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23 pages, 5585 KiB

Open AccessArticle

Application of Composite Bars in Wooden, Full-Scale, Innovative Engineering Products—Experimental and Numerical Study

by Agnieszka Wdowiak-Postulak, Grzegorz Świt and Ilona Dziedzic-Jagocka

Materials 2024, 17(3), 730; https://doi.org/10.3390/ma17030730 - 3 Feb 2024

Cited by 2 | Viewed by 1400

Abstract

The commercialization of modular timber products as cost-effective and lightweight components has resulted in innovative engineering products, e.g., glued laminated timber, laminated veneer lumber, I-beams, cross-laminated timber and solid timber joined with wedge joints. With the passage of time, timber structures can deteriorate, [...] Read more.

The commercialization of modular timber products as cost-effective and lightweight components has resulted in innovative engineering products, e.g., glued laminated timber, laminated veneer lumber, I-beams, cross-laminated timber and solid timber joined with wedge joints. With the passage of time, timber structures can deteriorate, or new structural elements are required to increase the stiffness or load-bearing capacity in newly built structures, e.g., lintels over large-scale glazing or garages, or to reduce cross-sectional dimensions or save costly timber material while still achieving low weight. It is in such cases that repair or correct reinforcement is required. In this experimental and numerical study, the static performance of flexural timber beams reinforced with prestressed basalt BFRP, glass GFRP and hybrid glass–basalt fiber bars is shown. The experimental tests resulted in an increase in the load-carrying capacity of BFRP (44%), GFRP (33%) and hybrid bars (43%) and an increase in the stiffness of BFRP (28%), GFRP (24%) and hybrid bars (25%). In addition to this, glued laminated timber beams reinforced with prestressed basalt rods subjected to biological degradation, 7 years of weathering and prolonged exposure to various environmental conditions were examined, and an increase in the load-bearing capacity of 27% and an increase in stiffness of 28% were obtained. In addition, full-size laminated timber beams reinforced with prestressed basalt bars were investigated in the field as an exploratory test under fire conditions at elevated temperatures, and the effect of the physical–mechanical properties during the fire was examined via an analysis of these properties after the fire. In addition, a satisfactory correlation of the numerical simulations with the experimental studies was obtained. The differences were between 1.1% and 5.5%. The concordance was due to the fact that, in this study, the Young, Poisson and shear moduli were determined for all quality classes of sawn timber. Only a significant difference resulted in the numerical analysis for the beams exposed to fire under fire conditions. The experimental, theoretical and numerical analyses in this research were exploratory and will be expanded as directions for future research. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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14 pages, 7474 KiB

Open AccessArticle

Structural Characteristics and Cementitious Behavior of Magnesium Slag in Comparison with Granulated Blast Furnace Slag

by Ping Lu, Yueqi Zhao, Na Zhang, Yidi Wang, Jiale Zhang, Yihe Zhang and Xiaoming Liu

Materials 2024, 17(2), 360; https://doi.org/10.3390/ma17020360 - 11 Jan 2024

Viewed by 1407

Abstract

Magnesium slag is a type of industrial solid waste produced during the production of magnesium metal. In order to gain a deeper understanding of the structure of magnesium slag, the composition and microstructure of magnesium slag were investigated by using characterization methods such [...] Read more.

Magnesium slag is a type of industrial solid waste produced during the production of magnesium metal. In order to gain a deeper understanding of the structure of magnesium slag, the composition and microstructure of magnesium slag were investigated by using characterization methods such as X-ray fluorescence, particle size analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. In addition, the state of Si occurrence in magnesium slag was analyzed using a solid-state nuclear magnetic resonance technique in comparison with granulated blast furnace slag. An inductively coupled plasma-optical emission spectrometer and scanning electron microscope with energy dispersive X-ray spectroscopy were used to characterize their cementitious behavior. The results show that the chemical composition of magnesium slag mainly includes 54.71% CaO, 28.66% SiO₂ and 11.82% MgO, and the content of Al₂O₃ is much lower than that of granulated blast furnace slag. Compared to granulated blast furnace slag, magnesium slag has a larger relative bridging oxygen number and higher [SiO₄] polymerization degree. The cementitious activity of magnesium slag is lower compared to that of granulated blast furnace slag, but it can replace part of the cement to obtain higher compressive strength. Maximum compressive strength can be obtained when the amount of magnesium slag replacing cement is 20%, where the 28-day compressive strength can be up to 45.48 MPa. This work provides a relatively comprehensive analysis of the structural characteristics and cementitious behavior of magnesium slag, which is conducive to the promotion of magnesium slag utilization. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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22 pages, 4482 KiB

Open AccessArticle

Diagnostics of Large-Panel Buildings—An Attempt to Reduce the Number of Destructive Tests

by Maciej Wardach and Janusz Ryszard Krentowski

Materials 2024, 17(1), 18; https://doi.org/10.3390/ma17010018 - 20 Dec 2023

Viewed by 944

Abstract

Structural condition diagnostics provides the basis for decision making regarding the possibility of continued safe operation, necessary reinforcement, repair work, and in extreme cases, dismantling of the structure. The most reliable results concerning the condition and strength of materials are provided by destructive [...] Read more.

Structural condition diagnostics provides the basis for decision making regarding the possibility of continued safe operation, necessary reinforcement, repair work, and in extreme cases, dismantling of the structure. The most reliable results concerning the condition and strength of materials are provided by destructive testing. However, these tests are very time-consuming, costly, and difficult to perform on in-service facilities. In addition, they involve the need to obtain the consent of the occupants of the premises and subsequent renovations. This article focuses on presenting an opportunity to reduce the number of destructive tests necessary to reliably assess the condition of large-panel structures, which constitute a significant housing stock in Europe. Based on tests carried out on a real building, the risk factors associated with obtaining reliable results by non-destructive methods were determined. Areas where destructive testing is necessary were identified. In addition, reference was made to standard recommendations and guidelines from a reputable research institution. Practical guidelines were formulated regarding the diagnostics of large-panel structures, resulting in a reduction in the number of destructive tests required. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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15 pages, 5369 KiB

Open AccessArticle

Experiments on the Dynamic Behavior of Curved Glass Panes Subjected to Low-Velocity Impact

by Marcin Kozłowski and Kinga Zemła

Materials 2023, 16(23), 7335; https://doi.org/10.3390/ma16237335 - 25 Nov 2023

Viewed by 766

Abstract

Curved glass enables designers to achieve unparalleled innovation in creating modern and undulating shapes for building enclosures. However, the curvature of panes changes the static and especially the dynamic behavior of the panes under loading. Studies on low-velocity impacts on curved glass have [...] Read more.

Curved glass enables designers to achieve unparalleled innovation in creating modern and undulating shapes for building enclosures. However, the curvature of panes changes the static and especially the dynamic behavior of the panes under loading. Studies on low-velocity impacts on curved glass have been limited and have primarily involved numerical studies. This paper experimentally investigates the dynamic response of cylindrically curved glass panes under a low-velocity impact. A flat, 5 mm thick, single-pane geometry with three curvature radii and the lack or presence of movement restraint is considered. Special attention is also paid to the variations caused by impacting bodies involving different stiffness, mass, and geometry parameters. It was found that flat plates have a lower capacity to dampen oscillations, resulting in longer decay times compared to curved panes. For impactors with a lower stiffness, the glass panes experience uneven oscillations at the moment of impact, followed by a chaotic period of transient vibrations before reaching a stationary state. This contrasts bodies with greater deformability in which the main dynamic behavior follows a more predictable pattern. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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20 pages, 44362 KiB

Open AccessArticle

Experimental Investigation on Strength and Stiffness Properties of Laminated Veneer Lumber (LVL)

by Alfredo Romero and Christoph Odenbreit

Materials 2023, 16(22), 7194; https://doi.org/10.3390/ma16227194 - 16 Nov 2023

Cited by 7 | Viewed by 2042

Abstract

This study presents a testing campaign aimed at evaluating the strength and stiffness properties of laminated veneer lumber (LVL) specimens. LVL is an engineered wood product composed of thin glued wood veneers whose use in construction for structural applications has increased due to [...] Read more.

This study presents a testing campaign aimed at evaluating the strength and stiffness properties of laminated veneer lumber (LVL) specimens. LVL is an engineered wood product composed of thin glued wood veneers whose use in construction for structural applications has increased due to its sustainability and enhanced mechanical performance. Despite LVL’s growing popularity, there is a lack of comprehensive information regarding stress–strain responses, failure modes, and the full set of strength and stiffness properties. These are particularly essential when LVL is employed in pure timber structures or composite systems such as steel–timber or timber–concrete load-bearing elements. This research aims to bridge this knowledge gap, focusing on crossbanded LVL panels, known as LVL-C, crafted from Scandinavian spruce wood, which is an LVL product with 20% of crossbanded veneers. The study explores LVL-C mechanical behavior in three primary orthogonal directions: longitudinal, tangential, and radial. A series of mechanical tests, including compression, tension, shear, and bending, was conducted to provide a thorough assessment of the material’s performance. In compression tests, different behaviors were observed in the three directions, with the longitudinal direction exhibiting the highest stiffness and strength. Tensile tests revealed unique stress–strain responses in each direction, with gradual tension failures. Shear tests showcased varying shear stress–strain patterns and failure modes, while bending tests exhibited significant strength and stiffness values in flatwise bending parallel to the grain and flatwise bending perpendicular to the grain. This paper summarizes the comprehensive testing results and discusses the obtained strength and stiffness properties of LVL-C panels, providing valuable insights into their mechanical behavior for engineering applications. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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16 pages, 2326 KiB

Open AccessArticle

The Multi-Objective Optimization Design and Hydrothermal Performance Evaluation of Anhydrous Calcium Sulfate Whisker and Polyester Fiber Compound Modified Asphalt Mixture in Hot-Humid Areas

by Taotao Fan, Qiuping Song, Chundi Si and Songkai Han

Materials 2023, 16(20), 6662; https://doi.org/10.3390/ma16206662 - 12 Oct 2023

Cited by 1 | Viewed by 859

Abstract

In hot and humid climates, asphalt pavements frequently encounter environmental factors such as elevated temperatures and rainfall, leading to rutting deformations and potholes, which can affect pavement performance. The primary objective of this study was to enhance the hydrothermal characteristics of asphalt mixtures [...] Read more.

In hot and humid climates, asphalt pavements frequently encounter environmental factors such as elevated temperatures and rainfall, leading to rutting deformations and potholes, which can affect pavement performance. The primary objective of this study was to enhance the hydrothermal characteristics of asphalt mixtures through an investigation into the impact of anhydrous calcium sulfate whisker (ACSW) and polyester fiber (PF) on the hydrothermal properties of asphalt mixtures. In this paper, a central composite concatenation design (CCC) was employed to determine the optimal combination of ACSW and PF contents, as well as the asphalt aggregate ratio (AAR). Each influencing factor was assigned three levels for analysis. The evaluation indexes included dynamic stability, retained Marshall stability, and tensile strength ratio. Using the analysis methods of variance and gray correlation degree analysis, the hydrothermal properties of the asphalt mixture were examined in relation to the contents of ACSW, PF, and AAR based on the CCC results. Consequently, the optimal mix design parameters for composite modified asphalt mixture incorporating ACSW and PF were determined. The results indicated that the asphalt mixtures with hydrothermal qualities exhibited optimal performance in terms of 4.1% ARR, 11.84% ACSW, and 0.4% PF. The interaction between AAR and ACSW content had a greater effect on the dynamic stability and tensile strength ratio of the asphalt mixture, whereas the incorporation of ACSW and PF had a greater effect on the retained Marshall stability of the asphalt mixture. Among the three contributing factors, AAR exhibited the strongest relationship with the hydrothermal characteristics of the asphalt mixture, followed by the ACSW content; the correlation of PF content was the lowest. Therefore, to enhance the hydrothermal characteristics of the asphalt mixture, it is important to conduct a full evaluation of the constituents of ACSW and PF, along with the AAR in hot–humid regions. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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23 pages, 8913 KiB

Open AccessArticle

Eco-Friendly Sustainable Concrete and Mortar Using Coal Dust Waste

by Evgenii M. Shcherban’, Sergey A. Stel’makh, Alexey N. Beskopylny, Levon R. Mailyan, Besarion Meskhi, Diana Elshaeva, Andrei Chernil’nik, Alexander L. Mailyan and Oxana Ananova

Materials 2023, 16(19), 6604; https://doi.org/10.3390/ma16196604 - 9 Oct 2023

Cited by 6 | Viewed by 2098

Abstract

Finding the solution to the problem of the accumulating waste from the mining and processing industries, as well as reducing their carbon footprint, is among the most important tasks today. Within the construction industry, in the field of the production of building materials [...] Read more.

Finding the solution to the problem of the accumulating waste from the mining and processing industries, as well as reducing their carbon footprint, is among the most important tasks today. Within the construction industry, in the field of the production of building materials such as concrete, these problems may be solved through the use of waste and by saving the binder component. The purpose of this study is to substantiate the feasibility of using waste coal dust (CD) in concrete and cement–sand mortars as a partial replacement for cement. Test samples were made by partially replacing cement with CD in an amount from 0% to 10% in increments of 2% by weight. The following main characteristics were studied: mobility and density of mixtures, as well as density, compressive strength, bending strength and water absorption of concrete and mortars. X-ray diffraction and microscopic analysis methods were used in this work. The introduction of CD to replace part of the cement, up to 10%, did not have a significant effect on the density of concrete and mortar mixtures but reduced their workability. The best values of physical and mechanical characteristics were recorded for concrete and mortar with 4% CD. The increases in the compressive strength of concrete and mortars were 6.6% and 5.7%, and in flexural strength 6.1% and 5.6%, respectively. Water absorption decreased by 9.7% for concrete and by 9.3% for mortar. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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17 pages, 8070 KiB

Open AccessArticle

Stiffness of Experimentally Tested Horizontally Loaded Walls and Timber-Framed Modular Building

by Czesław Miedziałowski, Krzysztof Robert Czech, Marta Nazarczuk, Marta Kosior-Kazberuk and Anna Żakowicz

Materials 2023, 16(18), 6229; https://doi.org/10.3390/ma16186229 - 15 Sep 2023

Cited by 1 | Viewed by 925

Abstract

This paper presents an overview of representative up-to-date research and the authors’ own experimental results from tests of wall elements and a horizontally loaded timber-framed modular building. The research has been conducted in connection with the development of timber-based structures in recent years. [...] Read more.

This paper presents an overview of representative up-to-date research and the authors’ own experimental results from tests of wall elements and a horizontally loaded timber-framed modular building. The research has been conducted in connection with the development of timber-based structures in recent years. In the present research, wall elements and modules of timber-frame construction with life-size dimensions were used. So far, these types of structures have mainly been tested in laboratories—especially with regard to anchoring and cyclic loading. An experimental testing was carried out on a natural scale in two stages based on the standard procedure described in EN 594. In the first stage, wall panels were tested. In the second stage, tests were carried out on a complete four-storey building. Dowel fasteners were used to fix the sheathing to the load-bearing wall structures. Additionally, the sheathing was glued to the timber frame of the walls. The same type of wall element was used for the construction of the tested building. Horizontal loads were applied at the height of the top of the walls in both stages. The building loads were applied in a direction perpendicular to the longitudinal axis of the modules. Based on test data, the stiffnesses of the wall panels and the whole building were derived, as well as the type of interaction between the modules and the influence of the walls on the spatial work of the building. On the basis of the conducted studies, both the stiffness of the walls in different configurations and the stiffness of the complete building were determined, as well as the nature of the interaction of neighbouring modules and the influence of wall connections on the 3D working of the building. The results show that the stiffness of the building in the horizontal plane in the direction of the applied load is almost twice as high as the sum of the stiffnesses of the building walls in the same direction. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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12 pages, 10681 KiB

Open AccessArticle

Influence of Fire Exposition of Fibre-Cement Boards on Their Microstructure

by Krzysztof Schabowicz, Tomasz Gorzelańczyk, Łukasz Zawiślak and Filip Chyliński

Materials 2023, 16(18), 6153; https://doi.org/10.3390/ma16186153 - 10 Sep 2023

Cited by 1 | Viewed by 1352

Abstract

The diagnostics of materials, elements and structures after fire exposure are very complicated. Researchers carrying out such diagnostics encounter difficulties at the very beginning, e.g., how to map fire conditions. In this publication, the authors focused on the analysis of the fibre-cement composite [...] Read more.

The diagnostics of materials, elements and structures after fire exposure are very complicated. Researchers carrying out such diagnostics encounter difficulties at the very beginning, e.g., how to map fire conditions. In this publication, the authors focused on the analysis of the fibre-cement composite used as facade cladding. The fibre-cement boards are construction products used in civil engineering. The fibre-cement boards are characterised by two phases: the matrix phase and the dispersed phase. The analysis of fibre-cement composite was performed using non-destructive methods. The use of non-destructive methods in the future will allow for the analysis of facades after fires without the need to obtain large elements, which will significantly reduce costs while increasing safety. The aim of the work was to determine internal changes in the microstructure of fibre-cement boards after exposure to fire. The degraded samples were compared with reference samples in the evaluation of the microstructure. An analysis was performed using a scanning electron microscope, images of backscattered electrons (BSE) and maps obtained using Energy Dispersive X-ray Spectroscopy (EDX), which allowed conclusions to be drawn. The observed changes were presented in the form of photos showing changes in the composition of the plates, and they were commented on. It should be noted that fire temperatures act destructively, and a number of changes can be observed in the microstructure. The results of the work indicate that, in the future, the use of non-destructive methods will make it possible to assess the degree of degradation of the façade after a fire. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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36 pages, 8094 KiB

Open AccessArticle

Computational Complexity and Its Influence on Predictive Capabilities of Machine Learning Models for Concrete Mix Design

by Patryk Ziolkowski

Materials 2023, 16(17), 5956; https://doi.org/10.3390/ma16175956 - 30 Aug 2023

Cited by 5 | Viewed by 1693

Abstract

The design of concrete mixtures is crucial in concrete technology, aiming to produce concrete that meets specific quality and performance criteria. Modern standards require not only strength but also eco-friendliness and production efficiency. Based on the Three Equation Method, conventional mix design methods [...] Read more.

The design of concrete mixtures is crucial in concrete technology, aiming to produce concrete that meets specific quality and performance criteria. Modern standards require not only strength but also eco-friendliness and production efficiency. Based on the Three Equation Method, conventional mix design methods involve analytical and laboratory procedures but are insufficient for contemporary concrete technology, leading to overengineering and difficulty predicting concrete properties. Machine learning-based methods offer a solution, as they have proven effective in predicting concrete compressive strength for concrete mix design. This paper scrutinises the association between the computational complexity of machine learning models and their proficiency in predicting the compressive strength of concrete. This study evaluates five deep neural network models of varying computational complexity in three series. Each model is trained and tested in three series with a vast database of concrete mix recipes and associated destructive tests. The findings suggest a positive correlation between increased computational complexity and the model’s predictive ability. This correlation is evidenced by an increment in the coefficient of determination (R²) and a decrease in error metrics (mean squared error, Minkowski error, normalized squared error, root mean squared error, and sum squared error) as the complexity of the model increases. The research findings provide valuable insights for increasing the performance of concrete technical feature prediction models while acknowledging this study’s limitations and suggesting potential future research directions. This research paves the way for further refinement of AI-driven methods in concrete mix design, enhancing the efficiency and precision of the concrete mix design process. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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12 pages, 3699 KiB

Open AccessArticle

A Constitutive Model for Describing the Tensile Response of Woven Polyethylene Terephthalate Geogrids after Damage

by Giovani Lombardi, Margarida Pinho-Lopes, António Miguel Paula and António Bastos Pereira

Materials 2023, 16(15), 5384; https://doi.org/10.3390/ma16155384 - 31 Jul 2023

Viewed by 808

Abstract

A constitutive model was used to describe the tensile response of two woven Polyethylene Terephthalate (PET) geogrids, before and after mechanical damage. The model parameters of undamaged and damaged specimens were estimated via numerical regressions of test results. For each sample, the experimental [...] Read more.

A constitutive model was used to describe the tensile response of two woven Polyethylene Terephthalate (PET) geogrids, before and after mechanical damage. The model parameters of undamaged and damaged specimens were estimated via numerical regressions of test results. For each sample, the experimental and fitted tensile strengths were statistically compared using hypothesis tests. For each geogrid, tensile load–strain curves of damaged samples were drawn by applying scaling factors to the plot of the undamaged sample. The curve fittings resulted in high R² values for undamaged and damaged specimens of the geogrids. For most samples, there was no significant mean difference between the experimental and fitted tensile strength. The model allowed us to describe the load–strain curve of a geogrid from its tensile properties: ε_max, T_max and J_i. Regardless of the type of damage (in laboratory or in situ), the model was able to describe the load–strain curves of damaged samples using data from undamaged samples and scaling factors. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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14 pages, 2448 KiB

Open AccessArticle

Effect of Vibration Procedure on Particle Distribution of Cement Paste

by Jia Ke, Zhonghe Shui, Xu Gao, Xibo Qi, Zihang Zheng and Shaolin Zhang

Materials 2023, 16(7), 2600; https://doi.org/10.3390/ma16072600 - 24 Mar 2023

Cited by 2 | Viewed by 1171

Abstract

Vibration procedures significantly affect the performances of cement-based materials. However, studies on the distribution of certain particles within cement-based materials are limited due to the complexity and difficulty of identifying each specific particle. This paper presents a new method for simulating and quantifying [...] Read more.

Vibration procedures significantly affect the performances of cement-based materials. However, studies on the distribution of certain particles within cement-based materials are limited due to the complexity and difficulty of identifying each specific particle. This paper presents a new method for simulating and quantifying the movements of particles within cement paste through the use of “tagged materials”. By separating the tagged particles from the cement paste after vibration, the distribution of the particles in the cement paste can be calculated statistically. The effect of the vibration time and frequency, fresh behavior, and powder characteristics of cement paste on particle motions are investigated. The results demonstrate that when the vibration exceeds 1800 s, it induces a significant uneven dispersion of microparticles. This effect is more pronounced at low viscosities (<1 Pa·s) of cement paste or high vibration frequencies (>200 Hz). Larger and denser particles exhibit greater dispersion. This method provides a valuable tool for investigating the theory of particle motion in cement paste, which is crucial for understanding the influence of vibration on the properties of cement-based materials. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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14 pages, 2842 KiB

Open AccessArticle

Long-Term Prestress Loss Calculation Considering the Interaction of Concrete Shrinkage, Concrete Creep, and Stress Relaxation

by Weiwei Han, Panpan Tian, Yigang Lv, Chaosheng Zou and Tao Liu

Materials 2023, 16(6), 2452; https://doi.org/10.3390/ma16062452 - 19 Mar 2023

Cited by 3 | Viewed by 3143

Abstract

In order to accurately calculate the long-term prestress losses of prestressed tendons, a time-varying model of long-term prestress loss considering the interaction between concrete shrinkage, creep, and the stress relaxation of prestressed tendons was constructed. Then, a method for calculating the long-term prestress [...] Read more.

In order to accurately calculate the long-term prestress losses of prestressed tendons, a time-varying model of long-term prestress loss considering the interaction between concrete shrinkage, creep, and the stress relaxation of prestressed tendons was constructed. Then, a method for calculating the long-term prestress losses of concrete structures was developed. A long-term prestress loss test of a prestressed concrete T-beam in a long-term field test environment was carried out. The measured values of long-term prestress losses are compared with the calculated results of JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model. The results show that the long-term effective tension of the T-beam decreases gradually with the increase in the load holding time. At the beginning of loading, the tensile force changes rapidly and then gradually slows down. The later the tensile age or the higher the initial loading stress level, the smaller the long-term prestress losses of the prestressed tendons. The long-term prestress loss values calculated by JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model increase with the increase in the load holding time. In the early stage of loading, the rate of change slows down and tends to be stable. The calculated results of JTG 3362-2018 and AASHTO LRFD-2007 are significantly different from the measured values. However, the calculated results of the time-varying law model are in good agreement with the measured values. The average coefficients of variation of the long-term prestress loss calculated by JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model are 17%, 10%, and 5%, respectively. The time-varying law model of the long-term prestress losses of prestressed tendons is accurate, and the long-term prestress loss of prestressed reinforcement can be predicted effectively. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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19 pages, 14353 KiB

Open AccessArticle

Modelling of Resinous Material Filling Expansion Joints in Reinforced Concrete Structures

by Krzysztof Schabowicz, Grzegorz Waśniewski and Krzysztof Wróblewski

Materials 2023, 16(5), 2011; https://doi.org/10.3390/ma16052011 - 28 Feb 2023

Viewed by 1285

Abstract

This paper is a continuation of the research and analysis to estimate hyperelastic material constants when only uniaxial test data are available. The FEM simulation was expanded and the results obtained from three-dimensional and plane strain expansion joint models were compared and discussed. [...] Read more.

This paper is a continuation of the research and analysis to estimate hyperelastic material constants when only uniaxial test data are available. The FEM simulation was expanded and the results obtained from three-dimensional and plane strain expansion joint models were compared and discussed. The original tests were carried out for a gap with a width of 10 mm, whereas in the case of axial stretching, the stresses and internal forces caused by the leading deformations were recorded for a smaller gap, and the axial compression was also recorded. The differences in the global response between the three- and two-dimensional models were also considered. Finally, using FEM simulations, the values of stresses and cross-sectional forces in the filling material were determined, which can be the basis for the design of expansion joints geometry. The results of these analyses could form the basis of guidelines for the design of expansion joint gaps filled with material, ensuring the waterproofing of the joint. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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20 pages, 8024 KiB

Open AccessArticle

Dynamic Diagnostic Tests and Numerical Analysis of the Foundations for Turbine Sets

by Jerzy Szolomicki, Grzegorz Dmochowski and Maciej Roskosz

Materials 2023, 16(4), 1421; https://doi.org/10.3390/ma16041421 - 8 Feb 2023

Viewed by 1447

Abstract

This paper shows current trends in testing and numerical analysis of dynamic loading in relation to a real frame foundation for a turbogenerator set. The analysis of the machine’s foundations, which are subjected to static and dynamic loads, is a complex problem combining [...] Read more.

This paper shows current trends in testing and numerical analysis of dynamic loading in relation to a real frame foundation for a turbogenerator set. The analysis of the machine’s foundations, which are subjected to static and dynamic loads, is a complex problem combining the issues of geotechnics, structural engineering, and vibration theory. The authors present a case study of the assessment of the foundation’s technical condition. The main objective of this study is to perform and compare experimental and numerical dynamic analysis which includes the measurement of the acceleration, speed, and amplitude of the natural vibrations of the foundation during the operational speed of the turbogenerator. In addition, auxiliary material tests were carried out to fully diagnose the foundation and obtain the material properties required for the numerical analysis. They included both destructive and non-destructive of concrete strength, the evaluation of the degree of its carbonation, and the scanning of the reinforcement distribution. The research presented in the paper is intended to facilitate the preparation of appropriate data for the design of the foundation renovation and strengthening. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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Review

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14 pages, 2296 KiB

Open AccessReview

Advanced Geopolymer-Based Composites for Antimicrobial Application

by Gabriel Furtos, Doina Prodan, Codruta Sarosi, Marioara Moldovan, Michał Łach, Mykola Melnychuk and Kinga Korniejenko

Materials 2023, 16(23), 7414; https://doi.org/10.3390/ma16237414 - 29 Nov 2023

Viewed by 1204

Abstract

In most studies about geopolymeric materials used in construction, the antibacterial properties of the building materials are treated as secondary features. Today, antimicrobial properties are a key feature in many building applications. The main objective of this article is to summarize the state-of-the-art [...] Read more.

In most studies about geopolymeric materials used in construction, the antibacterial properties of the building materials are treated as secondary features. Today, antimicrobial properties are a key feature in many building applications. The main objective of this article is to summarize the state-of-the-art in the area of design, development, and applications of nanoparticles as additives to geopolymer composites used in construction to improve their physical mechanical properties and induce a potential antibacterial effect, protecting them against alkali-resistant bacteria. On the basis of the literature and authors’ experience, the most important methods of obtaining especially the porous geopolymers, of nanomaterials used as additives, with potential antibacterial effect but also the potential mechanism of action against bacterial development were presented. The main findings show that using graphene oxide (GO) in geopolymer composites, but also other nanoparticles such as silver (Ag), zinc oxide (ZnO), silica (SiO₂), titanium dioxide (TiO₂), copper (Cu) as additives, is an effective way to induce a potential antibacterial effect and to improve the physical and mechanical properties in building materials. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering (3rd Edition))

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