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2024

Jump to: 2023, 2022, 2021, 2020

19 pages, 9732 KiB

Open AccessArticle

Mechanical Properties and Stress–Strain Constitutive Relations of Coal-Fired Slag Concrete

by Jianpeng Zhang, Gang Li, Daidong Yu, Yingdong Lei and Yonghua Zhang

Buildings 2024, 14(10), 3103; https://doi.org/10.3390/buildings14103103 - 27 Sep 2024

Viewed by 373

Abstract

In this study, we conducted a single-factor experiment where fine aggregates in each mixture were replaced with coal-fired slag at replacement rates in the range of 0–100%. We investigated the effect of slag substitution rate on the cubic compressive strength, splitting tensile strength, [...] Read more.

In this study, we conducted a single-factor experiment where fine aggregates in each mixture were replaced with coal-fired slag at replacement rates in the range of 0–100%. We investigated the effect of slag substitution rate on the cubic compressive strength, splitting tensile strength, axial compressive strength, and static modulus of elasticity of slag concrete. Based on the experimental data, the stress–strain curve of the coal-fired slag concrete was divided into four phases: elastic, elasto-plastic, peak, and decline phases. A stress–strain constitutive equation was established to describe the coal-fired slag concrete. A replacement rate of 50% of the formulated coal-fired slag concrete meets the strength requirements of C60 structural applications, and the cubic compressive strength is the same as that of ordinary concrete. Coal-fired slag can be utilized in large quantities, improving the economic value of coal-fired slag and expanding the scope of application of slag concrete. Full article

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19 pages, 3175 KiB

Open AccessArticle

Reinforced Autoclaved Aerated Concrete: Structural Assessment and Retrofitting

by Luigi Di Sarno and Danah Albuhairi

Buildings 2024, 14(8), 2570; https://doi.org/10.3390/buildings14082570 - 20 Aug 2024

Viewed by 684

Abstract

The sudden collapse of a school roof in the UK brought widespread attention to the structural integrity of buildings constructed with reinforced autoclaved aerated concrete (RAAC), a material widely used from the 1950s to the mid-1990s. RAAC, known for its lightweight and insulating [...] Read more.

The sudden collapse of a school roof in the UK brought widespread attention to the structural integrity of buildings constructed with reinforced autoclaved aerated concrete (RAAC), a material widely used from the 1950s to the mid-1990s. RAAC, known for its lightweight and insulating properties, has been found to suffer from weak compressive strength, poor reinforcement anchorage, and high susceptibility to environmental degradation. The structural profiles of RAAC panels in the UK are unique, particularly in their reinforcement configurations and failure modes, which limits the applicability of the existing literature from other regions. This paper conducts a state-of-the-art review, identifying a significant gap in current research due to the unique challenges posed by RAAC in the UK, and highlights the need for novel methodologies. In response to this gap, the paper introduces a multi-criteria decision analysis (MCDA) framework utilising the decision-making trial and evaluation laboratory (DEMATEL) method to assess the interdependencies of RAAC defects. This methodology quantifies the influence of observed defects and guides the selection of appropriate remediation strategies, offering a more structured and objective approach to RAAC panel assessment and retrofitting. Practically, this study aligns with ongoing research efforts towards the digitalisation of RAAC management by integrating the MCDA model within digital asset management systems. This integration supports a holistic approach to addressing the RAAC crisis, enhancing current efforts to digitalise the surveying and management processes and ensuring safer long-term solutions. Full article

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29 pages, 13043 KiB

Open AccessArticle

Improving Mixed-Mode Fracture Properties of Concrete Reinforced with Macrosynthetic Plastic Fibers: An Experimental and Numerical Investigation

by Ali Permanoon, Majid Pouraminian, Nima Khorami, Sina GanjiMorad, Hojatallah Azarkhosh, Iman Sadrinejad and Somayyeh Pourbakhshian

Buildings 2024, 14(8), 2543; https://doi.org/10.3390/buildings14082543 - 18 Aug 2024

Viewed by 1158

Abstract

This article offers a comprehensive analysis of the impact of MSPF on concrete’s mechanical properties and fracture behavior. Combining findings from numerical simulations and laboratory experiments, our study validates numerical models against diverse fiber percentages and aggregate distributions, affirming their reliability. Key findings [...] Read more.

This article offers a comprehensive analysis of the impact of MSPF on concrete’s mechanical properties and fracture behavior. Combining findings from numerical simulations and laboratory experiments, our study validates numerical models against diverse fiber percentages and aggregate distributions, affirming their reliability. Key findings reveal that mixed-mode fracture scenarios in fiber-reinforced concrete are significantly influenced by the mode mixity parameter (M^e), quantifying the balance between mode I and mode II fracture components, ranging from 1 (pure mode I) to 0 (pure mode II). The introduction of the effective stress intensity factor (K_eff) provides a profound understanding of the material’s response to mixed-mode fracture. Our research demonstrates that as M^e approaches zero, indicating shear deformation dominance, the concrete’s resistance to mixed-mode fracture decreases. Crucially, the addition of MSPF considerably enhances mixed-mode fracture toughness, especially when Me ranges between 0.5 and 0.9, resulting in an approximately 400% increase in fracture toughness. However, beyond a specific threshold (approximately 4% FVF), diminishing returns occur due to reduced fiber–cement mortar bonding forces. We recommend an optimal fiber content of around 4% by weight of the total concrete mixture to avoid material distribution disruption and strength reduction. The practical implications of these findings suggest improved design strategies for more resilient infrastructure, particularly in earthquake-resistant constructions and sustainable urban development. These insights provide a valuable framework for future research and development in concrete technology. Full article

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24 pages, 8840 KiB

Open AccessArticle

Durability Requirements for Reinforced Concrete Structures Placed in a Hostile Tropical Coastal Environment

by Abel Castañeda Valdés, Francisco Corvo Pérez, Ildefonso Pech Pech, Rigoberto Marrero Águila and Emilio Bastidas-Arteaga

Buildings 2024, 14(8), 2494; https://doi.org/10.3390/buildings14082494 - 12 Aug 2024

Viewed by 783

Abstract

In this work, a series of durability requirements are proposed for the construction of long-service-life reinforced concrete (RC) structures in a coastal environment with extreme atmospheric corrosivity. RC specimens were exposed in a coastal outdoor site in Cuba for three years. Carbon steel [...] Read more.

In this work, a series of durability requirements are proposed for the construction of long-service-life reinforced concrete (RC) structures in a coastal environment with extreme atmospheric corrosivity. RC specimens were exposed in a coastal outdoor site in Cuba for three years. Carbon steel corrosion evaluation revealed an annual average atmospheric corrosion rate over the maximum limit established (ISO 9223:2012) for extreme (CX) atmospheric corrosivity. The service life of the RC structures, considered as the sum of the time-to-corrosion-initiation and time-to-corrosion-induced concrete cracking, was determined as a function of durability requirements. The most important durability requirements to achieve a long service life (>70 years) in RC structures subjected to a CX corrosivity category were defined as follows: water/cement ratio, compressive strength, percentage of effective capillary porosity, and concrete cover thickness. Under these hostile environments, the expansion of the corrosion products formed on the reinforcement steel and the induced cracking of the concrete could be attributed partially to the formation of the akaganeite phase in reinforcement steel, which revealed a different morphology compared to the akaganeite typically formed in bare carbon steels. Full article

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19 pages, 7611 KiB

Open AccessArticle

Optimizing Seismic Performance of Tuned Mass Dampers at Various Levels in Reinforced Concrete Buildings

by Hosein Naderpour, Asghar SoltaniMatin, Ali Kheyroddin, Pouyan Fakharian and Nima Ezami

Buildings 2024, 14(8), 2443; https://doi.org/10.3390/buildings14082443 - 8 Aug 2024

Viewed by 858

Abstract

This study aimed to rigorously evaluate the impact of tuned mass dampers (TMDs) on structural response under seismic excitation. By strategically placing TMDs at various levels within the structures, the research sought to determine their effectiveness in mitigating structural movement. A single-degree-of-freedom (SDOF) [...] Read more.

This study aimed to rigorously evaluate the impact of tuned mass dampers (TMDs) on structural response under seismic excitation. By strategically placing TMDs at various levels within the structures, the research sought to determine their effectiveness in mitigating structural movement. A single-degree-of-freedom (SDOF) system incorporating TMDs was utilized to model structures of 10, 13, and 16 stories, each configured with TMDs at different heights. The structures were subjected to near-fault earthquakes to assess the efficacy of TMDs in reducing structural response. The findings revealed significant enhancements in structural performance when TMDs were optimally positioned. Specifically, a 50% reduction in both acceleration and displacement, alongside a 65% decrease in maximum drift, underscored the effectiveness of TMD deployment. Furthermore, the study demonstrated that distributing multiple TMDs along the height of the structure provided superior drift control. Notably, positioning TMDs within the upper one-third of the structure yielded the most pronounced improvements in acceleration, displacement, and maximum drift. Finally, the research indicates that the strategic incorporation of TMDs can significantly enhance the seismic resilience of structures. The results highlight the substantial benefits of TMDs in optimizing acceleration, displacement, and drift, thereby affirming their critical role in seismic design and retrofitting strategies. Full article

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24 pages, 14838 KiB

Open AccessArticle

Preparation of Green Sustainable Cement Paste Mixture Based on Inorganic Additives: An Experimental and Modelling Approach

by Aamir Mahmood, Miroslava Pechočiaková, Muhammad Tayyab Noman, Stanisław Wacławek, Mohammad Gheibi, Kourosh Behzadian and Jiří Militký

Buildings 2024, 14(7), 1922; https://doi.org/10.3390/buildings14071922 - 23 Jun 2024

Viewed by 1077

Abstract

Using waste materials in the mixture of building materials is an approach aligned with the circular economy, a viewpoint that creates sustainable building industries, especially in developed countries. This study concentrated on the application of laponite (LAP), fly ash (FA), and bentonite (BENT) [...] Read more.

Using waste materials in the mixture of building materials is an approach aligned with the circular economy, a viewpoint that creates sustainable building industries, especially in developed countries. This study concentrated on the application of laponite (LAP), fly ash (FA), and bentonite (BENT) materials in the mixture of cement pastes. The first step used experimental practices to examine the metrics of toughness, three-point bending, and compressive strength with different percentages of added LAP, FA, and BENT after the characterization of samples by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The next step entailed assessment of cement paste specifications through some regressive equations obtained by the application of 2D curve fitting and sensitive analysis of additive (FA, LAP, and BENT) fluctuations in the structure of cement paste. The results show that linear polynomial equations are the best for the evaluation of cement paste terms as per different percentages of the additives. The environmental impact assessment (EIA) of nine prepared samples demonstrated that LAP created the safest condition in comparison to others. However, the ordered weighted averaging (OWA) computations applied for the sustainability assessment (SA) of the samples showed that the LAP is the most appropriate option for use in the structure of cement paste. Using experimental analysis and mathematical modeling, the behavior of cement paste interacting with mineral additives is evaluated. Sustainable mixtures are then presented based on EIA. Full article

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23 pages, 6206 KiB

Open AccessArticle

The In-Plane Seismic Response of Infilled Reinforced Concrete Frames Using a Strut Modelling Approach: Validation and Applications

by Abdelghaffar Messaoudi, Rachid Chebili, Hossameldeen Mohamed, André Furtado and Hugo Rodrigues

Buildings 2024, 14(7), 1902; https://doi.org/10.3390/buildings14071902 - 21 Jun 2024

Viewed by 781

Abstract

Reinforced Concrete (RC) buildings often rely on masonry walls to increase their rigidity and strength, distinguishing them from bare frames. Consequently, the lateral capacity of the RC frames is significantly impacted by the presence or absence of these walls. Numerical models are fundamental [...] Read more.

Reinforced Concrete (RC) buildings often rely on masonry walls to increase their rigidity and strength, distinguishing them from bare frames. Consequently, the lateral capacity of the RC frames is significantly impacted by the presence or absence of these walls. Numerical models are fundamental to understanding this behavior interaction, but the development of robust simplified models is still scarce. Based on this motivation, the reliability of a simplified numerical modelling approach was examined in this study and compared to several experimental tests. An optimized approach was implemented to determine the strut parameters, rather than relying on existing empirical formulae. The reliability of the initial stiffness, maximum strength, and energy dissipation was studied. From the results, the accuracy of the considered modelling strategy can be observed in different types of masonry elements (strong and weak units) with and without openings. The validated simulation approach reveals that the adopted macro-modelling procedure can accurately represent the behavior of infilled masonry frames. The maximum deviation of the prediction of the initial stiffness and maximum strength was found to be around 23% and 14%, respectively. These findings illustrate that the strut model effectively replicates real behavior with a satisfactory level of accuracy. However, using a consistent formula to define the strut can result in significant errors, particularly in strut width. Full article

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28 pages, 30608 KiB

Open AccessArticle

Cracking Methods for Testing of Self-Healing Concrete: An Experimental Approach

by João Miguel Peres Medeiros and Luigi Di Sarno

Buildings 2024, 14(6), 1744; https://doi.org/10.3390/buildings14061744 - 10 Jun 2024

Viewed by 1106

Abstract

With the advent of new sustainable construction materials, self-healing concrete has been used and tested in the last decade, raising the question of the efficacy of said mechanisms to prevent water permeation after crack formation. Thus, new novel mechanical methodologies have been introduced [...] Read more.

With the advent of new sustainable construction materials, self-healing concrete has been used and tested in the last decade, raising the question of the efficacy of said mechanisms to prevent water permeation after crack formation. Thus, new novel mechanical methodologies have been introduced to induce controlled cracks in concrete specimens to improve the standardisation and effectiveness of permeability tests. This research explores those new mechanical techniques to create consistent and reproducible crack patterns, crucial for assessing the efficacy of self-healing mechanisms in concrete. This study systematically evaluates how different crack configurations influence the self-healing ability of the material. Findings from this research are expected to aid in refining testing protocols and to contribute significantly to the field of material science within civil engineering by demonstrating the potential of self-healing concrete to revolutionise building practices. Full article

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15 pages, 6484 KiB

Open AccessArticle

A New Experimental Setup to Characterize Binder–Vegetal Particle Compatibility in Plant-Based Concrete

by Elodie Prud’Homme, Fabien Delhomme, Clara Julliot, Loïc Corvalan, Sofiane Amziane, Evelyne Toussaint and Sandrine Marceau

Buildings 2024, 14(4), 1000; https://doi.org/10.3390/buildings14041000 - 4 Apr 2024

Viewed by 1136

Abstract

The good insulation properties and the low carbon footprint of vegetal concretes make them promising materials whose use tends to grow continuously. To produce optimized building materials, a better understanding of the interfacial transition zone (ITZ) between vegetal particles and cement paste in [...] Read more.

The good insulation properties and the low carbon footprint of vegetal concretes make them promising materials whose use tends to grow continuously. To produce optimized building materials, a better understanding of the interfacial transition zone (ITZ) between vegetal particles and cement paste in terms of the reactions involved and the size of the impacted surface was investigated. This research led to the setting of a reliable visual test to observe ITZ, which enables the monitoring of its appearance and development. Different combinations of vegetal particles and cement pastes were tested to compare the formed ITZ: hemp, rapeseed, and bamboo into Portland and Prompt cement. Finally, a clear link was drawn between the sugar concentration and the size of ITZ. Thanks to image analysis, it was shown that ITZ is due to physico-chemical reactions, with the extraction of free saccharide molecules from the vegetal and water suction followed by their release into the cement paste. Full article

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18 pages, 10994 KiB

Open AccessArticle

The Impact of Plasticizers on the Nature of the Alkali-Silicate Corrosion in Cement Composites

by Andrey P. Pustovgar, Yury R. Krivoborodov, Aleksey O. Adamtsevich, Aurika A. Elenova, Kseniya A. Butenko, Dmitrii V. Kramerov and Anton M. Bugaev

Buildings 2024, 14(1), 172; https://doi.org/10.3390/buildings14010172 - 10 Jan 2024

Viewed by 1006

Abstract

This research work attempts to reveal the mechanism of alkali corrosion in cement composites in the presence of plasticizers based on polycarboxylates (PCE), naphtha-lene-formaldehydes (SPNF), and lignosulfonates by maintaining a high pH of the liquid phase and additionally containing monovalent alkali earth metals [...] Read more.

This research work attempts to reveal the mechanism of alkali corrosion in cement composites in the presence of plasticizers based on polycarboxylates (PCE), naphtha-lene-formaldehydes (SPNF), and lignosulfonates by maintaining a high pH of the liquid phase and additionally containing monovalent alkali earth metals in cement stone, as well as stopping this process by introducing an active mineral additive. ASR is studied by changing the relative strain with time according to ASTM C-1260. Deformation changes were confirmed by SEM and RFA studies of hydration products and ASR in the microstructure. Separate use of PCE plasticizers in the cement composition increases deformation by 50% to the 56th day; the use of SPNF increases deformation by 10% compared with the additive-free composition. The use of PLS reduces the relative deformation by 25%. The introduction of silica fume into cementitious composites containing plasticizers actually stops ASR only for a short time. A reduction in deformation during MC use together with plasticizer based on naphthalene sulfonate and polycarboxylate occurs only when the dosage of MS is increased to 20–30%; at a lower dosage, the effect is negative, which also affects the phase composition of the composites. The introduction of MC increases the value of the relative deformation compared with plasticizer compositions based only on PLS. SEM studies have detected microcracks and dense fine-crystalline silicate gel, which cause deformation changes in cement composite samples. Research has shown that concrete modified with SPNF and PCE at the maximum dosage of MC (30%) has minimal deformation rates and can be used to select optimal concrete compositions. The results of this study could help to minimize risks, prevent unacceptable expansion, and ensure the high quality of concrete and concrete products during their use as part of various nature-modifying additives. Full article

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2023

Jump to: 2024, 2022, 2021, 2020

20 pages, 5523 KiB

Open AccessArticle

Development and Performance Evaluation of UHPC and HPC Using Eco-Friendly Additions as Substitute Cementitious Materials with Low Cost

by Mohammed Qusay Abdul Sahib, Masood Farzam and Khalid A. Sukkar

Buildings 2023, 13(8), 2078; https://doi.org/10.3390/buildings13082078 - 16 Aug 2023

Cited by 3 | Viewed by 1717

Abstract

Ultra-high-performance concrete (UHPC) and high-performance concrete (HPC) are widely used in construction engineering applications. The quality and economy of this type of concrete are the main challenges in real construction systems due to their expensive cost. In the present investigation, the performances of [...] Read more.

Ultra-high-performance concrete (UHPC) and high-performance concrete (HPC) are widely used in construction engineering applications. The quality and economy of this type of concrete are the main challenges in real construction systems due to their expensive cost. In the present investigation, the performances of UHPC and HPC were improved using eco-friendly additives from natural sources or industrial wastes. Accordingly, different kinds of concrete mixtures were prepared with the addition of various eco-friendly materials, such as metakaolin (10, 15, and 20%), silica fume (2.5, 5, 10, and 15%), cement kiln dust (CKD) (0, 5, and 10%), and 1 vol.% of steel and polypropylene fibers. All of these materials were subjected to efficient treatment and purification processes. The results indicated that the prepared UHPC was characterized by high compression and flexural strengths. The prepared UHPC (sample CR-2) with metakaolin (10%), CKD (10%), and 1 vol.% of steel fibers provided the highest compressive strength of 135 MPa at 28 days. Moreover, the results showed that reducing the cement amounts to 750, 500, and 250 kg/m³ provided concrete with efficient structural requirements and specifications and can be characterized as UHPC and HPC. Also, the mixture (sample CM15) with a metakaolin addition of 15%, CKD of 100 kg/m³, and 1 vol.% of steel fibers showed the highest flexural strength of 19.14 MPa at 28 d. Moreover, the highest splitting tensile strength of the prepared UHPC cylinders was 9.6 MPa at 28 d for the MSS1000 sample, which consisted of 15% metakaolin, a cement content of 1000 kg/m³, silica fume of 10%, and steel fibers of 1% vol. The prepared UHPC mixtures will reduce the amount of consumed cement and the production cost, with a high performance in comparison to classical concrete. Finally, it was clear that the prepared UHPC and HPC concrete with green additions can serve efficiently in specific construction applications, with high performance, economic feasibility, and safe environmental impacts. Full article

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14 pages, 4188 KiB

Open AccessArticle

High-Strength Building Material Based on a Glass Concrete Binder Obtained by Mechanical Activation

by Sergey S. Dobrosmyslov, Vladimir E. Zadov, Rashit A. Nazirov, Veronika A. Shakirova, Anton S. Voronin, Michail M. Simunin, Yuri V. Fadeev, Maxim S. Molokeev, Ksenia A. Shabanova and Stanislav V. Khartov

Buildings 2023, 13(8), 1992; https://doi.org/10.3390/buildings13081992 - 4 Aug 2023

Viewed by 1904

Abstract

As part of the work, the chemical interaction of finely ground glass (~1 μm), calcium oxide, and water was studied. It is shown that an increase in the fineness of grinding makes it possible to abandon autoclave hardening in the production of products [...] Read more.

As part of the work, the chemical interaction of finely ground glass (~1 μm), calcium oxide, and water was studied. It is shown that an increase in the fineness of grinding makes it possible to abandon autoclave hardening in the production of products on a hydrosilicate binder. The study of chemical interaction was carried out by calculating the thermodynamic equilibrium and was also confirmed by XRD analysis. DTA analysis showed that an increase in the treatment temperature leads to an increase in the proportion of the reacted phase at the first stage. Subsequently, phase formation is associated with the presence of CaO. The carrier of strength characteristics is the CaO×2SiO₂×2H₂O phase. The selection and optimization of the composition make it possible to obtain a high-strength glass concrete material with a strength of about 110 MPa. The micrographs of the obtained samples correspond to classical hydrosilicate systems. Full article

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18 pages, 7854 KiB

Open AccessArticle

Properties and Behavior of Rubberized Concrete Enhanced with PVA Fibers

by Hany El Naggar and Ahmad M. Abu Abdo

Buildings 2023, 13(7), 1681; https://doi.org/10.3390/buildings13071681 - 30 Jun 2023

Cited by 1 | Viewed by 1095

Abstract

Due to growing populations, approximately one billion scrap tires are generated annually worldwide. This is a problem particularly in more developed countries where the per-head share of scrape tires is much higher than the global average. The adverse environmental impacts associated with landfilling [...] Read more.

Due to growing populations, approximately one billion scrap tires are generated annually worldwide. This is a problem particularly in more developed countries where the per-head share of scrape tires is much higher than the global average. The adverse environmental impacts associated with landfilling scrap tires made it imperative to promote eco-friendly solutions such as utilizing them in civil engineering applications. This paper explores the use of tire-derived aggregates (TDAs) with large particle sizes that require less energy to produce as a substitute for traditional aggregates in concrete production. A comprehensive experimental program was conducted to study the effects of the TDA content on the density, compressive strength, elastic modulus, strain at failure, splitting tensile strength, and flexural strength of rubberized concrete at 28 days. Furthermore, with the aim of improving the tensile and flexural properties of rubberized concrete, the use of polyvinyl alcohol (PVA) fibers was also investigated in this study. A total of 126 specimens, half of them containing PVA fibers, were prepared from fourteen different concrete mixtures with varying percentages of TDAs replacing coarse aggregates. Results indicate that a reasonable TDA content of less than 20% can be used to produce concrete with comparable or even superior properties for specific applications requiring moderate strength and higher deformability while reducing waste tires in landfills. In addition, adding 1% PVA fibers to the mixtures was found to enhance the specimens’ compressive, tensile, and flexural strengths and reduce the observed loss of strength rate in rubberized concrete, especially at higher TDA contents. Overall, this research suggests that TDAs can be a sustainable and cost-effective solution for applications that do not require great concrete compressive strength but a more accommodating plastic behavior. Full article

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23 pages, 7390 KiB

Open AccessArticle

Performance of Geopolymer Mortar Containing PVC Plastic Waste from Bottle Labels at Normal and Elevated Temperatures

by Ronnakrit Kunthawatwong, Ampol Wongsa, Jindarat Ekprasert, Piti Sukontasukkul, Vanchai Sata and Prinya Chindaprasirt

Buildings 2023, 13(4), 1031; https://doi.org/10.3390/buildings13041031 - 14 Apr 2023

Cited by 12 | Viewed by 2568

Abstract

This work focused on reusing polyvinyl chloride (PVC) plastic waste from bottle labels (BLWA) as lightweight aggregates in geopolymer mortar. This way of reusing plastic waste is beneficial for diminishing the negative impacts of plastics on the environment and reducing CO₂ emissions [...] Read more.

This work focused on reusing polyvinyl chloride (PVC) plastic waste from bottle labels (BLWA) as lightweight aggregates in geopolymer mortar. This way of reusing plastic waste is beneficial for diminishing the negative impacts of plastics on the environment and reducing CO₂ emissions by using geopolymer as an alternative cementing material. BLWA was used to partially substitute natural fine aggregate at ratios of 0, 5, 10, 15, and 20% by volume. The geopolymer mortar properties were tested, and the durability after exposure to elevated temperatures was also assessed. It was found that the strengths were adversely affected by increasing BLWA content. The water absorption and porosity were also increased with beneficial benefits on the reduced density (9–17%) and thermal conductivity (28–44%). The geopolymer mortar containing 5–15% BLWA satisfied the requirement of a lightweight mortar used in masonry work. After exposure to temperatures up to 600 °C, the properties of geopolymer mortar containing BLWA reduced more than that of the control mortar due to the thermal degradation of BLWA at high temperatures. However, when increasing the temperature from 600 °C to 900 °C, there was no further loss in strength. Microstructure analysis indicated that increasing temperatures caused more increased voids and microcracks in geopolymer mortars, especially the ones containing BLWA. However, after exposure at 900 °C, these voids and cracks were minimized at 900 °C due to sintering effects. The findings in this work confirmed the feasibility of using this PVC waste derived to produce lightweight construction material with thermal insulation properties. Full article

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49 pages, 7789 KiB

Open AccessReview

Synthesized Evaluation of Reinforced Concrete Bridge Defects, Their Non-Destructive Inspection and Analysis Methods: A Systematic Review and Bibliometric Analysis of the Past Three Decades

by Eslam Mohammed Abdelkader, Tarek Zayed and Nour Faris

Buildings 2023, 13(3), 800; https://doi.org/10.3390/buildings13030800 - 17 Mar 2023

Cited by 9 | Viewed by 4096

Abstract

Defects are essential indicators to gauge the structural integrity and safety of reinforced concrete bridges. Non-destructive inspection has been pervasively explored over the last three decades to localize and characterize surface and subsurface anomalies in reinforced concrete bridges. In addition, different fuzzy set [...] Read more.

Defects are essential indicators to gauge the structural integrity and safety of reinforced concrete bridges. Non-destructive inspection has been pervasively explored over the last three decades to localize and characterize surface and subsurface anomalies in reinforced concrete bridges. In addition, different fuzzy set theory-based, computer vision and artificial intelligence algorithms were leveraged to analyze the data garnered from non-destructive evaluation techniques. In light of the foregoing, this research paper presents a mixed review method that encompasses both bibliometric and systematic analyses of the state-of-the-art work pertinent to the assessment of reinforced concrete bridge defects using non-destructive techniques (CBD_NDT). In this context, this study reviews the literature of journal articles and book chapters indexed in Scopus and Web of Science databases from 1991 to the end of September 2022. To this end, 505 core peer-reviewed journal articles and book chapters are compiled for evaluation after conducting forward and backward snowballing alongside removing irrelevant papers. This research study then exploits both VOSVIEWER and Bibiometrix R Package for the purpose of network visualization and scientometric mapping of the appended research studies. Thereafter, this paper carries out a multifaceted systematic review analysis of the identified literature covering tackled bridge defects, used non-destructive techniques, data processing methods, public datasets, key findings and future research directions. The present study is expected to assist practitioners and policymakers to conceive and synthesize existing research and development bodies, and future trends in the domain of the assessment of bridge defects using non-destructive techniques. It can also aid in raising awareness of the importance of defect management in bridge maintenance systems. Full article

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22 pages, 11954 KiB

Open AccessArticle

Performance of Rubberized Concrete and the Effect of Temperature and Stainless Steel Fibers

by Ayman El-Zohairy, Matthew Sanchez, Bahram Abediniangerabi and Perry Moler

Buildings 2023, 13(2), 280; https://doi.org/10.3390/buildings13020280 - 18 Jan 2023

Cited by 3 | Viewed by 2325

Abstract

Rubberized concrete is widely used in construction by utilizing the advantages of partially replacing fine or coarse aggregate with rubber to enhance several properties of concrete and provide an environmentally friendly solution. This paper experimentally explores the influence of utilizing crumb rubber (CR) [...] Read more.

Rubberized concrete is widely used in construction by utilizing the advantages of partially replacing fine or coarse aggregate with rubber to enhance several properties of concrete and provide an environmentally friendly solution. This paper experimentally explores the influence of utilizing crumb rubber (CR) as an alternate coarse aggregate in concrete. Concrete specimens were prepared with different percentages of rubber (0%, 5%, 10%, 15%, and 20%). Additionally, other parameters, such as freezing–thawing cycles, temperature, and stainless steel fibers (SSFs), were investigated. The workability of fresh concrete and the compression properties of hardened concrete were examined. Reductions in the mechanical properties of rubberized concrete were obtained. The compressive strength reductions ranged between 13% and 50%, based on the percentage of CR in the concrete mix. However, a lesser unit weight and higher toughness were obtained relative to conventional concrete. The average unit weight decreased by 1.3%, 2.5%, 3.4%, and 5.7% of the control mixture when 5%, 10%, 15%, and 20% of the CR were incorporated into the concrete mixtures, respectively. Regression models to predict the compressive strength and unit weight of concrete with CR were developed. In addition, a life cycle cost analysis (LCCA) to identify and quantify the possible benefits of using CR in concrete mixes was carried out. Using rubberized concrete mixtures for thin whitetopping offered a slightly lower net present value compared to the ordinary concrete mix. Full article

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18 pages, 3897 KiB

Open AccessArticle

Effect of Combining the Aggregate Grading with Cementitious Composition on Mechanical Properties of Ultra-High Performance Concrete

by Vinh Thi Hai Chu, Vinh Duc Bui and Tue Viet Nguyen

Buildings 2023, 13(1), 248; https://doi.org/10.3390/buildings13010248 - 16 Jan 2023

Cited by 1 | Viewed by 2771

Abstract

Ultra-High Performance Concrete (UHPC) improves the bearing capacity as well as the durability of structural concrete. This study aims to investigate the constituents of UHPC in both phases: aggregate and cementitious materials. The proper ratio of the mixture was chosen based on combining [...] Read more.

Ultra-High Performance Concrete (UHPC) improves the bearing capacity as well as the durability of structural concrete. This study aims to investigate the constituents of UHPC in both phases: aggregate and cementitious materials. The proper ratio of the mixture was chosen based on combining an aggregate gradation of quartz sand and crushed stone. In addition, the compressive strength of the hardened cement paste was investigated to achieve the optimal ratio of silica powder and blast furnace slag. The combination of aggregate (quartz sand and crushed stone) and cement paste (cement, silica fume, silica powder, and blast furnace slag) showed ultra-high performance. The compressive strength of UHPC reached 135.74 MPa at 7 days, corresponding to 90% of 28 days’ strength (150.98 MPa). The results of the present study provide a new mixture-proportioning for UHPC with economic efficiency. Moreover, the use of slag enhances concrete performance and reduces the negative environmental impact. Full article

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2022

Jump to: 2024, 2023, 2021, 2020

21 pages, 5873 KiB

Open AccessArticle

Full-Scale Test and Load-Bearing Capacity Evaluation of Synthetic-Polymer-Fiber-Reinforced Concrete Tetrapods under Quasi-Static Loading

by Žiga Unuk and Milan Kuhta

Buildings 2022, 12(12), 2143; https://doi.org/10.3390/buildings12122143 - 5 Dec 2022

Cited by 3 | Viewed by 4380

Abstract

This paper studies the load-bearing capacity of various concrete tetrapods under quasi-static loading. The tetrapods were made of plain concrete and synthetic-polymer-fiber-reinforced concrete. Load tests of the tetrapods were performed. The maximum load-bearing capacity and the residual-load-bearing capacity of the tetrapods (the load-bearing [...] Read more.

This paper studies the load-bearing capacity of various concrete tetrapods under quasi-static loading. The tetrapods were made of plain concrete and synthetic-polymer-fiber-reinforced concrete. Load tests of the tetrapods were performed. The maximum load-bearing capacity and the residual-load-bearing capacity of the tetrapods (the load-bearing capacity after the first crack or at different crack widths) were evaluated. The strength and residual-strength values were back-calculated from the load-bearing capacities, and compared with available data from the literature. The specimens with and without fibers achieved similar maximum load-bearing capacities, with cracks occurring at identical locations. However, the differences in residual-load-bearing capacity were more significant. The synthetic-polymer-fiber-reinforced concrete tetrapods exhibited relatively high residual-load-bearing capacities, even at higher displacements and crack widths. Two different calculation-procedures were used for the load-bearing-capacity evaluation. A load-displacement calculation based on the moment-versus-curvature relation and the plastic-hinge approach was performed, and additionally proved the applicability of the employed calculation-procedures for the concrete tetrapod load-bearing-capacity evaluation. Full article

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19 pages, 7182 KiB

Open AccessArticle

Experimental and Numerical Study on Steel Fiber Concrete under Blast Loading

by Huawei Yin and Yaoguo Ouyang

Buildings 2022, 12(12), 2119; https://doi.org/10.3390/buildings12122119 - 2 Dec 2022

Cited by 4 | Viewed by 1909

Abstract

In this paper, 30 SFRC (Steel Fiber Reinforced Concrete) spindle specimens with different steel fiber contents were subjected to static loading tests and blast wave loading tests on spindle specimens with different steel fiber contents using a self-developed planar blast wave loading device [...] Read more.

In this paper, 30 SFRC (Steel Fiber Reinforced Concrete) spindle specimens with different steel fiber contents were subjected to static loading tests and blast wave loading tests on spindle specimens with different steel fiber contents using a self-developed planar blast wave loading device (a new type of patent recognized by the State Intellectual Property Rights). The dynamic response, impact performance and damage mode of Steel Fiber Reinforced Concrete under blast loading were investigated. The experimental results show that with the increase of steel fiber content (within 2%), the strength of the Steel Fiber Reinforced Concrete increases slightly. The flatter the falling section of the stress-strain curve, the better the energy absorption effect. With the increase of explosive equivalent(24 g RDX and 36 g RDX), the more obvious the strain rate effect, the greater the increase of peak stress, and the SFRC with 2% steel fiber content has the best energy absorption effect. Furthermore, the dynamic response of SFRC spindle specimens was numerically simulated using the improved K&C material model with LS-DYNA explicit finite element dynamic analysis software. The results verify the validity and reliability of the improved K&C material model. Full article

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28 pages, 14982 KiB

Open AccessArticle

Effect of Fiber Type and Volume Fraction on Fiber Reinforced Concrete and Engineered Cementitious Composite Mechanical Properties

by Abd Elmoaty M. Abd Elmoaty, Alaa M. Morsy and Abdelrhman B. Harraz

Buildings 2022, 12(12), 2108; https://doi.org/10.3390/buildings12122108 - 1 Dec 2022

Cited by 17 | Viewed by 3477

Abstract

Engineered cementitious composites (ECC) are an ultra-ductile cement-based composite material reinforced with short randomly distributed fibers. It differs from fiber reinforced concrete (FRC) in that it has a distinct ductile behavior. The study aims to assign mechanical properties, such as tensile, flexural, and [...] Read more.

Engineered cementitious composites (ECC) are an ultra-ductile cement-based composite material reinforced with short randomly distributed fibers. It differs from fiber reinforced concrete (FRC) in that it has a distinct ductile behavior. The study aims to assign mechanical properties, such as tensile, flexural, and compressive strength using locally available fiber rather than polyvinyl alcohol (PVA) fiber, which is not widely available in many countries, to ECC. PVA fiber is also very expensive. Instead of PVA, lightweight fibers, such as polypropylene, polyolefin, and glass fiber, as well as heavyweight fibers, such as steel fiber, were used. To assess the mechanical properties, the influences of curing, fiber volume fraction (2%, 4%, and 6%), fiber type, and fiber hybridization were adjusted in this study. The formation of multiple cracks along the specimen is the governing factor in ECC formation. The test results show that increasing the fiber volume fraction improves flexural and tensile strength. Water curing increased compressive, tensile, and flexural strength. Lightweight fiber hybridization has no effect on compressive strength, whereas heavyweight fiber hybridization improves compressive strength. For tensile and flexural strength, hybridization was associated with an improvement in all mechanical properties. The hybridization of lightweight fiber achieved ECC behavior at a lower volume fraction than the use of a single fiber volume. Relationships between tensile strength and flexural strength depending on the compressive strength of ECC were driven by demonstrating high performance. Full article

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16 pages, 2607 KiB

Open AccessArticle

Shear Behavior of Granulated Blast Furnace Slag-Based Geopolymer-Reinforced Concrete Beams

by Mehdi Ozturk and Guray Arslan

Buildings 2022, 12(12), 2053; https://doi.org/10.3390/buildings12122053 - 23 Nov 2022

Cited by 5 | Viewed by 1453

Abstract

Active research is ongoing regarding the mechanical behavior of structural members manufactured from geopolymer concrete (GC), as it lacks standardized/codified manufacturing and design procedures. This study aims to address the shear behavior of GC beams. First, a consistent trial–error-based approach was used to [...] Read more.

Active research is ongoing regarding the mechanical behavior of structural members manufactured from geopolymer concrete (GC), as it lacks standardized/codified manufacturing and design procedures. This study aims to address the shear behavior of GC beams. First, a consistent trial–error-based approach was used to develop the optimal mixture ratio (102.38/234.0 for NaOH/Na₂SiO₃) in terms of workability and consistency for the production of six (6) test specimens with span-to-depth ratios of (a/d) of 2.5, 3.5, and 4.5 and transverse reinforcement intervals of 10, 15, and 20 cm. Then, shear failure tests using a three-point bending setup were conducted and analyzed statistically. As a first attempt in the literature, an empirical expression for shear capacity prediction that was specifically tuned for GC beams was given. This expression, along with seven other similar expressions for ordinary concrete beams from the literature, and various practice codes were tested against a pool of experimental shear failure results given by four (4) different researchers. As a measure of the predictive capability, coefficient of variation (COV = standard deviation/average) values were obtained, and the lowest COV value of 0.305 suggested that the expression obtained the highest predictive capability, whereas more common practice codes such as ACI318, EN1992, and ENV1992 produced COV values of 0.435, 0.374, and 0.627, respectively. Finally, this study provides a working expression for the shear capacity estimation of GC beams and a mixture ratio for the practical manufacturing conditions of workability and consistency, with a slump value of 270 mm and a 90 min setting time. Full article

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26 pages, 6264 KiB

Open AccessReview

A Review on Failure Modes and Cracking Behaviors of Polypropylene Fibers Reinforced Concrete

by Jawad Ahmad, Dumitru Doru Burduhos-Nergis, Mohamed Moafak Arbili, Saleh M. Alogla, Ali Majdi and Ahmed Farouk Deifalla

Buildings 2022, 12(11), 1951; https://doi.org/10.3390/buildings12111951 - 11 Nov 2022

Cited by 25 | Viewed by 3859

Abstract

Despite being strong under compression, concrete is rather weak when subjected to tensile stress. Concrete has been reinforced with a variety of materials over time in order to resist tensile stresses. Among various types of fibers, polypropylene fiber, which is available in a [...] Read more.

Despite being strong under compression, concrete is rather weak when subjected to tensile stress. Concrete has been reinforced with a variety of materials over time in order to resist tensile stresses. Among various types of fibers, polypropylene fiber, which is available in a range of sizes, is being used to strengthen concrete. The fiber also increases the concrete’s toughness, durability, and low permeability. Polypropylene fibers may be utilized in place of conventional reinforcement, according to a number of researchers. The aim of this study is to collect information from already carried out research on polypropylene fibers. Important characteristics of concrete, such as workability, compressive, tensile, and flexural strength, are reviewed. The review also explores cracking behavior and failure modes of polypropylene fiber reinforced concrete. Furthermore, durability aspects, such as water absorption, porosity, dry shrinkage, and microstructure study (scan electronic microscopy), were also reviewed. Results indicate that polypropylene fiber improved the mechanical strength and durability of concrete (particularly tensile capacity) but decreased the flowability of concrete. The optimum dose is important, as a higher dose adversely affects strength and durability due to a lack of flowability. Scanning electronic microscopy results indicate that the polypropylene fibers restrict the propagation of cracks, which improves the strength and durability of concrete. The review also indicates that shrinkage cracks are considerably reduced with the addition of polypropylene fibers. Finally, the review also provides future research guidelines for upcoming generations to further improve the performance of polypropylene fibers that reinforce concrete. Full article

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18 pages, 4879 KiB

Open AccessArticle

Punching Shear Capacity of Recycled Aggregate Concrete Slabs

by Satjapan Leelatanon, Thanongsak Imjai, Monthian Setkit, Reyes Garcia and Boksun Kim

Buildings 2022, 12(10), 1584; https://doi.org/10.3390/buildings12101584 - 1 Oct 2022

Cited by 13 | Viewed by 1748

Abstract

This article investigates the punching shear behavior of recycled aggregate concrete (RAC) two-way slabs. Ten 1500 mm × 1500 mm × 100 mm slabs were tested monotonically. Eight slabs were cast with RAC, whereas two control slabs were cast with natural aggregate concrete [...] Read more.

This article investigates the punching shear behavior of recycled aggregate concrete (RAC) two-way slabs. Ten 1500 mm × 1500 mm × 100 mm slabs were tested monotonically. Eight slabs were cast with RAC, whereas two control slabs were cast with natural aggregate concrete (NAC). The RAC incorporated coarse recycled concrete aggregate (RCA) at replacement levels of 25%, 50%, 75% and 100%. Two flexural reinforcement ratios (0.8% and 1.5%) were examined. The results show that the normalized punching shear strength of 100% RAC slabs decreased by 6.5% and 9% compared to NAC slabs for ρ = 1.5% and ρ = 0.8%, respectively. Doubling the amount of flexural reinforcement can increase the punching shear capacity of 100% RAC slabs by up to 45%. A punching shear database of 44 RAC slabs from literature and the 8 RAC slabs presented in this study revealed that the punching shear strength of RAC slabs predicted by ACI 318 was conservative, except for slabs with low reinforcement ratios (<0.6%). The punching shear strength predicted by Eurocode 2 gave more conservative results for all levels of RCA replacement and all flexural reinforcement ratios. A yield-line analysis also showed that the failure mode of the RAC slabs was controlled by punching shear. Full article

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18 pages, 4589 KiB

Open AccessArticle

Behavior of Waste Glass Powder in Concrete Deep Beams with Web Openings

by Mahmoud A. El-Mandouh, Jong-Wan Hu and Ahmed S. Abd El-Maula

Buildings 2022, 12(9), 1334; https://doi.org/10.3390/buildings12091334 - 30 Aug 2022

Cited by 2 | Viewed by 2186

Abstract

Waste Glass Powder (WGP) could be used as a cement replacement additive to manufacture concrete and solving the problem of environmental pollution. The experimental program was made up of ten simply supported reinforced High-Strength Concrete (HSC) deep beams tested under static loadings. Five [...] Read more.

Waste Glass Powder (WGP) could be used as a cement replacement additive to manufacture concrete and solving the problem of environmental pollution. The experimental program was made up of ten simply supported reinforced High-Strength Concrete (HSC) deep beams tested under static loadings. Five beams were with WGP, while the other five beams were without WGP. Eight beams had web openings while two reference beams were without openings. The principal studied parameters were the effect of using WGP, and the location and size of web openings. Using the three-dimensional finite element computer program ABAQUS, a numerical simulation for comparing the shear strength and behavior of tested deep beams has been suggested. The comparison between experimental failure loads of studied beams with that estimated by the Strut-and-Tie model was carried out. Three codes of practice were used to make this comparison: the American Concrete Institute (ACI 318-19), the New Zealand Code (NZS-06), and the Japan Society of Civil Engineering (JSCE-07). The results showed that using WGP in similar deep beams with web openings enhances the cracking shear strength (by about 17–25%) and the ultimate shear strength (by about 12–41%). The improvement in the ultimate failure load could be attributed to the developed concrete microstructures caused by WGP’s very fine grains, producing further gel, and decreasing the number of voids in the concrete matrix. The suggested finite element simulation accurately predicts the behavior of HSC deep beams with and without WGP beams and with web openings. Full article

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23 pages, 6404 KiB

Open AccessArticle

Thermal Optimization of Additively Manufactured Lightweight Concrete Wall Elements with Internal Cellular Structure through Simulations and Measurements

by David Briels, Stefan Kollmannsberger, Felicitas Leithner, Carla Matthäus, Ahmad Saleem Nouman, Oguz Oztoprak and Ernst Rank

Buildings 2022, 12(7), 1023; https://doi.org/10.3390/buildings12071023 - 15 Jul 2022

Cited by 14 | Viewed by 2870

Abstract

Combining the additive manufacturing (AM) process of extrusion with lightweight concrete, mono-material but multi-functional elements with an internal cellular structure can be created to achieve good thermal performance of a wall at low resource consumption. The aim of this paper is to analyze [...] Read more.

Combining the additive manufacturing (AM) process of extrusion with lightweight concrete, mono-material but multi-functional elements with an internal cellular structure can be created to achieve good thermal performance of a wall at low resource consumption. The aim of this paper is to analyze and optimize the actual thermal performance of such a component. A sensitivity analysis and a parametric optimization were conducted based on a mathematical description of heat transfer in cellular structures. To investigate the thermal performance, 2D and 3D heat transfer simulations were used and validated by heat flux measurements on an existing prototype. A geometric optimization led to a further reduction of the U-value by up to 24%, reaching 0.58 W/m² K. The ratio of solid material to air inside the cells (relative density) was identified as the main driver, in addition to cell diameter, cell height, and cell wall thickness. The comparison of analytical and numerical results showed high correspondence with deviations of 3–10%, and for the experimental results 25%. These remaining deviations can be traced back to simplifications of the theoretical models and discrepancies between as designed and as built. The presented approach provides a good basis for optimizing the thermal design of complex AM components by investigating practical thermal problems with the help of 2D and 3D simulations, and thus offers a great potential for further applications. Full article

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12 pages, 3277 KiB

Open AccessArticle

High Strength Construction Material Based on Sulfur Binder Obtained by Physical Modification

by Sergey Sergeevich Dobrosmyslov, Vladimir Efimovich Zadov, Rashit Anvarovich Nazirov, Gennady Efimovich Nagibin, Anton Sergeevich Voronin, Mikhail Maksimovich Simunin, Yuri Vladimirovich Fadeev and Stanislav Viktorovich Khartov

Buildings 2022, 12(7), 1012; https://doi.org/10.3390/buildings12071012 - 14 Jul 2022

Cited by 6 | Viewed by 2145

Abstract

In this work, a method for obtaining a high-strength composite material on a sulfur binder without the use of chemical modifiers was proposed. It consists in obtaining a thixotropic casting mixture in the vicinity of the yield point of the system during vibration [...] Read more.

In this work, a method for obtaining a high-strength composite material on a sulfur binder without the use of chemical modifiers was proposed. It consists in obtaining a thixotropic casting mixture in the vicinity of the yield point of the system during vibration laying. The compressive strength of the obtained composite was about 97.5–94.0 MPa. Physical and mechanical characteristics remained stable for 7 years. The samples were obtained for a model composition of sulfur/marshalite (finely ground 98% silicon dioxide). The microstructure of the synthesized material was studied by electron microscopy, the results of which showed that shrinkage cavities are characteristic of a material with a low density, and no shrinkage cavities were found for a high-strength material. The phase composition was determined by the methods of XRD analysis, according to the results of which it can be argued that sulfur is in the orthorhombic form (S₈). This technique can be proposed for obtaining the high-strength stable building material. Full article

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18 pages, 7760 KiB

Open AccessArticle

Environmental Impact on the Behavior of CFRP Sheet Attached to Concrete

by Ayssar Al-Khafaji, Ayman El-Zohairy, Mirnes Mustafic and Hani Salim

Buildings 2022, 12(7), 873; https://doi.org/10.3390/buildings12070873 - 21 Jun 2022

Cited by 2 | Viewed by 1688

Abstract

Carbon fiber-reinforced polymer (CFRP) has many advantages as a construction/structural-strengthening material. However, there are still concerns regarding the long-term performance of these materials when used with reinforced concrete (RC) structures. Environmental conditions have an adverse effect on the behavior of CFRP and the [...] Read more.

Carbon fiber-reinforced polymer (CFRP) has many advantages as a construction/structural-strengthening material. However, there are still concerns regarding the long-term performance of these materials when used with reinforced concrete (RC) structures. Environmental conditions have an adverse effect on the behavior of CFRP and the bond between these sheets and concrete. Therefore, the durability of CFRP used for strengthening RC beams was evaluated under different environmental scenarios, including subjection to immersion in deicing agents, tap water, and saltwater, freeze-and-thaw cycles, and outdoor environmental changes. Laboratory tests were performed to examine the influence of these environmental scenarios on the bonding behavior between CFRP sheets and concrete in terms of deformations and modes of failure. Two types of test setups were performed in this study, namely pull-off shearing and three-point bending. Forty-two concrete prisms with CFRP were prepared and tested by using the pull-off shearing setup. It was observed that as the period of exposure increased, noticeable effects on the CFRP sheet as well as the bond stiffness were observed. Exposure to tap water had a greater impact than saltwater on the CFRP–concrete bond strength as well as the CFRP. In addition, eighteen notched concrete beams strengthened with an external CFRP were tested under three-point bending. The tap water exposure showed a 3.6% increase in the bond strength compared to the control specimen. However, the saltwater exposure showed a 10% increase. Full article

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25 pages, 25472 KiB

Open AccessArticle

Study of the Durability Damage of Ultrahigh Toughness Fiber Concrete Based on Grayscale Prediction and the Weibull Model

by Chen Wang, Pei Fu, Zeli Liu, Ziling Xu, Tao Wen, Yingying Zhu, Yuhua Long and Jiuhong Jiang

Buildings 2022, 12(6), 746; https://doi.org/10.3390/buildings12060746 - 31 May 2022

Cited by 9 | Viewed by 1922

Abstract

The purpose of this research is to investigate the durability damage law for ultrahigh toughness cementitious composites (UHTCCs) under freeze–thaw environments and impact resistance. In this study, UHTCCs with fiber length-to-diameter ratios of 5/30, 8/30, 12/20, 12/30 and 12/48 were tested for impact [...] Read more.

The purpose of this research is to investigate the durability damage law for ultrahigh toughness cementitious composites (UHTCCs) under freeze–thaw environments and impact resistance. In this study, UHTCCs with fiber length-to-diameter ratios of 5/30, 8/30, 12/20, 12/30 and 12/48 were tested for impact resistance and freeze–thaw cycles. The freeze–thaw cycle process and impact resistance process for UHTCC are comprehensively analyzed and evaluated in terms of mass loss, compressive strength loss, relative dynamic elastic modulus loss and impact resistance number. The freeze–thaw damage prediction model for the relative dynamic elastic modulus of the UHTCC is established based on the regularity of the measured data for the relative dynamic elastic modulus of UHTCC and also on the GM(1,1) power model. The accuracy and reliability of the GM(1,1) power model is analyzed using the relative error, absolute correlation degree, mean variance and probability of small errors. According to the evolution law of the impact resistance number of the UHTCC, the impact damage prediction model for UHTCC is established based on the Weibull distribution model, and the accuracy of the model is analyzed by using the decision coefficient R². The results show that UHTCC has high durability performance, and the durability performance of UHTCC at a length-diameter ratio of 12/48 is optimal. The freeze–thaw damage evolution model and impact damage evolution model established in this research are sufficiently realistic, the average relative error of the GM(1,1) power model is less than 5%, and the coefficient of determination R² of the Weibull distribution model is greater than 0.93, which effectively reflects the damage development process for concrete under freeze–thaw and impact environment with high fitting accuracy. Full article

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17 pages, 4769 KiB

Open AccessArticle

Apparent Quality and Service Performance Evaluation of SCFFC in Tunnel Secondary Lining

by Caijin Xie, Tiejun Tao and Keyu Huang

Buildings 2022, 12(4), 479; https://doi.org/10.3390/buildings12040479 - 12 Apr 2022

Cited by 2 | Viewed by 1866

Abstract

After removing the mold from the secondary lining concrete of a tunnel, problems such as honeycomb and hemp surface easily occur. To obtain self-compacting fair-faced concrete (SCFFC) that can meet strength requirements and effectively solve the above problems, this research prepared SCFFC with [...] Read more.

After removing the mold from the secondary lining concrete of a tunnel, problems such as honeycomb and hemp surface easily occur. To obtain self-compacting fair-faced concrete (SCFFC) that can meet strength requirements and effectively solve the above problems, this research prepared SCFFC with different mix proportions and performed slump expansion, slump, J-ring expansion and mechanical tests. Additionally, this research comprehensively analyzed the SCFFC based on fuzzy mathematics to study its apparent quality and service performance. This research aimed to solve problems such as uneven bubbles and poor bubble diameter in C30 SCFFC, through a combination of defoaming and air entraining by adding defoamer and air-entraining agent according to different proportions for compound treatment. The defoamer dosage was 0.5‰ of that of water reducer, and the air-entraining agent dosage was 0.1‰ of that of cement. The workability and clearance passability of the concrete were optimal. At the same time, the apparent holes in the SCFFC were small, as were their area and quantity. The distribution and apparent color of the SCFFC were uniform. Considering the factors affecting the service performance of concrete and after a comprehensive analysis of the samples’ weights, subjection degree, variability, stability, and strength index, this research found that the ratio for obtaining a C30 SCFFC material with the highest apparent quality and service performance was as follows: cement:machine-made sand:crushed dtone:fly-ash:water = 4:8.6:9.3:1:2.2. The water reducer comprised 1.0% of the total mass of the cementitious materials. The defoamer dosage was 0.5‰ of that of water reducer, and the dosage of air-entraining agent was 0.1‰ of that of cement. Full article

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9 pages, 3129 KiB

Open AccessArticle

Electrical Resistivity and Strength Parameters of Prismatic Mortar Samples Based on Standardized Sand and Lunar Aggregate Simulant

by Petr Lehner, Petr Konečný and Jacek Katzer

Buildings 2022, 12(4), 423; https://doi.org/10.3390/buildings12040423 - 31 Mar 2022

Cited by 3 | Viewed by 2798

Abstract

In situ resource utilization (ISRU) and automation are necessary. The logical first step of intention is to focus on our neighbor, the Moon, first. This work aims to expand our knowledge of the lunar aggregate simulant (LAS) based on ilmenite rock, which is [...] Read more.

In situ resource utilization (ISRU) and automation are necessary. The logical first step of intention is to focus on our neighbor, the Moon, first. This work aims to expand our knowledge of the lunar aggregate simulant (LAS) based on ilmenite rock, which is available in Central Europe. Prismatic mortar samples were prepared based on standard sand and LAS. The measurements were conducted using several different destructive (DT) strength related tests and non-destructive (NDT) electrical resistivity measurement methods. The results were compared, and mutual correlation was evaluated. Finally, the ratio between volumetric (bulk) and surface resistivity tested on prismatic samples is presented. The results showed an average ratio of 7.19 for sand and 7.97 for ilmenite. The results show the potential feasibility of evaluating the properties of non-standard composite materials using durability-related NDT. The experimental testing presented that combines the DT and NDT methods in one sample represents a potential streamlining of the processes of future testing. Full article

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14 pages, 3502 KiB

Open AccessArticle

Investigation on Mechanical and Durability Properties of Concrete Mixed with Silica Fume as Cementitious Material and Coal Bottom Ash as Fine Aggregate Replacement Material

by Tariq Ali, Abdul Salam Buller, Fahad ul Rehman Abro, Zaheer Ahmed, Samreen Shabbir, Ali Raza Lashari and Ghulam Hussain

Buildings 2022, 12(1), 44; https://doi.org/10.3390/buildings12010044 - 4 Jan 2022

Cited by 18 | Viewed by 3050

Abstract

Cement production produces a high amount of carbon dioxide, which has a negative impact on the environment. By utilizing waste products instead of cement, environmental degradation can be reduced. The current study was undertaken to study the mechanical and durability performance of concrete [...] Read more.

Cement production produces a high amount of carbon dioxide, which has a negative impact on the environment. By utilizing waste products instead of cement, environmental degradation can be reduced. The current study was undertaken to study the mechanical and durability performance of concrete by replacing 7.5%, 10%, and 12.5% silica fume (SF) of cement weight. Additionally, coal bottom ash (CBA) was also substituted as fine aggregates with 10%, 20%, and 30%. Compressive strength and indirect tensile strength were the major parameters regarding mechanical properties, while corrosion analysis and sulfate attack were set for durability performance. Sixteen mixes were prepared including a control mix. Out of these, three mixes contained SF, three mixes contained CBA, and eight mixes contained both SF and CBA with 1:2:4 ratio at 0.5 w/b ratio. The results concluded that the addition of 12.5% SF and 30% CBA gives optimum compressive strength and tensile strength. Furthermore, using the SF and CBA reduces the workability of concrete. Furthermore, the use of these byproducts increased the durability in terms of corrosion and sulfate attack. Full article

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2021

Jump to: 2024, 2023, 2022, 2020

17 pages, 5016 KiB

Open AccessArticle

Bond of Ribbed Steel Bar in High-Performance Steel Fiber Reinforced Expanded-Shale Lightweight Concrete

by Mingshuang Zhao, Guirong Liu, Lingli Liu, Yanyan Zhang, Kang Shi and Shunbo Zhao

Buildings 2021, 11(12), 582; https://doi.org/10.3390/buildings11120582 - 25 Nov 2021

Cited by 7 | Viewed by 2061

Abstract

For the structural application of high-performance Steel Fiber Reinforced Expanded-shale Lightweight Concrete (SFRELC), a reliable bond of ribbed steel bar should be ensured. In this paper, an experimental study was carried out on the bond properties of ribbed steel bar embedded in SFRELC [...] Read more.

For the structural application of high-performance Steel Fiber Reinforced Expanded-shale Lightweight Concrete (SFRELC), a reliable bond of ribbed steel bar should be ensured. In this paper, an experimental study was carried out on the bond properties of ribbed steel bar embedded in SFRELC by the direct pull-out test. The SFRELC was produced with a strength grade of 35 MPa and a volume fraction of steel fiber as 0%, 0.8%, 1.2%, 1.6% and 2.0%, respectively. Fifteen groups of specimens were made with a central placed steel bar with diameter of 14 mm, 20 mm and 28 mm, respectively. Complete bond stress-slip curves were determined for each group of specimens, and the characteristic values of bond-stress and slip at key points of the curves were ascertained. Results show that the bond strength, peak-slip and residual bond strength increased with the increase of the volume fraction of steel fiber. With the increase of steel bar diameter, bond strength decreased while the peak-slip increased, and the descending curves became sharp with a decreased residual bond strength. Formulas for calculating the bond strength and peak-slip were proposed. The relationships were determined for the splitting bond strength, residual bond strength with the bond strength, the splitting bond slip and residual bond slip with the peak-slip. Combined with rational fitting analyses of bond strength and slip, a constitutive model was selected for predicting the bond stress-slip of ribbed steel bar in SFRELC. Full article

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16 pages, 2174 KiB

Open AccessArticle

Experimental Study on Engineering Properties of Cement Concrete Reinforced with Nylon and Jute Fibers

by Naraindas Bheel, T. Tafsirojjaman, Yue Liu, Paul Awoyera, Aneel Kumar and Manthar Ali Keerio

Buildings 2021, 11(10), 454; https://doi.org/10.3390/buildings11100454 - 2 Oct 2021

Cited by 36 | Viewed by 4709

Abstract

The use of synthetic fiber and natural fiber for concrete production has been continuously investigated. Most of the materials have become popular for their higher flexibility, durability, and strength. However, the current study explores the engineering properties of cement concrete reinforced with nylon [...] Read more.

The use of synthetic fiber and natural fiber for concrete production has been continuously investigated. Most of the materials have become popular for their higher flexibility, durability, and strength. However, the current study explores the engineering properties of cement concrete reinforced with nylon and jute fibers together. Varying proportions and lengths of nylon and jute fibers were utilized in the concrete mixture. Hence, the combined effects of nylon and jute fibers on workability, density, water absorption, compressive, tensile, flexural strength, and drying shrinkage of concrete were investigated. Results showed that concrete with 1% of nylon and jute fibers together by the volume fraction showed a maximum enhancement of the compressive strength, split tensile strength, and flexural strength by 11.71%, 14.10%, and 11.04%, respectively, compared to the control mix of concrete at 90 days. However, the water absorption of concrete increased with increasing nylon and jute fiber contents. The drying shrinkage of concrete decreased with the addition of nylon and jute fibers together after 90 days. Thus, the sparing application of both nylon and jute fiber as discussed in this study can be adopted for concrete production. Full article

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23 pages, 26776 KiB

Open AccessArticle

Transport Properties and Resistance Improvement of Ultra-High Performance Concrete (UHPC) after Exposure to Elevated Temperatures

by Yunfeng Qian, Dingyi Yang, Yanghao Xia, Han Gao and Zhiming Ma

Buildings 2021, 11(9), 416; https://doi.org/10.3390/buildings11090416 - 17 Sep 2021

Cited by 8 | Viewed by 3199

Abstract

Ultra-high performance concrete (UHPC) has a high self-healing capacity and is prone to bursting after exposure to high temperatures due to its characteristics. This work evaluates the damage and improvement of UHPC with coarse aggregates through mechanical properties (compressive strength and ultrasonic pulse [...] Read more.

Ultra-high performance concrete (UHPC) has a high self-healing capacity and is prone to bursting after exposure to high temperatures due to its characteristics. This work evaluates the damage and improvement of UHPC with coarse aggregates through mechanical properties (compressive strength and ultrasonic pulse velocity), transport properties (water absorption and a chloride diffusion test), and micro-properties such as X-ray diffraction (XRD), Mercury intrusion porosimetry (MIP), and Scanning electronic microscopy (SEM). The result demonstrates that polypropylene (PP) fibers are more suitable for high temperature tests than polyacrylonitrile (PAN) fibers. The result shows that 400 °C is the critical temperature point. With the increase in temperature, the hydration becomes significant, and the internal material phase changes accordingly. Although the total pore volume increased, the percentage of various types of pores was optimized within 400 °C. The mass loss gradually increased and the ultrasonic pulse velocity gradually decreased. While the compressive strength first increased and then decreased, and the increase occurred within 25–400 °C. As for the transport properties, the chloride migration coefficient and capillary absorption coefficient both increased dramatically due to the higher sensitivity to temperature changes. The results of the property improvement test showed that at temperatures above 800 °C, the compressive strength recovered by more than 65% and the ultrasonic pulse velocity recovered by more than 75%. In terms of transport properties, compared to the results before self-healing, the chloride migration coefficient decreased by up to 59%, compared with 89% for the capillary absorption coefficient, after self-healing at 800 °C. With respect to the enhancement effect after exposure to high temperatures, the environment of a 5% Na₂SO₄ solution was not as good as the clean water environment. The corresponding changes in microstructure during the high temperatures and the self-healing process can explain the change in the pattern of macroscopic properties more precisely. Full article

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22 pages, 24395 KiB

Open AccessArticle

Prediction of Shear Strength of Reinforced Recycled Aggregate Concrete Beams without Stirrups

by Monthian Setkit, Satjapan Leelatanon, Thanongsak Imjai, Reyes Garcia and Suchart Limkatanyu

Buildings 2021, 11(9), 402; https://doi.org/10.3390/buildings11090402 - 8 Sep 2021

Cited by 20 | Viewed by 2902

Abstract

For decades, recycled coarse aggregate (RCA) has been used to make recycled aggregate concrete (RAC). Numerous studies have compared the mechanical properties and durability of recycled aggregate concrete (RAC) to those of natural aggregate concrete (NAC). However, test results on the shear strength [...] Read more.

For decades, recycled coarse aggregate (RCA) has been used to make recycled aggregate concrete (RAC). Numerous studies have compared the mechanical properties and durability of recycled aggregate concrete (RAC) to those of natural aggregate concrete (NAC). However, test results on the shear strength of reinforced recycled aggregate concrete beams are still limited and sometimes contradictory. Shear failure is generally brittle and must be prevented. This article studies experimentally and analytically the shear strength of reinforced RAC beams without stirrups. Eight RAC beams and two controlled NAC beams were tested under the four-point flexural test with the shear span-to-effective depth ratio (a/d) of 3.10. The main parameters investigated were the replacement percentage of RCA (0%, 25%, 50%, 75%, and 100%) and longitudinal reinforcement ratio (ρ_w) of 1.16% and 1.81%. It was found that the normalized shear stresses of RAC beams with ρ_w = 1.81% at all levels of replacement percentage were quite similar to those of the NAC counterparts. Moreover, the normalized shear stress of the beam with 100% RCA and ρ_w = 1.16% was only 6% lower than that of the NAC beam. A database of 128 RAC beams without shear reinforcement from literature was analyzed to evaluate the accuracy of the ACI 318-19 shear provisions in predicting the shear strength of the beams. For an RCA replacement ratio of between 50% and 100%, it was proposed to apply a reduction factor of 0.75 to the current ACI code equation to account for the physical variations of RCA, such as replacement percentage, RCA source and quality, density, amount of residual mortar, and physical irregularity. Full article

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19 pages, 6703 KiB

Open AccessArticle

Influence of Fiber Shape and Volume Content on the Performance of Reactive Powder Concrete (RPC)

by Chuanlin Wang, Guojie Xue and Xianbo Zhao

Buildings 2021, 11(7), 286; https://doi.org/10.3390/buildings11070286 - 1 Jul 2021

Cited by 6 | Viewed by 2882

Abstract

This research studied the influence of three types of open (short-straight, long-straight, semicircular) and three different shapes of closed steel fibers (triangular, rectangular, circular) with different fiber contents by volume (0, 0.5%, 1%, 1.5%, and 2%) on the working and mechanical performance of [...] Read more.

This research studied the influence of three types of open (short-straight, long-straight, semicircular) and three different shapes of closed steel fibers (triangular, rectangular, circular) with different fiber contents by volume (0, 0.5%, 1%, 1.5%, and 2%) on the working and mechanical performance of reactive powder concrete (RPC). The results indicated that (1) the number of steel fibers and the enclosed area formed by closed steel fibers would remarkably impact the performance of RPC; (2) the semicircular fiber improves RPC’s strength the most among the three open shapes; (3) the short-straight fiber works more effectively than the closed steel fibers; (4) the circular fiber works the most efficiently in improving RPC’s mechanical performance while the triangular ones have the least effect among the three closed steel fibers; (5) both the closed and open steel fibers improve their compressive strength more than their flexural strength; (6) the closed steel fiber works more efficiently in improving the flexural strength but less efficiently in improving the compressive strength; (7) the open steel fibers enhance the mechanical performance of RPC via their anchoring performance while the closed steel fibers work by confining the concrete; (8) the hybrid utilization of steel fibers improves RPC’s mechanical performance to a higher level via combing the advantages of open and closed steel fibers. Full article

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15 pages, 7410 KiB

Open AccessArticle

Influence of the Concentration of Seawater on the Early Hydration Properties of Calcium Sulphoaluminate (CSA) Cement: A Preliminary Study

by Chuanlin Wang, Zeping Liu, Tengteng Zhang, Yuxuan Zhang, Zehong Liu and Xianbo Zhao

Buildings 2021, 11(6), 243; https://doi.org/10.3390/buildings11060243 - 6 Jun 2021

Cited by 8 | Viewed by 2950

Abstract

This research investigates the effect of seawater of different concentrations on the hydration process and microstructure of calcium sulphoaluminate (CSA) cement. It studies the CSA cement pastes via experiments carried out to determine the initial and final setting times, mechanical strength and chemical [...] Read more.

This research investigates the effect of seawater of different concentrations on the hydration process and microstructure of calcium sulphoaluminate (CSA) cement. It studies the CSA cement pastes via experiments carried out to determine the initial and final setting times, mechanical strength and chemical shrinkage with X-ray diffraction (XRD), scanning electron microscopy (SEM) and simultaneous differential thermal-thermogravimetric (DTA-TG) analysis. The DTA-TG and XRD results showed that the main hydration products were ettringite (AFt) and aluminum hydroxide in the CSA cement paste mixed with both freshwater and seawater, while a small amount of ettringite (AFt) became monosulfate (AFm) in the freshwater-mixed CSA cement. The SEM results demonstrate that seawater can improve the microstructure of CSA cement paste in the early stage of hydration (1 d) but impairs the microstructure of the CSA cement matrix in the later stage of hydration (7 d). The experimental results also indicate that a high concentration of seawater can extend the setting time, increase the chemical shrinkage and decrease the mechanical strength of CSA cement. Full article

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9 pages, 5510 KiB

Open AccessArticle

The Use of Crushed Cable Waste as a Substitute of Natural Aggregate in Cement Screed

by Pavel Reiterman and Martin Lidmila

Buildings 2021, 11(5), 190; https://doi.org/10.3390/buildings11050190 - 30 Apr 2021

Cited by 1 | Viewed by 2259

Abstract

This research is focused on the utilization of cable waste originating during the recycling of wires as a partial substitution of natural aggregate in cement screed. The main goal of the work performed was to find an optimal level of substitution in terms [...] Read more.

This research is focused on the utilization of cable waste originating during the recycling of wires as a partial substitution of natural aggregate in cement screed. The main goal of the work performed was to find an optimal level of substitution in terms of freezing–thawing resistance, which is a significant aspect for such type of concrete mixtures. The studied artificial aggregate was gradually dosed in cement screed by 5% in a volume of up to 30% of substitution. The influence of the substitution was also evaluated in terms of compressive strength, flexural strength, bulk density determination, and the ultrasonic pulse method. Gradual substitution led to the reduction of the bulk density and studied mechanical properties due to the considerable air-entraining effect. The utilization of cable waste reduced the value of modulus of elasticity and modified deformation behavior of studied mixtures, which exhibited significant softening during the flexural test. Studied screed mixtures incorporating waste material exhibited slightly lower values of the coefficient of freeze-thaw resistance in comparison with the control mixture, however, the attained values comply with technical requirements. Full article

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23 pages, 9438 KiB

Open AccessArticle

Effects of Coarse Aggregate Maximum Size on Synthetic/Steel Fiber Reinforced Concrete Performance with Different Fiber Parameters

by Haider M. Al-Baghdadi, Faiz H. Al-Merib, Ayoob A. Ibrahim, Rafea F. Hassan and Husam H. Hussein

Buildings 2021, 11(4), 158; https://doi.org/10.3390/buildings11040158 - 13 Apr 2021

Cited by 15 | Viewed by 3356

Abstract

Recently, fiber has been incorporated into concrete mixtures, where its distribution in the concrete matrix helps to improve and enhance the mechanical properties of fiber-reinforced concrete (FRC). The aim of this study is to investigate the influence of steel and synthetic fiber parameters, [...] Read more.

Recently, fiber has been incorporated into concrete mixtures, where its distribution in the concrete matrix helps to improve and enhance the mechanical properties of fiber-reinforced concrete (FRC). The aim of this study is to investigate the influence of steel and synthetic fiber parameters, along with different coarse aggregate maximum sizes (CAMZs) on FRC performance. Additionally, in past research, the empirical relationships among the compressive, tensile, and flexural strengths of plain concrete and FRC were assessed, and correlations between these mechanical properties of FRC were examined. For each CAMZ, four fiber dosages for each fiber type were considered. The results demonstrate the mechanical properties of FRC enhanced as the fiber length increased from 13 mm to 60 mm, the CAMZ increased from 9.5 mm to 37.5 mm, and the ratio of the fiber length to the CAMZ was in the range of 0.35–5.68. All mixtures have been intended to exhibit similar compressive strengths; however, the synthetic/steel fiber advanced the brittleness ratio of specimens with G10, G19, and G38 to approximately 36.8%, 40.7%, and 47.4% greater than the contral specimens, respectively. In addition, from the regression analysis investigation, there are strong correlations from the regression analysis of the mechanical property results of FRC. Full article

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23 pages, 9054 KiB

Open AccessEditor’s ChoiceArticle

Properties of Cementitious Materials with Recycled Aggregate and Powder Both from Clay Brick Waste

by Huixia Wu, Jianzhuang Xiao, Chaofeng Liang and Zhiming Ma

Buildings 2021, 11(3), 119; https://doi.org/10.3390/buildings11030119 - 17 Mar 2021

Cited by 35 | Viewed by 5110

Abstract

The utilization of recycled brick aggregate (RBA) and recycled brick powder (RBP) in cementitious materials helps the reclamation of clay brick waste in construction and demolition waste. This work studied the properties of cementitious materials with RBA as aggregate and RBP as supplementary [...] Read more.

The utilization of recycled brick aggregate (RBA) and recycled brick powder (RBP) in cementitious materials helps the reclamation of clay brick waste in construction and demolition waste. This work studied the properties of cementitious materials with RBA as aggregate and RBP as supplementary cementitious material. The RBA has lower apparent density and higher water absorption than natural aggregate, and RBP with an irregular micro-structure contains high content of silicon and aluminum oxides and possesses excellent pozzolanic activity. Incorporating RBP decreases the fluidity and increases the setting time, but the incorporated RBP improves the pore structure and decreases the average pore diameter of cementitious materials, thereby decreasing the permeability. Utilizing RBA increases the drying shrinkage, while the incorporated RBP decreases the drying shrinkage of cementitious materials; the mortar with 50% RBA and 30% RBP has the lower drying shrinkage than the common mortar without RBA and RBP. Incorporating RBA and high-volume RBP decreases the mechanical strength, while there is no obvious decrease in the mechanical strength for the mortar with 50% RBA and 30% RBP. Moreover, the flexural strength to compressive strength ratio increases with RBA and RBP incorporating. Utilizing RBA increases the water transport, while the water transport properties decrease with the RBP incorporation; incorporating appropriate content of RBA and RBP can obtain the cementitious materials with low permeability. Particularly, a significant decrease in chloride ingress occurs with the substitution of RBP. Full article

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14 pages, 37533 KiB

Open AccessArticle

Rechargeable Concrete Battery

by Emma Qingnan Zhang and Luping Tang

Buildings 2021, 11(3), 103; https://doi.org/10.3390/buildings11030103 - 9 Mar 2021

Cited by 25 | Viewed by 42996

Abstract

A rechargeable cement-based battery was developed, with an average energy density of 7 Wh/m² (or 0.8 Wh/L) during six charge/discharge cycles. Iron (Fe) and zinc (Zn) were selected as anodes, and nickel-based (Ni) oxides as cathodes. The conductivity of cement-based electrolytes was [...] Read more.

A rechargeable cement-based battery was developed, with an average energy density of 7 Wh/m² (or 0.8 Wh/L) during six charge/discharge cycles. Iron (Fe) and zinc (Zn) were selected as anodes, and nickel-based (Ni) oxides as cathodes. The conductivity of cement-based electrolytes was modified by adding short carbon fibers (CF). The cement-based electrodes were produced by two methods: powder-mixing and metal-coating. Different combinations of cells were tested. The results showed that the best performance of the rechargeable battery was the Ni–Fe battery, produced by the metal-coating method. Full article

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16 pages, 6741 KiB

Open AccessArticle

Structural Performance of Reinforced Concrete Beams Incorporating Cathode-Ray Tube (CRT) Glass Waste

by Jad Bawab, Jamal Khatib, Ali Jahami, Adel Elkordi and Elhem Ghorbel

Buildings 2021, 11(2), 67; https://doi.org/10.3390/buildings11020067 - 13 Feb 2021

Cited by 30 | Viewed by 3770

Abstract

The performance of reinforced concrete beams in the presence of cathode-ray tube (CRT) glass waste is examined. Four concrete mixes containing 0%, 10%, 20%, and 30% CRT glass waste as partial replacement of sand were prepared. The compressive and flexural strength as well [...] Read more.

The performance of reinforced concrete beams in the presence of cathode-ray tube (CRT) glass waste is examined. Four concrete mixes containing 0%, 10%, 20%, and 30% CRT glass waste as partial replacement of sand were prepared. The compressive and flexural strength as well as the modulus of elasticity of concrete were determined. Reinforced concrete beams with varying amounts of CRT glass were prepared and the three-point bending test was conducted. The load-deflection curve as well as the strain distribution along the depth of the beams were determined. Concrete containing CRT glass showed an increase in compressive strength, flexural strength, and modulus of elasticity especially at 10% replacement level. The load carrying capacity of reinforced concrete beam is higher when 10% of sand is replaced with CRT glass compared to the control beam and the beams with 20% and 30% CRT glass substitution. The failure mode of the reinforced concrete beams is flexural failure, and the failure pattern is similar for all beams. Strain distribution showed a better ductility at control beam where the deflection was higher than the other beams at the same load. Numerical analysis was conducted, and comparison was made with the experimental results. The comparison showed the accuracy of the software used, where the results of maximum load capacity and maximum deflection were very similar, and the difference did not exceed 5%. In addition, the tensile damage generated by the numerical analysis was very similar to that obtained by the experimental study. Full article

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20 pages, 5005 KiB

Open AccessArticle

Structural Behavior of Reinforced Concrete Slabs Containing Fine Waste Aggregates of Polyvinyl Chloride

by Nisreen S. Mohammed, Bashar Abid Hamza, Najla’a H. AL-Shareef and Husam H. Hussein

Buildings 2021, 11(1), 26; https://doi.org/10.3390/buildings11010026 - 12 Jan 2021

Cited by 10 | Viewed by 4046

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