A phenomenological approach on the influence of paramagnetic iron in cement stone on 2D T1-T2 relaxation in single-sided 1H nuclear magnetic resonance

Holthausen, Robert Schulte; Raupach, Michael

doi:10.1016/j.cemconres.2019.03.027

Cited by 37 publications

(29 citation statements)

References 59 publications

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“…This expected pore hierarchy is illustrated in Figure 7 [42][43][44]. No clear relaxation contributions are observed from solid 1 H-bearing hydration products [45], or from water within the associated interlayer spaces [46]; we attribute this absence to the very short 2 characteristics expected from such features, the measurement of which is likely beyond the echo time limitations of our NMR hardware.…”

Section: Initial Characterisationmentioning

confidence: 83%

Understanding the microstructural evolution of hypersaline cemented paste backfill with low-field NMR relaxation

Nasharuddin

Luo

Robinson

et al. 2021

Cement and Concrete Research

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Cemented paste backfill (CPB) comprising mineral tailings, binders and mixing waters is an important potential support material in the mining industry. As the mechanical properties of CPB are significantly influenced by its microstructural characteristics the development of measurement tools to better understand its pore structure evolution is important for its increased utilisation. This study reports the application of low-field nuclear magnetic resonance (NMR) relaxation time measurements to characterise the microstructural evolution of CPB materials over 56 days of hydration, contrasting common tap water and hypersaline water (~22 wt% salt) as mixing waters. Distinct NMR relaxation time populations were evidenced within each CPB sample, revealing the presence of both capillary (T1,2 ≈ 10 ms) and gel pore water (T1,2 ≈ 300 -500 µs), with time-dependent relaxation measurements facilitating characterisation of capillary pore structure evolution over the hydration period assessed. Hypersaline samples demonstrated a time-lag in this measured capillary pore evolution, relative to those hydrated with tap water, while pore structure evolution rates were observed to increase with increased CPB binder content. Further, both T1 and T2 NMR relaxation times were found to correlate with the uniaxial compressive strength of the CPB materials investigated, facilitating the formulation of a predictive correlation function between NMR relaxation characteristics and mechanical properties.

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Section: Initial Characterisationmentioning

confidence: 83%

Understanding the microstructural evolution of hypersaline cemented paste backfill with low-field NMR relaxation

Nasharuddin

Luo

Robinson

et al. 2021

Cement and Concrete Research

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“…This iron content, additional to the iron present in the ordinary Portland cement, enhances the relaxation of the protons, therefore reducing the T 2 * and T 2 lifetimes. It is known that the relaxation rate 1/T 2 is proportional to the concentration of paramagnetic impurities, like Fe 2 O 3 [ 14 ]. The very short T 2 * lifetime in the concrete sample precluded acquisition of an SPI profile even with the shortest encoding time (t p = 50 μs) that could be used in the MRI system.…”

Section: Resultsmentioning

confidence: 99%

“…This concrete contained ordinary Portland cement, natural river sand and gravel aggregates normally used in the local construction industry. Contrary to the silica sand used in the mortar samples, aggregates in the concrete sample contained paramagnetic impurities such as iron oxide that reduces the T 2 and T 2 * relaxation times [ 14 ].…”

Section: Methodsmentioning

confidence: 99%

Moisture Distribution during Water Absorption of Ordinary Portland Cement Mortars Obtained with Low-Field Unilateral Magnetic Resonance

Cano-Barrita

Díaz-Díaz

2021

Materials

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Moisture distribution in cement-based materials is important from the durability point of view. In the present study, a portable three-magnet array with an elliptical surface radio frequency coil was used to undertake magnetic resonance measurements of moisture content in ordinary Portland cement mortar and concrete samples. Measurements along the length of the samples during capillary water absorption produced moisture content profiles that were compared with reference profiles acquired using a magnetic resonance imaging instrument. Profiles obtained with the three-magnet array were similar in shape and in penetration depth to those acquired with magnetic resonance imaging. The correlation coefficient between the moisture content measured with both techniques was r2 = 0.97. Similar values of saturated permeability of the mortars with identical w/c ratio were computed with the Hydrus 1D software based on the moisture content profiles. Additionally, inverse Laplace transformation of the signal decays provided the water-filled pore size distribution in saturated and unsaturated regions of the samples. The three-magnet array was successfully used to acquire nuclear magnetic resonance signal from a concrete sample, which was not possible with the magnetic resonance imaging instrument using the single-point imaging technique.

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“…Hierbei erlaubt die gemessene Signalamplitude, nach entsprechender Normierung, direkte Rückschlüsse auf die Porosität [20,21]. Auf Basis der Relaxationszeiten konnten auch für Portlandzemente plausible Porengrößen abgeschätzt werden [20,22].…”

Section: Auslaugung Von Betonprobenunclassified

Zerstörungsfreie Bestimmung der Auslaugung von Beton mittels einseitiger Wasserstoff‐Kernspinresonanz

et al. 2020

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Der dauerhafte Kontakt zwischen Beton und Trinkwasser wird i. Allg. als unkritisch für Betonoberflächen angesehen. Im Falle besonders kalkarmer Wässer kann jedoch ein kombinierter Lösungs-/Diffusionsprozess [1-4] stattfinden, der Betonoberflächen empfindlich schädigen kann. Bei dem als Auslaugung oder hydrolytische Korrosion bezeichneten Prozess finden drei aufeinanderfolgende Prozesse statt [5]: (A) Zunächst wird das Portlandit im Zementstein aufgelöst. (B) In einem zweiten Schritt wird Calcium aus den festigkeitsbildenden Calcium-Silikat-Hydratphasen (CSH) des Zementsteins herausgelöst und dieser "calciumverarmt". (C) Zuletzt wird der Zementstein gänzlich zersetzt und es verbleibt ein weiches Hydroxidgel auf der Oberfläche [4], das ohne größere mechanische Einwirkung abgetragen werden kann [5]. Diese Auslaugungsprozesse sind alle drei von einem Anstieg der Materialporosität begleitet [6]. Durch den Abbau von Portlandit entsteht zusätzlicher Porenraum bei einem Porendurchmesser um 10 nm [7] sowie aufgrund der Calciumverarmung der CSH-Phasen bei größeren Porendurch-Keywords concrete; durability; leaching; drinking water; X TWB ; deionized water; cement stone, single-sided 1 H nuclear magnetic resonance

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A phenomenological approach on the influence of paramagnetic iron in cement stone on 2D T1-T2 relaxation in single-sided 1H nuclear magnetic resonance

Cited by 37 publications

References 59 publications

Understanding the microstructural evolution of hypersaline cemented paste backfill with low-field NMR relaxation

Understanding the microstructural evolution of hypersaline cemented paste backfill with low-field NMR relaxation

Moisture Distribution during Water Absorption of Ordinary Portland Cement Mortars Obtained with Low-Field Unilateral Magnetic Resonance

Zerstörungsfreie Bestimmung der Auslaugung von Beton mittels einseitiger Wasserstoff‐Kernspinresonanz

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