Contribution to the Prediction of the Recycling Potential of Recycled Concrete as a Cement Admixture Based on the Compressive Strength of the Parent Concrete

Abstract

When processing construction and demolition waste, determining the most effective waste management, potential use and recycling method for the identified materials is a key element. To do this, it is necessary not only to determine the type of materials, but also knowledge which aspects of the quality of the original materials are relevant for recycling and the ability to determine the values of these parameters as easily and quickly as possible, directly during demolition activities, is highlighted as an effective tool. This paper, intended as a case study, focuses on the evaluation of the effect of finely ground parent concrete as a cement component, the main objective being to find out whether the differentiation of the quality of the parent concrete, by compressive strength, plays a significant role. The parent concrete, the powder prepared from it, and the new standard mortar mixes, were analysed to obtain a comprehensive picture of the possibility of predicting the properties of the mixes based on the strength of the parent concrete. In general, no clear effect of the parent concrete strength on the flexural strength, compressive strength, water absorption, and ultrasonic pulse velocity values of the new generation mortar was observed. However, finely ground recycled concrete have shown a nice potential to be incorporated in Portland fine-grain cements, reaching strength classes 32.5 and 42.5. Care and precise verification require a 25% replacement, especially in the case of low strength parent concrete.

Full text

Sičákováetal. Int J Concr Struct Mater (2024) 18:80
https://doi.org/10.1186/s40069-024-00725-5
RESEARCH
Contribution tothePrediction
oftheRecycling Potential ofRecycled
Concrete asaCement Admixture Based
ontheCompressive Strength oftheParent
Concrete
Alena Sičáková1* , Jeonghyun Kim2, Magdaléna Bálintová1, Adriana Eštoková1, Natália Junáková1,
Peter Orolin1 and Andrzej Ubysz2
Abstract
When processing construction and demolition waste, determining the most effective waste management, potential
use and recycling method for the identified materials is a key element. To do this, it is necessary not only to deter-
mine the type of materials, but also knowledge which aspects of the quality of the original materials are relevant
for recycling and the ability to determine the values of these parameters as easily and quickly as possible, directly dur-
ing demolition activities, is highlighted as an effective tool. This paper, intended as a case study, focuses on the evalu-
ation of the effect of finely ground parent concrete as a cement component, the main objective being to find
out whether the differentiation of the quality of the parent concrete, by compressive strength, plays a significant
role. The parent concrete, the powder prepared from it, and the new standard mortar mixes, were analysed to obtain
a comprehensive picture of the possibility of predicting the properties of the mixes based on the strength of the par-
ent concrete. In general, no clear effect of the parent concrete strength on the flexural strength, compressive strength,
water absorption, and ultrasonic pulse velocity values of the new generation mortar was observed. However, finely
ground recycled concrete have shown a nice potential to be incorporated in Portland fine-grain cements, reaching
strength classes 32.5 and 42.5. Care and precise verification require a 25% replacement, especially in the case of low
strength parent concrete.
Keywords Parent concrete, Recycled concrete powder, Cement replacement, Compressive strength
1 Introduction
e demolition of structures increasingly (and to vary-
ing degrees in different countries) requires that the
waste generated is managed as efficiently as possible.
To this end, different procedures are in place for iden-
tifying materials in structures, designing further pro-
cessing streams, and possibly reusing or recycling the
waste, which is more or less covered by legislation.
Under the Waste Framework Directive (EU, 2018),
each EU member state is obliged to take measures to
introduce selective demolition to the greatest extent
Open Access
© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which
permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the
original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or
other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line
to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory
regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this
licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.
International Journal of Concrete
Structures and Materials
Journal information: ISSN 1976-0485 / eISSN 2234-1315.
*Correspondence:
Alena Sičáková
alena.sicakova@tuke.sk
1 Faculty of Civil Engineering, Technical University of Kosice, Vysokoškolská
4, 042 00 Košice, Slovakia
2 Faculty of Civil Engineering, Wrocław University of Science
and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland

Page 2 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
possible, with the aim of safely handling hazardous
substances and facilitating reuse and recycling, while
ensuring the establishment of sorting systems for con-
struction and demolition waste (C&DW). In order to
meet the objective, there is a need to focus on a more
consistent application of the waste recovery hierarchy,
i.e., an increase in the rate of reuse, as well as increasing
more valuable ways of recycling materials, but mainly
concrete, than is currently the case.
One of the tools for effective management of C&DW,
recommended by European Commission, is Pre-Demo-
lition Audit (European Commission, 2018). Its task is to
identify and give recommendations on the possibilities
of reuse and recycling of materials arising in the pro-
cess of demolition or renovation, thus contributing to a
lower rate of landfilling. e role of audit before demoli-
tion is increasingly important, especially when it comes
to planning demolition projects and providing informa-
tion contributing to sustainability and should be a part of
the specifications for tenders. Although pre-demolition
audits are not yet mandatory for all, they are increas-
ingly being promoted as there is a growing demand for
an accurate determination of environmental benefits in
relation to the application of circular economy principles.
For example, it is included within the BREEAM scheme
(BREEAM International New Construction, 2021) as part
of the building sustainability assessment process to ena-
ble project holders to gain credits for the environmental
management of demolition waste.
e point of the audit that we would like to highlight is
the auditor’s task to determine the most effective further
waste management, potential use and recycling method
for the identified materials. To do this, it is necessary not
only to determine the type of materials but also, where
possible, their quality. As for a detailed analysis of the
building and the products and materials it contains, ide-
ally, this will be informed by an existing documentation
research. e extent of the research is typically decided
by the auditor, but the minimum requirement is to study
technical drawings and material inventory from the
design documentation or any more recent documenta-
tion of the building or infrastructure (Wahlström etal.,
2019). However, the basic part of the audit is a field sur-
vey, which, mainly in case of old buildings, when there is
no documentation about the object, is a must. A range
of methods for determining the types of materials in the
construction comes into play, e.g., portable XRF, IR spec-
trometers, 3D scanners, as well as manual checklists sup-
ported by different national guidance documents with
information on the period of use of certain materials.
Many of these methods are used to distinguish between
materials, but, within a specific group of materials, these
are also used to describe their quality.
Concrete structures intended for demolition have—by
the very nature of concrete as a material—a considerable
variability of properties. is is due to a number of fac-
tors such as the composition of the original concrete, the
age of the structure, the conditions to which it has been
subjected during its service life (Liu etal., 2016; Naderi
& Kaboudan, 2021; Pani etal., 2020). For deciding on the
waste management and design of recycling in terms of
pre-demolition auditing, it is necessary:
– to know which quality aspects of the original con-
crete are relevant for recycling; and.
– to be able to determine the values of these parame-
ters as easily and quickly as possible, directly during
the audit.
ese aspects of the pre-demolition audit are still in
process and studies are needed to set up the activities
to determine how much the quality of the original con-
crete affects the properties of the new concrete. In fact,
several studies have shown that the strength of the parent
concrete, from which the recycled aggregate is obtained,
influences the strength of the new concrete. Specifi-
cally, concrete using recycled aggregates obtained from
high-strength concrete has superior mechanical proper-
ties and chloride resistance, compared to concrete using
recycled aggregates from normal-strength concrete (Kou
& Poon, 2015). Similarly, concrete made from recycled
aggregate derived from frost-resistant concrete, such as
air-entrained concrete, has been shown to exhibit bet-
ter freeze–thaw resistance (Liu etal., 2016). ese effects
are due to the characteristics of recycled aggregates gen-
erally having higher density and lower water absorption
obtained from high-quality concrete (Akbarnezhad etal.,
2013; Kim, 2022). e relationship between the quality
of recycled aggregates and the properties of the concrete
containing them is well established (Choi et al., 2016;
Mardani etal., 2024).
However, previous studies investigating the relation-
ship between the properties of the parent concrete and
those of the new concrete have focused solely on aggre-
gates obtained from the parent concrete. To achieve zero
waste from concrete waste and reduce dependence on
cement for sustainable concrete, the utilisation of recy-
cled concrete powder (RCP) generated from the recy-
cling process of concrete waste should be considered
(Kim et al., 2023). In general, using RCP as a cement
replacement reduces the performance of cementitious
materials due to low reactivity of RCP and dilution effect
caused by RCP. erefore, high-volume use of RCP in its
original form is not desirable from a performance per-
spective, and some studies have reported the acceptable
replacement rate of RCP to be 30% (Ma etal., 2020; Tang

Page 3 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
etal., 2020; Xiao etal., 2018). To overcome these draw-
backs, investigations into the efficient utilization of RCP
have been conducted. Various methods, including ther-
mal, chemical, and mechanical treatments, as well as car-
bonation, have been reported to enhance the reactivity of
RCP (Kim & Jang, 2024; Vashistha etal., 2022). Notably,
promising results have been observed with the use of 40%
RP combined with thermal treatment and mechanical
milling, showing only about a 7.8% reduction in 28-day
compressive strength compared to the control group
with no RCP (Vashistha etal., 2023a). Furthermore, it has
been reported that incorporating 10% silica fume allows
for the use of 50% of this thermally mechanically acti-
vated RCP, achieving higher 28-day compressive strength
than the control group, while also halving CO2 emissions
(Vashistha etal., 2023b).
erefore, this study, intended as a case study, aims to
evaluate the effect of powdery-grained parent concrete
as a cementitious component, with the main objective
being to determine whether the differentiation of par-
ent concrete quality by compressive strength plays a sig-
nificant role. Determining the compressive strength of
existing structures is one of the less demanding tasks,
either destructively when greater accuracy is required
(using cylindrical cores), but non-destructive determina-
tion using a hardness tester is faster and still sufficient.
e auditor would, thus, be able to very quickly recom-
mend an effective method of recycling and direct other
waste flows to the final processor. For this case study, a
60-year-old dam was chosen as a model building for the
design of a recycling method after possible demolition,
from which, real concrete samples (cores) were taken
for reconstruction work. In the case of a demolition
audit, the same procedure can be used to characterise
the quality of concrete, or strength data can be obtained
by non-destructive methods. e hardness method pro-
vides quick and easy support for the selective demoli-
tion of massive concrete structures and obtaining graded
material of defined quality. Core samples were obtained
from different parts of the structure. Ground parent
concrete was tested as a binding component, while two
aspects were respected during the design of the composi-
tion: a qualitative point of view (strength of the original
concrete) and a quantitative point of view (percentage
replacement of cement. e parent concrete, the powder
prepared from it, and the new standard mortar mixes,
were analysed by several methods to obtain a compre-
hensive picture of the possibility of predicting the prop-
erties of the mixes based on the strength of the parent
concrete. e results are also discussed in terms of the
time evolution of properties as well as the potential of
RCP to formulate modern types of Portland recycled
cements according to EN 197–6 (2023) Cement—Part
6: Cement with recycled building materials, with which
there is yet little experience.
2 Materials andMethods
2.1 Materials
Recycled concrete powder (RCP) for partial replacement
of cement was obtained from several core samples of a
concrete dam in Slovakia, which has been in use for about
60years. To study the effect of parent concrete strength
on the recycling of the concrete waste as a cement
replacement, the sample cores (Fig. 1a) were classified
into three groups based on their compressive strength
determined by the standard destructive test: low-strength
concrete in the range of 20–25MPa (RCP-L); medium
strength concrete in the range of 30–35MPa (RCP-M);
a
)
b
)
c
)
Fig. 1 Illustration of RCP materials in the sequence from a parent concrete samples, b intermediate crushing step, to c the new mortar samples

Page 4 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
high-strength concrete in the range of 40–45MPa (RCP-
H). Afterwards, to obtain RCP from the concrete cores,
several cycles of crushing were conducted using a labora-
tory jaw crusher, by gradually reducing the gap between
the jaws of the crusher: the first crushing removed par-
ticles larger than 4mm that could potentially be used as
coarse aggregate (Fig.1b). e second crushing removed
particles larger than 0.5 mm. e remaining particles
were repeatedly crushed and sieved to collect particles
smaller than 0.125mm and used as a partial replacement
for cement to produce new mortar samples (Fig.1c).
An ordinary Portland cement (CEM I 52.5 R), con-
forming to the European Standard, EN 197–1, was
employed as the binding agent. Standardized sand, con-
forming to EN 196–1, was used to prepare standard mor-
tar mixtures.
To characterise the powdery input materials (cement
and RCP-L, M, H), following three methods and relevant
parameters were determined:
– X-ray fluorescence analyser (SPECTRO IQII, AME-
TEK, Germany), to determine the chemical composi-
tion (Tab. 1)
– laser granulometer (Mastersizer 2000, Malvern
Instruments Ltd, UK), to determine the particle size
distribution (Tab. 2 and Fig.2)
– thermo-gravimetric analyser TG–DTA/DSC (STA
449 F3; NETZSCH, Germany), to determine the
thermal stability of materials. Tab. 3 presents mass
losses representing the decomposition of the CSH
phase, portlandite and carbonates. Fig.3 show DSC
and TG curves of RCPs, respectively.
From a cumulative view of the properties of the input
materials, it can be noted that the best quality RCP
specimen in terms of compressive strength (RCP-H) is
confirmed also by TG analysis. In Fig.3, it is possible to
see the peaks attributed to the decomposition of typical
Table 1 Chemical composition of cementitious binders
Type CaO SiO2Al2O3MgO Fe2O3K2O SO3TiO2MnO
Cement 64.06 19.93 4.35 4.95 2.87 0.31 2.45 0.25 0.46
RCP-L 29.83 47.51 5.69 2.97 1.99 0.99 1.04 0.21 0.14
RCP-M 28.41 46.32 6.35 3.40 2.00 1.10 0.93 0.21 0.17
RCP-H 26.64 42.43 5.13 3.13 1.58 0.79 0.90 0.18 0.14
Table 2 Particle size distribution of cementitious binders (µm)
Type D10 D50 D90
Cement 1.928 9.797 30.362
RCP-L 3.807 36.941 113.585
RCP-M 3.499 32.650 101.477
RCP-H 6.063 58.352 145.407
Fig. 2 Particle size distribution of cementitious materials, namely: cement (black), RCP-L (red), RCP-M (green), and RCP-H (blue)
Table 3 Mass losses of RCPs, determined by TG analysis
Type Mass loss (%)
70–400°C (CSH) 400–500°C
(portlandit) 600–900°C
(carbonates)
RCP-L 6.67 1.28 11.22
RCP-M 4.80 1.19 11.26
RCP-H 8.65 1.38 8.65

Page 5 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
hydration products of concretes (CSH phase and port-
landite), the polymorphic transformation of quartz, as
well as the peak attributed to the decomposition of car-
bonates. is peak indicates an ongoing carbonation
process in the concrete materials. Based on the area of
the carbonate decomposition peak, it can be concluded
that parent concrete M contained the highest amount of
carbonate, indicating that it was the most carbonation
damaged compared to the other two concretes. On the
contrary, parent concrete H contained the lowest amount
of carbonates and, therefore, showed the lowest degree of
carbonation, which is supported by the fact that the peak
of portlandite in the 400–500°C interval was also present
in concrete H (as seen in the DSC curve of concrete H—
Fig.3). e assumption of the highest quality of concrete
H is also supported by the highest weight loss of 8.65%
in the temperature range 70–400°C, which is attributed
to the decomposition of the CSH phase. e parent con-
crete sample M appears to have the worst functional
parameters in terms of the lowest CSH phase content
and the highest degree of carbonation, while sample H
appears to be the most stable in this respect. (Table3 and
Fig.3). On the other hand, a likely consequence of this
higher strength and overall quality of parent concrete H
was the coarser grain size of the RCP-H powder (Fig.2),
which was prepared by the same process as the other two
(as described above). is fact is subsequently echoed in
the results obtained, as will be discussed below.
2.2 Preparation ofRCP Mortars
e preparation of RCP-mortar samples, including the
mix compositions, was carried out according to EN
196–1: Methods of testing cement—Part 1: Determi-
nation of strength. e mix proportions of 10 groups
of mortars were prepared, including the control one
without RCP, and 3 groups of 3 mixtures according to
the strength of the parent concrete (L, M, H) and the
replacement rates of cement by RCP (5%, 15%, and
25%). Table4 shows the principle of mix compositions
for “L” group, namely, L5, L15 and L25. Sample groups
M and H were prepared with the same composition
rule. Each mixture was named by the strength of the
parent concrete and the replacement rate of the RCP.
For example, H25 describes a mixture containing 25%
RCP obtained from high strength concrete. e men-
tioned binders were designed in accordance with the
relatively new standard EN 197–6 ‘Cement—Part 6:
Cement with recycled building materials’ (EN197–6,
2023), according to which, they fall into the follow-
ing types: Portland fine-grained recycled cement CEM
II/A-F (5% and 15% of replacement), and CEM II/B-F
(25% replacement). e standard defines finely ground
recycled concrete as mostly non-reactive. Residual
hydraulic or pozzolanic reactivity is possible but does
not contribute significantly to the reactivity of the
cement. ese types of cement allow the specifier and
the user to contribute to the sustainability goals for
cement-based constructions and the circular economy
and to minimise the use of natural resources in accord-
ance with local production conditions.
After weighing, the materials were mixed in an auto-
matic mixer and cast into 40mm × 40 mm × 160 mm
prismatic moulds. e cast samples were demoulded
after 24h and cured in water at 20 ± 2°C until testing.
Fig. 3 DSC and TG curves of RCPs
Table 4 Mix proportions of mortars (g)
ID Water Cement RCP-L Sand
Control 225 450 0 1350
L5 225 427.5 22.5 1350
L15 225 382.5 67.5 1350
L25 225 337.5 112.5 1350

Page 6 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
2.3 Methods
Various properties of mortars were tested according to
standards.
e fluidity of the mortars in the fresh state was
tested in a flow table according to EN 1015–3 (EN,
1015–3, 1999). e mixture was dropped 15 times on
the flow table, and the diameters were measured in two
directions at right angles.
For the hardened properties of the mortars, the
strengths, water absorption, and ultrasonic pulse
velocity (UPV) were measured at ages of 28, 90, and
180days.
Flexural and compressive strengths were tested accord-
ing to the procedures specified in EN 196–1 (EN, 2018).
e flexural strength was performed on prism speci-
men, and the compressive strength was conducted on the
specimen split in two, by the flexural strength test.
Water absorption was determined according to KS
F4004 (KS, 2018) using the difference between the satu-
rated mass (immersed in water until the test date) and
the dry mass (heated at 105°C until there was no change
in mass) of the specimen.
e UPV, a type of non-destructive testing, was meas-
ured by placing an ultrasonic receiver and transmitter at
the longitudinal ends of the prism specimen. To deter-
mine whether the measured UPV could provide accept-
able predictions, it was utilised for correlation analysis
with other properties.
Finally, an X-ray diffractometer (D2 Phaser, Bruker
AXS, Germany) was used to identify the mineralogical
composition of the mortars and compare them. For the
test, hardened samples were grinded to obtain powdery
form.
For the hardened properties, three specimens per series
were tested and the average values are presented, includ-
ing the standard deviation.
3 Results andDiscussion
3.1 Flow Table
The test results of the flow table for the prepared
mortar mixtures are shown in Fig.4. The flow of the
standard mortar was 171mm and that of the recycled
mortar ranged from 151mm (M25) to 174mm (M5).
As the replacement rate of cement by RCP increased, a
clear decrease in the flow of the mixture was observed.
This is due to the increased water demand for flow
due to the coarser and more porous RCP particles
than cement (Jiang etal., 2022; Kim & Choi, 2012; Kim
etal., 2023). The effect of RCP obtained from parent
concretes with different strengths on the flow of mor-
tar was not clearly identified. At each replacement rate,
the difference in the flows of L, M, and H mixtures did
not exceed 10mm, which indicates that the influence
of the parent concrete on the flow of RCP mortar is
insignificant.
3.2 Flexural Strength
e test results of the flexural strength of mortars cured
for 28, 90, and 180days are shown in Fig.5. Regarding the
effect of RCP replacement rate, a gradual decrease in flex-
ural strength was expected with increasing replacement
rate, but some irregular results were observed. For exam-
ple, the 28-day flexural strength of M5 mortar was 6%
lower than that of the standard mortar, but M15 mortar
showed slightly higher flexural strength than M5 mortar.
In addition, the 28-day flexural strength of H15 mortar
was reduced by 20% compared to the standard mortar,
but the flexural strength of H25 was slightly increased
compared to H15. However, from an overall perspective,
as the replacement rate by RCP increased, the flexural
strength decreased, which is generally consistent with the
results of previous studies (Kim etal., 2023).
In general, the flexural strength of the mortars prepared
in this study peaked at 90days of age, but for some sam-
ples (L5, L25, and H25), the 90-day strength was lower
than the 28-day strength. Specifically, the 180-day flexural
strengths of all mortars, except for the L25 sample, were
lower than the 90-day flexural strengths, indicating that
the use of RCP did not have a favourable effect on long-
term development of flexural strength. is behaviour
is not only inconsistent with the compressive strength
results of this study, but also contradicts a study that
stated that extended curing period has a positive effect
on the flexural strength of RCP mortars due to the poz-
zolanic activity and filler effect of RCP (Tang etal., 2020).
Although not mainstream, similar results were reported
in a study by Topič etal. (Topič etal., 2016). In that study,
Fig. 4 Flow table test of mortar with and without RCP

Page 7 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
the long-term flexural strength (287days) was approxi-
mately 11% lower than the 28-day flexural strength, while
the compressive strength increased by 96% over the same
period, and authors point out that it needs to be further
studied and explained.
For here presented study, the authors would like to
put forward two views. e first is the assumption of a
degradation process just starting at around 180 days
(probably leaching of the Portlandite), which is not yet
reflected in the compressive strength, as concrete is more
effective against this action. is could be confirmed by
longer-term observations that would reflect degradation
processes for this strength as well. Second, the authors
would like to point out for the moment the likelihood of
more indicative res3 as well.ults for compressive strength
and other properties tested. It may be noted that (as
given below), the compressive strength results are more
consistent with standard assumptions (e.g., that strength
will decrease as the proportion of replacement increases,
which is always true for compressive strength but not
always true for flexural strength) or based on UPV
results, which correlate better with compressive strength
than with flexural strength—see Figs. 6, 7. While for
flexural strength the R2 values go from 0.5392 to 0.6872,
for compressive strength, they are from 0.8392 to 0.959.
Fig.8 compares the flexural strength at 28 and 180days
of age. For given replacement rates, the difference
between minimum and maximum flexural strengths
at 28days is relatively large, ranging from 0.79MPa to
1.84MPa, but this difference stabilised at 180days in the
range of 0.73MPa to 0.89MPa, so that the mortars show
similar flexural strengths. In line with the compressive
strength results, there was no clear observed effect of the
strength of the mother concrete on the flexural strength
of the next-generation cementitious mixture. In Fig. 8,
it can also be noticed that the mortars with the strong-
est RCP-H are at the lower end of the values compared
to mortars L and M. It is assumed that the effect of the
larger grain size of RCP-H on its reactivity is more pro-
nounced here than the effect of its strength.
Plotting the maximum and minimum limits of the
values obtained for each test batch in the graphs com-
paring the performance of mortars defined with waste
from concrete with different strength classes is given in
Fig.9. In this way, it is possible to visualize whether finely
ground parent concrete from more resistant parent con-
crete tends to generate mortars with better performance.
Fig. 5 Flexural strength of mortars: a RCP from low strength concrete; b RCP from medium strength concrete; c RCP from high strength concrete

Page 8 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
It can be said that the signatures of the individual values
are displayed essentially in a single line (with a larger
scatter in the L—28-day series, indicating the impor-
tance of the replacement level for low-quality parent
concrete in short-term horizon), and thus, the influence
of the strength class of the parent concrete appears to be
marginal.
R² =0.869
R² =0.959
R² =0.839 2
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
4350.004400.00 4450.004500.00 4550.004600.00 4650.004700.00 4750.00
Compressivestrength
(MPa)
UPV (m/s)
d28
d90
d180
Fig. 6 Relationships between results of UPV and compressive strength
R² =0.539 2
R² =0.647 8
R² =0.687 9
0.00
2.00
4.00
6.00
8.00
10.00
12.00
4350.004400.00 4450.004500.00 4550.004600.00 4650.004700.00 4750.00
Flexural strength (M Pa)
UP V(m/ s)
Fig. 7 Relationships between results of UPV and flexural strength
Fig. 8 Flexural strength of L, M and H mortars at 28 days a and 180 days b according to replacement level

Page 9 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
3.3 Compressive Strength
e test results of the compressive strength of the mortar
specimens cured for 28, 90, and 180days are shown in
Fig.10.
In general, the compressive strength of cementi-
tious mixtures is rapidly developed in the early stages
and becomes moderate in the later stages (Corinaldesi
etal., 2016; Kotwa, 2019). In addition, in this study, the
assumptions about the increase in strength with time
are more clearly fulfilled; except for L15 and M15, mor-
tars showed an increase in compressive strength with
age. is may be due to a change in the tobermorite
content as indicated, e.g., for sample H25 (Fig.11). e
figure shows the XRD recordings for the samples in
28days and 180days of curing. In 180days, there was
an increase in tobermorite peak intensity at 50.09° and
29.2° 2theta, representing the CSH phase.
Fig. 9 Flexural strength of L, M and H mortars at 28 days a and 180 days b according to quality level
Fig. 10 Compressive strength of mortars: a RCP from low strength concrete; b RCP from medium strength concrete; c RCP from high strength
concrete

Page 10 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
As is widely recognised, it is a familiar fact that
increasing the replacement rate of RCP reduces the
hydration rate, subsequently leading to a reduction in
the compressive strength of mortar (Kim & Kim, 2023;
Kim etal., 2023). However, it is worth noting that the
use of RCP, particularly at high-volume replacement,
increases the loss of compressive strength over time.
Specifically, when compared to a control mortar with
the same curing duration, the compressive strength of
M5 is 3% higher at 28days, 5% lower at 90days, and
12% lower at 180 days. Furthermore, for M15, the
28-day compressive strength is 8% lower, indicating
no concerning losses. However, this difference grows
significantly to −18% at 90days and -31% at 180days.
Similar behaviour can be seen with L samples, where
the compressive strength of L5 is 3% higher at 28days,
3% lower at 90days, and 1% higher at 180days. For L15,
the loss of compressive strength progressively increases
to -7%, -16%, and -32%, at the given ages.
is is associated with reduced strength develop-
ment in the later stages due to the exhaustion of lim-
ited amounts of unhydrated particles in the early stages
of hydration (Gao etal., 2022). e finding of a long-
term strength disparity between the control mortar and
RCP mortar can be of utmost significance in practical
application and performance assessment. It indicates
that the application of current standards, primarily
requiring 28-day strength, may not be adequate for
quality assessment of RCP-based mortars.
To investigate the effect of the strength of parent con-
crete of the RCPs, the 28-day compressive strengths of
RCP-L, RCP-M, and RCP-H are presented in Fig. 12a.
At replacement rates of 5% and 15%, mortars contain-
ing RCP-L and RCP-M show similar strength, while the
compressive strength of RCP-H mortar is 8–12% lower
than that of RCP-L and RCP-M mortars. With a certain
probability, these results can be attributed to the dif-
ferent particle sizes of the RCPs, as shown in Table2.
According to a study conducted by Du etal. (2023), the
fine RCP fraction exhibits a higher content of unhydrated
phases and aged hydration products, compared to the
coarse RCP fraction. In addition, the filling effect of the
fine RCP enhances the density and homogeneity of the
microstructure within the mixture, consequently improv-
ing its strength (Li etal., 2022). Hence, the strength of the
mortar with RCP-H, which has a larger particle size, is
comparatively lower than that of the others. e results
are also supported by a slightly lower content of hydrau-
lic oxides in RCP-H, as presented in Table1. Similar to
flexural strength results, it is assumed that the effect of
the larger grain size of RCP-H on its reactivity is more
pronounced than the effect of its strength.
Fig.12b shows the compressive strength at 180days of
age. At given replacement ratios, the difference between
Fig. 11 Comparison of XRD records of H-25 sample in 28 days (black) and 180 days of curing (red) with tobermorite peaks indicated

Page 11 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
the minimum and maximum compressive strength stabi-
lises, as is the case for the flexural strength. is is more
convincing at higher replacement levels (15% and 25%).
At 25% replacement and 180 curing days, the decrease
in strength compared to the control specimen is 40%
for L, 39% for M, and 42% for H, with strength values of
41.8MPa, 42.1MPa and 40.2MPa, respectively. ere-
fore, even here, no clear observed effect of the strength
of the parent concrete on the compressive strength of
the new generation cementitious mix can be deduced.
It appears that with increasing replacement ratio and
increasing age of the specimens, the strength of the par-
ent concrete becomes less significant.
Similar to flexural strength and according to visualiza-
tion given in Fig.13 can be said, that the signatures of
the individual values are displayed essentially in a single
line (with a larger scatter in the L—28-day series), and
thus, the influence of the strength class of the parent
concrete appears to be marginal. More important and
clearly visible are differences indicating the importance
of the replacement level in each strength group of parent
concrete.
In addition to the quality of the parent concrete, the
results obtained can be discussed in terms of testing
specific types of composite cements that contain RCP
as admixtures. According to EN 197–1, cement grades
can be categorised as 32.5, 42.5, and 52.5 based on their
28-day compressive strength (Fig. 12a). In this study,
certain mortars (L5 and M5) exhibited higher strength
than the control mortar, meeting the criteria for the 52.5
grade. While the compressive strength decreases as the
replacement rate increases, RCP-M and RCP-H satisfy
the requirements for the 42.5 and 32.5 grades. For RCP-
L, there is a significant decrease in strength observed at
25% replacement rate, which falls below the minimum
strength required by the standard. is indicates the need
for caution when considering high volume replacement
of RCP produced from low-strength concrete. However,
looking at the average results of all RCPs after 180days, it
can be noted that although the reductions in compressive
strengths compared to the control sample (69MPa) are
30% (15% replacement) and 40% (25% replacement), the
values of 48MPa and 41MPa, respectively, allow these
replacements to be considered and further tested for use
Fig. 12 Compressive strength of L, M and H mortars at 28 days (a) and 180 days (b) according to replacement level
Fig. 13 Compressive strength of L, M and H mortars at 28 days a and 180 days b according to quality level

Page 12 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
in CEM II/A-F or B-F type of cement according to EN
197–6.
3.4 Water Absorption
e water absorption by immersion of mortar samples is
shown in Fig.14. e replacement rate of RCP played a
role in increasing the water absorption of mortar. While
the 28-day water absorption of the standard mortars was
6.67%, that of RCP-mortars increased to 6.76%, 7.71%
and 8.85% for the L series; 7.00%, 7.77%, and 8.73% for
the M series; 7.00%, 7.74%, and 8.42% for the H series, at
replacement rates of 5%, 15%, and 25%, respectively. As
reported in previous studies (Kim et al., 2023; Sharaky
etal., 2021; Wu etal., 2021, 2022), the incorporation of
RCP in cementitious materials reduces the formation of
hydration products in the cement matrix and makes the
microstructure porous, providing more paths for water
inflow.
e influence of RCP on the long-term behaviour
of water absorption in mortars was not consistently
observed. For the L series, water absorption decreased
at 90days and increased again at 180days for 5% and
15% replacement rates, while the opposite pattern
was observed at 25% replacement rate (i.e., increase at
90days and decrease at 180days).
Fig.15 shows water absorption measured at 28 and
180 days. Like the strength test results, the effect of
RCP from parent concrete with varying strengths on
water absorption could not be conclusively interpreted.
For instance, at 5% replacement rate, the 28-day water
absorption followed the order of M = H > L. How-
ever, at 25%, the order reversed to L > M > H, which
reversed again to H > M > L at 180days. Nevertheless,
it is noteworthy that, at the same replacement rate, the
difference in water absorption between the L, M, and
H series was 0.43% at 28days and 0.67% at 180days.
Hence, it can be considered that the strength of par-
ent concrete does not have a significant effect. Fig.16
shows again marginal influence of the strength class of
the parent concrete on the water absorption of mortar
samples.
e water absorption results also support the con-
sistency of compressive strength results, exhibiting a
strong correlation. In Fig.17, a strong linear relation-
ship with an R2 value above 0.8 is demonstrated.
Fig. 14 Water absorption of mortars: a RCP from low strength concrete; b RCP from medium strength concrete; c RCP from high strength concrete

Page 13 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
3.5 Ultrasonic Pulse Velocity
e UPV results of the mortar samples at 28, 90, and
180 days are shown in Fig. 18. In cementitious mate-
rials, higher UPV values often indicate a denser
microstructure. With increasing replacement rates, the
mixture became more porous and, consequently, the
UPV gradually decreased. Using 5% RCP resulted in a
UPV reduction of up to 1.5% compared to the reference
mortar, while at 15% and 25%, the reduction reached up
to 3.8% and 6.2%, respectively. Overall, the UPV showed
an upward trend over time, but the increase in 90-day
and 180-day UPVs remained within the range of 1–3% of
the 28-day UPV.
UPV values are frequently applied to the prediction of
various properties of cementitious mixtures. Fig.19 plots
the relationship between UPV, compressive strength, and
water absorption, using regression analysis. As expected,
the UPV increased with higher compressive strength and
lower water absorption in the mortar samples, demon-
strating a good linear correlation irrespective of the par-
ent concrete’s strength.
3.6 XRD Analysis
e mortars were analysed for mineralogical composi-
tion by XRD to confirm or exclude any unexpected ele-
ment. As expected, all samples showed the presence of
the same minerals, such as P (Portlandite), Q (Quarts),
Fig. 15 Water absorption of L, M and H mortars at 28 days (a) and 180 days (b) according to replacement level
Fig. 16 Water absorption of L, M and H mortars at 28 days (a) and 180 days (b) according to quality level
Fig. 17 Relationship between compressive strength and water
absorption

Page 14 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
C (Calcite), CSH (hydration minerals), and some S (sul-
phate minerals). As an example, a comparison of mor-
tars prepared with high strength RCP (RCP-H), along
with a control sample, is shown in Fig.20. e XRD
patterns are essentially the same, indicating the forma-
tion of the same hydration products, without the pres-
ence of unexpected components.
4 Conclusions
For this case study, concrete samples from a 60-year-old
dam were taken from different parts of the structure to
obtain the parent concrete material, with different com-
pressive strengths. e samples were divided into three
groups of low, medium and high compressive strength
and ground into powder form: RCP-L, RCP-M, and
Fig. 18 Ultrasonic pulse velocity of mortars: a RCP from low strength concrete; b RCP from medium strength concrete; c RCP from highstrength
concrete
Fig. 19 Relationship between ultrasonic pulse velocity and compressive strength (a) and water absorption (b)

Page 15 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
RCP-H. ey were tested as components of a blended
binder where they replaced 5%, 15%, and 25% of cement.
Standard mortars were then prepared according to EN
196–1, to test selected properties and to investigate the
role of the compressive strength of the parent concrete.
e following can be concluded:
– e influence of the parent concrete strength on the
flow of RCP fresh mortar was found to be insignifi-
cant;
– ere is no clear observed effect of the strength of
the parent concrete on the flexural and compressive
strength of the next-generation cementitious mix-
ture;
– e results also indicate that the grain size of the
RCP has a greater effect on the final properties of the
mortars than its compressive strength or the pres-
ence of CSH phases;
– Differences between the strengths of the L, M, and H
mixtures are greater in younger ages (28 days), and
they are levelling off with age. At 180days, there is no
significant difference between the strengths of these
groups of samples;
– No significant effect of the strength of parent con-
crete was found also for water absorption and ultra-
sonic pulse velocity values of new-generation mor-
tars;
– RCPs have shown a nice recycling potential to be
incorporated in Portland fine-grain cements accord-
ing to EN 196–6, reaching strength classes 32.5 and
42.5. Looking at the average results of all RCPs after
180days, it can be noted that although the reduc-
tions in compressive strengths compared to the con-
trol value (69MPa) are 30% (at 15% replacement) and
40% (at 25% replacement), the values at 48MPa and
41MPa, respectively, allow these replacements to be
considered and further tested. e need for caution
comes when considering a high-volume replacement
of RCP (25%), especially in the case of low-strength
parent concrete, as here a 28-day results are not as
conclusive:
– Irrespective of the parent concrete’s strength,
strong linear relationships between ultra-
sound and compressive strength (R2L = 0.876,
R2M = 0.895, R2H = 0.882), ultrasound and water
absorption (R2L = 0.795, R2M = 0.919, R2H = 0.767),
and compressive strength and water absorption
(R228 = 0.8502, R290 = 0.8272, R2180 = 0.871) were
found using regression analysis. As expected, UPV
increases with higher compressive strength and
Fig. 20 XRD patterns of mortar samples containing RCP with different strengths of parent concrete

Page 16 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
lower water absorption in the mortar samples, and
water absorption increases with lower compressive
strength.
Although appropriate methods have been chosen in
the experiment for the exact specification of the nature
of the input materials used, their assumptions for efficacy
in the new mixtures, as well as the resulting properties of
the new mixtures, the study certainly has its limitations,
arising from the fact that it is an initial basic research,
reported for that reason as a case study (as mentioned
in the introduction). It can be concluded that continued
research would require, in particular, systematic and
multiple analyses of input materials (RCP) as well as out-
put materials (mortars, and these in a longitudinal time
sequence) to understand the material dependencies so
that a clear qualitative parameter could be determined
to predict the effectiveness of RCP in new cementitious
mixtures. e above would also need to be set up for the
possibility of applying reproducibility principles. As yet,
the compressive strength chosen by the authors, based
on an interest in adding to the body of knowledge on
this relatively new subject, as well as on practical expedi-
ency (ease of determination in the field, e.g., by a Schmidt
hardness tester), does not appear to be sufficient for this
purpose. It is preferable if it is supplemented by an addi-
tional parameter, e.g., chemical and mineralogical com-
position, content of hydration phases, rate and type of
degradation, or if it is conditional on the achievement
of certain processing parameters, e.g., granulometry,
together with a determination of which of these param-
eters predominates in its influence on the final properties
of the mixtures.
Acknowledgements
The support of the National Scholarship Programme of the Slovak Republic (ID
37273) is acknowledged.
Author contributions
AS: conceptualization, methodology, resources, supervision; validation, writ-
ing—original draft, writing—review and editing, and funding acquisition; JK:
conceptualization, methodology, investigation, data curation, writing—origi-
nal draft, and writing—review and editing; AE, MB, NJ, and PO: investigation;
AU: methodology and validation.
Funding
This research has been carried out within the project of Slovak Scientific Grant
Agency VEGA (Grant No. 1/0336/22) “Research on the effects of Lean Produc-
tion/Lean Construction for improving the efficiency of on-site and off-site
construction technologies”.
Data availability
Data are available on request from the authors.
Declarations
Ethics Approval and Consent to Participate
All authors of the manuscript confirm ethical approval and consent to partici-
pate following the Journal’s policies.
Consent for Publication
All authors of the manuscript agree on the publication of this work in the
International Journal of Concrete Structures and Materials.
Competing Interests
The authors declare that they have no known competing financial interests
or personal relationships that could have appeared to influence the work
reported in this paper.
Received: 18 January 2024 Accepted: 26 August 2024
References
Akbarnezhad, A., Ong, K. C. G., Tam, C. T., & Zhang, M. H. (2013). Effects of the
parent concrete properties and crushing procedure on the properties of
coarse recycled concrete aggregates. Journal of Materials in Civil Engineer-
ing, 25, 1795–1802. https:// doi. org/ 10. 1061/ (ASCE) MT. 1943- 5533. 00007 89
BREEAM International New Construction, Technical Manual—SD250, 2021.
Choi, H., Choi, H., Lim, M., Inoue, M., Kitagaki, R., & Noguchi, T. (2016). Evalua-
tion on the mechanical performance of low-quality recycled aggregate
through interface enhancement between cement matrix and coarse
aggregate by surface modification technology. Int J Concr Struct Mater, 10,
87–97. https:// doi. org/ 10. 1007/ s40069- 015- 0124-5
Corinaldesi, V., Nardinocchi, A., & Donnini, J. (2016). Reuse of recycled glass in
mortar manufacturing. European Journal of Environmental and Civil Engi-
neering, 20, s140–s151. https:// doi. org/ 10. 1080/ 19648 189. 2016. 12466 95
Du, J., Zhang, T., Chen, P., Guo, Y., Zhan, B., Wei, J., & Yu, Q. (2023). Phase separa-
tion of recycled concrete powder during grinding and consequent influ-
ences on its hydration behaviors in cement paste. Cement and Concrete
Composites, 142, 105203. https:// doi. org/ 10. 1016/j. cemco ncomp. 2023.
105203
EN 1015-3, methods of test for mortar for masonry—part 3: determination of
consistence of fresh mortar (by flow table), British Standards Institution
(1999).
EN 196–1, Methods of testing cement determination of strength, British
standards institution (2018).
EN 197-6, cement—part 6: cement with recycled building materials, British
Standards Institution (2023).
European Commission, Guidelines for the waste audits before demolition and
renovation works of buildings, 2018.
European Parliament and Council, Directive (EU) 2018/851 of the European
Parliament and of the Council of 30 May 2018 amending Directive
2008/98/EC on waste (Text with EEA relevance), (2018). https:// eur- lex.
europa. eu/ eli/ dir/ 2018/ 851/ oj (Accessed September 10, 2023).
Gao, Y., Cui, X., Lu, N., Hou, S., He, Z., & Liang, C. (2022). Effect of recycled pow-
ders on the mechanical properties and durability of fully recycled fiber-
reinforced mortar. Journal of Building Engineering, 45, 103574. https:// doi.
org/ 10. 1016/j. jobe. 2021. 103574
Jiang, Y., Li, B., Liu, S., He, J., & Hernandez, A. G. (2022). Role of recycled concrete
powder as sand replacement in the properties of cement mortar. Journal
of Cleaner Production, 371, 133424. https:// doi. org/ 10. 1016/j. jclep ro. 2022.
133424
Kim, J. (2022). Influence of quality of recycled aggregates on the mechanical
properties of recycled aggregate concretes: An overview. Construction
and Building Materials, 328, 127071. https:// doi. org/ 10. 1016/J. CONBU
ILDMAT. 2022. 127071
Kim, J., & Jang, H. (2024). Effect of thermal activation of powders obtained from
multi-recycled concrete on the performance of cementitious materials (pp.
421–426). Springer. https:// doi. org/ 10. 1007/ 978- 981- 99- 9227-0_ 39
Kim, J., & Kim, N. (2023). Exploring the role of thermal activation of cement
exposed to the external environment on the improvement of concrete
properties. Journal of Materials Research and Technology. https:// doi. org/
10. 1016/j. jmrt. 2023. 03. 195
Kim, J., Nciri, N., Sicakova, A., & Kim, N. (2023). Characteristics of waste concrete
powders from multi-recycled coarse aggregate concrete and their effects
as cement replacements. Construction and Building Materials, 398, 132525.
https:// doi. org/ 10. 1016/j. conbu ildmat. 2023. 132525

Page 17 of 17
Sičákováetal. Int J Concr Struct Mater (2024) 18:80
Kim, Y. J., & Choi, Y. W. (2012). Utilization of waste concrete powder as a substi-
tution material for cement. Construction and Building Materials. https://
doi. org/ 10. 1016/j. conbu ildmat. 2011. 11. 042
Kotwa, A. (2019). Parameters of mortars made of aluminium and portland
cement. IOP Conf Ser Mater Sci Eng, 471, 032016. https:// doi. org/ 10. 1088/
1757- 899X/ 471/3/ 032016
Kou, S. C., & Poon, C. S. (2015). Effect of the quality of parent concrete on the
properties of high performance recycled aggregate concrete. Construc-
tion and Building Materials, 77, 501–508. https:// doi. org/ 10. 1016/j. conbu
ildmat. 2014. 12. 035
KS F4004, Concrete bricks, Korean Agency for Technology and Standards
(2018).
Li, S., Chen, G., Xu, Z., Luo, X., & Gao, J. (2022). Particle-size effect of recycled
clay brick powder on the pore structure of blended cement paste.
Construction and Building Materials, 344, 128288. https:// doi. org/ 10. 1016/j.
conbu ildmat. 2022. 128288
Liu, K., Yan, J., Hu, Q., Sun, Y., & Zou, C. (2016). Effects of parent concrete and
mixing method on the resistance to freezing and thawing of air-
entrained recycled aggregate concrete. Construction and Building Materi-
als. https:// doi. org/ 10. 1016/j. conbu ildmat. 2015. 12. 074
Ma, Z., Liu, M., Duan, Z., Liang, C., & Wu, H. (2020). Effects of active waste pow-
der obtained from C&D waste on the microproperties and water perme-
ability of concrete. Journal of Cleaner Production, 257, 120518. https:// doi.
org/ 10. 1016/j. jclep ro. 2020. 120518
Mardani, A., Bui, N. K., & Noguchi, T. (2024). hybrid environmentally friendly
method for RCA concrete quality improvement. Int J Concr Struct Mater,
18, 29. https:// doi. org/ 10. 1186/ s40069- 024- 00664-1
Naderi, M., & Kaboudan, A. (2021). Experimental study of the effect of aggre-
gate type on concrete strength and permeability. Journal of Building
Engineering, 37, 101928. https:// doi. org/ 10. 1016/j. jobe. 2020. 101928
Pani, L., Francesconi, L., Rombi, J., Mistretta, F., Sassu, M., & Stochino, F. (2020).
Effect of parent concrete on the performance of recycled aggregate
concrete. Sustainability. https:// doi. org/ 10. 3390/ su122 29399
Sharaky, I., Issa, U., Alwetaishi, M., Abdelhafiz, A., Shamseldin, A., Al-Surf, M., Al-
Harthi, M., & Balabel, A. (2021). Strength and water absorption of sustain-
able concrete produced with recycled basaltic concrete aggregates and
powder. Sustainability, 13, 6277. https:// doi. org/ 10. 3390/ su131 16277
Tang, Q., Ma, Z., Wu, H., & Wang, W. (2020). The utilization of eco-friendly recy-
cled powder from concrete and brick waste in new concrete: A critical
review. Cement and Concrete Composites, 114, 103807. https:// doi. org/ 10.
1016/J. CEMCO NCOMP. 2020. 103807
Topič, J., Trejbal, J., Plachý, T., & Prošek, Z. (2016). Relationship between com-
pressive strength and young’s modulus of cement paste with recycled
concrete powder. Key Engineering Materials, 722, 254–259. https:// doi. org/
10. 4028/ www. scien tific. net/ KEM. 722. 254
Vashistha, P., Oinam, Y., Kim, H.-K., & Pyo, S. (2023a). Effect of thermo-mechan-
ical activation of waste concrete powder (WCP) on the characteristics of
cement mixtures. Construction and Building Materials, 362, 129713. https://
doi. org/ 10. 1016/j. conbu ildmat. 2022. 129713
Vashistha, P., Oinam, Y., & Pyo, S. (2023b). Valorization of waste concrete pow-
der (WCP) through silica fume incorporation to enhance the reactivity
and hydration characteristics. Developments in the Built Environment, 16,
100272. https:// doi. org/ 10. 1016/j. dibe. 2023. 100272
Vashistha, P., Park, S., & Pyo, S. (2022). A review on sustainable fabrication of
futuristic cementitious binders based on application of waste con-
crete powder, steel slags, and coal bottom ash. International Journal
of Concrete Structures and Materials, 16, 51. https:// doi. org/ 10. 1186/
s40069- 022- 00541-9
Wahlström M, Hradil P, Castell-Rudenhausen MZ, Bergmans J, van Cauwen-
berghe L, Van Belle Y, Sičáková A, Struková z, Li J, Pre-demolition audit
- overall guidance document: PARADE. Best practices for pre-demolition
audits ensuring high quality RAw materials, EIT RawMaterials (2019).
Wu, H., Liang, C., Wang, C., & Ma, Z. (2022). Properties of green mortar blended
with waste concrete-brick powder at various components, replacement
ratios and particle sizes. Construction and Building Materials, 342, 128050.
https:// doi. org/ 10. 1016/j. conbu ildmat. 2022. 128050
Wu, H., Yang, D., Xu, J., Liang, C., & Ma, Z. (2021). Water transport and resistance
improvement for the cementitious composites with eco-friendly powder
from various concrete wastes. Construction and Building Materials, 290,
123247. https:// doi. org/ 10. 1016/j. conbu ildmat. 2021. 123247
Xiao, J., Ma, Z., Sui, T., Akbarnezhad, A., & Duan, Z. (2018). Mechanical properties
of concrete mixed with recycled powder produced from construc-
tion and demolition waste. Journal of Cleaner Production, 188, 720–731.
https:// doi. org/ 10. 1016/j. jclep ro. 2018. 03. 277
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in pub-
lished maps and institutional affiliations.
Alena Sičáková Full professor at the Technical University of Kosice.
Jeonghyun Kim PhD. Student at the Wrocław University of Sci-
ence and Technology.
Magdaléna Bálintová Full professor at the Technical University of
Kosice.
Adriana Eštoková Full professor at the Technical University of
Kosice.
Natália Junáková Associated professor at the Technical University
of Kosice.
Peter Orolin Assistant professor at the Technical University of
Kosice.
Andrzej Ubysz Full professor at the Wrocław University of Science
and Technology.