A Review of the Use of Proton Magnetic Resonance to Study Superplasticizers
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A REVIEW OF THE USE OF PROTON MAGNETIC RESONANCE TO STUDY SUPERPLASTICIZERS
M. REGOURD C.E.R.I.L.H.,
23 Rue de Cronstadt, 75015 Paris,
FRANCE
ABSTRACT Proton pulse nuclear magnetic resonance can be used to follow the hydration of C3 S and C 3 A, individually and mixed, with and without gypsum The variation of the spin-lattice relaxation time and superplasticizers. to from early ages up to the times of setting and hardening is related first the mobility of water molecules in rapid exchange, then to the progress of solid-water interfaces. Plasticizers act as retarders to lengthen the induction period. They behave differently with pure phases taken separately than with mixtures, in which a mutual interaction of C3 S, C 3 A, gypsum and admixture has been characterized. Among the three superplasticizers studied, the sulfonated melanine formaldehyde was the strongest retarder, while the sodium sulfonated naphthalene was the weakest.
INTRODUCTION Nuclear magnetic resonance (NMR) studies have been carried out on C3 S, 29 C3 A and white cement. Both proton NMR [1-4] and solid state NMR on Si 27 [5,6] and A1 [2,7] have been used to follow hydration of silicates and aluminates. The proton NMR results show that it is possible to distinguish between free water and adsorbed or combined water [4]. As described by Blinc et al [3], water molecules within the adsorbed monolayer on the surface of minerals and in the form of micro- or macro-pore water above these monolayers are highly mobile. Fast exchange of the evaporable water reflects the solid surface activity, number of adsorptive sites and development of newly formed phases. The influence of chemical admixtures, specifically accelerators and retarders [6,8,9] and superplasticizers [8,10-12], on the hydration of cement minerals has also been studied by proton and solid state NMR. The action of superplasticizers corresponds to a retarding effect by prolonging the dormant period of fresh pastes. Moreover adsorbed water molecules remain in their early state up to the end of the dormant period as shown by proton NMR. This paper will report recent results on the evaluation of three superplasticizers: sulfonated polynaphthalene, sulfonated melamine formaldehyde, and lignosulfonate.
EXPERIMENTAL BACKGROUND Some atomic nuclei are characterized by a spin nuclear momentum associated with a magnetic momentum, 7p, where 7 is the gyromagnetic ratio [10]. The component of the magnetic momentum along the z-direction is Yz = where hk= h/2x, h is Planck's constant, 1 m - 2J + 1, and m = ±t for H.
Mat. Res. Soc. Symp. Proc. Vol. 85. e-1987 Materials Research Society
mImh and m is
(1) a quantum number;
246
If a magnetic field 60 is applied along the z-axis, there appears a nuclear magnetization with an interactive energy E between pz and f0 such that E -
-pz and P0 - -7hmf3o.
(2) 1
In a magnetic field 60, the energy levels of the proton H with I - ½ and I - - ½ have their degeneracy lifted and the energy difference AE between two adjacent levels is
AE -(3)flo ing a magnetic field o
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