MARCIN MA£EK et al.: INFLUENCE OF SILICONE CARBIDE ADDITIONS ON THE MECHANICAL PROPERTIES ...
595–599
INFLUENCE OF SILICONE CARBIDE ADDITIONS ON THE
MECHANICAL PROPERTIES OF CONCRETE
VPLIV DODATKOV SILICIJEVEGA KARBIDA NA LASTNOSTI
BETONA
Marcin Ma³ek
*
, Mateusz Jackowski, Wojciech ¯yciñski, Waldemar £asica,
Mariusz Owczarek
Military University of Technology in Warsaw, Faculty of Civil Engineering and Geodesy, 2 gen. Sylwestra Kaliskiego Street, 00-908 Warsaw,
Poland
Prejem rokopisa – received: 2019-07-25; sprejem za objavo – accepted for publication: 2020-05-02
doi:10.17222/mit.2019.173
In this work, the results of the chemical modification of concrete based on Portland cement by a silicon carbide F140 addition of
(5, 10 and 15) w/% to the mixture as a filler are summarized. The main goal of this study was to characterize the influence and
w/% of content addition of new commercial fillers on the concrete’s mechanical strength. A three-equation method for the refer-
ence recipe calculation is widely used. The process of concrete production including the white Portland cement (42.5 MPa), ba-
salt aggregate, water and deflocculant based on polycarboxylate according to the calculated recipe. To characterize the basic
properties of the studied concrete, SEM and LM observations, the chemical composition, and a slump cone test were investi-
gated. The thermal properties were also investigated using a thermal analyser. The samples of concrete were characterized by
compressive strength and bending tests after 28 d of curing. The results were compared with reference samples of concrete with-
out the chemical addition of the silicon carbide. This study proved that all the chosen modifications had an increased effect on
the final mechanical strength of the researched concrete samples. The thermal conductivity was also increasing. These kinds of
concretes are very promising for applications in civil engineering and new building technologies of the future.
Keywords: silicon carbide, concrete modification, mechanical strength, thermal properties
V ~lanku avtorji predstavljajo rezultate kemi~ne modifikacije betona na osnovi Portland cementa z dodatkom (5, 10 in 15) w/%
silicijevega karbida F140 v betonsko me{anico. Glavni cilj {tudije je bil dolo~iti vpliv dodatka novega komercialnega polnila in
njegove vsebnosti na mehansko trdnost betona. Uporabili so tri ena~be za referen~ni izra~un recepture. Postopek izdelave betona
je vklju~eval uporabo belega Portland cementa (42,5 MPa), bazaltnih agregatov, vode in deflokulanta na osnovi polikarboksilata
v skladu z izra~unom recepture. Karakterizacijo osnovnih lastnosti izdelanih betonov so sestavljale: metalografske analize z
vrsti~nim elektronskim (SEM) in opti~nim mikroskopom (LM), dolo~itev kemijske sestave in preizkus posedanja prisekanega
sto`ca (t.i.: slump cone test). Prav tako so avtorji dolo~ili termi~ne lastnosti betonov s termi~nim analizatorjem ter mehansko
tla~no in upogibno trdnost betonov po 28 dneh postopka utrjevanja. Rezultate so primerjali z referen~nim betonom brez dodatka
silicijevega karbida. S {tudijo so avtorji pokazali, da vse izbrane modifikacije izbolj{ajo kon~no mehansko trdnost betona.
Toplotna prevodnost betonov je prav tako narasla. Ta vrsta betonov je zelo perspektivna za uporabo v gradbeni{tvu in za nove
bodo~e gradbene tehnologije.
Klju~ne besede: silicijev karbid, modifikacija betona, mehanska trdnost, termi~ne lastnosti
1 INTRODUCTION
In view of its physical and mechanical properties, sil-
icon carbide is one of the most promising materials used
for a ceramic composite. Due to the high mechanical
strength, hardness and resistance to thermal shocks, the
application of this material in concrete can limit the
thickness of the used layers for fabricated components
that need a high thermal conductivity. This will consider-
ably reduce the weight and production costs.
1–2
Another
important advantage is the thermal and electrical conduc-
tivity of silicon carbide ceramic composites. Compared
to other concrete admixture materials, silicon carbide is
characterized by a several times higher thermal conduc-
tivity. Because of the high thermal transfer, the concrete
products can transfer more heat into the researched
space. This promotes the fragmentation of the micro-
structure and hence an increase of the mechanical
strength of the concrete products.
3–5
Nowadays, in prefabrication technology, concrete
processes are mostly automated, and many steps are car-
ried out by industrial robots. The newly developed ad-
mixture can be used for production in automated lines.
The maturing time of a single sample does not change,
and the technology is very similar. This kind of admix-
ture makes it possible to use it in all companies without
any modification.
6–9
The aim of this study was to investigate the influence
of a silicon carbide addition on the properties of concrete
based on Portland cement.
2 EXPERIMENTAL PART
2.1 Materials
The concrete mixtures were produced using silicon
carbide 99C as an admixture with an amount of (5, 10
Materiali in tehnologije / Materials and technology 54 (2020) 5, 595–599 595
UDK 67.017:621.791.725:669.715 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 54(5)595(2020)
*Corresponding author's e-mail:
marcin.malek@wat.edu.pl (Marcin Ma³ek)

and 15) w/% of cement was used. Additionally, to manu-
facture concrete mixture ballast aggregates, Portland ce-
ment (42.5 MPa), tap water and deflocculant based on
polycarboxylate were used. The amount of deflocculant
used was in accordance with the manufacturer’s instruc-
tions and amounted to 0.8 % of cement content. The
mixture was fabricated in a steel reactor with a mechani-
cal mixer equipped. The new recipe was calculated using
an iterative and experience method.
2.2 Methodology
The silicon carbide morphology was determined us-
ing a scanning electron microscope (SEM). The observa-
tions were carried out on powder samples placed on car-
bon films utilizing an acceleration voltage of 5 kV, using
a secondary-electron detector. The grain size was charac-
terized by a laser diffraction method. The purity of the
investigated powder was measured using an X-ray fluo-
rescent spectrometer.
The mixing process lasted for 5 min using a mechani-
cal mixer with 100 rotations per minute, in laboratory
conditions. After that, the concrete mixtures were trans-
ported into steel forms and left for the curing process of
28 d.
The measurement of the mechanical properties, such
as bending strength, tensile strength and compressive
strength, was analysed by a mechanical machine on sam-
ples prepared according to EN 206-1: 2014.
Research was carried out by measuring the basic
thermal parameters such as: thermal conductivity coeffi-
cient, specific hear per unit of volume and thermal diffu-
sivity. Additionally, the samples after the mechanical
tests were observed to obtain the correct time of mixing,
the time of vibration and the arrangement of the aggre-
gate and admixture particles using a transmission-reflec-
tion microscope.
For each test 20 samples were prepared and mea-
sured. The average values of the test are shown on the di-
agrams.
3 RESULTS
The morphology and surface of the researched silicon
carbide referred to as 400# on SEM images are presented
in Figure 1.
The average particle size of the silicon carbide is
equal 22.7 μm. The particles are irregular and exhibit
sharp edges and smooth surfaces. The particles do not
agglomerate. The XRD results showed that the purity of
the silicon carbide is 98 %; the rest are the pollutants
from the production process.
The basic properties of the fabricated concrete mix-
ture are shown in Table 1.
Table 1: Basic properties of cement-silicon carbide mortal
Recipe
Cone
fall
(mm)
Consis-
tency
class
Porosity
(%)
pH (–)
Bulk
density
(kg/m
)
Reference 5.50 S2 1.50 12.56 2542.04
5 w/% SiC 13.00 S3 0.70 12.64 2583.72
10 w/% SiC 4.80 S2 0.90 12.66 2578.21
15 w/% SiC 6.00 S2 0.90 12.62 2591.44
The results show that the three mixtures exhibit the
same consistency class: S2. The mixture with the 5 w/%
addition of silicon carbide had the S3 class. It is proba-
bly caused by an error during the preparation process of
the mixture. The highest porosity was observed for the
reference mixture (1.5 %). Small particles of silicon car-
bide decrease the volume of the pores to 0.7 % for 5 w/%
of SiC. The pH value is similar for all mixtures and is
equal  12.60. Moreover, as the content of silicon car-
bide increase, an increasing effect of the sample weight
was observed.
Table 2: Mechanical coefficients’ comparison for the researched sam-
ples
Recipe
Young modulus
(GPa)
Poisson coefficient
(–)
Reference 35.435 0.129
5 w/% SiC 35.561 0.130
10 w/% SiC 36.759 0.134
15 w/% SiC 37.346 0.135
MARCIN MA£EK et al.: INFLUENCE OF SILICONE CARBIDE ADDITIONS ON THE MECHANICAL PROPERTIES ...
596 Materiali in tehnologije / Materials and technology 54 (2020) 5, 595–599
Figure 1: SEM images of silicon carbide used as an admixture

The effect of the mechanical strength of the investi-
gated samples is shown in Figure 2. Also, the mechani-
cal coefficients were measured, calculated and presented
in Table 2. The increased effect of the addition of the sil-
icon carbide was observed. However, the very similar
value of the bending strength of the reference and
10 w/% were noted ( 7.7 MPa). The recipe was calcu-
lated using the mechanical strength class of C30/37
(37 MPa). All the tested samples exhibit the higher value
of mechanical strength compared with the design value,
respectively: 46.80 MPa, 49.66 MPa, 53.22 MPa and
59.86 MPa. Furthermore, the addition of 15 w/% of SiC
increased the final mechanical class of the concrete by
four levels to C50/60. The mechanical coefficients de-
pend on the mechanical strength and the same effect was
obtained. A slight difference of the Poisson coefficient
was noted. As the content of the silicon carbide in-
creased, the coefficients are increasing. This phenome-
non confirmed that the concrete sample was well-pre-
pared for the mechanical strength testing process.
The basic thermal parameters were characterized and
presented in Figure 3 and Table 3.
The new developed concrete samples revealed the in-
crease of the thermal properties in all cases. The highest
change in the thermal conductivity was observed. The
reference sample exhibited 1.16 W/mK, but the sample
with 15 w/% of SiC addition exhibited 1.65 W/mK. In
this case, a 20 % increase in the thermal conductivity
was observed. The thermal diffusivity was decreased, re-
spectively, until 1.01e
–6
for the reference and to 8.62e
–7
for 10 w/% SiC addition. The best thermal properties for
the 15 w/% addition of silicon carbide was obtained and
for this type of research the sample is the largest thermal
conductor.
Light transmission-reflection microscope images in
cross-section after the mechanical strength tests are
shown in Figure 4.
The surface of the observed images do not show
signs of poorly selected values of the vibration time and
the mixing time. All the particles do not form agglomer-
ates and are evenly distributed. No places were observed
MARCIN MA£EK et al.: INFLUENCE OF SILICONE CARBIDE ADDITIONS ON THE MECHANICAL PROPERTIES ...
Materiali in tehnologije / Materials and technology 54 (2020) 5, 595–599 597
Figure 2: Mechanical properties of the investigated samples
Figure 4: LM images after the mechanical properties
Figure 3: Thermal conductivity of characterized concrete with SiC
addition
Table 3: Basic thermal properties of researched concrete samples
Recipe
Specific heat
(J/m
3
K)
Thermal diffusivity
(m
2
/s)
Reference 1.36E+06 1.01E-06
5 w/% SiC 1.51E+06 1.01E-06
10 w/% SiC 1.53E+06 8.62E-07
15 w/% SiC 1.67E+06 9.90E-07

where the cement was not bonded to the rest of the addi-
tives. It can be seen that this is the sign of a well-pre-
pared sample for all the tested cases.
4 DISCUSSION
In this work the results of a silicon carbide addition
to the concrete matrix were summarized. The application
of this kind of admixture obtained the highest values of
mechanical strength and thermal properties of the inves-
tigated samples. The presented results shown that the ad-
mixture addition significantly increased the final
physio-mechanical properties of the tested samples.
Other authors showed similar properties.
6,10–13
Silicon
carbide is a very popular compound due its thermal prop-
erties. According to the new solution, silicon carbide is
widely used in the production of building materials. The
addition of SiC also caused an increase in the mechani-
cal strength and thermal conductivity. In this work the
authors added the largest value of silicon carbide (15
w/% of cement weight). An analysis of the results
showed that the cement can be replaced by a new com-
mercial filler as well, and the properties of the concrete
sample increased.
13–18
It is a very promising addition, be-
cause cement production is a very non-ecological pro-
cess and requires a lot of energy consumption. This kind
of admixturing provides the fabrication of ecological
concrete with unusual properties. It was proven that the
fabrication of a new concrete composite with the highest
amount of admixtures is possible and did not require a
special method of production. New synthesized commer-
cial admixtures occurring on the international markets
meet the requirements of new buildings technology in
civil engineering.
18–21
5 CONCLUSIONS
The goal of this research was to verify the influence
of silicon carbide additions on the physio-chemical prop-
erties of new prepared concrete samples. Nowadays, new
solutions are being sought for concrete admixtures for
improving its final properties. Special building technolo-
gies are required to develop chip and widely available
materials for concrete admixture. One of the solutions,
for the thermal and high mechanical strength, is the use
of silicon carbide. The designed recipe exhibits the high-
est mechanical strength and thermal properties compared
with the reference sample without SiC. The obtained re-
sults show that the SiC addition increased the mechani-
cal strength 4 levels up. The technology and prepared
conditions are the same, and the silicon carbide does not
need a special treatment in the process of fabrication for
the final concrete elements. SiC can be used as a filler,
admixture and aggregate on automatic line, handmade or
prefabrication process. This study proved that silicon
carbide as an admixture exhibits good mechanical and
thermal properties and can by used as a special additive
in civil engineering and military applications.
Acknowledgment
Financial support of Research Statutory Program fi-
nanced from Military University of Technology, Faculty
of Civil Engineering and Geodesy: "Research of materi-
als and construction elements of military infrastructure
special objects", No. 886/2019 is gratefully acknowl-
edged.
6 REFERENCES
1
A. Bahari, A. Sadeghi Nik, M. Roodbari E. Mirshafiei, B. Amiri, Ef-
fect of Silicon Carbide Nano Dispersion on the Mechanical and
Nano Structural Properties of Cement, Natl. Acad. Sci. Lett., 38
(2015) 361–364, doi:10.1007/s40009-014-0316-6
2
J. K. Choi, V. Fthenakis, Crystalline silicon photovoltaic recycling
planning: macro and micro perspectives, J.Clea. Prod., 66 (2014)1,
443–449, doi:10.1016/j.jclepro.2013.11.022
3
G. Li D, P. F. Xing, Y. X. Zhuang, F Li, G. F. Tu, Recovery of high
purity silicon from S0G crystalline silicon cutting slurry waste,
Trans. Nonfer. Met. Soc. Chi., 24 (2014) 4, 1237–1241,
doi:10.1016/j.jclepro.2013.11.022
4
H. S. G. K. Murthy, Evolution and present status of silicon carbide
slurry recovery in silicon wire sawing, Res., Conser. Rec.,104
(2015), 194–205, doi:10.1016/j.resconrec.2015.08.009
5
Z. Jiang, Q. Ren, H. Li, Q. Chen, Silicon carbide waste as a source of
mixture materials for cement mortar, Front. Environ. Sci. Eng., 11
(2017), 2, doi:10.1007/s11783-017-0974-y
6
M. Ma³ek, M. Jackowski, W. ¯yciñski, M. Wachowski, Characteriza-
tion of new filler additions affecting the mechanical strength of con-
crete, Mat. Tech., 53 (2019) 3, 399–403, doi:10.17222/mit.2018.155
7
S. Gwon, S. Y. Jang, M. Shina, Microstructure evolution and strength
development of ultra rapid hardening cement modified with
redispersible polymer powder, Construction and Building Materials,
192 (2018), 715–730, doi:10.1016/j.conbuildmat.2018.10.178
8
Y. J. Kim, A. Gaddafi, I. Yoshitake, Permeable concrete mixed with
various admixtures, Mat. & Des., 100 (2016), 110–119, doi:10.1016/
j.matdes.2016.03.109.
9
J. Zhang, X. P. Ding, Q. Wang, X. Zheng, Effective solution for low
shrinkage and low permeability of normal strength concrete using
calcined zeolite particles, Con. and Build. Mat., 160 (2018), 57–65,
doi:10.1016/j.conbuildmat.2017.11.029.
10
P. Wiœniewski, M. Ma³ek, J. Mizera, K. J. Kurzyd³owski, Effect of
adding water-based binders on the technological properties of ce-
ramic slurries based on silicon carbide, Mat. Tech 51 (2017) 2, 225,
doi:10.17222/mit.2015.194
11
M. Malek, P. Wisniewski, J. Szymañska, J. Mizera, K. J. Kurzyd-
lowski, Technological properties of ceramic slurries based on silicon
carbide with poly(vinyl alcohol) addition for shell moluds fabrication
in precision casting process, Act. Phys. Pol. A, 129 (2016)4 ,
528–530, doi:10.12693/APhysPolA.129.528
12
D. Zarzycka, P. Wisniewski, M. Malek J. Szymanska, J. Mizera, In-
vestigation of the Basic Properties of Ceramic Proppants in Raw
State Obtained by the Method of Mechanical Granulation, Act. Phys.
Pol. A, 129 (2016) 4, 552–555, doi:10.12693/APhysPolA.129.552
13
J. Szymañska, P. Wiœniewski, M. Ma³ek, J. Mizera, K. J. Kurzyd-
³owski, Investigation of key parameters influence on properties of the
green pellents and lightweight ceramic proppants obtained by me-
chanical granulation method, J. Ther. Analy. Calor., 125 (2016)3 ,
1411–1423, doi.org/10.1007/s10973-016-5704-3
14
J. Szymañska, P. Wiœniewski, M. Ma³ek, J. Mizera, Rheological
properties of alumina ceramic slurries for ceramic shell moulds fabri-
cation, Mat. Tech., 50 (2016) 5, 735–738, doi:10.17222/mit.
2015.188
MARCIN MA£EK et al.: INFLUENCE OF SILICONE CARBIDE ADDITIONS ON THE MECHANICAL PROPERTIES ...
598 Materiali in tehnologije / Materials and technology 54 (2020) 5, 595–599

15
T. Rudnicki, R. Jurczak. Recycling of a Concrete Pavement after
over 80 Years in Service. Materials, 13(10), (2020), 2262,
doi:10.3390/ma13102262
16
Szczeœniak, A.; Zychowicz, J.; Stolarski, A. Influence of Fly Ash
Additive on the Properties of Concrete with Slag Cement. Materials,
13, (2020), 3265. doi:10.3390/ma13153265
17
T. Rudnicki. The method of aggregate skeleton in self compacting
concrete designing with segment regression. CWB-1/2016, 10–19,
(2016), doi:10.5281/zenodo.3739533
18
A. Szczeœniak, A. Stolarski, Dynamic Relaxation Method for Load
Capacity Analysis of Reinforced Concrete Elements, Appl. Sci. 8,
(2018) 3, 396, doi:10.3390/app8030396
19
L. Akand, M. Yang, X. Wang, Effectiveness of chemical treatment on
polypropylene fibers as reinforcement in pervious concrete, Const.
Build. Mater., 163 (2018), 32–39
20
R. Serrano, A. Cobo, M. I. Prieto, M. González, Analysis of fire re-
sistance of concrete with polypropylene or steel fibers, Construction
and Building Materials, 122 (2016), 302–309
21
M. Szel¹g, Evaluation of cracking patterns of cement paste contain-
ing polypropylene fibers, Composite Structures, 220 (2019), 402-411
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