R. SOKOLAR: NON-TRADITIONAL WHITEWARE BASED ON CALCIUM ALUMINATE CEMENT
885–889
NON-TRADITIONAL WHITEWARE BASED ON CALCIUM
ALUMINATE CEMENT
NETRADICIONALNI PORCELAN NA OSNOVI KALCIJ
ALUMINATNEGA CEMENTA
Radomir Sokolar
Brno University of Technology, Faculty of Civil Engineering, Veveri 95, 602 00 Brno, Czech Republic
sokolar.r@fce.vutbr.cz
Prejem rokopisa – received: 2015-07-01; sprejem za objavo – accepted for publication: 2015-10-27
doi:10.17222/mit.2015.182
The article introduces the differences in the properties of whiteware (porosity, strength, thermal expansion coefficient) when a
non-traditional binder is used. Pure calcium aluminate cement and a mixture of kaolin and calcium aluminate cement compared
with traditional plastic raw material for whiteware – kaolin – are used for the preparation of whiteware bodies with a constant
content of non-plastic raw materials: K-Na feldspar and quartz sand. The results are discussed in connection with the micro-
structure of the fired body of prepared whitewares (mineralogical composition). Calcium aluminate cement (CAC) in whiteware
raw-material mixtures is an interesting alternative to kaolin for a higher strength of the green and fired bodies. Using calcium
aluminate cement reduces the sintering temperature of the fired body and significantly changes its mineralogical composition:
anorthite is the main mineralogical phase instead of mullite, which is typical for standard porcelain bodies made from
raw-material mixtures based on kaolin. The coefficient of thermal expansion increases with an increasing content of CAC in the
raw-materials mixture.
Keywords: calcium aluminate cement, kaolin, whiteware
^lanek predstavlja razlike v lastnostih porcelana (poroznost, trdnost, koeficient toplotnega raztezka), ~e se uporabi neobi~ajno
vezivo. ^isti kalcijev aluminatni cement in me{anica kaolina in kalcijevega aluminatnega cementa, v primerjavi s tradicionalno
plasti~no sestavino porcelana – kaolina, so bili uporabljeni za kerami~na telesa s konstantno vsebnostjo neplasti~nih surovin;
K-Na glinenec in kvar~ni pesek. Rezultati so razlo`eni v povezavi z mikrostrukturo telesa pripravljene keramike (mineralo{ka
sestava) po `ganju. Kalcijev aluminatni cement (CAC), v me{anici surovin za keramiko, je zanimivo nadomestilo za kaolin, za
vi{jo trdnost zelenega in `ganega telesa. Uporaba kalcijevega aluminatnega cementa zni`a temperaturo sintranja `ganega telesa
in mo~no spremeni njegovo mineralo{ko sestavo; anortit je glavna mineralo{ka faza namesto mulita, ki je zna~ilen v standardnih
porcelanskih telesih, izdelanih iz me{anice surovin na osnovi kaolina. Koeficient toplotnega raztezka se pove~uje z ve~anjem
vsebnosti CAC v me{anici surovin.
Klju~ne besede: kalcijev aluminatni cement, kaolin, porcelan
1 INTRODUCTION
Whiteware is a traditional ceramic material that has
been manufactured for centuries from a mixture of kao-
lin, quartz and feldspar. A new type of porcelain body –
the anorthite porcelain body – from feldspar, quartz and
calcium aluminate cement without using any other
binders and plastic ceramic raw materials (clays, kaolins)
– was fabricated at a temperature of 1300 °C and the
physical and mechanical properties were investigated.
The addition of calcium aluminate cement as a substitute
for clays exhibits a relatively high green strength and
lowers the density due to the formation of anorthite in all
the fired bodies.1
Increasing the strength of the green body, reducing
the coefficient of linear thermal expansion and increas-
ing the whiteness of the fired body can be achieved
primarily by replacing the kaolin for calcium aluminate
cement (70 % of Al2O3). A negative aspect of using
calcium aluminate cement with a high Al2O3 content is
reducing the sintering activity of the body and therefore
the need for higher firing temperatures.2
The single-phase anorthite ceramic was fabricated
(from a mixture of ball clay, quartz, calcite, feldspar and
alumina) by slip casting and sintering at 1230 °C for 1 h.
It has a high flexural strength of 103 MPa, which is
higher than that of the conventional porcelain. The
single-phase anorthite ceramic had a relatively low
(4.9×10–6 K–1) thermal expansion coefficient, which can
be easily matched with an applicable glaze and achieve
an excellent thermal shock resistance.3
A new, porcelainised stoneware material based on
anorthite was prepared from an undefined ratio of
wollastonite, alumina, quartz, Ukrainian Ball clay and
magnesia. After firing at 1220 °C we obtained a porce-
lainised stoneware body containing 70 % crystalline and
30 % glassy phases with a high modulus of rupture (110
MPa) that is two times higher compared to conventional
porcelainised stoneware materials based on mullite.4
Calcium aluminate cements are white (according to the
Al2O3 content), high-purity hydraulic bonding agents
providing controlled setting times and strength develop-
ment for today’s high-performance refractory products.
Materiali in tehnologije / Materials and technology 50 (2016) 6, 885–889 885
UDK 67.017:621.315.612:621.742.45 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 50(6)885(2016)
There are only laboratory results in the area of re-
placing kaolin with CAC for the production of whiteware
without any practical industrial impact. The aim of the
article is to introduce the differences in the properties
(porosity, strength, thermal expansion coefficient) of
whiteware when pure calcium aluminate cement or a
combination of the binders – a mixture of kaolin and
calcium aluminate cement – instead of kaolin is used.
The results will be discussed in connection with the
mineralogical composition of the fired whiteware body.
2 CHARACTERIZATION OF USED MATERIALS
Calcium aluminate cement SECAR® 51 (CAC51)
with 51 % of Al2O3 content (on average) was used for the
experimental study. Calcium aluminate cement contains
mainly CA and C12A7, C2AS and CT as minor minera-
logical phases. The chemical composition is clear from
Table 1. SECAR®51 is a fused hydraulic binder with a
mineralogy focused on mono-calcium aluminate to give
a strong hydraulic activity and impart excellent mecha-
nical properties to conventional concretes. This binder is
recommended when rapid hardening properties are
required. It is adapted to all types of placing methods,
particularly casting and gunning at a service temperature
of 1400 °C and above. The surface area is about 4 m2 g–1.
The equivalent mean spherical diameter (Laser PSD) of
CAC51 is d(0.5) = 14 μm.
Table 1: Typical chemical composition of used binders: calcium
aluminate cement CAC51 and kaolin
Tabela 1: Zna~ilna kemijska sestava uporabljenih veziv: kalcijev
aluminatni cement CAC51 in kaolin
Material CaO Al2O3 (K)Na2O SiO2 Fe2O3 MgO LOI
CAC51 36.9 52.2 0.5 4.9 1.8 1.0 0.0
Kaolin 0.7 36.6 1.2 46.8 0.9 0.5 13.2
LOI – lost of ignition
Kaolin Zettlitz Ia is the most renowned and the oldest
product of the company Sedlecký kaolin a. s. It has been
produced since 1892 when the company Zettlitzer
Kaolinwerke AG was founded; the present company
Sedlecký kaolin a.s. is its successor. The major features
of kaolin Zettlitz Ia are:
• relatively high plasticity, which enables good work-
ability in the raw state,
• easy deflocculation with available deflocculants
(addition of 0.1 % Na2CO3),
• high content of Al2O3 and a low content of alkalis,
which provides high stability in fire.
The original use of the kaolin Zettlitz Ia was in
porcelain production. Many producers use it today as the
main plastic component in bodies for plastic moulding,
slip casting or isostatic pressing of tableware. Good plas-
ticity in the raw state and high stability in fire are also
employed in the production of ceramic rollers for fast
firing kilns. A low content of harmful substances and
plasticity play a significant role in pencil production.
This feature is also important for use in cosmetics. The
mineralogical composition of the used washed kaolin is
91 % of kaolinite, 2 % of quartz and about 7 % of mica
minerals. The surface area of the kaolin is 17.5 m2 g–1.
Industrially milled potassium-sodium feldspar rock
and pure quartz sand were used for the experiments as
non-plastic materials. The mineralogical composition of
the sodium-potassium feldspar is potassium feldspar
(microcline) 20.0 %, sodium feldspar (albite) 22.6 %,
calcium feldspar (anorthite) 2.4 % and quartz 55.0 %.
The chemical composition of the used feldspar rock
(Table 2) reflects its mineralogical composition and the
volume of different types of pure feldspars (potassium,
sodium and calcium).
The micro-milled quartz sand ST 6 from Sklopísek
Støele~ Company (Czech Republic) was used. The ma-
terial is produced by milling in an iron-free environment,
by classification with the use of air separators. The raw
material used for the production of micro-milled sands,
i.e., silica flour, is treated silica sand with a SiO2 content
above 99 %. The chemical purity, favourable particle
size distribution, chemical inertness and the hardness of
the micro-milled sands – silica flour – is appreciated in
the production of glass fibres, ceramic enamels, glazes,
as a filler in plastics, in the production of special mortar
mixtures, tile adhesives and in the foundry industry for
the production of moulds. The surface area of the used
micro-milled quartz sand is 4.38 m2 g–1.
Granulometries of the milled feldspar and milled
quartz were determined according to the particle size
distribution (laser particle size analyser Malvern Master-
sizer 2000). The equivalent mean spherical diameters
d(0.5) = 20.8 μm (feldspar) and 16.0 μm (quartz sand)
are suitable for the production of the porcelain body.5
3 METHODOLOGY
Three different raw-material mixtures on the basis of
different binder bases (calcium aluminate cement
R. SOKOLAR: NON-TRADITIONAL WHITEWARE BASED ON CALCIUM ALUMINATE CEMENT
886 Materiali in tehnologije / Materials and technology 50 (2016) 6, 885–889
Table 2: Chemical composition of used non-plastic materials: K-Na feldspar rock and quartz sand
Tabela 2: Kemijska sestava uporabljenih neplasti~nih materialov: K-Na glinenec in kvar~ni pesek
Content, in mass fractions (w/%)
SiO2 Al2O3 Fe2O3 MnO TiO2 CaO MgO K2O Na2O LOI Total
Feldspar 79.76 12.37 0.42 0.00 0.05 0.48 0.10 3.35 2.67 0.80 100.00
Quartz 99.60 0.20 0.03 – – 0.10 0.10 0.00 – – 100.03
LOI – lost of ignition
CAC51, washed kaolin and its mixture), industrially
milled K-Na feldspar rock and industrially milled glass
quartz sand were prepared (Table 3).
Table 3: Composition of raw-material mixtures (test samples) in mass
fractions, (w/%)
Tabela 3: Sestava me{anice surovin (preizkusni vzorci), v masnih
odstotkih, (w/%)
Sample Kaolin CAC51 Feldspar Quartz sand
A 25 50 25
B 25
C 15 10
Raw-material mixtures according to Table 3 were
homogenized for 24 h in a homogenizer. The dry mixture
was then moistened with 9 % mass of water. The
moistened mixtures were pressed through the 1-mm
sieve. The pressing granulate was thus prepared and
subsequently mixed for 12 h in the closed plastic vase of
the homogenizer to produce a homogenous moisture.
Test samples with a green-body size of 100 mm × 50 mm
× 10 mm were uniaxially pressed in a steel mould at 20
MPa with 30 s of soaking time at the maximum pressure.
Drying in air at a temperature of about 21 °C was
followed by final drying in a laboratory drier at 110 °C
to achieve a constant weight.
The green bodies were fired in an electric laboratory
furnace at different temperatures with a heating rate
10 °C/min and a 30-min soaking time at the maximum
temperature to achieve the sintering temperature, which
is defined as the temperature when the fired body has a
water absorption E = 2 %. The subsequent cooling
proceeded spontaneously, following the natural cooling
rate of the furnace. After firing, the body properties (6
test samples) were defined according to the official
standard EN ISO 10545 (vacuum water absorption Ev,
modulus of rupture MOR). The mineralogical compo-
sitions of the pure feldspars and fired bodies were
determined by X-ray diffraction (XRD). The XRD
analysis was performed with a Phillips PW 1170 diffrac-
tometer using a Cu anti-cathode (1 = 0.15406 nm),
accelerating voltage 40 kV, beam current 25 mA and
scanning rate 1° 20’ min–1.
4 RESULTS OF EXPERIMENTS
The mixtures containing CAC51 (B and C) show a
significantly higher sintering activity (the ability of the
body to create a compact body during the firing through
the merging of the grains) according to dilatometric
curves (Figure 1). The sintering activity is described by
the shrinkage of the tested samples during the firing. The
higher content of CAC51 in the raw-material mixture
caused a lower sintering temperature of the body during
the firing (Table 4). The sintering temperatures (tempe-
rature when the fired body has water absorption E = 2 %)
are:
Sample A: approximately 1270 °C,
Sample B: approximately 1150 °C
Sample C: approximately 1250 °C
Table 4: Water absorption of fired bodies depending on the firing tem-
perature
Tabela 4: Absorpcija vode v `ganih telesih v odvisnosti od tempera-
ture `ganja
Sample
Water absorption after the firing (in mass
fractions, (w/%)
1150 °C 1250 °C 1270 °C
A 10.7 4.5 1.6
B 1.8
C 7.6 1.5
These are different results than when the calcium
aluminate cement with a higher content of Al2O3 (70 %)
was used.2 This situation reflects the different chemical
composition of CA cements: CAC51 contains a higher
portion of fluxing oxides (Fe2O3 and CaO especially) to
CAC70. The mineralogical composition of all the tested
bodies after the firing is characterized by the existence of
the quartz and the glass phase. The fired body based on
R. SOKOLAR: NON-TRADITIONAL WHITEWARE BASED ON CALCIUM ALUMINATE CEMENT
Materiali in tehnologije / Materials and technology 50 (2016) 6, 885–889 887
Figure 2: XRD of fired bodies based on different binders: kaolin or
CAC51 (M-mullite, Q-quartz, A-anorthite)
Slika 2: Rentgenogram `ganih teles na osnovi razli~nih veziv- kaolin
ali CAC51 (M-mulit, Q- kvarc, A-anortit
Figure 1: Thermal dilatometric analysis during the firing (1200 °C,
5 °C/min without soaking time)
Slika 1: Termi~na dilatometri~na analiza med `ganjem (1200 °C,
5 °C/min brez ~asa zalaganja)
kaolin also contains mullite, while the fired bodies based
on CAC51 contain anorthite without mullite (Figure 2).
In the case of a combination of the binders, the mullite
phase is missing.
By comparing the modulus of rupture (MOR) of the
fired samples at their sintering temperatures (with
similar porosity), it is evident that anorthitic type of body
(Figure 2) with a lower content of glass phase (based on
calcium aluminate cement) comprises a higher modulus
of rupture. This confirms the results published in 3,4.
Table 5: Modulus of rupture of tested whiteware bodies after the
firing at the sintering temperatures
Tabela 5: Prelomni modul preizku{enih porcelanskih teles po `ganju
na temperaturi sintranja
Sample Modulus of rupture (MPa)
A 34.4 (1270 °C)
B 37.4 (1150 °C)
C 33.8 (1250 °C)
The thermal expansion coefficient is the main factor
when considering the thermal matching between the
glaze and the body, and indirectly influences the thermal
shock resistance.6 The coefficient of linear thermal ex-
pansion was calculated from dilatometric curves (Figure
3) in the different temperature ranges from 30 °C to
1000 °C (Table 6). The whiteware fired body based on
calcium aluminate cement CAC51 (samples B and C)
shows a higher coefficient of thermal expansion com-
pared with the kaolin-based sample A (Figure 3). This is
an unexpected result due to the formation of anorthite in
the samples B and C (Figure 3). A very important tech-
nical property of anorthite is its low coefficient of linear
thermal expansion coefficient of 4.82×10–6 K–1 7 (com-
pared with mullite 6.00×10–6 K–1).8 Different results are
achieved when the CAC with 70 % of Al2O3 has been
used as the replacement for kaolin: the coefficient of
linear thermal expansion decreased from 9.24×10–6 to
8.08×.10–6 K–1.2 This may be connected with the higher
content of Fe2O3 in CAC51 (Table 1).
Table 6: The values of the coefficient of linear thermal expansion 
(K–1) depending on the temperature range and raw-materials mixture
Tabela 6: Vrednosti koeficienta linearnega toplotnega raztezka 
(K–1) v odvisnosti od temperaturnega obmo~ja in me{anice surovin
Temperature
range
A C B
·10–6 (K–1) ·10–6 (K–1) ·10–6 (K–1)
20-200 °C 5.73 6.43 6.35
20-300 °C 6.05 6.74 6.85
20-400 °C 6.42 7.13 7.31
20-500 °C 7.01 7.63 7.83
20-600 °C 8.25 8.71 8.73
20-700 °C 7.63 8.07 8.20
20-800 °C 7.15 7.71 8.20
20-900 °C 6.69 7.46 7.92
20-1000 °C 6.12 7.03 7.23
5 CONCLUSION
The presence of calcium aluminate cements in the
raw-materials mixture significantly changes the mine-
ralogical composition of a fired whiteware body, i.e.,
anorthite is the main mineralogical phase instead of
mullite, which is typical for standard porcelain bodies
made from raw-material mixtures based on kaolin. The
anorthite type of porcelain body is very suitable for the
high strength of the fired body. Using calcium aluminate
cement with a lower content of Al2O3 (51 %) reduces the
sintering temperature of the body, impairs the whiteness
of the body and increases the coefficient of linear ther-
mal expansion.
Acknowledgements
This work was financially supported by the Czech
Science Foundation, research project No. P104/13/
23051S "Anorthite porcelain body on the basis of
aluminous cement".
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