Moisture Buffering Potential of Plasters for Energy Efficiency in Modern Buildings

2017 ◽  
Author(s):  
Jan Fořt ◽  
Magdaléna Doleželová ◽  
Robert Černý
Keyword(s):  
Relative Humidity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Open Porosity ◽  
Building Materials ◽  
High Energy ◽  
Building Envelopes ◽  
Moisture Buffering ◽  
Ventilation Systems

Moisture level significantly affects durability of constructions, their thermal performance and quality of indoor air. Since building envelopes are subjected to a moisture gradient, additional ventilation systems are employed to maintain relative humidity on the desired level. Although modern advanced ventilation systems provide sufficient air exchange rate, their wider application is in conflict with sustainability development principles due to high energy demands. Moreover, according to the European legislation related to the Nearly Zero Energy Buildings (European Directives 2002/91/EC and 2010/31/EU), air tightness of building envelopes in order to provide high thermal resistance leads to large moisture loads in building interiors. Among other factors, a high level of relative humidity has negative effect on the work efficiency and health of building inhabitants. A detailed insight into building materials behavior during cyclic moisture loading was accessed within this study. The moisture buffering values of three interior plasters were investigated in order to describe influence of plasters on moderation of indoor environment. Particular materials were loaded according to the NORDTEST protocol by 8/16 h loading schema at 70/30% RH. Here, the excellent moisture buffer classification was obtained for lightweight perlite plaster (PT) with the highest total open porosity. However, contrary to the higher total open porosity of renovation plaster (PS), the core plaster (CP) achieved higher moisture buffer capacity than PS. This discrepancy refers to the influence of the pore size distribution which is, besides the total open porosity, essential for a detailed characterization of moisture buffering potential of building materials. Based on the results of Mercury intrusion porosimetry, a correlation between pore size distribution and moisture buffer value was revealed.

On the characterization of pore size distribution of building materials

2017 ◽  
Vol 41 (3) ◽  
pp. 247-263 ◽  
Author(s):  
LF Dutra ◽  
N Mendes ◽  
PC Philippi
Keyword(s):  
Relative Humidity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Building Materials ◽  
Mercury Porosimetry ◽  
Energy Performance ◽  
Volume Distribution ◽  
Wide Range

Moisture affects significantly the energy performance of air conditioning systems, the durability of materials, and the health of occupants. One way of reducing those effects, without increasing the energy costs, is by means of using porous material ability of absorbing and releasing moisture from/to the adjacent environment, which attenuates the indoor relative humidity variation. This natural ability is intrinsically related to the porous microstructure. Therefore, the characterization of the pore space is an important research theme in the building physics area. This article aims to present a method for obtaining the pore size distribution based on adsorption isotherms and mercury porosimetry data. First, the theoretical formulation based on the Gibbs free energy for a two-phase (liquid–vapor) system, using the De Boer and Zwikker model, is presented, allowing the calculation of the critical adsorbed thickness for pore filling, critical radius, adsorbed moisture content, capillary condensation content, available surface for adsorption, and the distribution of micropores for a wide range of radius. The adsorption isotherm curve is estimated for high relative humidity values through mercury porosimetry, along with the adsorption curve obtained from the experiment. The pore volume distribution calculated by this method can be used to estimate transport coefficients for liquid and vapor phases.

Influence of Hipping Pressure on the Strength and the Porosity of Porous Copper

1991 ◽  
Vol 251 ◽  
Author(s):  
Atsushi Takata ◽  
K. Ishizaki ◽  
Y. Kondo ◽  
T. Shioura
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Young’S Modulus ◽  
Open Porosity ◽  
Structural Parameters ◽  
High Strength ◽  
Porous Copper ◽  
Different Temperatures ◽  
Hip Process

ABSTRACTOpen porous copper metals, which have high strength, high open porosity and well controlled pore size distribution, were produced by a hot isostatic press (HIP) process. They were sintered at different temperatures from 973 to 1273K under various HIPping pressures up to 200MPa. Pore size distribution and Young's modulus of the sintered samples were analyzed. The HIPped products have greater strength and higher open porosity than those of the normally sintered ones. The internal structural parameters such as pore size distribution were controlled by changing the HIPping pressure.

scholarly journals Measurement of pore size distribution of building materials by thermal method

2020 ◽  
Vol 245 ◽  
pp. 118417
Author(s):  
Nicolas Dujardin ◽  
Thouraya Salem ◽  
Vincent Feuillet ◽  
Magali Fois ◽  
Laurent Ibos ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Building Materials ◽  
Thermal Method

scholarly journals Modeling and Simulations of the Sulfur Infiltration in Activated Carbon Fabrics during Composite Cathode Fabrication for Lithium-Sulfur Batteries

2021 ◽  
Vol 5 (3) ◽  
pp. 65
Author(s):  
Kyriakos Lasetta ◽  
Joseph Paul Baboo ◽  
Constantina Lekakou
Keyword(s):  
Activated Carbon ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Composite Cathode ◽  
High Energy ◽  
High Energy Density ◽  
Plate Temperature ◽  
Energy Simulations ◽  
Lithium Sulfur

During the manufacture of a composite cathode for lithium-sulfur (Li-S) batteries it is important to realize homogeneous infiltration of a specified amount of sulfur, targeted to be at least 5 mg cm−2 to achieve good battery performance in terms of high energy density. A model of the sulfur infiltration is presented in this study, taking into account the pore size distribution of the porous cathode host, phase transitions in sulfur, and formation of different sulfur allotropes, depending on pore size, formation energy and available thermal energy. Simulations of sulfur infiltration into an activated carbon fabric at a hot-plate temperature of 175 °C for two hours predicted a composite cathode with 41 wt% sulfur (8.3 mg cm−2), in excellent agreement with the experiment. The pore size distribution of the porous carbon host proved critical for both the extent and form of retained sulfur, where pores below 0.4 nm could not accommodate any sulfur, pores between 0.4 and 0.7 nm retained S4 and S6 allotropes, and pores between 0.7 and 1.5 nm contained S8.

scholarly journals Modeling Water Adsorption and Retention of Building Materials From Pore Size Distribution

2019 ◽  
Vol 7 (6) ◽  
pp. 547-556
Author(s):  
Abdelkrim Trabelsi ◽  
Zakaria Slimani ◽  
Akli Younsi ◽  
Joseph Virgone ◽  
Rafik Belarbi
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Building Materials ◽  
Water Adsorption

scholarly journals Open Porosity and Pore Size Distribution of Mesoporous Silica Films Investigated by Positron Annihilation Lifetime Spectroscopy and Ellipsometric Porosimetry

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3371
Author(s):  
Bangyun Xiong ◽  
Jingjing Li ◽  
Chunqing He ◽  
Jiale Lai ◽  
Xiangjia Liu ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Positron Annihilation ◽  
Open Porosity ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Silica Films ◽  
Ellipsometric Porosimetry ◽  
Positron Annihilation Lifetime

Tunable mesoporous silica films were prepared though a sol-gel process directed by the self-assembly of various triblock copolymers. Positron annihilation γ-ray energy spectroscopy and positron annihilation lifetime spectroscopy (PALS) based on intense pulsed slow positron beams as well as ellipsometric porosimetry (EP) combined with heptane adsorption were utilized to characterize the open porosity/interconnectivity and pore size distribution for the prepared films. The consistency between the open porosities was examined by the variations of orthopositronium (o-Ps) 3γ annihilation fractions and the total adsorbed volumes of heptane. The average pore sizes deduced by PALS from the longest-lived o-Ps lifetimes are in good agreement with those by EP on the basis of the Barrett–Joyner–Halenda model, as indicated by a well fitted line of slope k = 1. The results indicate that the EP combined with heptane adsorption is a useful method with high sensitivity for calibrating the mesopore size in highly interconnected mesoporous films, whereas PALS is a novel, complementary tool for characterizing both closed and open pores in them.

scholarly journals The Influence of Casein Protein Admixture on Pore Size Distribution and Mechanical Properties of Lime-Metakaolin Paste

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 530
Author(s):  
Przemysław Brzyski ◽  
Zbigniew Suchorab ◽  
Grzegorz Łagód
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Building Materials ◽  
Total Porosity ◽  
Organic Polymer ◽  
Partial Replacement ◽  
Average Pore

Biopolymers based on proteins are applied in the building materials technology to modify and improve their selected properties. These polymers are designed as natural admixtures that improve the workability of materials. Casein is an example of a protein-based organic polymer. It is a protein obtained from cow’s milk. The paper aimed at investigating the prospects of enhancing the strength properties of a binder prepared on a basis of metakaolin and hydrated lime. The mix was modified with powdered technical casein at 0.5%, 1%, 3%, and 5% as a partial replacement for the binder mix by mass. The study involved investigating the effect of the applied natural admixture on the flexural and compressive strengths, as well as pore size distribution. The average pore diameter decreased in the recipes with casein in the amount of 0.5% and 1%, while it increased when the amount of casein equaled 3% and 5%. Only the 0.5% casein admixture caused a decrease in the total porosity. The results show a clear dependence of the strength parameters on porosity. The admixture of casein significantly increased the flexural strength of the pastes, and decreased the compressive strength. The highest increase in flexural strength (by 205.7%) was caused by the admixture of 0.5% casein, while the greatest decrease in compressive strength (by 28%) was caused by the 3% casein admixture. The flexural strength was enhanced, i.a., due to the improved adhesion and mutual bonding of lime particles, resulting from the application of a sticky admixture. No notable difference was indicated during carbonation by the phenolphthalein test. The lime binder is characterized by a slow setting process and low mechanical strength. The results of the research showed the possibility of improving the flexural strength using small amounts of natural admixture, which may broaden the scope of application of this binder.

Evolution of Microstructural Characteristics of Different Cement Materials Caused by Carbonation

2014 ◽  
Vol 556-562 ◽  
pp. 628-632
Author(s):  
Son Tung Pham ◽  
William Prince
Keyword(s):  
Relative Humidity ◽  
Specific Surface ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrogen Adsorption ◽  
Microstructural Characteristics

The objective of this work was to examine the influence of carbonation on the microstructure of cement materials. Different materials, which were CEM I mortar and paste, CEM II mortar and paste, were carbonated at 20°C, 65% relative humidity and 20% of CO2 concentration. The specific surface area and pore size distribution were determined from the method of nitrogen adsorption. The results showed that the materials based on CEM II seemed to be more sensible to a creation of mesoporosity after carbonation than the CEM I based materials. The results of this study also helped to explain why observations in the literature diverge greatly on the influence of carbonation on specific surface area.

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

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