Probing the Water Phases and Microstructure in a Model Cement Blend Matrix used for the Encapsulation of Intermediate Level Nuclear Wastes

2006 ◽  
Vol 932 ◽  
Author(s):  
Jean-Philippe Gorce ◽  
Neil B. Milestone ◽  
Peter J. Mcdonald
Keyword(s):  
Freeze Drying ◽  
Cement Hydration ◽  
Mercury Intrusion Porosimetry ◽  
Bound Water ◽  
Gravimetric Analysis ◽  
Evaporable Water ◽  
Mercury Intrusion ◽  
H Nmr ◽  
Nmr Relaxometry ◽  
Median Pore

ABSTRACTThe changes in microstructure and content of water phases during hydration of a 3:1 BFS:OPC blend are investigated by Mercury Intrusion Porosimetry (MIP), freeze-drying, Thermal Gravimetric Analysis (TGA) and 1H Nuclear Magnetic Resonance (NMR) relaxometry. MIP indicates that during the blend hydration, a reduction in the population of capillary pores (larger than about 100 nm) occurs while the population of gel pores (smaller than few tens of nanometres) increases. Between 3 and 90 days, the porosity estimated by MIP decreases from about 36% down to 18% while the median pore size decreases from about 140 nm down to 6 nm.1H NMR relaxometry shows that after 1 day of hydration, nearly 70% of the evaporable water is held in capillary pores while about 30% is present in gel pores. After two weeks, most of the evaporable water (90%) is found in pores smaller than few tens of nanometres.The amount of evaporable water detected by freeze drying decreases from less than 20 wt.% after one week of hydration down to about 16.3 wt.% after 90 days while the amount of chemically bound water related to the degree of advancement of the cement hydration and detected by TGA increases from 8 wt.% to 10.3 wt.%.During hydration the BFS:OPC blend matrix evolves from an open microporous network to one of a poorly connected network of water rich nanopores with increasing amounts of chemically bound water.

scholarly journals Investigation of the effect of aging on wood hygroscopicity by 2D 1H NMR relaxometry

Holzforschung ◽  
2020 ◽  
Vol 74 (4) ◽  
pp. 400-411 ◽  
Author(s):  
Leila Rostom ◽  
Denis Courtier-Murias ◽  
Stéphane Rodts ◽  
Sabine Care
Keyword(s):  
Cell Walls ◽  
Molecular Level ◽  
Bound Water ◽  
Proton Nuclear Magnetic Resonance ◽  
Wood Material ◽  
H Nmr ◽  
Nmr Relaxometry ◽  
Wood Chemical Composition ◽  
S2 Layer ◽  
1H Nmr Relaxometry

AbstractTwo-dimensional proton nuclear magnetic resonance (2D 1H NMR) relaxometry is increasingly used in the field of wood sciences due to its great potential in detecting and quantifying water states at the level of wood constituents. More precisely, in this study, this technique is used to investigate the changes induced by “natural” and “artificial” aging methods on modern and historical oak woods. Two bound water components are detected and present differences in terms of association to the different wood polymers in cell walls: one is more strongly associated with wood polymers than the other. The evolution of the two bound water types is discussed in regard to aging methods and is related to the structure of the cell wall, especially with the S2 layer and the evolution of wood chemical composition (cellulose, hemicelluloses and lignin). The evolution of hydric strains is also discussed taking into account the effect of aging methods on the two bound water components. The obtained results confirm the ability of 2D 1H NMR relaxometry to evaluate the effect of aging at the molecular level and on hydric deformation. Furthermore, this method shows that it is possible to determine the moisture content of wood without the necessity to oven-dry the wood material.

Synthesis and Evaluation Methacrylate-Based Monolithic Materials Mixed with Carbon Nanotubes

2014 ◽  
Vol 900 ◽  
pp. 378-381
Author(s):  
Rui Feng
Keyword(s):  
Mercury Intrusion Porosimetry ◽  
Thermo Gravimetric Analysis ◽  
Reversed Phase ◽  
Gravimetric Analysis ◽  
Reversed Phase Liquid Chromatography ◽  
Hydrophobic Properties ◽  
Thermo Gravimetric ◽  
Mercury Intrusion ◽  
Phase Liquid

An effective approach to synthesize methacrylate-based hybrid monoliths was carried out by photopolymerization and the properties of the obtained monoliths mixed with mult-wall carbon nanotube (MWNT) were studied in this paper. The prepared hybrid materials with MWNT in the range of 0-5% total weight of monomers were characterized by Fourier transform infrared spectra, thermo-gravimetric analysis (TGA), and mercury intrusion porosimetry, respectively. Moreover, their porosities were evaluated by the determination of flow rate for different prepared monolithic capillaries. The results showed that the monoliths with more MWNT (1-5%) possessed larger pore sizes between 1-10 μm. The hybrid monoliths have the potential advantages including stronger hydrophobic properties and less resistance for the application of reversed phase liquid chromatography in the micro-column separation.

Study of the structure of a sensitive Champlain clay and of its evolution during consolidation

1984 ◽  
Vol 21 (1) ◽  
pp. 21-35 ◽  
Author(s):  
Pierre Delage ◽  
Guy Lefebvre
Keyword(s):  
Freeze Drying ◽  
Mercury Intrusion Porosimetry ◽  
Natural Clay ◽  
One Dimensional ◽  
Mercury Intrusion ◽  
Powerful Approach ◽  
Structure Observation ◽  
Pressure Increment ◽  
Intact Soil ◽  
Scanning Electron

Scanning electron microscopy and mercury intrusion porosimetry are used in parallel to identify the structure of a medium sensitivity Champlain clay. The clay structure is observed firstly on intact, remolded, and oven-dried soils and secondly on soils consolidated at various levels in one-dimensional compression. Both methods of investigation reveal for the intact soil the existence of an aggregated structure characterized by an interaggregate and an intra-aggregate porosity. Remolding affects interaggregate links but does not destroy aggregates.The observation of clay structure at various levels of one-dimensional compression shows that the collapse of the structure is progressive, the largest interaggregate pores being the first affected. As the consolidation proceeds, smaller and smaller pores are affected. For a given pressure increment, only the largest existing pores are affected. A structure anisotropy has been seen to develop with increasing compression.The scanning electron microscope and the mercury intrusion porosimeter used in conjunction with each other appear as a powerful approach for clay structure observation. Keywords: natural clay, microstructure, freeze-drying, porosimetry, microscopy, consolidation, aggregate.

scholarly journals NMR determination of sorption isotherms in earlywood and latewood of Douglas fir. Identification of bound water components related to their local environment

Holzforschung ◽  
2017 ◽  
Vol 71 (6) ◽  
pp. 481-490 ◽  
Author(s):  
Marie Bonnet ◽  
Denis Courtier-Murias ◽  
Paméla Faure ◽  
Stéphane Rodts ◽  
Sabine Care
Keyword(s):  
Relaxation Times ◽  
Bound Water ◽  
Sorption Isotherms ◽  
Local Environment ◽  
Douglas Fir ◽  
Adsorption Mechanisms ◽  
H Nmr ◽  
Nmr Relaxometry ◽  
Sorption Energy

Abstract Earlywood (EW) and latewood (LW) have different hygromechanical behaviors, if subjected to relative humidity (RH) variations. To understand this effect better, the adsorption mechanisms of EW and LW of Douglas fir were studied by 2D 1H NMR relaxometry under conditions of equilibrium moisture content (EMC) at 20°C. Two bound water components were detected with relaxation times T1 and T2 indicating that they are located in distinct environments but these are similar in EW and LW. Sorption isotherms were calculated and analyzed based on the sorption model of Dent. A difference of sorption energy between the two water components is in agreement with their mobility difference observed on T1−T2 correlation spectra. Moreover, for the two bound water components, EW and LW exhibit different sorption isotherms at high RH. This may be attributed to a difference of adsorption capacity. Based on the macrofibril models provided by the literature, the following hypothesis is proposed: bound water components are located in lamellar and lenticular areas, both leading to possible deformations.

scholarly journals Porosity and Pore Size Distribution of Native and Delignified Beech Wood Determined by Mercury Intrusion Porosimetry

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 416 ◽  
Author(s):  
Selin Vitas ◽  
Jana Segmehl ◽  
Ingo Burgert ◽  
Etienne Cabane
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Freeze Drying ◽  
Mercury Intrusion Porosimetry ◽  
Beech Wood ◽  
Functional Materials ◽  
Drying Methods ◽  
Mercury Intrusion ◽  
The Impact

The complex hierarchical structures of biological materials in combination with outstanding property profiles are great sources of inspiration for material scientists. Based on these characteristic features, the structure of wood has been increasingly exploited to fabricate novel hierarchical and functional materials. With delignification treatments, the density and chemistry of wood can be altered, resulting in hierarchical cellulose scaffolds with enhanced porosity for the fabrication of novel hybrid materials. In the present study, focusing on acidic delignification of beech wood and its influence on porosity, we report on a structural characterization and qualitative assessment of the cellulose scaffolds using mercury intrusion porosimetry (MIP). To account for the effect of water removal from the hygroscopic structure, different drying methods—e.g., standard oven and freeze-drying—were applied. While native beech wood is characterized by the presence of macro, meso and micro pores, delignification altered the porosity, increasing the importance of the macropores in the pore size distribution. Furthermore, we showed that the final porosity obtained in the material is strongly dependent on the applied drying process. Samples delignified under harsh conditions at high temperature (mass loss of ~35%) show a 13% higher porosity after freeze-drying compared to oven-dried samples. The obtained results contribute to a better understanding of the impact of the delignification and drying processes on the porosity of cellulose scaffolds, which is of high relevance for subsequent modification and functionalization treatments.

scholarly journals From Nanostructural Characterization of Nanoparticles to Performance Assessment of Low Clinker Fiber–Cement Nanohybrids

2019 ◽  
Vol 9 (9) ◽  
pp. 1938 ◽  
Author(s):  
Styliani Papatzani ◽  
Kevin Paine
Keyword(s):  
Flexural Strength ◽  
Mercury Intrusion Porosimetry ◽  
Manufacturing Processes ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mercury Intrusion ◽  
Differential Thermogravimetry

With the current paper three nano-Montmorillonites (nMt) are applied in cement nanohybrids: an organomodified nMt dispersion, nC2; an inorganic nMt dispersion, nC3; and an organomodified powder, nC4. nC4 is fully characterized in this paper (X-ray diffraction, scanning electron microscopy/X-ray energy dispersive spectroscopy and thermal gravimetric analysis/differential thermogravimetry. Consecutively a ternary non pozzolanic combination of fiber–cement nanohybrids (60% Portland cement (PC) and 40% limestone (LS)) was investigated in terms of flexural strength, thermal properties, density, porosity, and water impermeability. Flexural strength was improved after day 28, particularly with the addition of the inorganic nMt dispersion. There was no change in density or enhancement in pozzolanic reactions for the powder nMt. Mercury intrusion porosimetry showed that the pore related parameters were increased. This can be attributed to mixing effects and the presence of fibers. Water impermeability tests yielded ambiguous results. Clearly, novel manufacturing processes of cement nanohybrids must be developed to eliminate mixing issues recorded in this research.

scholarly journals Description of the concrete carbonation process with adjusted depth-resolved thermogravimetric analysis

2021 ◽  
Author(s):  
Nico Vogler ◽  
Philipp Drabetzki ◽  
Mathias Lindemann ◽  
Hans-Carsten Kühne
Keyword(s):  
Calcium Hydroxide ◽  
Bound Water ◽  
Reference Method ◽  
Microscopic Analysis ◽  
Limestone Powder ◽  
Gravimetric Analysis ◽  
Sample Material ◽  
Accelerated Carbonation ◽  
Temperature Range ◽  
Carbonation Process

AbstractThe thermal gravimetric analysis (TG) is a common method for the examination of the carbonation progress of cement-based materials. Unfortunately, the thermal properties of some components complicate the evaluation of TG results. Various hydrate phases, such as ettringite (AFt), C–S–H and AFm, decompose almost simultaneously in the temperature range up to 200 °C. Additionally, physically bound water is released in the same temperature range. In the temperature range between 450 °C and 600 °C, the decomposition of calcium hydroxide and amorphous or weakly bound carbonates takes place simultaneously. Carbonates, like calcite, from limestone powder or other additives may be already contained in the noncarbonated sample material. For this research, an attempt was made to minimise the influence of these effects. Therefore, differential curves from DTG results of noncarbonated areas and areas with various states of carbonation of the same sample material were calculated and evaluated. Concretes based on three different types of cement were produced and stored under accelerated carbonation conditions (1% CO2 in air). The required sample material was obtained by cutting slices from various depths of previously CO2-treated specimen and subsequent grinding. During the sample preparation, a special attention was paid that no additional carbonation processes took place. As reference method for the determination of the carbonation depth, the sprayed application of phenolphthalein solution was carried out. Microscopic analysis was examined to confirm the assumptions made previously. Furthermore, the observed effect of encapsulation of calcium hydroxide by carbonates caused by the accelerated carbonation conditions was examined more closely.

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