scholarly journals Hygric resistance in multilayer building materials – a prevision new methodology

2019 ◽  
Vol 282 ◽  
pp. 02017
Author(s):  
João Delgado ◽  
António Azevedo ◽  
Isabel Ribeiro ◽  
Ana. Guimarães ◽  
Vasco Freitas
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Contact Interface ◽  
Lime Mortar ◽  
Experimental Campaign ◽  
Knee Point ◽  
Air Space ◽  
Building Components ◽  
Wetting Process ◽  
Ray Methods

This work presents the results of an experimental campaign in order to determine the hygric resistance in multilayered building components, with different interface types. The results show a slowing of the wetting process due to the interfaces hygric resistance. The samples with hydraulic contact interface (cement mortar) present lower absorption rate than the samples with lime mortar. The influence of air space between layers was also demonstrated, i.e., the air space interfaces increase the coefficients of capillary significantly, as the distances from the contact with water increase. The hygric resistance was calculated by three different methods: gravimetric and gamma-ray methods, and the new methodology proposed, an automatic calculation method without human opinion/criteria. The “knee point” was detected, numerically, in water absorption curves and the moisture-dependent interface resistance was quantified and validated for transient conditions. The methodology proposed to detect the “knee point” can be also used in the future for different multilayer materials with an interface, in order to obtain more correct hygric resistance values to be used in future numerical simulations.

Hygric Permeance - New Calculation Methodology

2019 ◽  
Vol 24 ◽  
pp. 145-162 ◽  
Author(s):  
A.C. Azevedo ◽  
J.M.P.Q. Delgado ◽  
A.S. Guimarães ◽  
I.M. Ribeiro
Keyword(s):  
Contact Area ◽  
Gamma Ray ◽  
Mass Variation ◽  
Knee Point ◽  
Air Space ◽  
Calculation Methodology ◽  
Perfect Contact ◽  
Maximum Flows ◽  
Building Walls ◽  
Ray Methods

After intensifying the knowledge of hygric permeance (HP) in multi-layered test samples, which were subjected to the imbibition process, a significant set of HP values (with different interface types) was experimentally achieved. This was done in order to develop a new model which allows estimating more correctly the hygric permeance. The idea is predicts the HP with several scenarios, i.e., different interfaces (perfect contact, hydraulic contact and air space interface), interfaces heights and materials studied, in the attempt to estimate the HP without the need to resort to the measurement by the experimental route in the attempt to estimate the HP without the need to resort to the measurement by the experimental route and even with possible measurement, generator automatic calculation (without human opinion/criteria). In this paper, the Hygric Permeance will be calculated by two different methods, gravimetric and gamma ray methods, and a new methodology proposes. The maximum flows transmitted were determined by the slope of the mass variation per contact area in function of the time involved. When having interface, the calculations admit that the first layer is saturated and that all the increased weight stems becomes from the relative humidity that penetrates the interface. The new methodology proposed is analysis of the prevision mathematical model that describes the mass variation per contact area in function of the time, after the “knee point”. This work it is the first attempt to provide a set of values that refer from hygric permeance in masonry of building walls, these being random values experimentally determined.

Water Absorption Curves versus Gamma-Ray Attenuation Profiles: A Comparative Analysis of Hygric Permeance Results

2020 ◽  
Vol 400 ◽  
pp. 32-37
Author(s):  
A.S. Guimarães ◽  
I.M. Ribeiro ◽  
A.C. Azevedo ◽  
João M.P.Q. Delgado
Keyword(s):  
Comparative Analysis ◽  
Water Absorption ◽  
Building Materials ◽  
Gamma Ray ◽  
Moisture Transfer ◽  
Contact Interface ◽  
Perfect Contact ◽  
Gamma Ray Attenuation ◽  
Attenuation Profiles ◽  
Experimental Values

The knowledge of moisture transfer in multi-layered building materials and components using numerical simulations is fundamental to predict the behaviour of that building materials and components when in contact with moisture and to avoid some possible future pathology guarantying a correct performance.This paper describes a comparative analysis of experimental values of Hygric Permeance (HP) obtained by water absorption curves and gamma-ray attenuation profiles, for perfect contact interface.

scholarly journals Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area

2021 ◽  
Vol 15 (1) ◽  
pp. 29-37
Author(s):  
António C. Azevedo ◽  
João M.P.Q. Delgado ◽  
Klayne.K.S. Silva ◽  
André L.M.S. Leal ◽  
Ana S. Guimarães ◽  
...  
Keyword(s):  
Contact Area ◽  
Water Resistance ◽  
Capillary Absorption ◽  
Radial Compression ◽  
Contact Interface ◽  
Knee Point ◽  
Concrete Blocks ◽  
Interface Contact ◽  
Building Components ◽  
Perfect Contact

Introduction: Concrete sealing blocks are not only used in Brazil but worldwide. T he knowledge of the material properties in the presence of moisture becomes necessary to study the durability of buildings. Methods: An experimental study was carried out in order to analyse the effect of contact area on the capillary absorption coefficient of concrete samples used in sealing blocks, according to several standards: NBR 9779 (2012), EN 1015-18 (2002), ISO 15148 (2002) and ASTM C1794 (2015). Two types of specimens were analysed; monolithic samples and samples with a perfect contact interface. The monolithic samples were also subjected to axial and radial compression in order to enhance the capacity of masonry. Results: The experimental results for the samples with perfect contact interface indicate that the water absorption before the interface presents similar behaviour to the monolithic samples. However, it is possible to observe a reduction of the absorption rate when water reaches the interface due to the hygric resistance. In other words, the moisture transport is significantly retarded by the existence of an interface, i.e., the discontinuity of moisture content across the interface indicated that there was a difference in capillary pressure across the interface. Also, the interface contact area does not greatly influence the water-resistance values. Conclusion: Finally, the Hygric Resistance values (HR), in multilayer building components, with perfect contact interface are calculated using the “knee point” methodology.

Natural radioactivity in some building materials and assessment of the associated radiation hazards

2018 ◽  
Vol 106 (1) ◽  
pp. 79-86
Author(s):  
Amira Kasumović ◽  
Ema Hankić ◽  
Amela Kasić ◽  
Feriz Adrović
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Absorbed Dose ◽  
Absorbed Dose Rate ◽  
Radium Equivalent Activity ◽  
Radiation Hazards ◽  
Eu Member States ◽  
Gamma Ray Spectrometer ◽  
Radioactive Nuclides ◽  
Specific Activities

AbstractThe results of the specific activities of232Th,226Ra and40K measured in samples of commonly used building materials in Bosnia and Herzegovina are presented. Measurements were performed by gamma-ray spectrometer with coaxial HPGe detector. The surface radon exhalation and mass exhalation rates for selected building materials were also measured. The determined values of specific activities were in range from 3.16±0.81 Bq kg−1to 64.79±6.16 Bq kg−1for232Th, from 2.46±0.95 Bq kg−1to 53.89 ±3.67 Bq kg−1for226Ra and from 28.44±7.28 Bq kg−1to 557.30±93.38 Bq kg−1for40K. The radium equivalent activity, the activity concentration index, the external and internal hazard indices as well as the absorbed dose rate in indoor air and the corresponding annual effective dose, due to gamma-ray emission from the radioactive nuclides in the building material, were evaluated in order to assess the radiation hazards for people. The measured specific activities of the natural radioactive nuclides in all investigated building materials were compared with the published results for building materials from other European countries. It can be noted that the results from this study are similar to the data for building materials from neighbouring countries and for building materials used in the EU Member States. The radiological hazard parameters of the building materials were all within the recommended limits for safety use.

A preliminary intercomparison of gamma-ray spectrometry on building materials

2004 ◽  
Vol 61 (2-3) ◽  
pp. 381-388 ◽  
Author(s):  
M.J. Anagnostakis ◽  
C. Bolzan ◽  
P. De Felice ◽  
A. Fazio ◽  
G. Grisanti ◽  
...  
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Gamma Ray Spectrometry

Radiometric analysis of some building materials using gamma-ray spectrometry

2020 ◽  
Vol 324 (3) ◽  
pp. 1059-1067
Author(s):  
V. Thangam ◽  
A. Rajalakshmi ◽  
A. Chandrasekaran ◽  
B. Jananee
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Gamma Ray Spectrometry ◽  
Radiometric Analysis

ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIOLOGICAL HAZARDS IN BUILDING MATERIALS

2020 ◽  
Vol 188 (3) ◽  
pp. 316-321
Author(s):  
Fei Tuo ◽  
Xuan Peng ◽  
Qiang Zhou ◽  
Jing Zhang
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Absorbed Dose ◽  
Gamma Ray Spectrometry ◽  
Absorbed Dose Rate ◽  
Radium Equivalent Activity ◽  
Radiological Hazards ◽  
Radium Equivalent ◽  
Different Types ◽  
Radioactivity Levels

Abstract Radioactivity of 226Ra, 232Th, and 40K were measured in a total of 92 samples, including eight commonly used types of building materials that were obtained from local manufacturers and suppliers in Beijing. Concentrations were determined using high-purity germanium gamma-ray spectrometry. The 226Ra, 232Th, and 40K activity concentrations in all samples varied from 10.1 to 661, 3.3 to 555 and 3.2 to 2945 Bq per kg with an average of 127.8, 114.8, and 701.5 Bq per kg, respectively. The potential radiological hazards were estimated by calculating the absorbed dose rate (D), radium equivalent activity (Raeq), external hazard (Hex), and internal hazard (Hin) indices. The investigated building materials were classified into different types according to the radioactivity levels. Results from this research will provide a reference for the acquisition, sales, and use of building materials. Attention should be paid to the use of coal cinder brick, ceramic, and granite in the construction of dwellings.

The Radioactivity Levels and Safety Assessment of Building Materials in Nanjing, Jiangsu Province, China

2011 ◽  
Vol 243-249 ◽  
pp. 6913-6918
Author(s):  
Jian Lu ◽  
Hao Yang ◽  
Ming Li Zhang
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Natural Radionuclides ◽  
Jiangsu Province ◽  
Internal Exposure ◽  
External Exposure ◽  
Exposure Index ◽  
Radium Equivalent Activity ◽  
Radium Equivalent ◽  
Radioactivity Levels

In order to invetigate the natural radioactivity levels of typical building materials in Nanjing, Jiangsu Province,China, the specific activities of natural radionuclides (226Ra,232Th and40K) in samples of building materials were measured by ORTEC HPGe gamma ray spectrometer. And the radium equivalent activity, the internal and external exposure index, and relative annual effective dose equivalents were also claculated. The average concentrations of all the samples ranged from 64 to 318.79 Bq·kg-1, 11.35 to 144.83 Bq·kg-1and 92.57 to 951.68 Bq·kg-1for226Ra,232Th and40K, respectively. Their average values were in the ranges: 0.33-1.50 for the internal exposure index (Ira); 0.29-1.51 for the external exposure index (Ir); 0.34-1.74 mSv·a-1 for HEextand 0.36-1.76 mSv·a-1for HEint. The average radium equivalent activity varied from 106.49 to 541.77 Bq·kg-1. According to the standard, most samples were in a lower radioactivity level expect a few of artificial tiles. But, we must perfect detection and management system of many materials to ensure radiation safety and physical health.

Ermittlung der Kapillartransportkoeffizienten mineralischer Baustoffe aus dem w-Wert / Estimating the capillary transport coefficients of mineral building materials from the water absorption coefficient

1997 ◽  
Vol 3 (3) ◽  
pp. 219-234
Author(s):  
M. Krus ◽  
A. Holm ◽  
Th. Schmidt
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Building Materials ◽  
Transport Coefficients ◽  
Capillary Transport ◽  
Water Absorption Coefficient ◽  
Standard Material ◽  
Moisture Balance ◽  
Computer Calculations ◽  
Building Components

Abstract Computer calculations are of increasing importance for the assessment of moisture balance in building components, since modern calculation methods achieve good agreement with measurements. A broader application of these methods is hampered, however, by the laborious measurements needed to determine the capillary transport coefficients essential for the calculations. A new method is therefore presented which allows to estimate the coefficients from wellknown standard material properties (free capillary saturation, practical moisture content and water absorption coefficient). These coefficients are sufficient for estimative assessment of the moisture balance of many materials, as is demonstrated by comparison of suction profiles calculated in this way and measured profiles.

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