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Following
absorbability of building materials
JAN SKRAMLIK, MILOSLAV NOVOTNY
Institut
of Building Structures, University of Technology Brno, Faculty of Civil
Engineering,
Veveri
95, 602 00 Brno , Czech Republic
E-mail:
skramlik.j@fce.vutbr.cz
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Keywords: capillary
conductivity coefficient, moisture transfer, electromagnetic microwave radiation
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The article deals with the experimental monitoring of the
moisture transfer in the building constructions. The moisture transport is
measured by a non-destructive method by use of an electromagnetic microwave
radiation. A device for measurement of the moisture transport by a
non-destructive method by use of a MW radiation was designed at the Faculty
of Civil Engineering of the University of Technology in Brno. Testing
measurements were proceeded on normally used building materials as the brick
and AAC block. The aim is to present a methodic for practical evaluation of
the chosen construction material for the application in the specific
placement in the building construction.
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Introduction
The behavior of construction materials in
the building structures influenced by the environmental moisture is a crucial
and intensively searched field of the construction physics. The most of broadly
used building materials are characterized by porous structure and such they are
able to receive water in a fluid as well as in gaseous form into the inner
cavities. The water fills under certain conditions the accumulation space of
the pores and is transported and transferred again into the environs. There is
a teaching in literature references about mostly only experimental searches of
the moisture permeability. The existing mathematical formula introduced e.g. by
Glaser, which became in the sixties the base for the standard’s calculations in
many European countries cannot be always applied with respect to the
requirements for the building constructions.
The basic
teaching for presented search are the published formulas of moisture transfer
and moisture accumulation in the construction
physics respective description of the moisture behavior of construction materials. From publication
references calculation models are known - e.g. KRISCHER (1975), HUSSEINI
(1982), KIESSL (1984), RICKEN (1991) and further some numerical moisture
characteristics for selected building constructions from the construction/physics point of view.
The moisture
has the dominant influence on service life and above all on the
thermo-technical characteristics of the building materials. From all known types
of moisture spreading is used in the construction physics only a method for
assessment of one dimensional diffusion of the water steam at the stationary
conditions. Other types of moisture spreading are studied experimentally and
their theoretical physics description is created gradually. For practical
description in the fields, where the moisture occurs as a fluid phase, an empirical model is rather used, which is
in context with the studied problem (e.g. physics of the ground earth, construction
physics, hydrodynamics etc.). For the calculation of the denominator of
capillary moisture conductivity K by
the use of known methods (Matan's method, integral method) the moisture curves
are applied, which are settled by the gravimetrical method.
The aim of
the experiment is to verify the possibility of obtaining of the entrance data
in the non-stationary stadium of the moisturizing process by a non-destructive
method to define the moisture transport and moisture accumulation models by use
of a microwave radiation. The aim is to create a methodic for definition of the
moisture transport behavior, which would be able to differentiate between
construction materials according to the moisture parameters and which would
serve for practical application by the choice of the building material and for
its specific placement in the building construction.
STATE OF THE ART
In
publication references many various results can be found but these are not in a
mutual conformity.
Main element of the Krischer's theory is a denominator
of the moisture conductivity K,
which describes the transportability of the building material depending on the
moisture content uv. Later on PHILLIP and DE VRIES have proved, that
the reason for speeding up effect of the spreading of the moisture content in
the porous materials is the establishing of the fluid bridges. In narrow
pores of varying width of the capillary
the accumulation of water is enhanced with enhancing moisture as an effect of
capillary condensation, first in the more narrow profiles. In the fluid water
in capillary the water molecules can easy move, consequently the fluid bridges
create new routes without any „inner resistance“. With increasing moisture the number of bridges is increasing and the
route which the molecules have to pass is shortening. It is proven, that it is
uneasy to bring the creation of bridges in a balanced state.
Knowledge of
the spatial and time distribution of the moisture in the specific material is
applied to the setting of capillary conductivity coefficient K as a characterizing parameter. In
cases, when it can be secured that the border condition on the dry end cannot
be applied, usually Matan's method is used, as a method for the non-stationary
state of moisturizing in combination with the gravimetrical method. Matan's
method supposes to know one moisture curve and the respective time interval
corresponding with this curve (see Fig.1).
For
settlement of moisture curves were used in this case the output data from measurement by use of a microwave radiation
device, which indicates the reduction of radiation intensity due to the moisture included in the pore
system of the studied building material. It is a non-destructive monitoring of
a searched specimen of the material. This method of studying of the moisture
distribution by use of the electromagnetic microwave radiation (further EMWR),
as well as the NMR method, enables to obtain desired data by continuous measurement.
On one and the same specimen data for creating of more moisture curves can be
obtained, which are taken in selected time intervals, and this enables the application of the integral calculation method.
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Fig 1 Assumed moisture
profiles u (x) in the time intervals
tx by the moisturizing of the searched specimen with indication of
the initial and border conditions for calculation of the capillary conductivity
coefficient.
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In Fig.1 moisture curves are illustrated in the time
intervals t1 , t2 , t3 and t4
from beginning of the moisturizing process and indication of the border condition for calculation of the
capillary conductivity coefficient κ.
Axle x indicates the length coordinate as a perpendicular distance from the
water level, it means the distance between the contact surface of the specimen
and the water level: The portion A is a coordinate of the beginning of the
moisture profile. Moisture profile can be found on the specimen starting from
the face and protruding into the specimen as the moisture gets up along the
specimen. B is lengths coordinate of
the moisture profile. The distance X determines the coordinate of the inflexion
point of the moisture curve within the time t4. At the perpendicular
axle there are the values of the moisture by weight, where u2 is the
starting moisture by weight of the searched specimen and u1 is the
moisture by weight of the searched specimen settled during the non-stationary
moisturizing process.
Capillary
conductivity coefficient is defined by a Lykov's quotation, which defines the
density of the flood of the capillary water q, driven by the capillary mechanisms
in a common form and it applies practically in the whole field of the moistures
u ε (0, u1 ):
[kg.m-2.s-1] (1)
Where
κm - capillary conductivity coefficient
q - density of the flood of the capill.
water [ kg.m-2 . s-1]
δu/δx -
relative moisture gradient, which has the role of the drive
thermodynamic moisture potential [ m-1],
ρs weight by volume of the solid phase [ kg.m-3]
u – moisture by weight [-]
Czech Standard No. CZ 731901 determines the construction
project in such way, that the favorable moisture state can be obtained and
recommends to limit the amount of the unabsorbed rain water, protruding of the
water into the construction and condensation of the water steam.
The water
transport is always determined also by the moisture gradient [7]
(2)
Km is depending on the moisture gradient
and is a denominator of the direct proportion between the density of the flood
of the capillary water and negatively assumed moisture gradient.
For moisture
transfer in the porous material by thermal and moisture gradient following
differential quotation is proposed:
(3)
The calculation according to CZ Standard No.7305040 concerns
the quantity evaluation of the moisture. The moisture influences
thermo-insulating properties of the material. By a change of the
thermo-insulation properties of the construction also the thermal and diffusion
scheme of the construction is changed and its thermal resistance is decreasing.
Faults in the thermo-technical projects occurs when for thermal conductivity
coefficient λ values for material in a dry state are substituted.
The calculation of the capillary conductivity coefficient κm
is derived from the information about the moisture distribution u(x) during the
time t [8]:
(4)
κm(u(x)) - the capillary conductivity
coef. [m2 . s-1]
t – time interval, when the moisture was measured as a
function of the curve u(x) [s]
ζ – substitution of distance from a point on the curve of the
moisture front expressed in the
distance, where the moisture is in the stable state
x – length coordinate of the searched specimen [m]
Capillary moisture spreading through the building
materials cannot be precisely
analytically described because of the existence of the porous structure, which
is determining for the movement of moisture phases of the moisture and the moisture calculations can be only approximate.
For studying
of the moisture transport with EMWR method specimens of construction material
were chosen, which are normally used by the building constructions. It is the
inert porous material of a brick and an autoclaved aerated concrete block
(further only AAC block).
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Fig .2 Microscope picture
of the surface structure of the brick (enlarged 220 x)
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Fig .3 Microscope picture
of the surface structure of the AAC block (enlarged 220 x)
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On the Figs. 2 and 3 pictures of material structure of
the searched specimens taken by optical
microscope are shown. Lykov (1958) has proposed, that the pores with the radius
r < 10-7 m should be
called as micropores and the pores with the radius r < 10-6 m should be called as macropores, because
the transport mechanism of the fluid phase is running in another way. Pores
with r < 10-7 m are not
fully fulfilled with the fluid water because of the capillary condensation but
only as a result of a direct contact with the water. The interval of capillary
radiuses 10-7 m < r
< 10-6 m corresponds according Thompson – Kelvin formula to the
relative moisture 99,0 – 99,9% and in this range fluid water can move in e.g.
hard concrete stones and even the capillary condensation can occur.
For the study
of physical processes of mutual interaction
of the water in gaseous and fluid state with the porous material the large of
the pores has the dominant importance from the visible range (10-3 m) up to the molecular size range (10-9 m). Validity of the Darcy's formula
can be used provided that the anti-flow resistance is only due to the viscosity
of water; it means that the resistance is only due to the inner forces. By the
fine porous materials (concrete, brick) it represents the total fulfillment
with water, because otherwise, at the presence of water, water steam and air in
the pores, the capillary forces can influence importantly the conditions of the
capillary flow.
Description
of the phenomenon of the capillary spreading in the porous materials is up to
now developed on the exact theoretical base, but due to the strongly changing
cross sectional shapes of the pores in the materials as well as their links and
hydroscopic properties can not be expressed with simple and mathematically
precise formulas.
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Fig.4
Distribution of the pore's size of the brick *)
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Fig. 5 Distribution of the pore's size of the AAC block
*)
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*) Measured with the mercury porosimetrics
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In the figs. 4 and 5 graphical illustration of the distribution of the
pore's size of the searched building materials is presented. Full line illustrates
the distribution of the porosity of the material; the dashed line is the
summary curve, which expresses the whole volume of all pores. It can be seen
from the graphs that the ACC block includes dominant macrospores at the large
of 2 μm and more and also pores at the large from 0,001 up to 0,3 μm.
The brick has the porosity in
the area of capillary pores and macrospores from 0,1, up tu 2 μm. From
these data an assumption about the moisture characteristics of these materials
can be derived (e.g. by the lower moisture the brick is dried more quickly in a
comparison with AAC block).
EXPERIMENTAL MEASUREMENT DEVICE
At the Department of Building Structures of the University
of Technology in Brno an experimental device for measurement of moisture
transport in building materials with use of the electro-magnetic microwave
radiation (EMWR) was developed and it operates according to the theoretical
assumptions for definition of the entrance data for calculation of the
denominator of capillary conductivity.
In Fig.1
assumption of moisture curve is illustrated and this is a base assembly of the
measurement device. The arrangement of the device is based on the
one-dimensional approximation of the moisture transport by the measurement of
the moisture curves as the moisture distribution along the specimen's axis u (x,t).
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Fig.6 Construction scheme of the experimental device for measurement
of the moisture transport in the building materials
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Fig.7 Detailed
view on the specimen in the experimental device
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In Fig.7
a construction scheme of the experimental device for measurement of the
one-dimensional moisture transport in the porous building materials by the
non-destructive EMWR method is shown.
The device consists of a basin (1) with water and an
adjustment mechanism (2), which can change the height of the water level. Above
the basin a searched specimen (3) is hung, attached in the hanger (4), which is
hung on the digital scale (5). In the area above the basin a waveguide (6) of
the microwave radiation is arranged, which is connected to a source of the
radiation, in this case to the Gunn's diode, which is connected to the electric
current generator (14). From the other side of the basin against the waveguide
transmitter a waveguide receiver (8) is
arranged. Both waveguides as one unit can be adjust in the height direction on
the non-illustrated frame (9) and that by use of the positioning mechanism
(10). On both waveguides screens (11) are arranged, by use of them the
radiation intensity can be regulated. The specimen is inserted between the
mutually towards turned ends of the waveguides. The microwave receiver is connected to a the multimeter (12), where
values of the radiation intensity change on the output can be read. Multimeter
is connected to a PC (13) where the results in the form of indicated changes
of EMWR intensity in the set time
intervals can be read. To the transfer of indicated values a communication
program for reading of the values on display of the digital scale and a
programming software for multimeter are used. Synchronized drive unit for
waveguides enables the conversion of the speed of their motion to the length's
indications for expression of the coordinate x for the position of the moisture
concentration as a profile of the moisture front face (see Fig.1). In Fg.7 a
detail of the specimen's position by the measurement is shown. To the detection
of the position of the moisture in a porous structure of the inert material the
microwave radiation is used, which enables the non-destructive measurement.
Microwave radiation has relatively high sensibility and the result of the
measurement is not influenced by the chemical composition of the material or by
the amount of chemically bound water. Microwaves protrude through the material
without the influence on their properties.
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RESULTS AND
DISCUSION
In Fig.8 and 9 graphs with schematically illustrations
of the dependence of the intensity change of EMWR are shown, which corresponds
to the preset value of the current (in this case 500 mV) and its lowering
(absorption) after the passage through the specimen. Measurement was applied on
the piece of the brick with the bulk density pm =
1800 kg/m3 , and on the piece of
AAC block with pm = 430 kg/m3 in a dry state.
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Fig.8 Dependence of the intensity change
detection at the preset level of elmg. MW radiation in interaction with the
brick specimen
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Fig.9 Dependence
of the intensity change detection at the preset level of elmg. MW radiation
in interaction with the AAC block specimen
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Remark: *) measured in a dry state; material thickness 20 mm
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For calculation of the moisture conductivity denominator
by a non-destructive method curves indicating the dependence between the
moisture content in a specimen with use of the measurement apparatus with the
gravimetrical method were drawn. It is a dependence
between the moisture by weight um
in a specimen and the radiation
intensity z, which goes through the
searched specimen.
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Fig 10 Indication of the functional dependence of the intensity
change of elmg MW radiation on the moisture by weight for a brick specimen *)
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Fig 11 Indication of the functional dependence of the intensity
change of elmg MW radiation on the moisture by weight for a AAC block
specimen *)
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Remark:
*) From values measured on 6
specimens the dependence of moisture by weight on the amount of radiation z, which goes through the specimen
was set
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In Fig.10 and 11 there are graphs of the functional
dependence of the intensity change of elmg MW radiation on the moisture by
weight for a brick specimen with the bulk density pm = 1800 kg/m3, and on
the piece of
AAC block with pm = 430 kg/m3
. The specimens were prepared in a form of a stag dimensioned 20x60x250
mm (see Fig.12).
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Fig.12 Specimens of the brick material
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Fig.13 Specimens of the AAC block material
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(dimensions 20x60x250 mm)
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Searched specimen of material is by the measurement
attached in the hanger, which is hung on the digital scale (see Fig.7) and by
use of the adjustment mechanism is contacted with its front face with the water
in the basin. The other end of the specimen is in contact with the air of the
same moisture as it is in the pores at the beginning of the moisturizing
process. By the moisture transfer only in one direction, the steaming of water on the other faces of
the specimen is prevented by the steam seal hydro insulation except of the low
and upper front faces.
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Fig.14 Specimen
of the brick during the moisturizing process
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Fig.15 Specimen
of the AAC block during the moisturizing process
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In Figs. 14 and 15 a positioning of the specimens in
the measurement device is shown. By the vertical motion of the waveguides by a
constant speed in the direction of the moisturizing into the searched specimen
the intensity of the protruding radiation is measured, which changes in a
dependence on the amount of the local fluid moisture.
In Fig.16 a graphs of the result curve indicating the
radiation intensity change in intervals of 1 second during the motion of the
hanger with waveguides are presented. By the conversion of the known speed of
the waveguides hanger motion along the length of the specimen (in this case 3
mm.s-1) on the length coordinate x, it is the detection position of
the electro-magnetic MW radiation, a dependence curve illustrated in Fig.17 can
be presented.
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![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image027.gif)  Time interval of detection [s]
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![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image030.gif)
 Length (depth) of sample
1 section is 3,3 mm
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Time interval of detection [s]![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image033.gif)
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![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image036.gif)
Length
(depth) of sample, 1
section is 3,3 mm
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 ![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image040.gif) Time interval of detection [s]
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![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image041.gif)
 lenght (depth) of sample, 1
section is 3,3 mm
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Fig.16 Measured
values for settlement of the position of the moisture face profile by
monitoring of the moisture transport by the brick in the subsequent time
intervals of 10 minutes
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Fig.17
Conversion of the time data according to the motion speed of the waveguides
on the lenth's data of the coordinate
of the position of the moisture face profile X by the brick in the
subsequent time intervals of 10 minutes
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To express the conductivity relations of the water in
the porous specimen a conversion of intensity of the protruding MW radiation on
the specific moisture amount was made. For individual materials individual
relations are valid because there is an influence of many material features,
above all the shape and arrangement of the inner pore system. The searched
dependence was settled with a correlated relation which describes the
functional dependence as close as possible. A cubic polynom u(z) = P3(u)
was applied. For calculation of the constants a method of the least squares was
applied. Such constants of the function P are looked for, for which the
aggregate of squares of deviations of the calculated values from values which
were measured is as least as possible.
The measured
values have always some fault included of the measurement and therefore it is more
precise to respect only the character of the dependence of two quantities so,
that the total fault of the approximation is as small as possible. In case of
the searched specimen from the brick the quotation is u(z) = P3(u).
From values
measured as the functional dependence of the radiation intensity change of the
elmg MW radiation on the moisture by weight for 6 specimens by use of method of least squares in the
Maple program following question of the function showing the dependence of the
moisture um on the intensity of elmg. MW radiation z,
which is protruding through the specimen was settled:
um = -1,342033167.10-7 .z3
+ 0,0001936510773 .z2 - 0,1038753765
.z +
20,78641097
where z is the radiation intensity protruding
through the specimen
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Fig.18 Indication of the functional dependence of
the intensity change of the elmg. MW radiation on the moisture by weight in a
linear manner
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Fig.19 Indication of the functional
dependence of the intensity change of the elmg. MW radiation on the moisture
by weight
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Remark: applies for searched
piece of brick, expressed in Maple program
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On Fig.18 is a line graph of the functional dependence
of the intensity change of the elmg MW radiation by a specimen of brick. More
precise it should be to use the approximation by a of the k-degree polynom. For
practical applications a 3rd degree polynom was used – see Fig.19. From values measured for three different
times (10,20,30 min.) from the beginning of the moisturizing process, the quotations of the radiation dependence
z on the distance from the moisture source, expressed by a coordinate x –
see Fig. 17 (and in accordance with moisture curves in Fig.1 is by the quotation
of moisture regression, it is possible to define the distribution of the
moisture by weight in a porous material as the moisture curves – see Fig 21.
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![Ïîäïèñü: Change of EMWR intensity
dependent [mV]](./36232.doc.files/image046.gif)
![Ïîäïèñü: Length of specimen [m]](./36232.doc.files/image047.gif)
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![Ïîäïèñü: Length of specimen [m]](./36232.doc.files/image048.gif)  ![Ïîäïèñü: Moisture by weight [%]](./36232.doc.files/image051.gif)
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Fig.20
Illustration of the functional dependence of of the intensity change of the
elmg. MW radiation on the moisture by
weight along the specimen's length by a specimen of brick.
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Fig.21
Illustration of the functional dependence of the intensity change of the
elmg. MW radiation on the moisture by weight along the specimen's length by a
specimen of AAC block.
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Legend of
graphical marking: Remark:
expressed with help of Maple program
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Moisture curves are developed by the compilation of
functions from previous calculations. The construction of graphs of functions
expressing the dependence of the moisture by weight um on the distance x from the moisture source, it is
graphs of cumulated functions are determined as graphs of the cumulated
functions
um,t = f(zt
(x)).
Where t is the time interval of the respective moisture
curve, as the expression of the
distribution of the moisture by weight on the length of the specimen, it is the
moisture curve set in the non-stationary state of moisturizing in the time
intervals e.g. 10,20,30 min. (mentioned quotations are valid for searched specimen
from a brick).
From values measured in three different times intervals
(10,20,30 min.) since the beginning of the moisturizing were set by a method of
least squares in the Maple program quotations of the dependence of the
radiation z on the distance from the moisture source expressed by a
coordinate x as an assumption of the sorption curves and functional dependence
of the detected change of the intensity
of MW radiation on the length of the
specimen in the chosen selected time interval of its moisturizing:
where z is the radiation intensity
protruding through the specimen.
Values of the capillary conductivity
coefficient for the specimens of the searched materials of brick and AAC block
were calculated in the Maple program according to the quotation (5)
Table 1 Average value of capillary conductivity coefficient
for the specimens of the searched material of brick
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Moisture by weight [%]
brick
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after 10 min. of moisturizing
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after 30 min. of
moisturizing
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average
value
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divergence
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average
value
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divergence
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10
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1.67325 .
10-7
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0.4667 . 10-7
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0.86585 .
10-7
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0.0952 . 10-7
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11
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1.6929 . 10-7
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0.4412 . 10-7
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0.91235 .
10-7
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0.1157 . 10-7
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12
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1.71385 .
10-7
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0.4399 . 10-7
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0.96235 .
10-7
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0.1391 . 10-7
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13
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1.7366 . 10-7
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0.4599 . 10-7
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1.0174 . 10-7
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0.1708 . 10-7
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14
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1.7664 . 10-7
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0.5018 . 10-7
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1.08185 .
10-7
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0.2146 . 10-7
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15
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1.8022 . 10-7
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0.5698 . 10-7
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1.19625 .
10-7
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0.2774 . 10-7
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In tables 1 and 2 average values and divergence
(assessment of faults) from measurement of the set of 6 specimens for some moisture values for the settlement of
interval, in which capillary
conductivity coefficient is changing
Table 2 Average value of capillary conductivity coefficient
for the specimens of the searched material of AAC block
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Moisture by weight [%]
AAC block
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after 10 min. of moisturizing
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after 30 min. of
moisturizing
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average value
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divergence
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average value
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divergence
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25
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2.16175 . 10-7
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0.2536 . 10-7
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0.6348 . 10-7
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0.0334 . 10-7
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30
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1.7771 . 10-7
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0.1503 . 10-7
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0.5661 . 10-7
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0.0123 . 10-7
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35
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1.4319 . 10-7
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0.0911 . 10-7
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0.4861 . 10-7
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0.0047 . 10-7
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40
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1.25105 . 10-7
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0.064 . 10-7
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0.439 . 10-7
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0.0022 . 10-7
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 ![Ïîäïèñü: Coefficient of capillary conductivity[m2.s-1]](./36232.doc.files/image065.gif)
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Fig. 22 Capillary conductivity
coefficient for specimens of the searched material of the brick and AAC block
and its average value after 10 min of moisturizing
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Legend:
Set of six specimens of the brick
set of six specimens of AAC block
marked as C01 -
C02
marked as S01 -
S02
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CONCLUSION
In a comparison with methods of the moisture distribution
in a non-stationary state for evaluation of the transport coefficient by use of
Gamma radiation or by the NMR method (Kunzel,H.M. Masea, ENOB Freiburg Mai
2004) are the results of the moisture transport measurement by use of EMWR more
suitable for application in the civil construction engineering and they are
supposed to be more suitable concerning the protection as well as concerning
the costs.
In a comparison with the destructive method enables
the presented methodic obtaining of more data with higher preciseness of the
data about the moisture conditions in the detailed cross sections for the calculation
of the capillary conductivity coefficient along the lengths of the searched
specimen. The advantage is the relatively fast obtaining of the measurement
results and the possibility of continuous measurement of more moisture curves
on one specimen of the material in time
intervals without the measurement interruption and without any manipulation
with the specimen.
The values from the continuous measurement in more
time intervals on one specimen are from the point of view of the measurement exactness
suitable basis for mathematical evaluations in such way that by the modeling of
the moisture field and calculations of the
capillary conductivity coefficient
the most closeness to the real state of the moisture distribution is enabled.
Acknowledgement
This
paper was written when working on partial projects entailed in the MSM0021630511 research proposal entitled
“Progressive building materials using secondary raw materials and their impact
on service life of structures”, with the specific material support of the Department of Civil Engineering, Faculty
of Civil Engineering, University of Technology
Brno.
References
1. Kiessl,K., Kapillarer und
dampfförmiger Feuchte
Transport in mehrschichtigen
Bauteilen. Rechnerische
Erfassung und Bauphysikalische Anwendung, Fach
bereich Bauwesen, Essen 1983
2. Künzel,H., Bestimmt der
volumen- oder der Masse
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MONITORING OF ONE-DIMENSIONAL MOISTURE TRANSPORT WITH THE
ELECTROMAGNETIC MICROWAVE RADIATION
JAN SKRAMLIK,
MILOSLAV NOVOTNY
Department of
Building Structures, Faculty of Civil Engineering of the University of
Technology in Brno, Veveri 95, Brno, Czech Republic
The aim is to present a methodic for
practical evaluation of the chosen construction material for the application in
the specific placement in the building construction.
A prototype of device for measurement of
the moisture transport by a non-destructive method by use of a MW radiation was
designed. By the design as well as by the measurement known physical presuming
and measurements method were applied. Testing measurements were preceded on
normally used building materials.
With utilization of the achieved results
further continuation of the specific moisture process modeling in the capillary porous material is supposed
and these results should be taken into account by the description of the heat spreading process.
Simplified calculation models are usually
in the building practice taken as a
base for calculation of the assumed moisture behavior of the building
constructions. The aim is to prove if the projected building material is suitable
from the point of view of the influence of the moisture by the thermo-technical
design of buildings.
