scholarly journals A round robin campaign on the hygric properties of porous building materials

2019 ◽  
Vol 282 ◽  
pp. 02011 ◽  
Author(s):  
Chi Feng ◽  
Ana Sofia Guimarães ◽  
Nuno Ramos ◽  
Lixin Sun ◽  
Dariusz Gawin ◽  
...  
Keyword(s):  
Building Materials ◽  
Round Robin ◽  
Capillary Absorption ◽  
Reliable Determination ◽  
Porous Building Materials ◽  
Vacuum Saturation ◽  
Experimental Protocols ◽  
Hygric Properties ◽  
Data Processing Methods

The reliable determination of the hygric properties of porous building materials is important. In earlier round robin campaigns large discrepancies of measured hygric properties were found among different labs. Later studies indicated that differences in lab conditions and more importantly, personnel’s operation procedures and data processing methods, might have the greatest impact. To gain further insight, a new round robin campaign has been launched by KU Leuven (Belgium), to which another eight institutes contributed. A relatively stable and homogeneous ceramic brick is tested, and 3 standard tests are performed: the vacuum saturation test, the capillary absorption test and the cup test. During the campaign, two rounds of measurements are performed. In the 1st round, tests are performed according to participants’ respective experimental protocols. Next, a strict and detailed common protocol is prescribed. This paper reports on the results obtained in the 1st round of measurements. Results show that not much progress has been made since the EC HAMSTAD project: the vacuum saturation test leads to the most consistent results, while the cup test produces the largest discrepancies, most probably originating from sample sealing and humidity control.

scholarly journals Hygric properties of porous building materials (VI): A round robin campaign

2020 ◽  
Vol 185 ◽  
pp. 107242 ◽  
Author(s):  
Chi Feng ◽  
Ana Sofia Guimarães ◽  
Nuno Ramos ◽  
Lixin Sun ◽  
Dariusz Gawin ◽  
...  
Keyword(s):  
Building Materials ◽  
Round Robin ◽  
Porous Building Materials ◽  
Hygric Properties

COMPUTATIONAL APPROACH FOR ESTIMATING HYGRIC PROPERTIES OF HETEROGENEOUS MATERIALS IN LONG-TERM ASSESSMENT OF MOISTURE-INDUCED DAMAGE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Václav Kočí ◽  
Jiří Maděra ◽  
Robert Černý
Keyword(s):  
Building Materials ◽  
Heterogeneous Materials ◽  
Computational Time ◽  
Computational Techniques ◽  
Computing Power ◽  
One Dimensional ◽  
Dimensional Modeling ◽  
Hygric Properties

Long-term assessment of degradation processes is a very useful tool for an analysis of building materials performance. Since computational techniques are mostly used for this purpose, hygric properties of involved materials are required as substantial input data. Unfortunately, some construction details or heterogeneous materials have to be solved by means of multi-dimensional modelling which is demanding on computing power and thus the calculations may take a lot of time. The presented paper aims at determination of effective hygric properties of heterogeneous materials which would allow one-dimensional transformation. The parameter identification process is carried out on the basis of results of multi-dimensional modeling, using genetic algorithms. The main objective is to find such effective global moisture transport and accumulation functions that provide in one-dimensional modeling as similar results to multidimensional modeling as possible. The obtained functions give a very good agreement; the investigated relative humidity profiles differ only by 1.48 percentage points in average. The correctness of obtained results is also verified using the Lichtenecker's mixing rule as homogenization technique. The transformation of the original multidimensional problem into one-dimensional is found to substantially contribute to minimization of computational time, which is reduced from weeks to minutes.

scholarly journals Hygric properties of hydrophobized building materials

2019 ◽  
Vol 282 ◽  
pp. 02048 ◽  
Author(s):  
Vasilis Soulios ◽  
Ernst Jan de Place Hansen ◽  
Hans Janssen
Keyword(s):  
Absorption Coefficient ◽  
Water Vapour ◽  
Open Porosity ◽  
Building Materials ◽  
Capillary Absorption ◽  
Vapour Permeability ◽  
Vacuum Saturation ◽  
Low Concentrations ◽  
Brick And Mortar ◽  
Water Vapour Transfer

Moisture loads due to wind-driven rain can lead to accelerated decay of exposed building facades. Hydrophobic impregnation reduces water absorption of facade materials and is thus presumed to decrease moisture related damages. Hydrophobic impregnation however also lowers the drying speed of the exposed facade, leaving mainly water vapour transfer to take place. This study examines the open porosity and capillary absorption coefficient of impregnated brick samples as well as the effect of hydrophobic impregnation on the vapour permeability of brick and mortar samples. The open porosity was measured with vacuum saturation test, the absorption coefficient was determined by water uptake tests, both done after one month of curing of the impregnated brick samples. The vapour permeability was `derived from cup tests and from drying tests. The resulting open porosity from brick samples indicates that the changes in the overall pore structure are minimal after impregnation. In addition, the absorption coefficient of brick was found to be fairly close to zero, even with low concentrations of active ingredient, and regardless the percentage of silane/siloxane. Our findings support the claim that the hydrophobic impregnation does not influence significantly the water vapour permeability of brick and mortar.

Fast Inverse-Analysis Calculation of Diffusion Coefficient for Salt Transport in Porous Building Materials

2015 ◽  
Vol 1126 ◽  
pp. 117-122 ◽  
Author(s):  
Igor Medveď ◽  
Zbyšek Pavlík ◽  
Milena Pavlíková ◽  
Robert Černý
Keyword(s):  
Diffusion Coefficient ◽  
Inverse Analysis ◽  
Analytical Approach ◽  
Building Materials ◽  
Salt Transport ◽  
Porous Building Materials ◽  
Advection Diffusion ◽  
Analysis Calculation ◽  
Salt Diffusion

An analytical approach to the determination of a varying salt diffusion coefficient is discussed. It is argued that the approach is fast and reliable and can be very convenient in various civil engineering applications dealing with the transport of salts in porous building materials. The advection-diffusion model of Bear and Bachmat is used to describe the salt transport, and the Bolztmann-Matano inverse analysis is applied to calculate the salt diffusion coefficient. Possible extensions to other models of transport are pointed out. The results are applied to a sandstone from the Msene quarry, Czech Republic.

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