Laser diffraction and gas adsorption techniques

Palacios, Marta; Kazemi-Kamyab, Hadi; Mantellato, Sara; Bowen, Paul

doi:10.1201/b19074-10

Cited by 10 publications

(10 citation statements)

References 43 publications

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“…The porosity of (low CaO) geopolymers is characterized by a high degree of connectivity [ 57 ] and depends mainly on the amount of water in the mixtures [ 57 , 66 ], the Si/Al ratio of the network, and the type of alkaline activator solution [ 67 , 68 ]. However, due to the ink-bottle effect, mercury intruded pore size distribution does not represent the pore size but the pore entry size [ 69 ]. Therefore, larger pores are often not detected by MIP measurements, especially in the case of geopolymers [ 67 ].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis

et al. 2020

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Geopolymers are synthesized by mixing powdery solids, rich in amorphous silicon and aluminum species, with an alkaline solution, which leads to the formation of an inorganic alumosilicate network. Their acid resistance is affected by the composition, the porosity, and pore size distribution of the hardened binder as well as the type and concentration of the acidic solution. In the present study, two geopolymer mixtures with varying liquid-to-solid ratios and Si/Al ratios were exposed to a sulfuric acid solution (pH = 1) and analyzed after different durations of exposure (7, 14, 28, 56, and 70 days) by using a light microscope and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). SEM-EDX elemental mapping was used to evaluate the degradation from depth profiles of silicon (Si), aluminum (Al), and potassium (K) leaching. The results clearly show the leaching kinetics of potassium and the dealumination of the network. The separate consideration of specific reaction steps in the course of degradation, namely the depth of erosion (DE), the depth of deterioration (DD), and the depth of reaction for certain elements (DR(e)), indicate a combination of chemical and diffusion controlled degradation mechanisms.

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Section: Discussionmentioning

confidence: 99%

Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis

et al. 2020

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“…The pore structure characteristics of the paste samples was assessed using mercury intrusion porosimetry (MIP) [10] after 12 months of exposure. Samples were dried by solvent exchange method, as for TGA.…”

Section: Methodsmentioning

confidence: 99%

Changes of microstructure and diffusivity in blended cement pastes exposed to natural carbonation

et al. 2018

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This study compares the phase assemblage and pore structure variation of Portland cement and blended cements, containing limestone and burnt oil shale, during carbonation. Hardened cement paste was exposed to natural carbonation (400 ppm of CO2) at a relative humidity of 70 % for one year. Samples were prepared and cured at 95 % RH for 28 days. Reference mixes were exposed to CO2-free atmosphere to decouple the effect of ongoing hydration and drying from that of carbonation. The phase assemblage was investigated using XRD-Rietveld refinement and thermogravimetric analyses. The porosity and pore structure was assessed based on the results from mercury intrusion porosimetry. Additionally preliminary results of gas diffusion experiment of carbonated and non-carbonated samples are presented.

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“…According to mercury intrusion porosimetry (MIP) results from the same study, 37% of the pores were larger than 0.48 µm. Since MIP measures the pore entry sizes rather than the pore sizes themselves [34], there was a good Since the equilibrium moisture content depends not only on the ambient climate, but also on the previous moisture level, there are also intermediate curves, connecting the desorption and isotherm isotherms, called scanning isotherms [4,31,32]. These curves describe the equilibrium moisture content obtained when starting from another initial moisture state than a dry or water-saturated state.…”

Section: Influence Of Wood Structurementioning

confidence: 99%

“…According to mercury intrusion porosimetry (MIP) results from the same study, 37% of the pores were larger than 0.48 µm. Since MIP measures the pore entry sizes rather than the pore sizes themselves [34], there was a good correlation between the water potential at which the desorption isotherm dropped and the size of the "ink-bottle necks" determined by MIP. In addition, the relative volume of vessels, fiber lumina, and axial parenchyma was determined to be 38%, and this volume was, thus, well correlated with the amount of water lost between these two levels.…”

Section: Influence Of Wood Structurementioning

confidence: 99%

On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

Fredriksson

2019

Forests

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Wood is a hygroscopic material that absorbs and desorbs water to equilibrate to the ambient climate. Within material science, the moisture range from 0 to about 95–98% relative humidity is generally called the hygroscopic moisture range, while the exceeding moisture range is called the over-hygroscopic moisture range. For wood, the dominating mechanisms of moisture sorption are different in these two moisture ranges; in the hygroscopic range, water is primarily bound by hydrogen bonding in cell walls, and, in the over-hygroscopic range, water uptake mainly occurs via capillary condensation outside cell walls in macro voids such as cell lumina and pit chambers. Since large volumes of water can be taken up here, the moisture content in the over-hygroscopic range increases extensively in a very narrow relative humidity range. The over-hygroscopic range is particularly relevant for durability applications since fungal degradation occurs primarily in this moisture range. This review describes the mechanisms behind moisture sorption in the over-hygroscopic moisture range, methods that can be used to study the interactions between wood and water at these high humidity levels, and the current state of knowledge on interactions between modified wood and water. A lack of studies on interactions between modified wood and water in the over-hygroscopic range was identified, and the possibility of combining different methods to acquire information on amount, state, and location of water in modified wood at several well-defined high moisture states was pointed out. Since water potential is an important parameter for fungal growth, such studies could possibly give important clues concerning the mechanisms behind the increased resistance to degradation obtained by wood modification.

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Laser diffraction and gas adsorption techniques

Cited by 10 publications

References 43 publications

Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis

Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis

Changes of microstructure and diffusivity in blended cement pastes exposed to natural carbonation

On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

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