Characterization of Building Stones Involved in Historical Masonry

2011 ◽  
Vol 324 ◽  
pp. 388-391 ◽  
Author(s):  
Zbyšek Pavlík ◽  
Eva Vejmelková ◽  
Milena Pavlíková ◽  
Martin Keppert ◽  
Robert Černý
Keyword(s):  
Mercury Porosimetry ◽  
Moisture Diffusivity ◽  
Water Vapor Transport ◽  
Historical Buildings ◽  
Water Absorption Coefficient ◽  
The Czech Republic ◽  
Vacuum Saturation ◽  
Historical Masonry ◽  
Saturation Method

Basic physical properties, pore size distribution and hygric properties of several types of stones which are used in reconstructions of historical buildings on the territory of the Czech Republic, namely several types of sandstone and argillite, are investigated. Basic physical characteristics are measured using the water vacuum saturation method, pore distribution by mercury porosimetry. Values of water absorption coefficient and apparent moisture diffusivity are determined by methods utilizing the results of water sorptivity measurements. Water vapor transport properties are accessed by the cup method. The obtained data represents valuable information for the application of studied materials in reconstructions and renewal of historical buildings.

Basic Physical and Mechanical Properties of Composites Based on Three Different Cements

2016 ◽  
Vol 677 ◽  
pp. 186-190 ◽  
Author(s):  
Monika Čáchová ◽  
Eva Vejmelková ◽  
Kateřina Šestáková ◽  
Pavel Reiterman ◽  
Martin Keppert ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Open Porosity ◽  
Mercury Porosimetry ◽  
Physical And Mechanical Properties ◽  
Mineralogical Composition ◽  
Physical Parameters ◽  
Vacuum Saturation ◽  
Saturation Method ◽  
Properties Of Composites

This article is focused on cement based composites. Two cements differing in mineralogical composition are utilised as main binder in composites mixtures. Results of measured physical parameters of studied materials are presented. For the sake of comparison, a reference material with Portland cement was also prepared. Basic physical properties (measured by water vacuum saturation method and by helium pycnometry), characterizations of pore system (determined by mercury porosimetry) and mechanical properties are the matter of this study. Composites show various open porosity; the results of open porosity of materials containing special cements show higher values, in comparison with composite based on Portland cement. This fact of course influences other material characteristics - mainly mechanical properties.

Pore System and Hydric Properties of Two Different Lime Plasters with Finely Crushed Brick

2016 ◽  
Vol 675-676 ◽  
pp. 597-600 ◽  
Author(s):  
Monika Čáchová ◽  
Eva Vejmelková ◽  
Kirill Polozhiy ◽  
Robert Černý
Keyword(s):  
Reference Material ◽  
Liquid Water ◽  
Mercury Porosimetry ◽  
Silica Sand ◽  
Pore System ◽  
Vacuum Saturation ◽  
Lime Plaster ◽  
Crushed Brick ◽  
Helium Pycnometry

Two different lime plasters with finely crushed brick are studied in this article. In the first plaster the pozzolan mixture was used as silica sand while in the second it was dosed as replacement of the lime substitute and silica sand (the substitution levels being 20% and 50%). Classic lime plaster was used as a reference material. Studied parameters were basic physical properties (measured by water vacuum saturation and by helium pycnometry), characterization of pore system (by mercury porosimetry) and transport of liquid water.

Basic and Thermal Characteristics of Render with Crushed Brick

2015 ◽  
Vol 824 ◽  
pp. 7-11
Author(s):  
Monika Čáchová ◽  
Eva Vejmelková ◽  
Martin Keppert ◽  
Lukáš Fiala
Keyword(s):  
Mercury Porosimetry ◽  
Thermal Characteristics ◽  
Waste Material ◽  
Silica Sand ◽  
Thermal Insulating ◽  
Vacuum Saturation ◽  
Cement Binder ◽  
Saturation Method ◽  
Crushed Brick ◽  
Pozzolanic Properties

Recycled finely crushed brick appears to be a suitable additive to lime or cement binder in render mixtures. This waste material indicates good pozzolanic properties and actively takes part in formation of chemical bonds in materials structure. The main objective of this paper is to find an appropriate ratio of waste crushed brick that is used as a replacement of other constituents represented by lime hydrate and silica sand. Besides it aims to find out a perspective utilization of such a waste material. Finely crushed brick originates from the production of thermal insulating brick blocks which is ecologically and economically advantageous. In this work, results of measured material parameters of render mixtures with different replacement ratios of binder (lime hydrate) and simultaneously filler (silica sand) by finely crushed brick are presented. Among the studied parameters basic physical properties (measured by water vacuum saturation method and by helium pycnometry), characterization of pore system (by mercury porosimetry) and thermal characteristics are presented.

A Contribution to the Treatment of Salt Damage in Historical Buildings

2015 ◽  
Vol 824 ◽  
pp. 127-132
Author(s):  
Iñigo Antepara ◽  
Igor Medveď ◽  
Jaromír Žumár ◽  
Robert Černý
Keyword(s):  
Building Materials ◽  
Historical Buildings ◽  
Research Teams ◽  
Porous Building Materials ◽  
Salt Damage ◽  
Advantages And Disadvantages ◽  
Historical Masonry

Salts and water may cause serious damage to historical masonries. Therefore, numerous conservation treatments have been developed by research teams for the consolidation and protection of porous building materials affected by salt attack. Here the focus is on methods for obtaining an effective desalination of historical masonry, indicating their advantages and disadvantages. It is pointed out that cellulose is a favourite material added to poultices used in desalination.

Fabrication and characterization of air-impedance electrospun polydioxanone templates

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Gretchen S. Selders ◽  
Allison E. Fetz ◽  
Shannon L. Speer ◽  
Gary L. Bowlin
Keyword(s):  
Tissue Engineering ◽  
Mercury Porosimetry ◽  
Synthetic Polymers ◽  
Pore Analysis ◽  
Exceptional Value ◽  
Preliminary Study ◽  
Fabrication And Characterization ◽  
Fiber Deposition ◽  
Retention Strength

AbstractElectrospinning, a fabrication technique used to create non-woven, porous templates from natural and synthetic polymers, is commonly used in tissue engineering because it is highly tailorable. However, traditional electrospinning creates restrictive pore sizes that limit the required cell migration. Therefore, tissue engineering groups have sought to enhance and regulate porosity of tissue engineering templates. Air-impedance electrospinning generates templates with tailorable, patterned areas of low and high density fiber deposition. Here we demonstrate an improved air-impedance electrospinning system, consisting of a newly designed funnel equipped to hold changeable porous deposition plates and administer air flow in a confined and focused manner, with parameters that maintain template integrity. In this preliminary study, we quantify the increase in porosity of polydioxanone templates with use of traditional fiber and pore analysis as well as with mercury porosimetry. Additionally, we validate the system’s significance in fabricating enhanced porosity templates that maintain their mechanical properties (i.e. elastic modulus, tensile strength, and suture retention strength) despite the deliberate increase in porosity. This is of exceptional value to the template’s integrity and efficacy as these parameters can be further optimized to induce the desired template porosity, strength, and texture for a given application.

scholarly journals Characterization of the Complete Nucleotide Sequences of mcr-1-Encoding Plasmids From Enterobacterales Isolates in Retailed Raw Meat Products From the Czech Republic

2021 ◽  
Vol 11 ◽  
Author(s):  
Marketa Zelendova ◽  
Costas C. Papagiannitsis ◽  
Adam Valcek ◽  
Matej Medvecky ◽  
Ibrahim Bitar ◽  
...  
Keyword(s):  
Meat Products ◽  
Study Data ◽  
Sequence Type ◽  
Sequence Database ◽  
The Czech Republic ◽  
Raw Meat ◽  
Geographical Regions ◽  
Antimicrobial Resistance Genes ◽  
Retail Meat

The aim of our study was to determine complete nucleotide sequence of mcr-1-carrying plasmids from Enterobacterales isolates recovered from domestic and imported raw retailed meat and compare them with plasmids available at the GenBank sequence database. A set of 16 plasmids originating from Escherichia coli (n = 13), Klebsiella pneumoniae (n = 2), and Citrobacter braakii (n = 1) were analyzed. In our previous study, data from whole genome sequencing showed that mcr-1 gene was located on plasmids of different incompatibility groups (IncHI2, IncI2, and IncX4). The IncI2 (n = 3) and IncX4 (n = 8) plasmids harbored mcr-1.1 gene only, whereas IncHI2 sequence type 4 plasmids (n = 5) carried large multidrug resistance (MDR) regions. MDR regions of IncHI2 plasmids included additional antimicrobial resistance genes conferring resistance to β-lactams (blaTEM−1), aminoglycosides [aadA1, aadA2, and aph(6)-Id], macrolides [mef (B)], tetracycline (tetA, tetR), and sulphonamides (sul1, sul2, and sul3). Likewise, IncHI2 plasmids carried several insertion sequences including IS1, IS3, IS26, IS1326, and ISApl1. In conclusion, our findings confirmed the involvement of IncX4, IncI2, and IncHI2 plasmids in the dissemination of mcr-1.1 gene in several environmental niches, as in samples of retail meat originating from different geographical regions. In contrast to IncX4 and IncI2, IncHI2 plasmids were more diverse and carried additional genes for resistance to heavy metals and multiple antimicrobials.

scholarly journals Reología, comportamiento físico-mecánicos y de durabilidad de hormigones con nanosílice.

2012 ◽  
Vol 2 (2) ◽  
pp. 82-88
Author(s):  
E. Téllez Girón ◽  
A .N. Martín Acosta ◽  
A. Pérez Hernández ◽  
U. Verdecia Rodríguez
Keyword(s):  
Resistance Coefficient ◽  
Ultrasonic Pulse ◽  
Effective Porosity ◽  
Capillary Absorption ◽  
Water Absorption Coefficient ◽  
Characterization Methods ◽  
Natural Pozzolans ◽  
Chemical Admixtures ◽  
Microscopy Analysis

RESUMENLa nanosílice es una de las aplicaciones de la nanotecnologia en la construcción, a base de sílica amorfa nanométrica, que se emplea igual que la microsílice, pero con la ventaja que no produce contaminación al medio ambiente y la agresión a la salud por inhalación de ésta. Se dan los resultados de la caracterización física de dos compuestos de nanosílice comerciales mediante los métodos de la caracterización de aditivos y el empleo de la microscopia para la determinación de compuestos fundamentales, de sus actividades puzolánicas en morteros, así como la determinación de la absorción capilar, velocidad ultrasónica, masa volumétrica, coeficientes de resistencia a la penetración de agua, coeficiente de absorción de agua y porosidad efectiva en hormigones elaborados con los compuestos evaluados y en hormigones con aditivos superplastificantes y tobas zeolitizadas como patrones de comparación. Los valores demuestran un mejor comportamiento de durabilidad en los hormigones elaborados con nanosílice.Palabras Clave: nanotecnología; nanosílice; microsílice; aditivos químicos; adiciones.ABSTRACTNanosilice based in nanometric amorphous silica is one of the aplications of nanotechnology in the building industry, that has the same use than microsilica, but with the advantage that it does not produce environmental pollution or respiratory complains due to inhalation. We give the results of the physical characterization of two commercial nanosilice compounds by the admixtures characterization methods and electronic microscopy analysis to determine the fundamental compound, its pozzolanic activity in mortars, as well as its capillary absorption, ultrasonic pulse speed, volumetric mass, water penetration resistance coefficient, water absorption coefficient and effective porosity in concrete with nanosilice and in ordinary concrete with natural pozzolans and superplasticizer admixtures like comparative patterns. Results show a better behavior of durability in concretes with nanosilice.Keywords: nanotechnology; nanosilica; microsilica; chemical admixtures; additions.

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