Multi-scale Approach Continuously Relating the Microstructure and the Macroscopic Mechanical Properties of Plaster Pastes during Their Settings

Abstract

A new multi-scale experimental approach is proposed to continuously relate the microstructure and the macroscopic mechanical properties of plaster pastes during their settings. (1)H NMR relaxometry is used to follow continuously and not destructively, the degree of hydration and the microstructure evolution during the setting and hardening of plaster paste. Transmission of shear and compressional ultrasonic velocities enable the determination of macroscopic mechanical properties of the material during the setting. On the basis of similar behaviors of Young's modulus and NMR-population of confined water as function of the degree of hydration, we conclude that NMR gives a better understanding of the evolution of the microstructure at the origin of a better control of the macroscopic mechanical properties.

Multiscale nuclear magnetic relaxation dispersion of complex liquids in bulk and confinement

“…9b), and the results of this procedure show that the same nuclear magnetic relaxation process is occurring for all durations of hydration. Quantitative ESR reveals the presence of g S = 1.17 Â 10 19 paramagnetic Fe 3+ ions per gram of dry material and a very small quantity of Mn 2+ (Fig. 10a).…”

“…It is well known that proton NMR spectroscopy characterizes the proton chemical species within the gypsum crystal [99]. NMR proton relaxometry at low magnetic fields has been used during the setting of plaster, simultaneously varying the water to plaster ratio (w/p) between 0.4 and 1 [18,19]. 2D spin correlation T 1 -T 2 measurements have also been proposed to compare the hydration and microstructure in b-plaster with ground gypsum mineral and the effects of citric acid as an accelerant and retardant, respectively [100].…”

“…Systems typically studied by NMRD, and which will be covered in this review, mainly comprise high surface-area microporous materials [13][14][15] chromatographic supports [15,16], heterogeneous catalytic materials [17], plasters [18,19], concretes [20], cement pastes [21], natural microporous organic kerogens and clay minerals in shale oils [22]. Standard NMR techniques at constant magnetic field have been also proposed for probing the molecular dynamics at pore surfaces despite the very low fraction of molecules in a surface layer.…”

“…Section 6 presents the basic relaxation equations of nuclear magnetic relaxation dispersion of 1/T 1 in calibrated micropores in turn for aprotic [15] and protic [16] liquids embedded in calibrated pores, while Section 7 outlines the first application of the multiscale NMRD relaxation investigation of microstructure evolution (ageing) of various cement-based materials [20,21]. This section also presents an application of NMRD for probing directly the nano-wettability of plaster pastes under various conditions of preparation [18,19]. Section 8 extends the analysis of NMRD profiles for separating oil and water contributions in real multimodal macroporous petroleum rocks [27], focussing on the separation of the dynamics and wettability of oil and water in the organic and mineral dual microporosity of shale oil rocks [22].…”

Direct Correlation between Adsorption Energetics and Nuclear Spin Relaxation in a Liquid‐saturated Catalyst Material

“…Such measurements have been widely applied to the study of fluids confined to heterogeneous porous media, and provide information on the effects of pore structure and surface interactions on molecular dynamics. Representative fields of investigation include rock and shale wettability studies for the hydrocarbon recovery industry, and the characterisation of plaster and cement paste hydration kinetics …”