**Preface to "Actions for Bioenergy and Biofuels: A Sustainable Shift"**

The pandemic period has led to a socioeconomic crisis that will have serious repercussions for production systems, as well as citizens' lives. This is furthered by the pollution caused by fossil fuels and concerns about damage to health and the environment. However, it is precisely in times of difficulty that it is necessary to identify a turning point and introduce a paradigmatic shift that can reconcile wellbeing with environmental and health protection. Increased citizen awareness, new employment outlets, the growing economic opportunities associated with the sustainable management of natural resources, as well as a growing respect for ecosystems, point to sustainability as a key driver of recovery. This Topic introduces the concept of sustainable hand, in which the point of connection between nature and man can occur if we adopt a systemic vision, which is participatory and oriented to social welfare. The use of natural resources, biofuels and bio-based products is one direction in which we can move. Are you ready for this green transition?

> **Idiano D'Adamo and Piergiuseppe Morone** *Editors*

### *Editorial* **Bioenergy: A Sustainable Shift**

**Idiano D'Adamo 1,\*, Piergiuseppe Morone 2 and Donald Huisingh 3**

The European Commission emphasised that a bioeconomy is an economy that uses renewable biological resources from the land and sea (e.g., animals, crops, fish, forests and microorganisms) to produce energy, food and materials [1]. Consequently, the topic of bioenergy must be included within the sectors of the bioeconomy, which also includes traditional sectors (e.g., agriculture and forestry) and innovative sectors (e.g., manufacturing). Europe plays a key role in the evolving bioeconomy, but the performance of individual countries shows different values in terms of turnover, added value and personnel [2]. The aim is to support the development of these sectors globally in order to reach the 17 Sustainable Development Goals [3] with a special focus on circular bioeconomy [4].

Bioenergy, derived from biomass is applicable in all energy sectors (heat, electricity and transport). Human vulnerability to climate change—amplified by the COVID-19 pandemic—is a very serious threat to modern societies that requires urgent action. Given the complexity of the challenges, the efficient and sustainable usage of all resources is needed. The question we start with is: if people consume energy, are they responsible for environmental pollution? We believe that this is not the correct question to be posed, but certainly consumers are expected to engage in responsible behaviors. Similarly, should producers be expected to generate and use clean energy even if this leads to economic losses? Again, we believe this is not a valid question, yet producers are urged to make forward-looking choices when defining their production strategy—able to incorporate social and environmental (external) costs along with private costs.

Technological progress in transitioning to renewable energy-based systems is proving the greater competitiveness of these green resources that in various scenarios have become competitive with respect to gray resources, especially in the context of the fact that more than 10,000,000 people die each year due to air pollution, most of which is due to combustion of fossil fuels [5,6]. These and many climate-change related costs that are currently externalized must be integrated into our transition policies, practices and timetables.

Thus, we envisage two levels of analysis: first, all externalities should be properly identified; second, a sound and agreed upon methodology able to assign values to each of these externalities should be developed. However, this second phase is complex because not everything can always be translated into economic terms and because the value assigned may not be objective. While for the first problem, the solution may be to compare with comparable items, the second is simpler because it only requires alternative analyses to be carried out alongside the baseline ones.

The balance sheet associated with renewable energy tends to assign a positive value to externalities, but how high is this value? The social cost of carbon still has a low value, but in recent years it has grown significantly. Is the social component actually included in this externality? Unfortunately, we have to give a negative answer. It is precisely this absence that weighs on policy choices. How much do the exploitation of minors, the low

**Citation:** D'Adamo, I.; Morone, P.; Huisingh, D. Bioenergy: A Sustainable Shift. *Energies* **2021**, *14*, 5661. https://doi.org/10.3390/ en14185661

Received: 4 September 2021 Accepted: 7 September 2021 Published: 9 September 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

1

rates of schooling, the serious poverty in which some families live, the lack of healthcare, the inefficiency of the Public Administration and some judicial criticalities really cost? For all these reasons, we can and should act now. This editorial focuses on the energy part which is only one component of this great revolution. Renewables should not compete with each other, as they are all required to replace fossil sources. The rapid advances in efficiency and falling prices of wind and solar power make them increasingly cost-effective. Sourcing and efficient usage of bio-energy based materials is also improving in many ways.

Analyzing bioenergy specifically, the International Energy Agency (IEA) concluded that a reduction in environmental impact occurs in the following scenarios: (i) "Biomass is grown sustainably or based on waste/residues"; (ii) "Converted to energy products efficiently"; and (iii) "Used to displace GHG-intensive fuels". Bioenergy includes several potential feedstocks (e.g., organic residues and waste; forestry and agriculture), production processes (e.g., fermentation; anaerobic digestion; gasification; pyrolysis; pelletisation; advanced biofuel processes; chipping and torrefaction), products (e.g., biodiesel; bioethanol; biogas; biomethane; renewable diesel; woodchips; pellets; pyrolysis oil; bio-synthetic gas; refuse derived-fuel and other advanced biofuels) and final energy use (e.g., biofuels for transport; combustion for electricity; combustion for heat and biomass-based materials and products) [7].

The literature has shown an exponential growth in the number of papers published on the topic of bio-resources for energy applications [8] and it has been documented that economic growth is influenced by the productivity of resources, including bioenergy [9]. Thus, it is evident that the growth of the bioenergy industry helps to reduce pollution and unemployment [10]. However, bio-resources have many other potential attributes that must be analyzed. Several authors have concluded that bioenergy can play an important role in the decarbonization of society. Thus, the uses and trade-offs of bioenergy must be explored from multiple perspectives.

It is essential to identify decision-making models that support both policy-makers and other stakeholders by comparing different alternatives [11]. The development of bioenergy must be integrated within emerging markets that support ecologically sound economic development of these territories based upon sustainable models [12]. In this direction, the comparison among countries is valuable in helping researchers to identify which business models have shown the main advantages [13].

In this context, it is essential to broaden and deepen the analyses of bio-energy materials that could be used to help to achieve sustainability objectives [14]; additionally, analyses must be performed that consider the bio-based system's sustainability by performing holistic analyses of the competing demands for and alternative uses of bio-based materials [15].

Analyses must be made on specific cases [16] as well as on local, regional, national and global bases for the short and long term future in the context of climate change, pandemics such as COVID-19 and one more giant factor.

What is that factor? It is that if the world's human population continues to increase at the current net increase of approximately 83 million people per year, the global population will increase from 7.9 billion to 9.7 billion by 2050 [17]. In that context, societies must factor in the increasing land that will be needed for food production and decide about the trade-offs between land for producing food and land for producing bio-based materials for non-dietary purposes.

Renewable energies are essential parts of the energy revolution in which the goal is to replace production from fossil fuels with those from renewable sources. In this framework, biomasses are the sources that can present the highest impact compared to other green sources, such as wind, photovoltaic and hydropower, but nevertheless energy consumption, both at the industrial and domestic level, are significant. Having a reduction due to energy efficiency interventions is certainly positive news; having a reduction due to a lower purchasing power indicates an economic decrease, and as such it cannot be welcomed. Biomasses are appropriate in the systems of supply and energy consumption at a local level. This means that the production of energy from biomass obtained locally is significantly more sustainable than that obtained with biomass from other territories, in some cases even crossing national borders. This practice must be monitored and must include sustainability analyses that justify its application. In fact, the objective is to encourage the use of renewable sources to allow a circularity alongside an optimal trade-off between food production, and the production of bio-based energy resources. It must be remembered that the current transport sector contributes significant quantities of global emissions and the percentage of renewable energies in this sector has not yet achieved optimal levels [18].

Another delicate issue is certainly represented by the choice of bio-substrates. There is a perception that many of the available resources are not fully utilized, for example the proper use of forest trees, organic residues from agriculture, forestry or landscaping, or residues from the animal breeding sector. In addition, uncultivated (marginal) agricultural land could be used and the whole system could be optimized while ensuring an equitable and sustainable balance of the water–energy–food nexus.

The objective of future research should be focused on solving daily and longer-term problems; therefore, it is necessary to encourage collaboration among research centers and business structures to propose methodologies and solutions that will be able to develop answers to the food and bio-energy needs of society.

Unsustainable, intensive agricultural practices and burning forests and other vegetation are steadily increasing demands for bio-resources, and also causes serious environmental consequences. In this context, the European Commission highlighted the following points for reflection on the theme of bioenergy [19]:

These issues have a much broader perspective than the issue of bioenergy itself. They concern a model of sustainable and inclusive development that depends on an enhancement of the human component, particularly the collective, empowerment-oriented to identify and solve problems and not to amplify clashes that only benefit fossil fuel-based power lobbies. Education and training can play an essential role [20] and are manifested by university courses that have belatedly begun to be provided via public seminars and webinars.

Society can be empowered to demand answers from the political world to change the status quo, while at the same time, the great global challenges are not based solely on competitiveness, but on the reality that all of us must cooperate to help to ensure truly sustainable futures for our children's children's children!

It is undeniable that the economic component has always had a primary role in the choices of powerful institutional actors, and it is necessary to find a balance that does not create short-term profitability for the few monopolies to impede the transition to equitable, sustainable post-fossil-carbon societies globally, as soon as possible! We do not have time to waste!

The concept of Adam Smith's invisible hand could be readapted to that of a sustainable hand, which, within a market, seeks the social optimum, as this is the only truly sustainable approach, in the long term. For this to happen, new social norm paradigms models and customs must be developed and implemented to help to govern social interactions to truly sustainable futures.

In this sense, bio-based materials and products for all purposes, from food to other uses, are essential renewables that require changes in one's attitudes, visions, strategies and actions, based on a principle of sharing resources. However, this challenge is very complex—and becomes even more complex in those regions of the world characterized by armed conflicts and where there are dictatorial regimes. It is increasingly serious in regions where climate change is causing dramatic changes from flooding due to the sea level rising on the one side and to rapid expansion in desertification on the other side.

We have many challenges to address, but by co-working locally, regionally, nationally and globally, we can and will make urgently needed transitions. Bio-based production for food and other purposes is essential for humans and other life-forms on this planet.

**Author Contributions:** Conceptualization, I.D., P.M. and D.H.; writing—original draft preparation, I.D., P.M. and D.H.; writing—review and editing, I.D., P.M. and D.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


**Author details**

Muhammad Nawaz National University of Singapore, Singapore

\*Address all correspondence to<EMAIL_ADDRESS>
© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Earth Crust*

**5.2 Exogenous factors**

**6. Summary and conclusion**

Another example of the evolution of the crust due to endogenous processes is volcanism, where material from the mantle or the deep crust is deposited onto the surface where it contributes in renewing the crust surface with new igneous rock and landforms. In some places the crust is weaker such as along plate boundaries, the magma forces its way through the rock, extruding rock and releasing pressure, which is why volcanic activity tends to occur near the borders of tectonic plates, for example, the Pacific Ring of Fire [22]. The composition and origin of the lava determine the type of volcanic landform created, with more fluid mafic lava forming structures such as shield volcanoes and more viscous felsic lava forming structures such as stratovolcanoes from the accumulation of ejecta. However, in cases where magma does not breach the surface, the magma in horns or magma chambers may solidify to form intrusive or plutonic rocks. Over time, the surrounding softer rock erodes away, revealing the harder plutonic rock beneath, which creates landforms

such as plutons, batholiths, dykes, sills, laccoliths and volcanic necks.

impact structure as opposed to a simple bowl shape [25].

The evolutionary processes mentioned above were all a result of forces originating from within the Earth. However, the crust is also shaped by a multitude of processes from external forces such as climate and extraterrestrial material. An overt example of an extraterrestrial force on the crust would be an impact crater, in which materials from space such as asteroids, meteoroids or comets collide with the Earth, leaving scars on the surface. While fairly infrequent in recent geological time, impacts were a major force of change during the late heavy bombardment period of the Earth's history [24], as the orbital path of the planet had not been fully cleared. The size of the impactor and extension diameter of the resultant impact crater is a decisive factor on the type of crater formed, with crater diameters above 2 km for sedimentary rocks and 4 km for crystalline rocks having a more complex

Climate and weathering are also significant drivers in the continued evolution of the crust. And while the parameters that control climate are complex and not fully understood, its effects can be seen widely. These processes can be observed in many forms, such as the exposure of batholiths by the erosion of soft rock, the carving of the Grand Canyon or the deposition of sediment by fluvial processes to create river deltas [26]. Additionally, biological processes also play a role in weathering and erosion. For example, plant roots hold the soil together, providing resistance to erosion [25]. Plants and burrowing animals also contribute to the mechanical breakdown of rock through wedging caused by growth and burrowing, respectively. All of the above processes are but a fraction of the factors that keep the Earth's crust in a state of constant flux. And while we may be unable to observe all geological evolutionary phenomena in the span of a human lifetime, we have more than enough examples

While the crust may only comprise the superficial layer of the Earth, it is truly a dynamic and fascinating thing to learn about.  From its early origins as a hot lifeless shell covering our planet to its current state as the home for all life on Earth, it has changed so much over the geological timespan of the Earth's history and continues to evolve to

and evidence to show that truly drastic changes occur in geological time.

**6**


4.1.2 Time evolution at the plasma density above the critical one

According to Figure 19, if a critical plasma density of 9 � 1019m�3 is exceeded, no stationary state can be sustained for the assumed impurity concentration cI ¼ 0:01. The latter, however, does not remain at the same level since the plasma detachment from divertor target plates leads to the vanishing of the impurity source due to physical and chemical sputtering of the plate material [7]. As a result, impurities diffuse out of the plasma core and their concentration decreases. The characteristic time for the impurity concentration decay is of τI ≈l 2 I =D⊥, where lI is the characteristic penetration depth of the mostly radiating Li-like ions of carbon and D⊥ is the charged particle diffusivity. Impurity transport analysis [42] shows that if lI ≈0:05 � 0:1 m and for D⊥ ≈0:5 m2 s�1, we get τI ≈ 5 � 20 ms. In the simplest way, the time evolution of impurity concentration can be described by the equation:

#### Figure 19.

Dependence of time derivative of the plasma temperature at the outer boundary of the stochastic layer, xs, the rhs of Eq. (3), on Ts for different plasma density and impurity concentration. Steady states, dTs=dt ¼ 0 with ∂ ∂Ts dTs dt >0, ∂ ∂Ts dTs dt <0 (black circles) are stable and that with d2 Ts=dt2 <0 (transparent circle) are unstable.

Experimental Studies of and Theoretical Models for Detachment in Helical Fusion Devices DOI: http://dx.doi.org/10.5772/intechopen.87130

$$d\mathbf{c}\_I/d\mathbf{t} = \left[\mathbf{c}\_I^0(T\_s) - \mathbf{c}\_I\right]/\mathbf{r}\_I \tag{5}$$

For the stationary impurity concentration, we assume c0 I Ts ≥T∗ s ¼ 10�2 and c0 I Ts <T∗ s ¼ 10�3 with T ∗ s ≈5 eV. Figure 20 demonstrates the time evolution of the impurity concentration cI and of the radiation level qrad=qc, calculated for n ¼ 1020 m�3 and τI ¼ 15 ms. Without knowing the exact temperature profile T xð Þ, needed to assess the flux density of radiation losses qrad firmly, we estimated this by assuming a linear one T xð Þ¼ ½ � Tsð Þþ x � xc Tcð Þ xs � x =ð Þ xs � xc .

One can see that the frequency of these oscillations is of 100 Hz, in agreement with observations.

By concluding this section, we discuss qualitatively possible causes for the difference in the behavior of the detached plasma in LHD without and with RMP, respectively, an unstoppable penetration of cold plasma into the core, leading to the radiation collapse, and the existence of the plasma density range where the radiation layer is stably confined at the plasma edge. As it has been demonstrated in [42], the mechanisms both of plasma heating and heat transfer through the plasma are of the importance for the discharge behavior by achieving the critical density. In ohmically heated discharges in the tokamak TEXTOR, where the plasma current was maintained at a preprogrammed level, a radial detachment was stopped by the increase in the density of the heat flux from the hot plasma core due to decreasing minor radius of the current carrying plasma column. If, however, the main heating is predominantly supplied from other sources such as NBI, this stabilization mechanism is ineffective and, as calculations in [42] have shown, a radiation collapse occurs, similar as this happens in LHD without RMP.

What occurs as a detachment set is determined by the competition between the decay of the impurity concentration in the plasma, characterized by the time τI, and time for the cooling front spreading into the plasma core. As it has been discussed in the first part, in addition to the magnetic island with strongly increased transport, RMP induce a region deeper into the plasma core. With the experimentally measured Te profiles, one can assess that with the RMP, the heat conduction in this region is reduced by a factor of 10 and the heat conductivity χ⊥ ¼ κ⊥=n is of 1 m2 s�1. For the penetration of the cooling front through this region, with a width Δ of 0:15 m, a time of Δ2 =χ⊥ ≈ 20 ms is needed. This is at the upper limit of the impurity decay time, and

#### Figure 20.

The time evolution of the impurity radiation level qrad=qc and concentration, calculated by integrating Eqs. (4) and (5) for n ¼ 1020 m�3 and τI ¼ 15 ms.

therefore, the cooling wave most probably fades out. This mechanism is to some extend similar to that of the excitation of self-sustained oscillations in a plasma-wall system with strongly inhomogeneous diffusivity of charged particles [40].


*Edited by Maria C. Hernandez-Soriano*

Soil is an irreplaceable resource that sustains life on the planet, challenged by food and energy demands of an increasing population. Therefore, soil contamination constitutes a critical issue to be addressed if we are to secure the life quality of present and future generations. Integrated efforts from researchers and policy makers are required to develop sound risk assessment procedures, remediation strategies and sustainable soil management policies. Environmental Risk Assessment of Soil Contamination provides a wide depiction of current research in soil contamination and risk assessment, encompassing reviews and case studies on soil pollution by heavy metals and organic pollutants. The book introduces several innovative approaches for soil remediation and risk assessment, including advances in phytoremediation and implementation of metabolomics in soil sciences.

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**Theorem 14.** *m*

$$\sum\_{n=0}^{m} \sum\_{k=0}^{n} (-1)^{n} \frac{(n)\_{k} a^{n-k} S\_{2}(m, n)}{k + 1} = \sum\_{j=0}^{m} \binom{m}{j} B\_{m-j} B l\_{j} \left( -a \right) \,. \tag{67}$$

By applying the fermionic *p*-adic integral to Equation (58) and combining the final equation with Equations (63) and (66), we also arrive at the following theorem:

### **Theorem 15.** *m*

$$\sum\_{n=0}^{m} \sum\_{k=0}^{n} \left(-1\right)^{n} \frac{\left(n\right)\_{k} a^{n-k} S\_{2}\left(m, n\right)}{2^{k}} = \sum\_{j=0}^{m} \binom{m}{j} E\_{m-j} B l\_{j}\left(-a\right) \,. \tag{68}$$

Moreover, by integrating Equation (58) with respect to *x* from 0 to 1, we have:

$$\sum\_{n=0}^{m} a^n S\_2(m, n) \int\_0^1 \mathbb{C}\_n \left( x; a \right) dx = \sum\_{j=0}^m \binom{m}{j} B l\_j \left( -a \right) \int\_0^1 x^{m-j} dx. \tag{69}$$

On the other hand, by integrating Equation (2) with respect to *x* from 0 to 1, we also have:

$$\int\_0^1 \mathbb{C}\_n\left(\mathbf{x}; a\right) d\mathbf{x} = \sum\_{j=0}^n (-1)^{n-j} \binom{n}{j} \frac{1}{a^j} \int\_0^1 \left(\mathbf{x}\right)\_j d\mathbf{x},\tag{70}$$

By making use of the following definition of the well-known Cauchy numbers (or the Bernoulli numbers of the second kind) *bn* (0) (*cf*. [4]):

$$b\_n(0) = \int\_0^1 (\mathbf{x})\_n \, d\mathbf{x}\_\prime \tag{71}$$

Equation (70) yields:

$$\int\_0^1 \mathbb{C}\_n\left(\mathbf{x}; a\right) d\mathbf{x} = \sum\_{j=0}^n \left(-1\right)^{n-j} \binom{n}{j} \frac{b\_j\left(0\right)}{a^j}.\tag{72}$$

Combining the above equation with Equation (69), we arrive at the following theorem:

**Theorem 16.** *m*

$$\sum\_{n=0}^{m} \sum\_{j=0}^{n} (-1)^{n-j} \binom{n}{j} a^{n-j} \mathbb{S}\_2(m, n) b\_j(0) = \sum\_{j=0}^{m} \binom{m}{j} \frac{Bl\_j(-a)}{m-j+1}.\tag{73}$$

#### **6. Applications in the Probability Distribution Function**

In this section, we investigate some applications of the numbers *Y*(−*k*) *n* (*λ*). Assume that 0 < *p* ≤ 1 and *n* = 0, 1, 2, . . . , *k*. We set the following discrete probability distribution:

$$f\left(p;k,n\right) = \frac{\left(-1\right)^{k-n}2^k}{n!p^n}Y\_n^{(-k)}\left(p\right) \tag{74}$$

where *p* is a probability of success, *k* is number of trials, *n* is number of successes in *k* trials, and *n* = 0, 1, 2, . . . , *k*. Therefore, *f* (*p*; *k*, *n*) is binomially distributed with parameters (*k*, *p*).

*Properties of Discrete Probability Distribution f* (*p*; *k*, *n*)

Here, we give some properties of discrete probability distribution *f* (*p*; *k*, *n*). We examine the properties of the probability distribution *f* (*p*; *k*, *n*) with a random variable with parameters *k*, *n*, and *p* as follows:

For all *k*, *n*, *p* with 0 ≤ *n* ≤ *k* and 0 < *p* ≤ 1, 0 ≤ *f* (*p*; *k*, *n*) ≤ 1. That is *f* (*p*; *k*, *n*) ≥ 0. The probability distribution function *f* (*p*; *k*, *n*) satisfies that:

$$\sum\_{n=0}^{\infty} f\left(p; k, n\right) = 1.$$

Computing the distribution function *f* (*p*; *k*, *n*). Suppose that *X* is a binomial with parameters (*k*, *p*). To computing its distribution function:

$$P(X \le j) = \sum\_{n=0}^{j} f\left(p; k, n\right),$$

where *j* = 0, 1,. . . ,*k*.

In order to compute its expected value and variance for random variable with parameters *k* and *p*:

$$E\left[X^{\overline{v}}\right] = \sum\_{n=0}^{k} n^{v} f\left(p; k, n\right) \tag{75}$$

Observe that the probability distribution function *f* (*p*; *k*, *n*) is a modification of the binomial probability distribution function with parameters (*k*, *p*). Substituting *v* = 1 into Equation (75), *E* [*X*] = *kp*. Substituting *v* = 2 into Equation (75), variance *E X*2 − (*E* [*X*])2 = *kp* (1 − *p*).

If we take *k* → ∞, then the distribution *f* (*p*; *k*, *n*) goes to the Poisson distribution. On the other hand the Poisson–Charlier polynomials are orthogonal with respect to the Poisson distribution (*cf*. [18,24]).

#### **7. Conclusions**

Applications of generating functions are used in many areas, and we used them to study new families of combinatorial numbers and polynomials. We then studied properties of these new families, which yielded a handful of new identities and relations. Namely, these identities were related to numerous special numbers, special polynomials, and special functions such as the Bersntein basis functions, the Stirling numbers, the Bell polynomials (or exponential polynomials), the Poisson–Charlier polynomials, and the probability distribution functions. Furthermore, we should note that newly defined combinatorial numbers in this paper gave a different approach to the binomial (or Newton) distribution and the Poisson distribution, as well as combinatorial sums including the Bernoulli numbers, the Euler numbers, the Cauchy numbers (or the Bernoulli numbers of the second kind), and combinatorial numbers. This is why the results of this paper have the potential to be used in numerous areas such as mathematics, probability, physics, and in other associated areas.

**Author Contributions:** Investigation, I.K., B.S., Y.S.; wirting-original draft, I.K., B.S., Y.S.; writing-review and editing, I.K., B.S., Y.S.

**Funding:** This research received no external funding.

**Acknowledgments:** This paper is dedicated to Hari Mohan Srivastava on the occasion of his 80th Birthday. Yilmaz Simsek was supported by the Scientific Research Project Administration of Akdeniz University.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

c 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).


*Supporting open minds since 2005*

Multifunctionality and Impacts of Organic and Conventional Agriculture http://dx.doi.org/10.5772/intechopen.73737 Edited by Jan Moudrý, Kassio Ferreira Mendes, Jaroslav Bernas, Rafael da Silva Teixeira and Rodrigo Nogueira de Sousa

#### Contributors

Mauro Wagner Oliveira, Luis Cláudio Silveira, Alexandre Bosco De Oliveira, Márcio Barbosa, Manoel Pereira, Terezinha Bezerra Albino Oliveira, Olufemi M. Adesope, Charity N. Atoma, Linda C. Familusi, Terrence Thomas, Cihat Gunden, Befikadu Legesse, Anton Perpar, Andrej Udovč, Hamadttu El-Shafie, Ojeda-Silvera Carlos Michel, José Manuel Mazón-Suástegui, García-Bernal Milagro, Avilés-Quevedo María Araceli, Abasolo-Pacheco Fernando, Batista-Sánchez Daulemys, Tovar-Ramírez Dariel Dariel, Arcos-Ortega Fabiola Fabiola, Murillo-Amador Bernardo, Nieto-Garibay Alejandra, Ferrer-Sánchez Yarelys, Morelos-Castro Rosa María, Díaz-Díaz Miriam, Alvarado-Mendoza Alex, Bonilla-Montalvan Boris, Nader Heydari, Agbalagba O. Ezekiel, Oghenetejiri Hannah Agbalagba, Helena Saraiva Koenow Pinheiro, Lúcia Helena Cunha dos Anjos, Pedro Armentano Mudado Xavier, Cesar da Silva Chagas, Waldir de Carvalho Júnior, Kassio Ferreira Mendes, Rodrigo Nogueira de Sousa, Ana Flávia Souza Laube

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Multifunctionality and Impacts of Organic and Conventional Agriculture Edited by Jan Moudrý, Kassio Ferreira Mendes, Jaroslav Bernas, Rafael da Silva Teixeira and Rodrigo Nogueira de Sousa p. cm. Print ISBN 978-1-78985-931-7 Online ISBN 978-1-78985-932-4 eBook (PDF) ISBN 978-1-83880-073-4


**4. National creative industries and policies in the digital era**

Despite the importance of various areas of policy and development, it is crucial to comprehend that Hallyu is not the end-product of any particular framework or singular set of policies, either at governmental or corporate level. It is impossible to identify a singular strategy that set out to create Hallyu or something resembling it, and the success of Hallyu as it exists today has surpassed the expectations of even the most optimistic Koreans. Besides the digital foundation discussed in this chapter, Kim [50] identifies four other factors that made Hallyu possible: the competitiveness of Korea's culture industries, the persistent ambition of Korean show business entrepreneurs, economic development and political liberalization in East Asian countries, and 'fragmentary' governmental support. It is within the scope of this chapter to focus on the latter of these factors.

#### **4.1 Ministry of culture & Hallyu's humble beginnings**

In the mid-1990s, the Korean government established a culture industry bureau and began supporting the Korean record industry's expansion into international markets. They collected information on major music fairs worldwide and encouraged Korean companies to participate, while a public booth exclusively for Korean record companies was set up at overseas music fairs. The Ministry of Culture invested 42 million won in producing promotional CDs and pamphlets to introduce Korean pop musicians to foreign buyers [50].

In 1999, the Ministry made a more significant effort to help the Korean music industry enter the global market by funding a project to create sample K-pop CDs for distribution abroad. Three compilation CDs were produced, featuring popular Korean songs performed by original K-pop singers with translations in Chinese, Japanese, and English, which were then sent to entertainment-related organizations in China and neighboring countries. Additionally, the Korean government sponsored pop band H.O.T's concert in China in 2000, overcoming travel restrictions for young Korean men who had not completed military service [50].

The Ministry of Culture took further measures to support the introduction of Korean pop music in several Asian countries. They sponsored music programs like "Seoul Vibration", which was widely broadcast across Asia, and "Listening to Korea," a joint production between Korean and Chinese companies aired in Southeast Asian countries and China. The government also published booklets in Chinese, Japanese, and English in order to promote Korean pop music and the record industry to international markets [50].

Korea's Ministry of Culture has been instrumental in guiding the Korean government's approach to the cultural industries, fulfilling both its traditional role of overseeing the sector from a public welfare perspective and an additional responsibility of acting as an industrial developer since the 1990s [51]. This dual role has shaped the cultural industry policy during this period, and with the cultural industry becoming a significant contributor to the economy, the Ministry's role as an industrial developer has only increased in prominence over time. Recognizing the cultural industries' pivotal position in the new economic development framework, the Ministry has also taken on the central role of coordinating support for various government agencies involved in the growth of electronics, information and communication technology (ICT), and cultural sectors. The Korean government acknowledges that a diverse range of cultural industries, including film, television dramas, gaming, animation, and music, can have far-reaching impacts on other sectors, mainly due to their reliance on advancements in electronics and ICT [51]. As discussed in previous sections, this demand from cultural industry businesses has spurred innovation and the development of new products in Korea's electronics and ICT industries.

#### **4.2 Hallyu content as commodity**

The Hallyu phenomenon provides arguably the most insightful case study on the increasing significance of cultural exports and the creative arts in the global economy, particularly in the digital age. While industrial policies have traditionally prioritized sectors such as manufacturing, the creative industries have emerged as integral and potentially vast drivers of economic growth, job creation, and cultural influence.

Building upon the digital groundwork covered in the preceding analysis of this chapter, Korea has cemented the sustainability of its cultural media through the

### *Creative Industry Strategies in a Globalized and Digitized Media Landscape: The South Korean… DOI: http://dx.doi.org/10.5772/intechopen.112902*

successful implementation of a national creative industries strategy. The country's approach can be traced back to the 1990s when policymakers were first beginning to recognize the potential of exporting cultural content alongside more traditional goods, transforming its perception of cultural industries as something to be controlled to something that is central to its export-based national economy [51].

The country's industrial policies, which had propelled it to become a global leader in areas such as electronics and automobiles, were extended to nurture the growth of its creative sectors. Strategic subsidies and investments were made to foster innovation, talent development, and the marketing of Korean cultural products. In terms of policy implementation, Korea struck a balance between providing an enabling environment for creative industries to thrive and avoiding excessive micromanagement of the marketplace [4]. This point is particularly crucial if it is to be acknowledged that public policy has as much capacity to stifle the growth of creative industries as it does to boost them. Freedom of expression is also a key component of cultural development, as exemplified by the early success of K-pop, which was seen as non-threatening by Korea's military regime and thus allowed to express and develop organically [51].

During Park Geun-hye's inaugural address in 2013, the newly elected President defined the creative economy as the "convergence of science and technology with industry, the fusion of culture with industry, and the blossoming of creativity in the very borders that were once permeated by barriers [52]". Referring back to the opening remarks of this section which made the case that Hallyu cannot be traced back to any singular policy or corporate framework, the significance of this definition of the creative economy is the recognition of a much wider ecosystem, in which business, technology, policy, and industry must support the entire ecosystem, as opposed to favoring one part of the ecosystem over another.

Shain Shapiro, founder and executive Director of the Center for Music Ecosystems, reflects this sentiment by making the case that K-pop is the result of "an intentional, top-down and bottom-up strategy that aligned a number of collective interests—fostering investment, promoting tourism, educational advancement and soft power. Over time, it infiltrated more than the music economy, becoming what it is now and that combined, structured approach is what supported that to happen, through patience, direct investment and content [4]".

The approach taken by Korea in nurturing its creative industries has not gone unnoticed. Other countries, such as Thailand, Mexico, Zimbabwe, Belize, and the Philippines, have been inspired to develop their own national strategies for fostering creative sectors while harnessing emerging technologies. UNESCO has also recognized the importance of national creative industries strategies and has provided a template that focuses on areas such as human capital, business models, and financing [4]. It is crucial to note however, that Korea's cumulative approach took decades of persistence and gradual growth to bear fruit, and thus the challenges faced by these countries is likely related to the viability of sustaining the necessary human, political, and financial investment in these endeavors over the long-term, particularly given the fickle nature of political and economic agendas.

## **4.3 Prioritizing people-first policies**

Despite the multifaceted success of Korea's digital revolution in joining forces with its cultural rejuvenation strategy, the outcomes of this transformation as a whole should not be mistaken for some kind of digital utopia. Invasions of privacy, digital

addiction, online bullying, social isolation, and public divisiveness are just some of the negative/unintended consequences of digitalization that countries across the world are increasingly grappling with. These issues have inevitably become particularly prominent in Korea [20]. However, what the digital-cultural convergence analyzed throughout this chapter does suggest is that the potentials of emerging technologies are most positively harnessed when intentional, forward-thinking, and bold strategies are in place that are centered around user experience and collaboration—particularly in ways that integrate and enhance core aspects of social life, rather than neglecting them to be left behind in the technological march forward. These lessons are significant not just for countries seeking to replicate Korea's success, but for Korea itself as it confronts the growing sociopolitical and sociocultural challenges of inequality, underemployment, falling birth rates, and an increasingly fragile geopolitical environment.


*Article* **Chemical, Physical, and Mechanical Properties of 95-Year-Old Concrete Built-In Arch Bridge**

**Andrzej Ambroziak \* , Elzbieta Haustein ˙ and Maciej Niedostatkiewicz**

Faculty of Civil and Environmental Engineering, Gdansk University of Technology, 11/12 Gabriela Narutowicza Street, 80-233 Gda ´nsk, Poland<EMAIL_ADDRESS>(E.H<EMAIL_ADDRESS>(M.N.) **\*** Correspondence<EMAIL_ADDRESS>Tel.: +48-(58)-347-2447

**Abstract:** This research aimed to determine the durability and strength of an old concrete builtin arch bridge based on selected mechanical, physical, and chemical properties of the concrete. The bridge was erected in 1925 and is located in Jagodnik (northern Poland). Cylindrical specimens were taken from the side ribs connected to the top plate using a concrete core borehole diamond drill machine. The properties of the old concrete were compared with the present and previous standard requirements and guidelines. The laboratory testing program consisted of the following set of tests: measurements of the depth of carbonated zone and dry density, water absorption tests, determination of concrete compressive strength and frost resistance, determination of modulus of elasticity, measurement of the pH value, determination of water-soluble chloride salt and sulfate ion content, and X-ray diffraction analyses. Large variations in the cylindrical compressive strength (14.9 to 22.0 MPa), modulus of elasticity (17,900 to 26,483 MPa), density (2064 to 2231 kg/m3 ), and water absorption (3.88 to 6.58%) were observed. In addition to the experiments, a brief literature survey relating to old concrete properties was also conducted. This paper can provide scientists, engineers, and designers an experimental basis in the field of old concrete built-in bridge construction.

**Keywords:** structural concrete; reinforced concrete; bridge engineering; material characterization; mechanical properties; chemical properties

**1. Introduction**

Since the second half of the 19th century when reinforced concrete was invented, there has been a rapid development of this composite material, which is made up of a combination of steel and concrete [1]. Reinforced concrete is a material used in the construction of a wide range of civil and engineering structures. Due to concrete degradation, high traffic, and the impact of high load, old concrete and reinforced concrete bridges or other types of structures require improvement, repair, and reconstruction. Before taking any action and starting the design process, it is necessary to form an expert opinion by carrying out a detailed examination and laboratory tests of the construction materials used in the old structure. In several cases, it is necessary to incorporate the scientific and engineering community to evaluate the performance of old structures. In the literature, it is possible to find many interesting descriptions related to the process of testing and repairing old concrete structures. Hellebois et al. [2,3] performed an investigation on hardened concrete samples removed from a narrow-gauge railway viaduct (Colo-Hugues viaduct) built in Belgium in 1904. Mechanical and durability performance of the 100-year-old hardened concrete samples were found to be remarkably good. Sena-Cruz et al. [4] described historical, geometrical, and damage surveys of a reinforced concrete bridge built in 1907 (the Luiz Bandeira bridge). Selected structural material properties were also determined, e.g., the strength class was found to be greater than C30/37 and the average modulus of elasticity was 30 GPa. Wolert et al. [5] investigated an 11-span flat slab reinforced concrete bridge constructed between 1914 and 1916 that goes over Barnes Slough and Jenkins Creek

**Citation:** Ambroziak, A.; Haustein, E.; Niedostatkiewicz, M. Chemical, Physical, and Mechanical Properties of 95-Year-Old Concrete Built-In Arch Bridge. *Materials* **2021**, *14*, 20. https:// dx.doi.org/10.3390/ma14010020

Received: 29 November 2020 Accepted: 18 December 2020 Published: 23 December 2020

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/).

in the USA. The authors confirmed the overall good condition of the structure and its reserve flexural capacity. Onysyk et al. [6] described the strength of the reinforced concrete ribbed dome of Centennial Hall in Wrocław, Poland, which was built in 1911–1913. Gebauer and Harni [7] examined the composition and microstructure of the hydrated cement paste of an 84-year-old reinforced concrete bridge construction. Tests showed that the main hydration products were calcium hydroxide, fibrous calcium silicate hydrate incorporated frequently with calcium hydroxide into hexagonal plates, and calcium aluminate carbonate hydrate. Qazweeni and Daoud [8] studied the physical, mechanical, and chemical properties of a 20-year-old concrete structure in an office building. Blanco et al. [9] investigated the chemical reactions leading to the degradation of a 95-year-old concrete dam manufactured with sand–cement as a binder. Ambroziak et al. [10] determined the durability and strength of reinforced concrete continuous footing based on selected mechanical and chemical properties of a 70-year-old concrete structure in an office building. Melchers et al. [11] performed observations and analysis on a 63-year-old reinforced concrete promenade railing exposed to the harsh sea-spray environment of the North Sea in Arbroath, Scotland. Castro-Borges et al. [12] studied the physical and mechanical properties of a 60-year-old concrete pier with stainless steel reinforcement. The pier showed no visible sign of deterioration after 60 years of service. Sohail et al. [13] investigated the effects of concrete degradation in structural concrete elements in reinforced concrete structures built in the 1960s, 1970s, and 1980s in the Arabian Gulf region. The carbonation depth and chloride concentration profiles were determined from concrete core samples. Papé and Melchers [14] performed load tests on full-scale prestressed beams sampled from the 45-year-old Sorell Causeway bridge in Tasmania, Australia. The prestressing strands showed severe localized corrosion with cross-section losses between 75% and 100%. Dasar et al. [15] tested 40-year-old reinforced concrete beams exposed to real marine environments for up to 20 years at Sakata Port, Japan. The deterioration and performance reduction were investigated, and a good correlation was observed between the crack width and cross-section loss. Czaderski and Motavalli [16] performed experimental investigations on a full-scale concrete bridge girder strengthened with prestressed carbon fiber-reinforced polymer (CFRP) plates obtained from the Viadotto delle Cantine a Capolago bridge, which was constructed in 1964–1966. Usage of the gradient method for anchorage of prestressed CFRP plates on large-scale girders was confirmed. Pettigrew et al. [17] carried out experiments on 48-year-old concrete bridge girders fabricated using lightweight concrete after the decommissioning of a bridge in the USA. The designed flexural capacities were overestimated by an average of 34.0% compared to the values measured in laboratory tests. Khan et al. [18] tested reinforced concrete beams corroded by 26 years of exposure to a chloride environment. The corrosion had a significant impact on the load-carrying capacity, stiffness, and deflection of the beams. Prassianakis and Giokas [19] determined the mechanical properties of 28-year-old concrete using destructive and ultrasonic nondestructive testing methods. Chen [20] studied the dynamic mechanical properties of 10-year-old concrete exposed to high temperatures. Zhu et al. [21] studied the durability and mechanical properties of a 10-year-old crumb rubber concrete bridge deck. The investigation concluded that the deck was in good condition. Kou and Poon [22] investigated the mechanical properties of five-year-old concrete prepared with 0, 20, 50, and 100% recycled aggregates used as replacements of natural aggregates. Dasar et al. [23] studied the applicability of seawater as a mixing and curing agent in four-year-old mortar cement. The laboratory tests indicated that the effect of seawater on corrosion activity was considerably higher as a curing agent than as a mixing agent. Many engineering and scientific studies investigating the mechanical, chemical, and/or physical properties of built structures take into consideration the subject of old concrete. A proper assessment of the properties of old concrete helps determine the range of repair or reconstruction required as well as the load capacity of the investigated structure, which is needed for ensuring extended working life and the safe use of old facilities.

The present study aimed to determine selected mechanical, physical, and chemical properties of a 95-year-old concrete arch bridge. Cylindrical specimens were taken from the

side ribs connected to the top plate using a concrete core borehole diamond drill machine. The drilling locations were selected based on their availability and limited interference to the bridge structure. The investigation presented in this study can be treated as part of expert opinion on the bearing capacity of the arch bridge in order to determine the possibility of the bridge carrying additional loads and help extend its working life. This paper provides scientists, engineers, and designers an experimental assessment of the mechanical, physical, and chemical properties of 95-year-old concrete. the side ribs connected to the top plate using a concrete core borehole diamond drill machine. The drilling locations were selected based on their availability and limited interference to the bridge structure. The investigation presented in this study can be treated as part of expert opinion on the bearing capacity of the arch bridge in order to determine the possibility of the bridge carrying additional loads and help extend its working life. This paper provides scientists, engineers, and designers an experimental assessment of the mechanical, physical, and chemical properties of 95-year-old concrete.

reconstruction required as well as the load capacity of the investigated structure, which is

The present study aimed to determine selected mechanical, physical, and chemical properties of a 95-year-old concrete arch bridge. Cylindrical specimens were taken from

needed for ensuring extended working life and the safe use of old facilities.

*Materials* **2021**, *14*, x FOR PEER REVIEW 3 of 17

### **2. Materials and Methods 2. Materials and Methods**

The arch bridge investigated in this study is located above a forest canyon and the Kumiel river (watercourse) (see Figure 1). The structure of the center span bridge (about 12.95 m) is a reinforced concrete slab, monolithically connected to reinforced concrete shields supported on a plate arch. The arch bridge was built in 1925 in Jagodnik (Poland) by Karl Metzger & Co. building company (see p. 181 in [24], where a photo of the investigated arch bridge is inserted). In 1925, Jagodnik (Berendshagen) was part of the district of Elbing in Germany (present-day Elbl ˛ag in Poland). The arch bridge was erected under the guidelines of the German Committee for Structural Concrete issued in January 1916 [25] for structural use of concrete, design, and construction. This guideline was in force until September 1925, when the German standard DIN 1045 [26] was introduced. The arch bridge investigated in this study is located above a forest canyon and the Kumiel river (watercourse) (see Figure 1). The structure of the center span bridge (about 12.95 m) is a reinforced concrete slab, monolithically connected to reinforced concrete shields supported on a plate arch. The arch bridge was built in 1925 in Jagodnik (Poland) by Karl Metzger & Co. building company (see p. 181 in [24], where a photo of the investigated arch bridge is inserted). In 1925, Jagodnik (Berendshagen) was part of the district of Elbing in Germany (present-day Elbląg in Poland). The arch bridge was erected under the guidelines of the German Committee for Structural Concrete issued in January 1916 [25] for structural use of concrete, design, and construction. This guideline was in force until September 1925, when the German standard DIN 1045 [26] was introduced.

**Figure 1.** Jagodnik arch bridge before (**a**) and after (**b**) reconstruction. **Figure 1.** Jagodnik arch bridge before (**a**) and after (**b**) reconstruction.

Laboratory tests were carried out to determine the chemical, physical, and mechanical properties of old concrete. For this purpose, concrete specimens were taken from structural elements of the bridge, namely the side ribs connected to the top plate, using a concrete core borehole diamond drill machine. The thickness of the reinforced concrete side ribs was approximately 15 cm. Cylindrical specimens were taken from five different side ribs connected to the top plate using a concrete core borehole diamond drill machine. The spacing between the side ribs was approximately 2 m. The samples were marked as location number\_specimen number (e.g., 1\_2, 5\_1, etc.). These denotations were used for all laboratory tests. Laboratory tests were carried out to determine the chemical, physical, and mechanical properties of old concrete. For this purpose, concrete specimens were taken from structural elements of the bridge, namely the side ribs connected to the top plate, using a concrete core borehole diamond drill machine. The thickness of the reinforced concrete side ribs was approximately 15 cm. Cylindrical specimens were taken from five different side ribs connected to the top plate using a concrete core borehole diamond drill machine. The spacing between the side ribs was approximately 2 m. The samples were marked as location number\_specimen number (e.g., 1\_2, 5\_1, etc.). These denotations were used for all laboratory tests.

Two types of cylindrical samples were prepared for mechanical tests from the exploratory bore holes: Two types of cylindrical samples were prepared for mechanical tests from the exploratory bore holes:

The dimensions of the concrete cores for concrete compressive strength tests were determined according to the standard EN 12504-1 [27], with the preferred length/diameter ratio of 1.0. The strength results determined for the concrete cores *f* c,cycl 100 were comparable to the cube strength *f* c,cube of 15 × 15 × 15 cm concrete specimens (i.e., *f* c,cube = *f* c,cycl 100). The ASTM C469M standard [28] states that the ratio between the specimen length *L* and the dimension *D* should be greater than 1.50; thus, the concrete cores for the determination of the modulus of elasticity was taken as *L*/*D* = 1.5. In laboratory tests, the application of a greater diameter and/or greater length to core diameter ratio (e.g., *L*/*D* = 2 as in the ASTM C31 standard [29]) is often impossible for old concrete structures [10].

Selected chemical, physical, and mechanical properties of the 95-year-old concrete built-in arch bridge were investigated using laboratory tests. The laboratory testing program consisted of the following sets of tests.

### *2.1. Measurements of the Depth of Carbonated Zone*

The depth of the carbonated zone was measured with phenolphthalein solution. Freshly fractured surfaces of old concrete were submitted under an alcoholic solution of phenolphthalein, which immediately reacted, turning to pink/purple color, indicating the presence of calcium hydroxide, except at the thin, already carbonated external layers.

### *2.2. Measurements of Dry Density*

The method specified in the EN 12390-7 standard [30] was applied for determining the density of the 95-year-old concrete. The tested specimens were dried in a ventilated oven at 105 ± 5 ◦C until the mass changed by less than 0.2%. Before weighing, each specimen was cooled to near room temperature in a dry, airtight vessel.

## *2.3. Tests of Water Absorption*

Water absorption tests were carried out following EN 13369, Annex G [31]. To measure the water uptake capacity of concrete samples, the specimens were soaked in drinking water to a constant mass and then oven-dried in a ventilated drying oven at 105 ± 5 ◦C to a constant mass.

### *2.4. Determination of Concrete Compressive Strength and Frost Resistance*

Uniaxial compressive tests were undertaken using a computer-controlled mechanical testing machine with a constant rate of loading and a range of 0.6 MPa/s according to the EN 12390-3 standard [32]. The frost resistance of the old concrete was determined according to guidelines given by the PN-B-06250 standard [33]. A freezing chamber with a temperature- and time-controlled refrigerating and heating system was used. The freezer cycle consisted of freezing at −18 ± 2 ◦C for 4 h and thawing by total immersion in water at 18 ± 2 ◦C for 4 h.

## *2.5. Determination of Modulus of Elasticity*

The ASTM C469M standard [28] guideline was used to determine the modulus of elasticity. Diamond-drilled concrete cores with a length to diameter ratio of 1.50 were used in a compressometer device to measure the static modulus of elasticity.

### *2.6. Measurement of the pH Value and Determination of Water-Soluble Chloride Salts (Cl*−*) and Sulfate Ions (SO4 2*−*)*

The pH was measured according to ISO 10523 [34]. The extract with water-soluble sulfate ions and chloride ions were specified according to EN 1744-1 + A1 standard [35]. The extract with chloride ions was determined in accordance with the Volhard method. The concentration of water-soluble chloride salts and sulfate ions as well as the pH of the test samples were measured after dissolving a given amount of mass of crushed concrete in distilled water. After filtration through a mixed cellulose ester (MCE) membrane filter with a pore size of 45 µm, the obtained filtrates were tested.

### *2.7. X-ray Diffraction (XRD) Analyses*

The microstructure of the cross sections of samples was studied using a JEOL JSM-7800F (Akishima, Tokyo, Japan) scanning electron microscope (SEM) equipped with an

energy-dispersive X-ray spectrometer (EDAX, Octane Elite, Mahwah, NJ, USA), which allowed the element composition of the tested samples to be identified. The acceleration voltage in the X-ray tube for surface analysis of samples was 15 kV. The X-ray beam current was 5 nm. Observations were carried out to identify different phases of the microstructure. 7800F (Akishima, Tokyo, Japan) scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDAX, Octane Elite, Mahwah, NJ, USA), which allowed the element composition of the tested samples to be identified. The acceleration voltage in the X-ray tube for surface analysis of samples was 15 kV. The X-ray beam current was 5 nm. Observations were carried out to identify different phases of the

*Materials* **2021**, *14*, x FOR PEER REVIEW 5 of 17

with a pore size of 45 μm, the obtained filtrates were tested.

*2.7. X-ray Diffraction (XRD) Analyses*

The concentration of water-soluble chloride salts and sulfate ions as well as the pH of the test samples were measured after dissolving a given amount of mass of crushed concrete in distilled water. After filtration through a mixed cellulose ester (MCE) membrane filter

The microstructure of the cross sections of samples was studied using a JEOL JSM-

### **3. Results and Discussion** microstructure.

### *3.1. Measurements of Depth of Carbonated Zone* **3. Results and Discussion**

The chemical reaction of calcium hydroxide dissolved in pore water with atmospheric carbon dioxide (conversion into calcium carbonate, which is then mainly calcite [36]) is called carbonation of concrete. Carbon dioxide in the air penetrates into concrete and diminishes the pH value and also causes shrinkage in the concrete [37]. The depth of the carbonated zone measured with the phenolphthalein solution is illustrated in Figure 2. Freshly fractured surfaces of all specimens reacted with the alcoholic solution of phenolphthalein, immediately turning to pink/purple color, indicating the presence of calcium hydroxide, except at the thin, already carbonated external layers. Large variations in depth of the carbonated zone was observed in the investigated specimens of old concrete, ranging approximately 20 to 55 mm (see Table 1). The average depth of carbonation of the old concrete was 36 ± 2 mm. The result of the mean value is presented as the sum of mean values and standard error of the mean of the specified range. *3.1. Measurements of Depth of Carbonated Zone*  The chemical reaction of calcium hydroxide dissolved in pore water with atmospheric carbon dioxide (conversion into calcium carbonate, which is then mainly calcite [36]) is called carbonation of concrete. Carbon dioxide in the air penetrates into concrete and diminishes the pH value and also causes shrinkage in the concrete [37]. The depth of the carbonated zone measured with the phenolphthalein solution is illustrated in Figure 2. Freshly fractured surfaces of all specimens reacted with the alcoholic solution of phenolphthalein, immediately turning to pink/purple color, indicating the presence of calcium hydroxide, except at the thin, already carbonated external layers. Large variations in depth of the carbonated zone was observed in the investigated specimens of old concrete, ranging approximately 20 to 55 mm (see Table 1). The average depth of carbonation of the old concrete was 36 ± 2 mm. The result of the mean value is presented as the sum of mean values and standard error of the mean of the specified range.

(**b**)

**Figure 2.** Depth of carbonated zone: (**a**) about 5 cm; (**b**) about 2.5 cm. **Figure 2.** Depth of carbonated zone: (**a**) about 5 cm; (**b**) about 2.5 cm.

**Table 1.** Measurements of depth of carbonated zone.

*3.2. Measurements of Dry Density and Water Absorption Tests*

The dry density is one of the important parameters determined for concrete. Concrete is a mixture, and its density depends on its ingredients and their proportions. The mean dry density value specified in laboratory tests was 2175 ± 7 kg/m3 (see Table 2). The dry density ranged from 2000 to 2600 kg/m3 ; thus, according to the EN 206 standard [38], the investigated old concrete could be categorized as normal concrete. The mean dry density value also fulfilled conditions for normal-weight concrete according to the ACI 318-19 standard [39] (density between 2160 and 2560 kg/m3 ).

**Table 2.** Dry density and water absorption.

The laboratory tests determined water absorption of the old concrete as ranging from 3.88 to 6.58% (see Table 2). The mean value of water absorption was 5.84 ± 0.11%. According to the PN-88/B-06250 standard [33] guidelines, water absorption should not be greater than 5% for concrete exposed to atmospheric conditions and not greater than 9% for concrete protected from atmospheric conditions. PN-S-10040 [40] states that the water absorption of concrete used in bridge structures should not be greater than 5%. The mean water absorption values in our study were greater than 5%; thus, according to the International Federation for Structural Concrete (fib) report [41], the concrete quality could be categorized as poor quality.

### *3.3. Concrete Compressive Strength, Frost Resistance, and Modulus of Elasticity*

Uniaxial compressive experimental tests were carried out using the Advantest 9 C300KN mechanical testing machine. Experiments were performed on the failure of the concrete cylinder specimens (see Figure 3). The uniaxial tensile test results of compressive strength for cylindrical samples *f* c,cycl 100 is presented in Table 3. The mean value of compressive strength of cylindrical samples *f* c,cycl 100 was 18.8 ± 0.7 MPa. The strength results of the cylindrical samples *f* c,cycl 100 with length/diameter ratio of 1.0 were comparable to the cube strength *f* c,cube of 15 × 15 × 15 cm concrete specimens according to the EN 12504-1 standard [27], i.e., *f* c,cycl 100 = *f* c,cube = 18.8 ± 0.7 MPa. The variation in compressive strength

values of the 95-year-old concrete (see Table 3) can be explained by the production technology, which was probably based on portable concrete mixers with handmade proportions of concrete components. Portland cement was used as a binder in ordinary old concrete mixes. It should be noted that the new cementitious materials, e.g., geopolymer concrete (called alkali-activated materials, see e.g., [42–46]), have higher compressive strength and better durability compared to concrete mixes containing Portland cement. technology, which was probably based on portable concrete mixers with handmade proportions of concrete components. Portland cement was used as a binder in ordinary old concrete mixes. It should be noted that the new cementitious materials, e.g., geopolymer concrete (called alkali-activated materials, see e.g., [42**–**46]), have higher compressive strength and better durability compared to concrete mixes containing Portland cement.

concrete cylinder specimens (see Figure 3). The uniaxial tensile test results of compressive strength for cylindrical samples *f*c,cycl 100 is presented in Table 3. The mean value of compressive strength of cylindrical samples *f*c,cycl 100 was 18.8 ± 0.7 MPa. The strength results of the cylindrical samples *f*c,cycl 100 with length/diameter ratio of 1.0 were comparable to the cube strength *f*c,cube of 15 × 15 × 15 cm concrete specimens according to the EN 12504- 1 standard [27], i.e., *f*c,cycl 100 = *f*c,cube = 18.8 ± 0.7 MPa. The variation in compressive strength values of the 95-year-old concrete (see Table 3) can be explained by the production

*Materials* **2021**, *14*, x FOR PEER REVIEW 8 of 17

**Figure 3.** Concrete specimens after uniaxial compressive tests: (**a**,**b**) views of the form of failure. **Figure 3.** Concrete specimens after uniaxial compressive tests: (**a**,**b**) views of the form of failure.

**Table 3.** Concrete compressive strength. **Table 3.** Concrete compressive strength.

With regard to evaluation of freezing resistance, according to the PN-B-06250 standard [33], the compressive strength should not decrease by more than 20% in comparison to the base samples and the specimens should not show cracks [47]. In this study, we started the test by saturating the concrete samples with water. Then, 10 concrete samples were placed in a freezing chamber with a temperature- and time-controlled refrigerating and heating system (see Figure 4). The concrete samples were placed in the freezer compartment with a minimum 20 mm gap. A total of 50 freezer cycles were carried out consisting of freezing at −18 ± 2 °C for 4 h and thawing by total immersion in water at 18 ± 2 °C for 4 h. After the last defrosting, a strength test was carried out. The frost With regard to evaluation of freezing resistance, according to the PN-B-06250 standard [33], the compressive strength should not decrease by more than 20% in comparison to the base samples and the specimens should not show cracks [47]. In this study, we started the test by saturating the concrete samples with water. Then, 10 concrete samples were placed in a freezing chamber with a temperature- and time-controlled refrigerating and heating system (see Figure 4). The concrete samples were placed in the freezer compartment with a minimum 20 mm gap. A total of 50 freezer cycles were carried out consisting of freezing at −18 ± 2 ◦C for 4 h and thawing by total immersion in water at 18 ± 2 ◦C for 4 h. After the last defrosting, a strength test was carried out. The frost resistance assessment was based on measuring the change in compressive strength. The mean value of compressive strength of the cylindrical samples after 50 freezer cycles *f* 50 freezer cycles c,cycl 100 was 17.9 ± 1.0 MPa, which was about 5% lower than the compressive strength of cylindrical samples *f* c,cycl 100 without freezing (base samples). The difference between compressive strength *f* c,cycl 100 and *f* 50 freezer cycles c,cycl 100 was small (<20% according to PN-B-06250 [33]); therefore, it could be stated that the 95-year-old concrete possessed freezing resistance.

resistance assessment was based on measuring the change in compressive strength. The mean value of compressive strength of the cylindrical samples after 50 freezer cycles

c,cycl 100 *f* was 17.9 ± 1.0 MPa, which was about 5% lower than the compressive strength of cylindrical samples *f*c,cycl 100 without freezing (base samples). The difference between

[33]); therefore, it could be stated that the 95-year-old concrete possessed freezing

c,cycl 100 *f* was small (<20% according to PN-B-06250

**Figure 4.** Frost resistance tests: (**a**) view of freezing chamber; (**b**) view of concrete specimens inside the freezing chamber. **Figure 4.** Frost resistance tests: (**a**) view of freezing chamber; (**b**) view of concrete specimens inside the freezing chamber.

The two moduli of elasticity of applicable customary working stress ranged from 0 to 40% (*E*0.0**–**0.4) and from 10 to 30% (*E*0.1**–**0.3) were specified. Seven cylindrical specimens with a length/diameter ratio of 1.5 were stored and tested at room temperature (approximately 20 °C) in air-dry conditions. According to the laboratory tests, the modulus of elasticity ranged from 17.9 to 27 GPa for *E*0.0**–**0.4 and from 20 to 27 GPa for *E*0.1**–** 0.3 (see Table 4). The mean values of the modulus of elasticity were 22,890 ± 1320 MPa for *E*0.0**–**0.4 and 22,730 ± 890 MPa for *E*0.1**–**0.3. The difference between the mean values of modulus of elasticity for *E*0.0**–**0.4 and *E*0.1**–**0.3 was very small (less than 1%). It should be noted that the EN 1992-1-1 standard [48] defines the modulus of elasticity as a secant value of 0 to 40% of the ultimate strength for concrete with quartzite aggregates. A limit of 10**–**30% should be used for limestone and sandstone aggregates. The ASTM C469M standard [28] also indicates 40% ultimate load to calculate modulus of elasticity. On the other hand, 30% of the ultimate strength is required in the ISO 1920-10 standard [49]. The two moduli of elasticity of applicable customary working stress ranged from 0 to 40% (*E*0.0–0.4) and from 10 to 30% (*E*0.1–0.3) were specified. Seven cylindrical specimens with a length/diameter ratio of 1.5 were stored and tested at room temperature (approximately 20 ◦C) in air-dry conditions. According to the laboratory tests, the modulus of elasticity ranged from 17.9 to 27 GPa for *E*0.0–0.4 and from 20 to 27 GPa for *E*0.1–0.3 (see Table 4). The mean values of the modulus of elasticity were 22,890 ± 1320 MPa for *E*0.0–0.4 and 22,730 ± 890 MPa for *E*0.1–0.3. The difference between the mean values of modulus of elasticity for *E*0.0–0.4 and *E*0.1–0.3 was very small (less than 1%). It should be noted that the EN 1992-1-1 standard [48] defines the modulus of elasticity as a secant value of 0 to 40% of the ultimate strength for concrete with quartzite aggregates. A limit of 10–30% should be used for limestone and sandstone aggregates. The ASTM C469M standard [28] also indicates 40% ultimate load to calculate modulus of elasticity. On the other hand, 30% of the ultimate strength is required in the ISO 1920-10 standard [49].

**Table 4.** Modulus of elasticity. **Table 4.** Modulus of elasticity.

50freezer cycles

resistance.

compressive strength *f*c,cycl 100 and 50freezer cycles

Hallauer [50] indicated that Hennebique seems to recommend a mixture consisting either of 1 part cement, 2 parts sand, and 4 parts gravel or 1 part cement, 3 parts sand, and 5 parts gravel (aggregate mix: sand: 0/7 mm, gravel: 7/70 mm, stone grit: 7/25 mm, stone chip: 25/70). Forecast compressive strength was about 15**–**18 MPa after 28 days and 18**–** 24.5 MPa after 45 days. Note that the decrease in strength with the same cement content Hallauer [50] indicated that Hennebique seems to recommend a mixture consisting either of 1 part cement, 2 parts sand, and 4 parts gravel or 1 part cement, 3 parts sand, and 5 parts gravel (aggregate mix: sand: 0/7 mm, gravel: 7/70 mm, stone grit: 7/25 mm, stone chip: 25/70). Forecast compressive strength was about 15–18 MPa after 28 days and 18–24.5 MPa after 45 days. Note that the decrease in strength with the same cement content was due to the addition of water. The old Polish PN-B-195 standard [51] specified concrete strength equal to 0 (zero) MPa to emphasize that the amount of water should be limited and controlled in the concrete mix. The present guidelines on concrete standards state the requirements for water to cement ratio without mentioning zero-strength concrete. Wolert et al. [5] obtained compressive test results varying from 12.1 to 23.0 MPa for core samples cut out from an 11-span flat slab reinforced concrete bridge constructed between 1914 and 1916. Our laboratory tests determined the mean compressive strength of the 95-year-old concrete built-in arch bridge as *f* c,cycl 100 = 18.8 MPa, which is similar to concrete

structures build during this time period. The 95-year-old concrete also had frost resistance (after 50 freezer cycles, the compressive strength decreased only 5% to *f* 50 freezer cycles c,cycl 100 = 17.9 MPa). However, the compressive strength of old concrete construction sometimes varies and exhibits a wide range of compressive strengths [10]. Hellebois and Espion [3] investigated 107-year-old concrete samples taken from the Colo-Hugues viaduct, which was designed and built in 1904 in Belgium, and found different compressive strengths: 54.2 MPa for the slab, 33.3 MPa for beams, and 19.7 MPa for the column. Variation in the compressive strength of concrete is related to the type of aggregates and cement applied in concrete mixes [52] and is also affected by environmental conditions during the placement process of concrete mixes [53].

The characteristic in-situ compressive cube strength *f* ck,is,cube can be estimated according to the EN 13791 standard [54] as follows:

$$f\_{\text{ck,is,cube}} = \min \left\{ \begin{array}{l} f\_{\text{m(n),is}} - k\_{\text{n}} \cdot s \\ f\_{\text{is,lowest}} - M \end{array} \right\} = \min \left\{ \begin{array}{l} 18.8 - 1.96 \cdot 0.7 \\ 14.9 + 2 \end{array} \right\} = \min \left\{ \begin{array}{l} 17.43 \\ 16.9 \end{array} \right\} = 16.9 \text{ MPa} \tag{1}$$

where *f* m(n),is is the mean in-situ compressive strength of *n* test results (in the present investigation, *n* = 9), *f* is,lowest is the lowest in-situ compressive strength test results, *k*n is the factor that depends on the number of test results (*k*n = 1.96 for *n* = 9 test results, see Table 6 in EN 13791 [54]), *s* is the standard deviation of in-situ compressive strength, and *M* is the value of margin (*M* = 2, see Table 7 in the EN 13791 standard [54]). The characteristic in-situ cube compressive strength *f* ck,is,cube = 16.9 MPa; thus, the C12/15 compressive strength class according to the EN 206 [38] and EN 13791 [54] standards could be specified. The secant modulus of elasticity for the C12/15 concrete strength class specified in the EN 1992-2 standard [48] is 27,000 MPa. The mean modulus of elasticity *E*0.0–0.4 determined by laboratory tests (see Table 4) was 22,890 MPa, which was about 15% lower than that specified in the EN 1992-2 standard [48] for design of new concrete structures. However, it should be noted that the modulus of elasticity depends not only on the strength class but also on the types and properties of the aggregates used to prepare concrete mixes. For the design of new concrete bridge structures, the EN 1992-2 standard [55] recommends the application of minimum strength classes not less than C30/37. According to the EN 206 standard [38], the C30/37 compressive strength class should have a minimum characteristic cylinder strength (*f* ck,cyl) of 30 MPa (N/mm2 ) and cube strength (*f* ck,cube) of 37 MPa. The Polish standard PN-S-10042 [56] states that the C20/25 strength class may be applied for new foundations, supports, and retaining walls where the dimension of the structural elements are not less than 0.6 m thick, while the C25/30 strength class may be applied for new elements of supports and retaining walls less than 0.6 m thick and for reinforced concrete spans.

### *3.4. Chemical Properties*

The pH value and the content of water-soluble chloride salts (Cl−) and sulfate ions (SO4 2−) were determined using a chemical testing program. Samples for chemical analysis were taken from the cover layer (denotated as 1s, 2s, 3s, 4s, and 5s) and center layer (denotated as 1c, 2c, 3c, 4c, and 5c) of the 95-year-old concrete samples. The cover layer samples for chemical investigations were obtained by cutting approximately 2–2.5 cm cylindrical samples from the exploratory boreholes.

The mean value of the pH was 10.6 ± 0.4 for the cover layer (range from 9.47 to 11.68) and 12.29 ± 0.04 for the center layer of samples (range from 12.14 to 12.37) (see Tables 5 and 6). The pH value of the concrete pore solution decreased as carbonation proceeded. The pH value for freshly made concrete varies from 12.5 to 13.5 [57]. The pH value is one of the most useful factors (influencing the corrosion rate [58]) for specifying the ability of concrete to protect steel rebar by the formation of a passive film protecting reinforcement from corrosion [59]. The corrosion of rebar generally occurs when the pH

value is less than 9 (the passive film is not stable, see e.g., [60]). Despite the large depth of the carbonated zone (see Table 1), the pH of the old concrete was still in the safety range.

**Table 5.** pH values of concrete specimens and content of chloride ions and sulfate ions in concrete as a percentage of dry weight for the cover layer.

**Table 6.** pH values of concrete specimens and content of chloride ions and sulfate ions in concrete as a percentage of dry weight for the center layer.

The content of water-soluble chloride salts and sulfate ions was determined as a percentage of dry weight (see Tables 5 and 6). The water-soluble chloride salt values ranged from 0.012 to 0.036% dry weight for the cover layer and from 0.010 to 0.018% dry weight for the center layer of samples. The mean values of water-soluble chloride salt were 0.019 ± 0.004% and 0.014 ± 0.001% for the cover layer and the center layer, respectively. The sulfate ion values ranged from 0.127 to 0.670% dry weight for the cover layer and from 0.011 to 0.089% dry weight for the center layer of samples. The mean values of sulfate ions were 0.39 ± 0.11% and 0.031 ± 0.014% for the cover layer and the center layer, respectively.

In 1925, the cement content was usually set at 300 kg/m3 ; it could be 270 kg/m3 for buildings without the influence of moisture (see e.g., [50]). Assuming usage of 300 kg/m3 cement and specified dry density of 2175 kg/m3 (see Table 2), it was possible to convert the percentage content of chloride ions and sulfate ions by mass of cement (see Table 7). The chloride content of the concrete samples expressed as a percentage of chloride ions by mass of cement did not exceed 0.2 and 0.15%, which are limits for reinforced concrete stated by the EN 206 standard [38] and the ACI 318 code [61], respectively. The 95-year-old concrete built-in arch bridge was not exposed to chloride attack. A chloride content in concrete of over 0.2–0.3% of cement weight can be treated as being exposed to chloride attack.

**Table 7.** Mean content of chloride ions and sulfate ions in concrete as a percentage of mass of cement.

The mean percentage content of sulfate ions SO4 2− by mass of cement was 2.83 for the cover layer and 0.22 for the center layer of concrete samples (see Table 7). The concrete samples did not exceed 4%, which is the limit by mass of cement based on the total acidsoluble sulfate given by the BS 8110-1:1985 standard [62] (this guideline was excluded in

the new edition of the BS 8110-1 standard [63]). The low concentration of sulfate ions in the concrete samples indicated that the low contamination was due to external sources. the new edition of the BS 8110-1 standard [63]). The low concentration of sulfate ions in the concrete samples indicated that the low contamination was due to external sources.

*3.5. X-Ray Diffraction Analyses*

*Materials* **2021**, *14*, x FOR PEER REVIEW 12 of 17

**Layer Cl− (%) SO42− (%)**  Cover 0.14 2.83 Center 0.10 0.22

The mean percentage content of sulfate ions SO42− by mass of cement was 2.83 for the cover layer and 0.22 for the center layer of concrete samples (see Table 7). The concrete samples did not exceed 4%, which is the limit by mass of cement based on the total acidsoluble sulfate given by the BS 8110-1:1985 standard [62] (this guideline was excluded in

### *3.5. X-ray Diffraction Analyses*

Based on the specified chemical properties, samples from 1s and 1c concrete specimens were chosen for XRD analyses to assess the presence of crystalline compounds and identify them. For the tests, specimens measuring 10 × 10 × 10 mm were taken from the cover layer and the center layer (about 7.5 cm below the surface of the concrete) of the tested concrete element. Microstructure tests were carried out for four samples (two samples from the cover and two samples from the center layer of old concrete specimens). Element composition tests (EDS) were carried out for four samples (three samples from the cover and three samples from a depth of about 7.5 cm below the surface). The results of the microstructure (SEM images) and element composition of the tested samples are shown in Figures 5 and 6. Based on the specified chemical properties, samples from 1s and 1c concrete specimens were chosen for XRD analyses to assess the presence of crystalline compounds and identify them. For the tests, specimens measuring 10 × 10 × 10 mm were taken from the cover layer and the center layer (about 7.5 cm below the surface of the concrete) of the tested concrete element. Microstructure tests were carried out for four samples (two samples from the cover and two samples from the center layer of old concrete specimens). Element composition tests (EDS) were carried out for four samples (three samples from the cover and three samples from a depth of about 7.5 cm below the surface). The results of the microstructure (SEM images) and element composition of the tested samples are shown in Figures 5 and 6.

(**a**) (**b**)

Si (silica) and Ca (calcium) (see Figure 7). The content of these elements for samples taken from the cover layer was 29.4 to 34.7% for silica and 54.1 to 57.5% for calcium. For the

to 60% for calcium. The content of other elements, such as Al, Fe, Mg, K, and Na, was

**Figure 7.** Energy-dispersion X-ray spectrometer (EDS) spectra of samples taken from the (**a**) cover

**Table 8.** Element compositions of samples taken from the cover layer of the concrete structure as

**Type of Element Sample 1 Sample 2 Sample 3 Mean (%)**  Mg 1.2 1.0 1.4 1.2 Al 4.8 5.0 6.2 5.3 Si 36.8 34.7 25.6 32.4 S 1.3 1.3 1.8 1.5

definitely lower compared to the Si and Ca content in all samples.

(**a**) (**b**)

*Materials* **2021**, *14*, x FOR PEER REVIEW 13 of 17

**Figure 5.** Scanning electron microscope (SEM) images of the samples taken from the cover layer of the concrete structure: (**a**) ×10,000; (**b**) ×5000. **Figure 5.** Scanning electron microscope (SEM) images of the samples taken from the cover layer of the concrete structure: (**a**) ×10,000; (**b**) ×5000.

**Figure 6.** SEM images of the samples taken from center layer of the concrete structure: (**a**) ×10,000; (**b**) ×5000. **Figure 6.** SEM images of the samples taken from center layer of the concrete structure: (**a**) ×10,000; (**b**) ×5000.

The results of element composition tests are presented in Tables 8 and 9. They indicated the dominance of two main elements in the microstructure of the tested samples: The results of element composition tests are presented in Tables 8 and 9. They indicated the dominance of two main elements in the microstructure of the tested samples: Si (silica)

layer; (**b**) center layer.

determined by EDS.

and Ca (calcium) (see Figure 7). The content of these elements for samples taken from the cover layer was 29.4 to 34.7% for silica and 54.1 to 57.5% for calcium. For the specimen samples taken from center layer, the content was 25.6 to 36.8% for silica and 51.6 to 60% for calcium. The content of other elements, such as Al, Fe, Mg, K, and Na, was definitely lower compared to the Si and Ca content in all samples.

**Table 8.** Element compositions of samples taken from the cover layer of the concrete structure as determined by EDS. *Materials* **2021**, *14*, x FOR PEER REVIEW 13 of 17

**Table 9.** Element compositions of samples taken from the center layer of the concrete structure as determined by EDS. (**a**) (**b**)

definitely lower compared to the Si and Ca content in all samples.

**Figure 7.** Energy-dispersion X-ray spectrometer (EDS) spectra of samples taken from the (**a**) cover layer; (**b**) center layer. **Figure 7.** Energy-dispersion X-ray spectrometer (EDS) spectra of samples taken from the (**a**) cover layer; (**b**) center layer.

**Table 8.** Element compositions of samples taken from the cover layer of the concrete structure as

Si 36.8 34.7 25.6 32.4 S 1.3 1.3 1.8 1.5

### **4. Conclusions**

determined by EDS. **Type of Element Sample 1 Sample 2 Sample 3 Mean (%)**  Mg 1.2 1.0 1.4 1.2 Al 4.8 5.0 6.2 5.3 The main objective of the present research was to determine the durability and strength of a 95 year-old concrete built-in arch bridge in Jagodnik (northern Poland) based on selected mechanical, physical, and chemical properties. Based on the experimental investigation, the following conclusions can be drawn:

The design team of the Jagodnik arch bridge made a decision on the possibility of reconstructing the 95-year-old arch bridge and designing it for car traffic to a limited tonnage. On top of the existing old structure, a new deck slab with pavement covers was made. The entire surface of the old concrete was protected with repair mortars.

Deterioration of old concrete due to corrosion is a serious problem. Proper assessment of the properties of old concrete is critical to make decisions regarding the reconstruction and repair of old concrete structures. Inappropriate or incorrect estimation of the properties of old concrete can have catastrophic consequences. Reconstruction and renovation of old civil and building structures often require incorporation of the scientific and engineering community in order to evaluate the performance of old structures and give them "new life" and extended service. The authors are hopeful that this investigation sparks interest among a wide group of engineers and scientists to take into consideration the subject of old concrete structures.

**Author Contributions:** Conceptualization, A.A.; methodology, A.A.; validation, A.A. and E.H.; formal analysis, A.A.; investigation, A.A. and E.H.; resources, A.A.; data curation, A.A. and E.H.; writing—original draft preparation, A.A., E.H., and M.N.; writing—review and editing, A.A.; visualization, A.A. and E.H.; supervision, A.A.; project administration, A.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** All laboratory test results (data) are included in Tables 1–9 in the present paper. No new data were created or analyzed in this study. Data sharing is not applicable to this article.

**Conflicts of Interest:** The authors declare no conflict of interest.

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