M. JACKOWSKI et al.: CHARACTERIZATION OF NEW RECYCLED POLYMER SHOTS ADDITION FOR ...
355–358
CHARACTERIZATION OF NEW RECYCLED POLYMER SHOTS
ADDITION FOR THE MECHANICAL STRENGTH OF CONCRETE
VPLIV DODATKA RECIKLIRANIH POLIMERNIH [IBER NA
MEHANSKO TRDNOST BETONA
Mateusz Jackowski, Marcin Ma³ek
*
, Wojciech ¯yciñski, Waldemar Lasica,
Mariusz Owczarek
Military University of Technology in Warsaw, Faculty of Civil Engineering and Geodesy, Poland
Prejem rokopisa – received: 2019-07-16; sprejem za objavo – accepted for publication: 2020-01-29
doi:10.17222/mit.2019.160
This work summarized the experimental results of modified concrete samples by recycled polymer shots. The polymer shots
were equal to (5, 10, 15) w/% of the amount of cement. The main purpose of this research was to characterize the final
mechanical strength of the concrete samples and investigate the basic physio-chemical properties of the newly fabricated
concrete. The concrete mixtures were prepared using a new, laboratory-calculated recipe with polymer shots, basalt as an
aggregate, deflocculant based on polycarboxylates and portland cement (42.5 MPa). After 28 d the mechanical properties such
as the compressive strength and bending strength were characterized. The initial and final binding times were determined. SEM
micrographs and LM images were taken. The thermal conductivity was also measured. Additionally, the thingness test was
investigated. The presented research shows that the tested samples containing polymer shots exhibit lower mechanical properties
than the samples without modifications. Compared to the reference sample the rest of the investigated properties are higher.
These kinds of concrete are very promising for applications in civil engineering in special building constructions in the future.
Keywords: concrete modifications, polymer shots, mechanical properties, special building constructions
V tem prispevku avtorji povzemajo opis eksperimentalnih rezultatov modifikacije betona z dodatkom recikliranih polimernih
{iber (krogel). Dodatek polimera je bil enak vsebnosti 5-, 10- in 15-tih masnih % cementa. Glavni razlog te raziskave je bil
dolo~itev mehanske trdnosti vzorcev in fizikalno-kemijskih lastnosti izdelanega betona. Betonske me{anice so bile pripravljene
z uporabo novih laboratorijskih receptov z dodatkom polimernih krogel, bazaltnega agregata, deflokulanta na osnovi
polikarboksilatov in Portland cementa (42,5 MPa). Po 28 dneh so dolo~ili mehanske lastnosti betonov, kot sta tla~na in upogibna
trdnost. Avtorji so dolo~ili za~etek in konec vezanja betonov, izvedli preiskave na opti~nem (LM) in vrsti~nem elektronskem
mikroskopu (SEM) ter dolo~ili njihovo toplotno prevodnost. Dodatno so izvedli tudi teste njihove realne kvalitete. Rezultati
raziskave so pokazali, da imajo vzorci, ki vsebujejo dodatek polimernih {iber slab{e mehanske lastnosti kot jih ima
nemodificiran beton, medtem ko so ostale lastnosti vi{je (bolj{e). Avtorji v zaklju~ku ugotavljajo, da bo v prihodnosti ta vrsta
modificiranega betona zelo uporabna v gradbeni{tvu za izdelavo specialnih konstrukcij.
Klju~ne besede: modifikacija betona, polimerne {ibre (krogle, naboji), mehanske lastnosti, specialne zgradbe
1 INTRODUCTION
Concrete was already produced in antiquity and it led
to the currently used building materials. For this purpose,
the process of crushing and burning gypsum or limestone
was used primarily. When sand and water were added to
these materials, they became a mortar, which was a
plaster-like material. It was used to stick stones to each
other. For thousands of years, these materials have been
improved, and finally, by combining with others, trans-
formed into modern concrete.
1–3
Currently, concrete is the most commonly used
building material. Due to the numerous requirements
posed by subsequent realizations of buildings, it is
possible to obtain the necessary properties of hardened
concrete by modifying the concrete mix (higher com-
pressive strength, lower porosity, etc.) with different
additions, e.g., zeolite, kaolin, and polymer shots.
4–7
The polymer shots are made of urea-type compo-
nents. Urea, also known as carbamide, is an organic
compound with the chemical formula CO(NH
2
)
2
. This
amide has two –NH
2
groups joined by a carbonyl (C=O)
functional group. Polymer shots are mostly used as an
abrasive that allows faster processing of the details,
where damage and deformation of the surface are un-
desirable. It is a high-quality, ecological, clean, reusable
abrasive.
8–10
Many authors have shown effect of polymer additions
on concrete.
11–15
This study contains the results of our
own experimental research on concrete modification
conducted with recycled polymer shots.
2 MATERIALS AND METHODS
The subject of these studies was polymer shots used
as an addition to concrete mixtures. Analysis of the
microstructure of the additives used during the execution
of the concrete was performed with a Transmission-
Reflection Microscope. Concrete mixtures with polymer
Materiali in tehnologije / Materials and technology 54 (2020) 3, 355–358 355
UDK 620.1:666.97.035.5:539.4 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 54(3)355(2020)
*Corresponding author's e-mail:
marcin.malek@wat.edu.pl (Marcin Ma³ek)

shots added for consistency, pH and porosity were tested.
The basic thermal parameters of the concrete samples
using the ISOMET 2114 gauge were tested. The variab-
ility of the thermal parameters of the concrete samples,
subjected to drying in the open air and dryer at a tem-
perature of 40 °C during 18 h was evaluated.
Portland cement, basalt aggregates of 0–0.063;
0.063–0.125; 0.125–0.250; 0.250–0.500; 0.500–1.000;
1.000–2.000 and 2.000–4.000 mm, water, deflocculant
based on polycarboxylates and polymer shots were used
to fabricate the concrete mixtures. Drinking water, also
known as potable water, has been used as the mixing
water for concrete (according to PN-EN 1008:2004).
Also, to three recipes polymer shots (shortcut PS)
instead of the same amount of cement were added (5, 10
and 15) w/%. The recipe without polymer shots addition,
as a reference sample, was treated. Test results of the
samples containing the additive in all figures and tables
were marked as PS5, PS10 and PS15. In addition, the
sieve analysis for the filler was made. Samples fabricated
under laboratory conditions (52 % humidity and 22 °C
temperature) and with mechanical mixer and aluminum
reactor were carried. After adding the powder products
and mixing them for 1 min, liquid products were added.
For 5 min the whole mixture in a mechanical mixer were
mixed. The concrete mixture was transported into steel
forms and compacted with the vibration method in 45 s.
Testing of the compressive strength of concrete in
accordance with PN-EN 12390-3: 2002 on cubic
samples (150 × 150 × 150) mm was carried out. Dried
and cleaned of any loose impurities the samples were
placed between the pressure plates of the testing machine
in such a way that the load was applied perpendicular to
the direction of sample formation. All samples under
laboratory conditions (52 % humidity and 22 °C tem-
perature) and with a 0.5 kN/min displacement of load
were tested. The average compressive strengths were
calculated.
Testing of the concrete’s tensile strength in bending
was carried out in accordance with PN-EN 12390-5:
2002 on rectangular samples with dimensions of (100 ×
100 × 500) mm. Dried and cleaned of any loose impuri-
ties the samples were placed on two support rollers. The
sample was destroyed by applying a force constantly
rising to the sample through the upper roller. All the
rollers are made of steel with a diameter of 20 mm.
Tested samples were placed in such a way that the
pressure roll of the testing machine applied the load
perpendicular to the direction of the sample’s formation.
3 RESULTS
The sieve curve of basalt aggregates (filler) is shown
in Figure 1. The results of the light-microscopy exami-
nation after mechanical tests are shown in Figure 2.
The distribution of individual grains in the concrete
mix shows the correct mixing time of the concrete mix-
ture. The amount and small quantity of air voids in the
concrete mix shows the appropriate vibration time of the
mixture.
The tested addition is shown in Figure 3. The image
presents that polymer shots’ typically sharp-edged struc-
ture and its particles are nonregular and exhibit different
sizes.
During the slump test comparable results for each of
four recipes were obtained. All results –presented in
Table 1 – are within the range of dry consistency in
accordance with EN 12350-2:2011. Table 2 shows the
results of the pH tests for all four recipes.
Table 1: Results of the cone fall tests
Recipe cone fall (cm) Consistency
Reference 1.5 dry
PS5 1.1 dry
PS10 0.9 dry
PS15 0.5 dry
Based on the presented results (Table 2), the pH of
all the recipes exhibits an alkaline reaction. The polymer
shots’ addition does not affect the pH of the concrete
M. JACKOWSKI et al.: CHARACTERIZATION OF NEW RECYCLED POLYMER SHOTS ADDITION FOR ...
356 Materiali in tehnologije / Materials and technology 54 (2020) 3, 355–358
Figure 2: Results of the light-microscopy examination after the
mechanical tests (a – reference,b–PS5,c–PS10,d–PS15)
Figure 1: Sieving curve of basalt aggregate (filler)

mix. However, during the concrete production and its
care, the concrete mix did not reach the melting tempe-
rature of the shot or the softening temperature of the
polymer, which can affect the pH value.
Table 2: The results of pH tests
Recipe pH
Reference 12.74
PS5 12.76
PS10 12.78
PS15 12.80
The presented porosity test results (Figure 4) show
that the quantity of polymeric shots slightly affects the
quantity of pores in the concrete. An increase of the
polymer shot in the concrete composite means that the
quantity of pores increases. In order to reduce the pore
surface, each time the fraction of polymer shot in the
aggregate sieve curve should be taken into account. In
this way a reduction of the pore quantity in the concrete
will occur, which will affect the physical properties of
the concrete positively.
Analyzing the results of the physics research (Figure
5), a decreasing effect on the thermal conductivity coeffi-
cient can be observed. The lowest value of the coefficient
was obtained for the PS15 recipe (15 w/% of polymer
shots), i.e., 1.40 W/mK, and it is 4.8 % lower than for the
reference sample.
The test results presented in Figure 6 show that poly-
mer shot is negatively affecting the compressive strength
of the concrete. The decrease in the strength of modified
M. JACKOWSKI et al.: CHARACTERIZATION OF NEW RECYCLED POLYMER SHOTS ADDITION FOR ...
Materiali in tehnologije / Materials and technology 54 (2020) 3, 355–358 357
Figure 6: Compressive-strength test results
Figure 3: Microstructure of polymer shots
Figure 4: The porosity tests results
Figure 5: Thermal conductivity tests results
Figure 7: Tensile strength test results

recipes results from the lower density of the polymer
shot compared to the density of the cement and aggre-
gate, and as the concrete density decreases, its com-
pressive strength decreases.
A survey of the tensile-strength parameters after 28 d
of the concrete samples is shown in Figure 7. Com-
paring with the reference sample, samples with the
polymer-shots addition revealed lower values of tensile
strength. All the studied amounts (5 w/%, 10 w/% and
15 w/%) showed a decreasing effect on the mechanical
properties. Samples with 15 w/% of polymer shots
revealed the lowest values after bending, i.e., a 16 %
decrease of the tensile strength.
4 DISCUSSION
This article presents the results of concrete samples
modified with polymer shots. The addition of polymer
shots to the concrete mix resulted in a decrease in the
value of the mechanical strength. The presented results
(Figure 6 and 7) show that the addition of polymer shots
reduces both the tensile and compressive strength of the
tested samples. For an amount of 15 w/%, the largest
decrease was observed. Analyzing the results of the
non-hardened concrete mix tests, no negative impact of
the polymer shots’ addition on the concrete properties
and physical properties was found. The quantity of the
additive will not change the consistency and pH of the
concrete mix. Only the porosity of mix was slightly
increased. The hardened concrete samples, however,
show a decrease in the thermal conductivity, which indi-
cates a lower heat transfer. The newly obtained compo-
site shows promise for applications in special construc-
tions that should have a lower heat transfer.
5 CONCLUSIONS
The goal of determining the impact of polymer shots
on concrete mixtures has been achieved. The article
characterizes the effect of the additive on the properties
of concrete. In concrete containing 5 w/% of polymer
shots, no significant changes in the strength of the
concrete, both compression and tensile, were observed.
No problems in the mixing process during the production
of concrete were detected. Furthermore, the production
process is simple and possible to reproduce under normal
environmental conditions. The study confirmed that it is
possible to produce new concrete with less cement and
comparable parameters.
Acknowledgment
Financial support of Research Statutory Program
financed from Military University of Technology,
Faculty of Civil Engineering and Geodesy: "Research of
materials and construction elements of military infra-
structure special objects", No. 886/2019 is gratefully
acknowledged.
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M. JACKOWSKI et al.: CHARACTERIZATION OF NEW RECYCLED POLYMER SHOTS ADDITION FOR ...
358 Materiali in tehnologije / Materials and technology 54 (2020) 3, 355–358