Influence of the Granite Waste into a Clayey Ceramic Body for
Rustic Wall Tiles
MONICA Castoldi Borlini Gadioli1,a, MARIANE Costalonga de Aguiar2,b,
Abiliane de Andrade Pazeto1,c, Sergio Neves Monteiro2,d, Carlos
Maurício Fontes Vieira2,e
1
Mineral Technology Center - CETEM/MCTI, Regional Nucleus of the Espírito Santo,
Rodovia Cachoeiro-Alegre, km 05, Bloco 10, Morro Grande, Cachoeiro de Itapemirim,
Espírito Santo, 29300-970, Brazil
2
State University of the North Fluminense-UENF, Advanced Materials Laboratory-LAMAV,
Av. Alberto Lamego 2000, Campos dos Goytacazes, RJ, 28013-602, Brazil
a
[email protected], [email protected], [email protected], [email protected],
e
[email protected]
Keywords: granite waste, rustic wall tiles, physical and mechanical properties,
environment.
Abstract: This work has as its objective to evaluate the influence of a granite waste into a
clayey ceramic body for obtaining of rustic wall tiles. As raw materials, a clayey ceramic
body for red ceramic production and a granite waste, resulting from ornamental stones
cutting with the multi-wire technology were used. Compositions using 0, 10, 20 and 30% of
waste incorporated into ceramic body were prepared. Specimens were fabricated by uniaxial
press-molding at 20 MPa and sintered at 1050°C. The following properties were determined:
linear shrinkage, water absorption and flexural rupture strength. In general, within the error
bar, there was no influence of the waste in the values of water absorption of the clayey
ceramic body. The results showed that all investigated formulations used in this work for the
production of rustic wall tiles attend the standards for water absorption and mechanical
strength.
Introduction
The ornamental stones sector is one of the most important economic segments in the
southeast of Brazil. In 2010 the Brazilian production reached 8.9 million tons, being the
state of Espírito Santo responsible for more than 60% of that production [1]. In spite of this
auspicious aspect, the ornamental stones sector represents a great potential of pollution
owing to the high amount of wastes generated both in the quarrying and during processing
that have been impacting the environment since long time. In fact, during the sawing stage,
the amount of waste generated is of approximately 20 to 25% of the raw material. The
Espírito Santo state (ES) is the main ornamental stones pole of the country. In the city of
Cachoeiro de Itapemirim (ES) approximately 300,000 ton/year of wastes are generated,
which constitutes a serious environmental issue. The most used technology for stone sawing
is conventional gangsaw. However, the multi-wire represents a great technological
innovation to the sector, because the block cutting system is accomplished only by the use of
diamond wires and water. As there is no use of the required inputs to the conventional
gangsaw (metal shot and lime), the waste produced is also free from such impurities, being
constituted mainly by the stone powder and water. The waste used in this work is originating
from the granite sawdust using multi-wire technology. Given the importance of integrating
sustainability in all economic sectors of the society, it becomes a recurring need to reduce
the environmental impact inherent in productive processes, especially regarding both the
generation and disposal of wastes. In this context, one of the technological alternatives to
reduce the environmental impact of ornamental stones waste is their incorporation into red
ceramic and ceramic tile, which has been widely studied [2-8]. For instance, Borlini et al.
[8] investigated the use of a granite waste, after being processed by magnetic separation to
eliminate ferrous residues, as an addition to clay ceramics for building tile production. The
results showed that those ceramics incorporated with 20% of granite waste, by their
technological properties, could be classified as a semi-porous tile.
Additionally to the ornamental stone industry, the southeast region of Brazil has also a
concentration of clayey ceramic industries that manufacture products such as red bricks,
structural blocks, roofing tiles, pipes and rustic wall tiles. Campos dos Goytacazes, a large
municipal area in the north of the state of Rio de Janeiro, is one of the main producer with
more than 110 ceramic industries. Located relatively near the main ornamental stone
industries, the ceramic plants in Campos dos Goytacazes would be a convenient alternative
for incorporation of granite wastes from Espirito Santo. Thus, in the present work, the
possibility of incorporating granite waste into a clayey ceramic body to obtain rustic wall
tiles was evaluated in terms of technological properties of the final product.
Experimental Procedure
The raw materials used in this work were a clayey body and a granite waste. The clayey
body prepared from a yellow type of clay was supplied by the firm Ceramica Rodolfo
Azevedo Gama in Campos dos Goytacazes. This clayey body was commonly used to
fabricate solid and perforated bricks as well as rustic tiles. The waste used in this
investigation was obtained from an ornamental stone industry located at the city of
Cachoeiro de Itapemirim. It was supplied by a local firm and indicated as being originated
from a type Iberê Crema Golden granite using the multi-wire cutting technology. The
characteristics of the clayey body have been presented elsewhere [9], while those for the
granite waste will be presented in this work. Table 1 displays the chemical composition of
the clayey body, which is predominantly kaolinitic.
Table 1 - Chemical composition of the clayey body (wt. %) [9].
Yellow Clay
Composition
MgO
Al2O3
SiO2
TiO2 P2O5 K2O CaO MnO Fe2O3
%
0.66
25.64
43.59
1.55
Traces
0.25
1.63
0.15
0.11
10.38
LoI
15.20
Na, Cr, Rb, Sr
The chemical composition of the waste was determined by X-ray fluorescence (XRF) in a
model Philips PW 2400 equipment. The mineral constitution of the waste was analyzed by
X-ray diffraction (XRD) in a model AXS D5005 Bruker diffractometer, with Goebel mirrior
for parallel beam, operating with Co K radiation, at 35 kV and 40 mA. The powder sample
was scanned at 0,02º steps per second for a 2 range of 5 to 80°. The waste density was
measured in a model AccuPyc 1330 Micrometics Instrument Corporation helium
pycnometer. The particle size distribution of the waste was evaluated in a model Mastersizer
2000 Malvern Instruments equipment. The four different clay body incorporation are
presented in Table 2.
Table 2. Granite waste incorporated clay body compositions (wt.%).
Compositions
Raw materials
Clay
Waste
C0W
C10W
C20W
C30W
100
90
80
70
0
10
20
30
Rectangular specimens were prepared by 20 MPa uniaxial press-molding and tested
according to procedures described elsewhere [8,10]. In short, after molding, the specimens
were dried in an electrical stove at 120°C for 24 hours and then fired in a laboratory furnace
at 1050°C with a heating rate of 2°C/min. The evaluated technological parameters were the
water absorption, linear shrinkage and three points bend tests for the rupture strength.
Results and Discussion
Table 3 presents the chemical composition of the granite waste. In this table, it is observed
that the waste is basically constituted by SiO2, Al2O3 and alkaline oxides (K2O and Na2O).
The higher amount of SiO2 is probably associated with quartz. Taking into account that the
kaolinitic clay in this work, Table 1, is excessively plastic [9], the inert quartz in the waste
may contribute to a reduction in the plasticity of the clayey body. By contrast, the quartz
particles may impair the mechanical strength of the final ceramic [11].
Table 3 - Chemical composition of the granite waste (wt. %).
SiO2 Al2O3 Fe2O3
K2O Na2O
MgO CaO
MnO
TiO2 P2O5
77.92 11.86
4.44 3.52
0.09
0.05
0.09
1.25
0.62
LoI
traces 0.5
The composition of SiO2, Al2O3 and alkaline oxides could eventually form feldspar phases.
The reason for the evaluated percentage of K2O and Na2O is probably due to presence of the
minerals such as microcline, albite and biotite in the granite. These alkaline oxides could act
as fluxing agents, forming a liquid phase and so contributing to the ceramic sintering [11].
The low loss of ignition (LoI) in Table 3 indicates the absence of organic matter and/or
carbonates, which is an advantage for the ceramic quality.
Figure 1 shows the XRD pattern of the granite waste with indication of mineralogical phases
related to the peaks. As above-suggested by the results of the chemical composition, Table
3, the main peak corresponds to quartz, an inert and non-plastic phase. Other relevant peaks
are related to albite and microcline. Biotite was also detected in the XRD pattern in Fig. 1.
As already mentioned, albite and microcline may act as flux and enhance the ceramic
sintering process.
60000
Q
50000
Intensity (a.u.)
40000
A
30000
M
20000
Q
10000
B
A
B Q A Q
AA
Q
Q
B,Q
0
10
20
30
40
50
60
70
80
2 (degree)
Figure 1 - XRD pattern of the granite waste. Q = quartz, M = microcline, B = biotite, A =
albite
Figure 2 shows the particle size distribution of the granite waste. In this figure, one should
notice that around 10% of the waste particles present particle size below 2 m, which
corresponds to a clay mineral. This is an indication that the granite waste is compatible with
the clay in terms of ceramic sintering. Moreover, the fact that about 50% of the particles are
below 24 m of equivalent diameter also indicates that the granite waste is as finer as
common sand [10]. This is another important aspect as the production of rustic wall tiles
usually applies a mixture of clay and sand. Thus, the granite waste could substitute the sand
and result in a ceramic with finer texture. The density of the granite waste was calculated as
2.65 g/cm3, which is close to that of quartz and clay.
Figura 2. Particle size distribution of the granite waste.
Figure 3 shows the fired linear shrinkage of an incorporated ceramic as a function of the
amount of granite waste. In this figure, within the precision given by the error bars, the
linear shrinkage tends to decrease with increasing waste addition. In this figure, the
abnormally higher value for 20% waste could be interpreted as a consequence of the clay
mineral particles, Fig. 2, smaller than 2 m that are very reactive during the sintering
process.
18
16
Linear skrinkage (%)
14
12
10
8
6
4
2
0
0
10
20
30
Granite waste (%)
Figure 3. Linear shrinkage of fired ceramic as a function of granite waste percentage.
Figure 4 presents the water absorption of the fired ceramic as a function of the amount of
incorporated granite waste. In this figure, it should be noted that the water absorption, within
the error bars, remains almost constant with the percentage of waste. Furthermore, all values
are below 18% and above 10%, which is the level specified by the Brazilian standards [12]
for wall tiles.
22
20
Water absorption (%)
18
16
14
12
10
8
6
4
2
0
0
10
20
30
Granite waste (%)
Figure 4. Water absorption of the fired ceramic as a function of the granite waste
percentage.
Figure 5 displays the variation of the flexural rupture strength (ultimate bend stress) of the
fired ceramic as a function of the percentage of incorporated granite waste. In this figure, the
average value of all points are above 8 MPa, marked as horizontal dashed line, which is the
minimum strength specified by the Brazilian standards [12] for wall tiles. The relative
decrease in strength as compared to the pure clayey ceramic can be attributed to the quartz
content of the waste. In Fig. 5, the ceramic with 30 wt.% of granite waste might not be
accepted due to the lower value of the error bar, which is below 8 MPa. However, an
improved clay body processing with a more homogeneous mixture of clay and waste would
probably contribute to high strength values.
28
Flexural strength (MPa)
24
20
16
12
8
4
0
0
10
20
30
Granite waste (%)
Figure 5. Flexural rupture strength of the fired ceramic as a function of the percentage of the
granite waste.
Conclusions




The granite waste employed in this investigation is mainly composed of quartz and
feldspar phases, albite and microcline. The alkaline oxide content, approximately 8%
of Na2O + K2O, indicates a fluxing potential for ceramic sintering.
The density and particle size distribution also make the granite waste a material
compatible with clay for ceramic production.
The water absorption of the fired ceramic remained almost constant, while the linear
shrinkage and flexural strength tend to be below the corresponding values of the pure
clay (0% waste) ceramic.
In spite of this decrease, probably caused by the quartz particles in the waste, the
strength level as well as the water absorption fell within values recommended by the
Brazilian standards.
Acknowledgements
The authors thank to CETEM, UENF, CNPq and Pemagran Pedras Mármores e
Granitos Ltda. for the support to this research.
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