In conventional NMR, samples from works of art in sizes above those considered acceptable in the field of art conservation would have to be removed to place them into the bore of large superconducting magnets. The portable permanent-magnet-based systems, by contrast, can be used in situ to study works of art, in a noninvasive manner. …
Unilateral NMR Applied to the Conservation of Works of Art Read More »
Two nuclear magnetic resonance (NMR) devices, a standard imaging apparatus and a portable single-sided relaxometer (with geometry that allows non-destructive in-situ relaxation measurements on samples of any dimensions), were used to assess the hydrophobic performance of an acrylic polymer (Paraloid B-72) applied as a trichloromethane (chloroform) solution on a biocalcarenite (Lecce stone). The NMR images …
Wall paintings in the XVI century Serra Chapel in the “Chiesa di Nostra Signora del Sacro Cuore” Rome, have been studied using unilateral NMR. In order to map the distribution of moisture content in the wall painted, a large number of Hahn echo measurements, covering large areas of the wall painting were performed. Because the intensity of the …
Unilateral NMR Study of a XVI Century Wall Painted Read More »
Unilateral NMR has been used to monitor the state of conservation of frescoes in the Vasari’s house in Florence. The causes of deterioration of ancient frescoes are varied, which result in the detachment and crumbling of the painted film from the supporting plaster and in the outcropping of salts. Unilateral measurements of Hahn echo performed on such frescoes have allowed a perfect identification …
The present work systematically investigates the influence of silica fume and organosilane addition on the hydration dynamics and the capillary pore formation of a cement paste. The cement samples were prepared with two water-to-cement ratios with increasing amounts of silica fume and of (3-Aminopropyl)triethoxysilane (APTES) organosilane. Low-field 1H nuclear magnetic resonance (NMR) relaxation measurements were performed …
The Effect of Silica Fume and Organosilane Addition on the Porosity of Cement Paste Read More »
Binders with large portions of carbon-intensive Portland cement replaced by supplementary cementitious materials (e.g. fly ash) are more susceptible to carbonation mainly due to their lower CO2 buffering capacity. This conclusion is usually drawn from accelerated experiments at elevated CO2 levels involving processes that seriously differ from natural carbonation. The resulting presence of H2O reactant in the …
Moisture is a main cause for weathering effects in historical façades made of natural stones. If applied correctly, hydrophobic agents can successfully protect these façades without altering the appearance. The major challenge is to ensure the required surface penetration. In-situ measurements for quality assurance on historical façades are still mainly done destructively through the extraction …
Quantitative determination of moisture with nuclear magnetic resonance is usually a simple task, since the initial amplitude is proportional to the moisture content. However, situations can arise where the combination of short relaxation times, low signal-to-noise ratio and the ill-posed nature of the inverse Laplace transformation lead to a significant bias of the initial amplitude impeding it being an …
In this study, single-sided proton nuclear magnetic resonance (1H NMR) was used to quantify the porosity of the concrete cover. Laboratory concrete samples were prepared with different formwork surfaces as well as varying fresh concrete pressures. Furthermore, to separate the influence of aggregates on porosity, hardened cement paste and mortar samples of otherwise similar composition …
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