B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
491–498
POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN
CEMENT COMPOSITES USING COMPUTED TOMOGRAPHY
AND OTHER METHODS
MO@NOSTI DOLO^ANJA VSEBNOSTI ZRA^NIH POR V
CEMENTNIH KOMPOZITIH Z UPORABO RA^UNALNI[KE
TOMOGRAFIJE IN DRUGIH METOD
Bronislava Moravcová, Petr Põssl, Petr Misák, Michal Bla`ek
Brno University of Technology, Faculty of Civil Engineering, Veveøí 331/95, 602 00 Brno, Czech Republic
BlazekM7@study.fce.vutbr.cz
Prejem rokopisa – received: 2014-08-13; sprejem za objavo – accepted for publication: 2015-08-24
doi:10.17222/mit.2014.193
The aim of the paper is to outline the possibilities and predictive values of the selected methods for determining air-pore
characteristics in concrete and cement composites in general. Four samples (mixtures) of cement concrete without additives or
admixtures were chosen for the measurement, differing in cement content while maintaining the consistency of fresh concrete
S3 according to EN 206. Both standardized and non-standardized methods are used in Europe, therefore providing a possibility
of comparing their outcomes.
Keywords: concrete, durability, porosity, surface, covering layer, X-ray computed micro-tomography
Namen ~lanka je prikazati mo`nosti za splo{no napovedovanje izbranih metod za dolo~anje zna~ilnosti zra~nih por v betonu in v
kompozitih iz cementa. Za meritve so bili izbrani {tirje vzorci (me{anice) betona brez dodatkov in primesi z razli~no vsebnostjo
cementa ob zadr`anju konsistence sve`ega betona S3, skladno z EN 206. Standardizirane in nestandardizirane metode se
uporabljajo v Evropi in zato omogo~ajo primerjavo rezultatov.
Klju~ne besede: beton, zdr`ljivost, poroznost, povr{ina, prekritje, rentgenska ra~unalni{ka mikro-tomografija
1 INTRODUCTION
The durability of cement composites has been a topic
of increasing importance. It is illustrated by the fact that
the requirement for the durability of concrete structures
has become part of CPR (Construction Products Regu-
lation).1 The content, size and distribution of air pores,
i.e., porosity, influence not only on the durability but also
the physical/mechanical properties of cement composites
and thus concrete structures in general.2
Recently, there have been claims that concrete air
entrainment in percent is not sufficiently informative as
both the air-entrained concrete and the traditional con-
crete contain a broad spectrum of air voids (Figure 1).
Not all the pores are beneficial for the required property.
Recent investigations argue that an effective entrainment
(a pore diameter of 1 μm–1000 μm) above 2 % can signi-
ficantly increase the resistance to water and chemical
thawing agents.3–5
The pores can be divided, according to their charac-
ters3, into gel, capillary, entrained and entrapped ones, or
by their size4, into micropores (<1.25 nm), mesopores
(1.25–25 nm), macropores (25–5000 nm) and other large
pores (5000–50000 nm).
Figure 1 shows a detailed diagram of the division of
pores and the possibilities of their detection by means of
the methods discussed below.
In connection with what was mentioned above, four
methods for determining various pore characteristics
dealing with the air-void content in concrete (total air
content, micropore air content, average pore diameter
and specific surface of an air-void system) were chosen.
Out of these, two are used for determining the properties
of fresh concrete (the pressure method and the air-void
analyser) and the remaining two for determining the
properties of hardened concrete (a microscopic analysis
and CT).
The goal is to determine the air-pore-system charac-
teristics using the above-mentioned methods and to
Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498 491
UDK 67.017:666.972:004.42 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 50(4)491(2016)
Figure 1: Example of pore size in concrete
Slika 1: Primer velikosti por v betonu
select the optimum method for determining the characte-
ristics of specific types of the air-pore system in con-
crete.
2 METHODS USED IN THE EXPERIMENT
There is a number of situations where there is a need
to have information about the pore distribution in
concrete. This paper is concerned with the determination
of concrete-cover porosity, which has a significant influ-
ence on the quality of the concrete and thus the durabi-
lity of the whole structure.2 This experiment determines
the concrete cover to be 40–60 mm, taken from the
surface of the specimen.
The following paragraphs describe standardised and
non-standardised methods for the above-specified
properties of fresh and hardened concrete, used in the
experimental part of the research.
It must be emphasised that the results of the methods
differ because of their different abilities to detect the
pore size, due to the physical nature of the methods and
differently sized specimens used for each method.
2.1 Pressure method
The method is applied for determining the air content
in compacted fresh concrete made of dense or heavy-
weight aggregate. It is based on the Boyle-Mariotte law,
which says that the product of the pressure and volume
of a gas is constant. This method uses an air meter
according to EN 12350-75 (Figure 2).
2.2 Air-void analyser (AVA)
For the analysis of the air-void structure in fresh con-
crete, AVA (an air-void analyser, Figure 3) was used.6,7
Its advantages are the possibility of taking samples
directly from the vibrated mixture without any further
processing and, as in the case of the previous method,
the possibility of performing a measurement in situ. The
apparatus also detects the content of microscopic air
pores A300, but it is necessary to note that it cannot detect
pores smaller than 50 μm.
It was discovered that, under certain conditions, the
air pores in a cement mixture can be transported into a
liquid without affecting their content or size.8 Successful
transport depends on the viscosity and hydrophilic
character of the liquid. Once air bubbles have exited the
cement paste, they start to rise through the liquid. The
function of the air-bubble movement can be described
with reversed Stokes’ law, according to which larger
bubbles rise faster than smaller ones. The total distribu-
tion of an air-void structure can be calculated by
recording the amount of air that has risen up to a given
level over the elapsed time. The number of pores escap-
ing the cement paste is observed through the changes in
the mass of an upside-down Petri dish placed just below
the surface of the liquid.
The principle is that the apparatus determines the
amount and size of air pores and thus enables an assess-
ment of the spacing and the specific air-void surface. The
method is primarily used for air-entrained concretes.
However, even for non-entrained concretes, it is better at
determining the air-void characteristics than method 2.1
as it can be used also for the determination of other cha-
racteristics, not just the total air content.
The following characteristics can be determined
using this method:
• spacing factor,
• micro-air-void content (A300),
B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
492 Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498
Figure 3 Air Void Analyzer (AVA)
Slika 3: Analizator praznin (AVA)
Figure 2: Concrete pressure-air meter
Slika 2: Merilnik tlaka zraka v betonu
• total air content,
• specific surface of an air-void system.
2.3 Determining air-void characteristics in hardened
concrete according to EN 480-11
A stereoscopic microscope was used for the observa-
tion of the air-void diameter and distribution in hardened
concrete according to the standard EN 480-11.9 This
device detects pores of 1–4000 μm and is able to identify
microscopic air pores (A300). Prior to its use, the speci-
mens need to be prepared from a concrete cured for a
minimum of 7 d. The measurement results can be
recorded manually or automatically. Both procedures
differ depending on human errors (the subjectivity of an
evaluation) during pore detections (e.g., mistaking a
hollow after a missing piece of the aggregate for an air
pore).
The ability to detect air pores depends on the human
ability to recognise a pore based on the contrast in the
adapted specimen. During an automatic assessment, the
factor is the resolution, at which a specimen is examined.
The following values can be determined using this
method:
• spacing factor,
• micro-air-void content (A300),
• total air content,
• specific surface of an air-void system,
• average pore diameter.
2.4 Computed tomography
Computed tomography (CT) is a method, which
enables us to look inside the specimens non-destruc-
tively. CT detects differences in the material density. A
3D visualisation of a specimen can be constructed
through the processing of several consecutive slices.10
Using special SW, the following characteristics can
be determined on a 3D image of a specimen:
• spacing factor,
• micro-air-void content (A300),
• total air content,
• specific surface of an air-void system,
• average pore diameter.
3 EXPERIMENTAL PART
The goal of this experiment was to compare the re-
sults of the selected methods used for the determination
of air-pore characteristics in concrete and, at the same
time, to ascertain whether the outputs of these methods
correspond to one another. Four mixtures of cement
concrete without additives or admixtures were chosen for
the measurement, differing in the water/cement ratio
while maintaining the consistency of fresh concrete S3
according to EN 206.11 The components of the concretes
identified as R (0/1, 0/2 and 0/3) are in Table 1. The
components in individual concretes were identical, i.e.,
of the same type of aggregate from the same location,
one type of cement from the same mill.
The relevant properties of the concrete components
were monitored according to EN 196-612, EN 93313, and
EN 109714 (Table 2). Samples were taken according to
EN 12350-1.15 Properties of fresh concrete were deter-
mined according to EN 12350-2, 5, 6 and 7.5,16–18
Although some of the methods are intended primarily
for air-entrained concrete (2.2 and 2.3), it should be
noted that, in terms of the entrained-air-void content,
even non-entrained concretes contain voids correspond-
ing, in size, to the entrained-air pores in air-entrained
concrete.
Table 1: Composition of individual mixtures
Tabela 1: Sestava posameznih me{anic
Com-
ponent
Aggregates (kg) Cement
42,5 R,
Mokrá
(kg)
Water
(kg)
Water
ratio
(-)
0 – 4
Brat~ice
4 – 8
Olbra-
movice
8 – 16
Olbra-
movice
Concrete mixture R - C12/15 X0 S3 D16
978 177 693 255 206 0.81
Concrete mixture 0/1 - C20/25 X0 S3 D16
927 182 698 309 202 0.65
Concrete mixture 0/2 - C30/37 X0 S3 D16
892 175 695 358 192 0.54
Concrete mixture 0/3 - C35/45 (45/55) X0 S3 D16
888 202 692 402 203 0.50
Table 2: Characteristics of fresh concrete for individual mixtures
Tabela 2: Zna~ilnosti sve`ega betona posameznih me{anic
Characteristics
Concrete
Flow table
test
(mm)
Density of
fresh con-
crete
(kg/m3)
Total air
content (%)
(pressure
method)
Micro air
content A300
(%)
(AVA)
R 435 2250 2.7 0.2
0.1
0/1 410 2315 2.7 0.0
0/2 385 2315 2.5 0.1
0/3 420 2290 2.5 0.1
For method 2.1, the specimen volume was 8 dm3.
This method enables a detection of pores > 300 μm. It is
the most commonly used method; however, its dis-
advantage is that it only allows a determination of the
total air content and gives no information the on pore
distribution and size.
In the case of method 2.2, the specimen volume was
approximately 50 cm3. As it was a relatively small spe-
cimen, obtained with an impact drill, it was highly proba-
ble that it contained only smaller-sized pores (< 2 mm).
For the procedure according to 2.3, the specimen was
a concrete slab of 100 mm × 100 mm. The evaluation
was performed in two ways, i.e., manually and automa-
tically, both of which have their drawbacks, see 2.3.
Automatic evaluation took place at a resolution of 1 μm
B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498 493
per pixel, which corresponds to the minimum size of a
detectable pore.
For the measurement with method 2.4, cylindrical
specimens of 50 mm in diameter and 60 mm in height
were used. All the cylinders were obtained from larger
specimens, using a core drill. The drilling was performed
perpendicular to the surface of the concrete and each
specimen was cut to a length of 60 mm in order to repre-
sent the concrete cover. At this specimen size, the device
was able to detect the pores of above 100 μm.
Each cylinder was scanned in consecutive slices
using device Phoenix v|tome|x L 240 (Figure 4).19 All
the data was recorded and subsequently processed in the
laboratory of the Central European Institute of Technol-
ogy – Brno University of Technology (CEITEC BUT). A
module of VG Studio MAX was used for the pore anal-
ysis.20
4 RESULTS AND DISCUSSION
Tables 3 to 6 show the air-pore characteristics ob-
tained with the selected methods for fresh and hardened
concrete. Figures 5 to 9 show the method outputs. In the
cases, where the measurement was performed on more
specimens, the tables include their average values and
standard diversions. The number of decimal places in the
tables is based on the output of individual methods.
Table 4: Characteristics of air voids for concrete 0/1
Tabela 4: Zna~ilnosti zra~nih por v betonu 0/1
Used methods
Fresh concrete Hardened concrete
Pressure
method
Air-void
analyser
Microscopy analysis
spacing
Computer
tomo-
graphymanual automatic
Total air
content A
(%)
2.7 0.9 1.48
x = 4.44
1.85
s = 0.15
Micro air
content
A300 (%)
– 0.0 0.27
x = 1.93
0.02
s = 0.01
Spacing
factor L
(mm)
– 1.80 0.27
x = 0.13
1.01
s = 0.01
Average
pore
diameter
D (μm)
– – –
x = 99.00
416.0
s = 12.00
Specific
surface of
air-void
system 
(mm–1)
– 6.0 31.80
x = 41.06
7.82
s = 5.13
Table 5: Characteristics of air voids for concrete 0/2
Tabela 5: Zna~ilnosti zra~nih por v betonu 0/2
Used methods
Fresh concrete Hardened concrete
Pressure
method
Air-void
analyser
Microscopy analysis
spacing
Computer
tomo-
graphymanual automatic
Total air
content A
(%)
2.5 1.0 1.76
x = 2.90
1.95
s = 0.33
Micro air
content
A300 (%)
– 0.1 0.39
x = 1.33
0.01
s = 0.36
Spacing
factor L
(mm)
– 1.28 0.28
x = 0.14
1.16
s = 0.04
Average
pore
diameter
D (μm)
– – –
x = 86.50
406.0
s = 18.50
Specific
surface of
air-void
system 
(mm–1)
– 8.1 29.1
x = 48.68
6.68
s = 10.47
B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
494 Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498
Figure 4: Phoenix v|tome|x L 24019
Slika 4: Naprava Phoenix v|tome|x L 24019
Table 3: Characteristics of air voids for concrete R
Tabela 3: Zna~ilnosti zra~nih por v betonu R
Used methods
Fresh concrete Hardened concrete
Pressure
method
Air-void
analyser
Microscopy analysis
spacing
Computer
tomo-
graphymanual automatic
Total air
content A
(%)
2.7
x = 1.1 x = 2.86 x = 10.72
1.69
s = 0.3 s = 0.21 s = 0.49
Micro air
content
A300 (%)
–
x = 0.15 x = 1.20 x = 5.58
0.05
s = 0.05 s = 0.11 s = 0.67
Spacing
factor L
(mm)
– 1.13
x = 0.11 x = 0.08
0.70
s = 0.00 s = 0.01
Average
pore
diameter
D (μm)
– – –
x = 114.50
320.0
s = 6.50
Specific
surface of
air-void
system 
(mm–1)
– 7.5
x = 57.65 x = 35.04
11.48
s = 1.65 s = 1.95
Table 6: Characteristics of air voids for concrete 0/3
Tabela 6: Zna~ilnosti zra~nih por v betonu 0/3
Used methods
Fresh concrete Hardened concrete
Pressure
method
Air-void
analyser
Microscopy analysis
spacing
Computer
tomo-
graphymanual automatic
Total air
content A
(%)
2.5 1.0 2.48
x = 3.51
1.70
s = 0.78
Micro air
content
A300 (%)
– 0.1 0.26
x = 1.69
0.01
s = 0.44
Spacing
factor L
(mm)
– 1.26 0.40
x = 0.13
0.93
s = 0.03
Average
pore
diameter
D (μm)
– – –
x = 88.5
445.0
s = 10.5
Specific
surface of
air-void
system 
(mm–1)
– 8.4 18.20
x = 45.8
9.20
s = 5.45
When determining the total air content in fresh con-
crete, the AVA method gave lower values than the
pressure method (Figure 5), which could have been
caused by the amount of fresh concrete being tested.
Different values of manual and automatic microscopy
may have been caused by the ability/inability to dis-
tinguish between an air pore and a hollow created by a
particle of the aggregate forced out during the cutting or
grinding of the specimen. The differences may have also
been caused by the operator during the manual measure-
ment of the factor. During automatic measurement, the
ability to detect a pore depends on the resolution (in our
case, 1μm per pixel), while during manual measurement,
this ability lies with the technician performing the test.
Figure 6 shows that out of all the methods used, the
measurement results obtained with CT and AVA corres-
ponded most closely to each other. A small difference
between these results was probably caused by different
abilities to detect air voids at the bottom threshold of the
detection: AVA (at 50 μm), CT (at 100 μm).
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Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498 495
Figure 7: Results of spacing factor for individual concretes
Slika 7: Rezultati faktorja lo~ljivosti pri posameznih betonih
Figure 5: Results of total air content for individual concretes
Slika 5: Rezultati vsebnosti vsega zraka v posameznem betonu
Figure 6: Results of micro-air-void content A300 for individual
concretes
Slika 6: Rezultati vsebnosti zraka v mikroporah A300 pri posemeznih
betonih
In general terms, it can be stated that, in determining
the A300 value, a comparison of the results of individual
methods was very demanding. All the methods exhibited
a trend of a decrease in the resulting values of A300 de-
pendent on the increasing cement content in the indivi-
dual concretes; however, each method displayed signifi-
cantly different absolute values of A300.
Based on the results shown in Figure 7, it could be
stated that a comparison of the outcomes of the methods
was again very demanding. The results that at least part-
ially corresponded to each other were the values from the
measurement using manual and automatic microscopy.
No conclusive proof was found for the premise that
the spacing-factor results obtained with CT and the mi-
croscope would differ only minimally. This fact may
have been caused by a difference in the mathematical
model of the calculation between the microscope and
CT. In the case of the microscope, the spacing factor was
calculated from 2D scanning of the specimen, while in
the case of CT, it was calculated from 3D scanning.
All the used methods displayed significantly different
values of the average pore size for different concretes, as
shown in Figure 8. The cause of the higher values in
case of CT was probably its measurement range, where
the bottom threshold was defined at 100 μm and the top
threshold was not defined in this experiment; therefore,
B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
496 Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498
Figure 11: Volume of air-void system – cross-section: 1 – air void, 2 –
aggregate particle, 3 – cement paste
Slika 11: Volumen sistema zra~nih por – presek: 1-zra~na pora, 2 –
delec agregata, 3 – cementna osnova
Figure 9: Results of specific surface of air-void system for individual
concretes
Slika 9: Rezultati specifi~ne povr{ine sistema zra~nih por pri posa-
meznih betonih
Figure 8: Results of average pore diameter for individual concretes
Slika 8: Rezultati povpre~ne velikosti por pri posameznih betonih
Figure 10: Volume of air-void system – 3D
Slika 10: Volumen sistema zra~nih por – 3D
possible air voids may have also been included in the
calculation. On the other hand, the microscope had its
range limited to the maximum pore diameter of 4000
μm.
The measurements using CT and AVA displayed
lower final values of the specific surface of the air-void
system, while the results obtained with microscopy were
significantly higher. It was nearly impossible to find any
correlation between these results (Figure 9).
A possible cause for this great difference in the
results may have been, much like in the case of most of
the other properties, a different range of the diameter of
the air pores being measured with the above methods
and, in the case of CT, also the detection of possible air
voids.
Some outcomes of the measurement with CT (the
pore distribution and volume) are shown in Figures 10
and 11.
5 CONCLUSION
The performed measurements allowed the following
conclusions:
• The results of the used methods are difficult to com-
pare. The main causes for this difficulty are probably
different air-pore measurement ranges and the
measurement of different types of pores (Figure 1).
The characteristics determined with the individual
methods performed on the concretes hardly corres-
pond to one another. If one method indicates a certain
trend in the results based on the cement content in the
concrete, the other methods do not generally follow
the trend or they even contradict it.
• A conclusive comparison of the results of the me-
thods for determining the air content in concrete
would require us to include, in the calculation, only
the pore diameters within the intersection of the
measurement ranges of the all the methods used
(Figure 1).
• When measuring according to EN 480-11, differen-
ces are found in the results for the pores recorded
manually and automatically. Possible causes are the
inability of automatic recording to differentiate bet-
ween an air pore and a missing particle of the aggre-
gate and different abilities of detecting a pore at the
bottom resolution threshold during each method of
evaluation.
• AVA and stereoscopic microscope are primarily in-
tended for determining the pore characteristics of
aerated concretes. Based on the obtained results, it
can be concluded that these methods probably give
lower predictive values when used for non-aerated
concretes.
• CT is a modern method for determining the concrete
porosity with a great potential lying in the possibility
of rendering the complete pore structure of a concrete
specimen in 3D. Given the fact that it is demanding
to set up the device along with the evaluation soft-
ware, it appears that a correct interpretation of results
is rather difficult. The results include possible voids,
which would have to be filtered out of the chosen
algorithm, thus increasing the accuracy of the predic-
tive values.
• The results of this experiment may have been influ-
enced by the small number of the specimens used,
e.g., in the case of CT, each type of concrete was re-
presented by one specimen only.
• CT appears to be a very suitable method for measur-
ing air-pore characteristics in concrete; it is, however,
necessary to tackle the above-mentioned flaws (filter-
ing possible voids, a correct set-up of the device).
When these problems are removed, the outputs of CT
can be used as a benchmark for the results of the
other methods measuring the pore structure in con-
crete, mainly thanks to detailed 3D mapping.
• During the determination of concrete-pore characte-
ristics, it is necessary to consider the types and sizes
of the pores being examined, which are the key fac-
tors for the purpose and characteristics of a pore
system. It is then possible to choose the most suitable
method of their determination in line with Figure 1.
Acknowledgement
This paper was elaborated with the financial support
of the Czech Science Foundation, project GA13-18870S,
and Junior Specific Research FAST-J-15-2703.
6 REFERENCES
1 Regulation (EU) No 305/2011 of the European parliament and of the
council of 9 March 2011 laying down harmonised conditions for the
marketing of construction products and repealing Council Directive
89/106/EEC, http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=
celex:32011R0305
2 B. Kucharczyková, P. Misák, T. Vymazal, Determination and
evaluation of the air permeability coefficient using Torrent
Permeability Tester, Russian Journal of Nondestructive Testing, 46
(2010) 3, 226–233, doi:10.1134/S1061830910030113
3 M. Golová, Relationship between the basic properties of aerated
concrete and its resistance to influence of environment, Diploma
Thesis, Technical University of Ostrava, Ostrava 2012
4 F. Collins, J. G. Sanjayan, Effect of pore size distribution on drying
shrinking of alkali-activated slag concrete, Cement and Concrete
Research, 30 (2000) 9, 1401–1406, doi:10.1016/S0008-8846(00)
00327-6
5 EN 12350-7 Testing fresh concrete – Part 7: Air content – Pressure
methods, ÚNMZ, 2009
6 Apparatus for analysis of air pore structure: Quality Guarantee of air
pores in concrete, http://www.avas-concrete.com, 23.07.2015
7 J. Distlehorst, G. Kurgan, Development of Precision Statement for
Determining Air Void Characteristics of Fresh Concrete with Use of
Air Void Analyzer, Transportation Research Record: Journal of the
Transportation Research Board, 2020 (2007), 45–49, doi:10.3141/
2020-06
8 AVA – Air Void Analyzer, http://www.germann.org/, 18.08.2015
B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498 497
9 EN 480-11, Admixtures for concrete, mortar and grout – Test
methods – Part 11: Determination of air void characteristics in
hardened concrete, ÚNMZ, 2005
10 J. Kaiser, M. Holá, M. Galiová, K. Novotný, V. Kanický, P. Martinec,
J. [~u~ka, F. Brun, N. Sodini et al., Investigation of the
microstructure and mineralogical composition of urinary calculi
fragments by synchrotron radiation X-ray microtomography: a
feasibility study, Urological Research, 39 (2011) 4, 259–267,
doi:10.1007/s00240-010-0343-9
11 EN 206 Concrete - Specification, performance, production and
conformity, ÚNMZ, 2013
12 EN 196-6 Methods of testing cement - Part 6: Determination of
fineness, ÚNMZ, 2010
13 EN 933 Tests for geometrical properties of aggregates, ÚNMZ, 2012
14 EN 1097 Tests for mechanical and physical properties of aggregates,
ÚNMZ, 2011
15 EN 12350-1 Testing fresh concrete - Part 1: Sampling, ÚNMZ, 2009
16 EN 12350-2 Testing fresh concrete - Part 2: Slump test, ÚNMZ,
2009
17 EN 12350-5 Testing fresh concrete - Part 5: Flow table test, ÚNMZ,
2009
18 EN 12350-6 Testing fresh concrete - Part 6: Density, ÚNMZ, 2009
19 V|tome|x L 240 Brochure, GE Measurement & Control, 2014,
http://www.ge-mcs.com/download/x-ray/phoenix-x-ray/GEIT_
31205_flyer_vtomex_L_EN_1213.pdf, 23.7.2015
20 VG studio MAX software, http://www.volumegraphics.com/en/
products/vgstudio-max
B. MORAVCOVÁ et al.: POSSIBILITIES OF DETERMINING THE AIR-PORE CONTENT IN CEMENT COMPOSITES ...
498 Materiali in tehnologije / Materials and technology 50 (2016) 4, 491–498