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Title: Microstructure and texture of hydrated cement-based materials: A proton field cycling relaxometry approach

Abstract

We show how the measurement of proton nuclear magnetic spin-lattice relaxation as a function of magnetic field strength (and hence nuclear Larmor frequency) can provide reliable information on the microstructure (specific surface area and pore size distribution) throughout the progressive hydration of cement-based materials. We present in details the experimental and theoretical characteristic features of the relaxation dispersion to support an interpretation in terms of coupled solid-liquid relaxation at pore interfaces, surface diffusion, and nuclear paramagnetic relaxation. The measurement does not require any drying temperature modification and is sufficiently fast to be applied continuously during the progressive hydration of the material. Coupling this method with the standard proton nuclear spin relaxation and high resolution NMR allows us to follow the development of micro-scale texture within the material.

Authors:
 [1];  [2];  [3];  [3]
  1. Laboratoire de Physique de la Matiere Condensee, UMR 7643 du CNRS, Ecole Polytechnique, 91128 Palaiseau (France). E-mail: jean-pierre.korb@polytechnique.fr
  2. Laboratoire de Physique de la Matiere Condensee, UMR 7643 du CNRS, Ecole Polytechnique, 91128 Palaiseau (France)
  3. School of Electronics and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom)
Publication Date:
OSTI Identifier:
20995366
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 37; Journal Issue: 3; Conference: International Conference on cementitious materials as model porous media: Nanostructure and transport processes, Centro Monte Verita (Switzerland), 17-22 Jul 2005; Other Information: DOI: 10.1016/j.cemconres.2006.08.002; PII: S0008-8846(06)00196-7; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CEMENTS; DIFFUSION; DISPERSIONS; HYDRATION; INTERFACES; MAGNETIC FIELDS; MICROSTRUCTURE; MORTARS; NUCLEAR MAGNETIC RESONANCE; PARAMAGNETISM; PROTONS; SOLIDS; SPECIFIC SURFACE AREA; SPIN-LATTICE RELAXATION; SURFACES; TEXTURE

Citation Formats

Korb, J.-P., Monteilhet, L., McDonald, P.J., and Mitchell, J. Microstructure and texture of hydrated cement-based materials: A proton field cycling relaxometry approach. United States: N. p., 2007. Web. doi:10.1016/j.cemconres.2006.08.002.
Korb, J.-P., Monteilhet, L., McDonald, P.J., & Mitchell, J. Microstructure and texture of hydrated cement-based materials: A proton field cycling relaxometry approach. United States. doi:10.1016/j.cemconres.2006.08.002.
Korb, J.-P., Monteilhet, L., McDonald, P.J., and Mitchell, J. Thu . "Microstructure and texture of hydrated cement-based materials: A proton field cycling relaxometry approach". United States. doi:10.1016/j.cemconres.2006.08.002.
@article{osti_20995366,
title = {Microstructure and texture of hydrated cement-based materials: A proton field cycling relaxometry approach},
author = {Korb, J.-P. and Monteilhet, L. and McDonald, P.J. and Mitchell, J.},
abstractNote = {We show how the measurement of proton nuclear magnetic spin-lattice relaxation as a function of magnetic field strength (and hence nuclear Larmor frequency) can provide reliable information on the microstructure (specific surface area and pore size distribution) throughout the progressive hydration of cement-based materials. We present in details the experimental and theoretical characteristic features of the relaxation dispersion to support an interpretation in terms of coupled solid-liquid relaxation at pore interfaces, surface diffusion, and nuclear paramagnetic relaxation. The measurement does not require any drying temperature modification and is sufficiently fast to be applied continuously during the progressive hydration of the material. Coupling this method with the standard proton nuclear spin relaxation and high resolution NMR allows us to follow the development of micro-scale texture within the material.},
doi = {10.1016/j.cemconres.2006.08.002},
journal = {Cement and Concrete Research},
number = 3,
volume = 37,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • Diffusion coefficients of water in hydrated cement pastes and mortars obtained from proton field cycling NMR spin lattice relaxation over three orders of magnitude in magnetic field strength are in good agreement with values from molecular dynamics simulations of water on the surface of tobermorite. The level of agreement from these two independent approaches provides mutual support for their validity.
  • Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220–258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF{sub 4}, 243–318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF{sub 6}, 258–323 K). The dispersion of {sup 1}H spin-lattice relaxation rate R{sub 1}(ω) is measured in the frequency range of 10 kHz–20 MHz, and the studies are complemented by {sup 19}F spin-lattice relaxation measurements on BMIM-PF{sub 6} in the corresponding frequency range. From the {sup 1}H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF{sub 4}, and BMIM-PF{sub 6} are determined. This is done by performing an analysismore » considering all relevant intra- and intermolecular relaxation contributions to the {sup 1}H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R{sub 1} on square root of frequency. From the {sup 19}F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF{sub 6}. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.« less
  • Numerous mercury intrusion porosimetry (MIP) studies have been carried out to investigate the pore structure in cement-based materials. However, the standard MIP often results in an underestimation of large pores and an overestimation of small pores because of its intrinsic limitation. In this paper, an innovative MIP method is developed in order to provide a more accurate estimation of pore size distribution. The new MIP measurements are conducted following a unique mercury intrusion procedure, in which the applied pressure is increased from the minimum to the maximum by repeating pressurization-depressurization cycles instead of a continuous pressurization followed by a continuousmore » depressurization. Accordingly, this method is called pressurization-depressurization cycling MIP (PDC-MIP). By following the PDC-MIP testing sequence, the volumes of the throat pores and the corresponding ink-bottle pores can be determined at every pore size. These values are used to calculate pore size distribution by using the newly developed analysis method. This paper presents an application of PDC-MIP on the investigation of the pore size distribution in cement-based materials. The experimental results of PDC-MIP are compared with those measured by standard MIP. The PDC-MIP is further validated with the other experimental methods and numerical tool, including nitrogen sorption, backscanning electron (BSE) image analysis, Wood's metal intrusion porosimetry (WMIP) and the numerical simulation by the cement hydration model HYMOSTRUC3D.« less
  • The appearance of patch microstructure, i.e. broad dense and porous regions separated by sharp and distinct boundaries and occurring randomly in bulk and interfacial transition zones, has been reported previously in various site- and laboratory-mixed concretes and mortars. In this paper, evidence is presented to show that patch microstructure is an artefact of sample preparation and does not reflect the true nature of the hydrated cement paste. The appearance of dense patches comes from paste areas that have been ground and polished beyond the epoxy resin intrusion depth. In a backscattered electron image, pores not filled with epoxy are notmore » visible because the signal is generated from the base or side walls of the pores. A modified method for epoxy impregnation, which can achieve a much deeper epoxy penetration than conventional vacuum impregnation, is presented.« less
  • Nitrogen and butane sorption data have been obtained on a wide range of hardened cement pastes. In general, it is believed that data from the two adsorptives provide a consistent and reliable description of the pore systems developed. When dried rapidly, hardened pastes contain slit-shaped pores whose widths lie between 2 and 4 nm for a range of paste densities. The hydration products approximate to platelike aggregations with overall average thicknesses between 30 and 1,000 nm, depending on the water/cement ratio and the degree of hydration. Slowly dried pastes have much reduced surface areas and contain wider, more symmetrical pores.