions varying in the course of formation of the structure o f cement stone. The maximum change with time was found for the occupan cy of the shortest T-2 component. During several hours of cement harde ning, the occupancy of this water fraction ranged up to 96-97% (from t he total signal of water protons). Consideration of adsorption isother ms and NMR relaxation data for samples containing PPG and hexanol addi tives suggests that the mobility of water molecules, which determine t he intermediate T-2 components, is associated with the behavior of wat er near the interface in the presence of adsorbed substance. It is sho wn that, in the presence of additives, boundary layers of water are ch anged. At the end of the second week of the hardening process, the fra ction of the short T-2, component ranged up to 78-84% from the total p roton signal. A scheme of the water distribution in pores of cement st one in the presence of additives and its interrelation with relaxation processes are discussed.