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 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.

scholarly journals How effective is kaolin clay for the creation of a perfect hydraulic interface contact between materials?

2020 ◽  
Vol 172 ◽  
pp. 14002
Author(s):  
Evy Vereecken ◽  
Petra Schůtová ◽  
Staf Roels
Keyword(s):  
Water Uptake ◽  
Moisture Transfer ◽  
Kaolin Clay ◽  
Contact Interface ◽  
Uptake Curve ◽  
Interface Resistance ◽  
Interface Phenomena ◽  
Interface Contact ◽  
Perfect Contact ◽  
Composite Samples

Due to interface phenomena such as compaction pores, a mismatch of the pore structure, etc., moisture transfer in multi-layered building elements can deviate from the moisture transfer observed for the combination of the separate materials. Several studies on interface phenomena make use of kaolin clay to provide – as a reference – a perfect hydraulic contact between materials. This paper investigates, based on a series of imbibition experiments, whether kaolin clay truly creates this perfect contact, and thus, whether the hydraulic interface resistance between materials can be nullified by use of kaolin clay. For a low absorptive material or a large distance between the contact interface and the water surface, composite samples put together with kaolin clay show an identical water uptake curve as observed for homogeneous samples. For a material with a high absorptivity and a contact interface closer to the water plain, however, even with kaolin clay a hydraulic interface resistance is observed and estimated to be in the order of 6 000 m/s till 12 000 m/s. If present, such an interface resistance is furthermore shown to have no impact on the water uptake curve for samples composed of low absorptive bricks or with a contact interface further away from the water plain.

Moisture Measuring Device Based on Non-Destructive Method of Gamma Ray’s Attenuation

2017 ◽  
Vol 380 ◽  
pp. 55-59
Author(s):  
A.S. Guimarães ◽  
J.M.P.Q. Delgado ◽  
V.P. de Freitas ◽  
A.C. Azevedo
Keyword(s):  
Gamma Rays ◽  
Building Materials ◽  
Gamma Ray ◽  
Moisture Transfer ◽  
Measuring Device ◽  
Water Diffusivity ◽  
Building Physics ◽  
Non Destructive ◽  
Kinetics Of ◽  
Transfer Study

A moisture measuring device based on non-destructive method of gamma rays attenuation, allows measures to deepen concepts in building physics related to the moisture transfer; study the influence of the interface between layers in moisture transfer; analyse the influence of gravity on absorption and drying of different building materials; study the kinetics of absorption and drying of walls of one or more layers; analyse the importance of the temperature gradient in the movement of moisture; calculate the coefficient of water diffusivity of some building materials. In this work the proposed non-destructive method of gamma ray’s attenuation was used to analyse the transport of liquid water along a constructive element. For that propose gamma ray hydric profiles with red brick samples, 2 types: “A” and “B”, were obtained. Gamma ray hydric profiles are very interesting and original considering that the equipment exists in just a scarce laboratory. It is also intended to show how the equipment works and the way that those profiles can be taken. The water content profiles experimentally measure are very interesting, and the preliminary results obtained, for red brick samples with different densities and sectional area, will be shown and discussed.

scholarly journals Gamma-Ray Attenuation to Evaluate Soil Porosity: An Analysis of Methods

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Luiz F. Pires ◽  
André B. Pereira
Keyword(s):  
Gamma Ray ◽  
Particle Density ◽  
Pore Space ◽  
Physical Property ◽  
Soil Bulk Density ◽  
Soil Porosity ◽  
Porous System ◽  
Soil Pore Space ◽  
Gamma Ray Attenuation ◽  
Dry Soil

Soil porosity (ϕ) is of a great deal for environmental studies due to the fact that water infiltrates and suffers redistribution in the soil pore space. Many physical and biochemical processes related to environmental quality occur in the soil porous system. Representative determinations ofϕare necessary due to the importance of this physical property in several fields of natural sciences. In the current work, two methods to evaluateϕwere analyzed by means of gamma-ray attenuation technique. The first method uses the soil attenuation approach through dry soil and saturated samples, whereas the second one utilizes the same approach but taking into account dry soil samples to assess soil bulk density and soil particle density to determineϕ. The results obtained point out a good correlation between both methods. However, whenϕis obtained through soil water content at saturation and a 4 mm collimator is used to collimate the gamma-ray beam the first method also shows good correlations with the traditional one.

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