Buildings

Editorial

8 pages, 181 KiB

Open AccessEditorial

Mechanical Behavior and Innovative Applications of Fiber-Reinforced Cementitious Composite and Fiber-Reinforced Polymer in Infrastructures

by Jianzhe Shi, Haitao Wang and Xuyang Cao

Buildings 2024, 14(12), 3993; https://doi.org/10.3390/buildings14123993 - 16 Dec 2024

Viewed by 652

Abstract

Fiber-reinforced cementitious composite (FRCC) and fiber-reinforced polymer (FRP) have been widely applied in infrastructures. Their mechanical behavior and innovative applications are examined in this article. Firstly, the mechanical behaviors of FRCC and the corresponding improving methods are elaborated. The bond behavior of the [...] Read more.

Fiber-reinforced cementitious composite (FRCC) and fiber-reinforced polymer (FRP) have been widely applied in infrastructures. Their mechanical behavior and innovative applications are examined in this article. Firstly, the mechanical behaviors of FRCC and the corresponding improving methods are elaborated. The bond behavior of the FRP–concrete interface, which has a significant effect on the strengthening effect of FRP, is reviewed. A proposed method to enhance the bond behavior is also introduced. In addition, the effectiveness of FRP is demonstrated in terms of improving the load-bearing capacity, stiffness, crack resistance, fatigue resistance, and other behaviors of existing structures. Furthermore, the feasibility of fibers or FRPs in new constructions is also validated. Finally, the future prospects of the research and applications of FRCC and FRP are discussed. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

3 pages, 157 KiB

Open AccessEditorial

Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering

by Jianzhe Shi

Buildings 2023, 13(7), 1755; https://doi.org/10.3390/buildings13071755 - 10 Jul 2023

Cited by 6 | Viewed by 2104

Abstract

Concrete has become one of the most widely used structural materials in civil engineering [...] Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

Research

Jump to: Editorial, Review

23 pages, 10176 KiB

Open AccessArticle

Experimental Study on Bond Fatigue Between Carbon Fiber-Reinforced Polymer Bars and Seawater–Sea Sand Concrete Under Seawater Immersion and Dry–Wet Cycle Conditions

by Fu Yang, Weiquan Gan, Bingsan Chen, Jiangchuan Wu and Shiwen Yuan

Buildings 2025, 15(3), 438; https://doi.org/10.3390/buildings15030438 - 30 Jan 2025

Viewed by 710

Abstract

The durability of carbon fiber-reinforced polymer (CFRP) bars in marine environments is essential for their application in seawater–sea sand concrete (SWSSC), especially under cyclic loading conditions. While previous studies primarily focused on static bonding performance, the effects of seawater immersion and dry–wet cycles [...] Read more.

The durability of carbon fiber-reinforced polymer (CFRP) bars in marine environments is essential for their application in seawater–sea sand concrete (SWSSC), especially under cyclic loading conditions. While previous studies primarily focused on static bonding performance, the effects of seawater immersion and dry–wet cycles on bond fatigue behavior at CFRP–SWSSC interfaces remain underexplored. This study investigated the bond fatigue performance of CFRP bars and SWSSC under seawater immersion and dry–wet cycling conditions. Eighteen CFRP bar-SWSSC bond specimens were divided into three categories and prepared for static and fatigue pull-out tests. The effects of varying stress levels (fatigue upper load/static bond ultimate load) after seawater immersion and dry–wet cycling on fatigue failure modes, bond–slip behavior, and fatigue characteristics were evaluated. The results show that seawater immersion and dry–wet cycling significantly degrade the performance of bonds between CFRP bars and SWSSC, with an average bond strength reduction of 10.31%. These conditions reduce fatigue cycles and stiffness while increasing bond–slip (relative displacement at the bar–concrete interface) and residual–slip (displacement after unloading). Moreover, dry–wet cycling has a greater negative impact on fatigue bond performance than seawater immersion. Higher fatigue stress levels exacerbate damage and crack propagation at the CFRP–SWSSC interface, leading to significant increases in both bond–slip and residual-slip. Under similar conditions, higher stress levels enhance bond stiffness. However, excessively high stresses may lead to bond fatigue failures. Using experimental data and existing fatigue bond–slip constitutive models, a customized model for CFRP bars in SWSSC was developed. These findings highlight that marine environments and fatigue loading severely impair bond performance, thereby emphasizing the importance of careful design for marine applications. The proposed model offers a reliable framework for predicting bond–slip behavior under fatigue conditions, enhancing the understanding of CFRP–SWSSC interactions and supporting the design of durable marine infrastructure. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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16 pages, 22470 KiB

Open AccessArticle

In Situ Testing Evaluation and Numerical Simulation of CFRP-Strengthened Reinforced Concrete Two-Way Slab with Initial Defect

by Yepu Sheng and Yu Gong

Buildings 2025, 15(1), 82; https://doi.org/10.3390/buildings15010082 - 30 Dec 2024

Viewed by 802

Abstract

Carbon fiber-reinforced polymer (CFRP) composites, renowned for their high strength-to-weight ratio, are increasingly utilized in the strengthening of structural components. The application of CFRP for strengthening concrete components notably improves the cracking moment and substantially elevates the ultimate load-bearing capacity. This study focuses [...] Read more.

Carbon fiber-reinforced polymer (CFRP) composites, renowned for their high strength-to-weight ratio, are increasingly utilized in the strengthening of structural components. The application of CFRP for strengthening concrete components notably improves the cracking moment and substantially elevates the ultimate load-bearing capacity. This study focuses on a reinforced concrete (RC) two-way slab with an initial defect, specifically an initial deflection. To avert deformations or damages that could break structural integrity during service, the slab was strengthened by adhering CFRP to its underside. An in situ multi-stage loading test was conducted to evaluate the load-bearing capacity of the CFRP-strengthened slab, and the findings revealed that the mid-span deflection of the two-way slab incrementally reached 1.64 mm after the loading stages, with no observable signs of concrete cracking, debonding, or tearing of the CFRP-strengthened slab. The failure modes indicated a transition from concrete compression damage to CFRP anchorage stress concentrations, highlighting the effective stress distribution and load-sharing synergy provided by CFRP-strengthening. Additionally, a numerical model based on the finite element (FE) method was developed using ABAQUS to simulate the component’s performance during the loading process. A comparison between the measured mid-span deflection of the strengthened slab and the numerically simulated values confirmed the high accuracy and rationality of the simulation method. Utilizing the validated numerical model, an analysis of the slab’s ultimate load capacity was conducted, demonstrating that the CFRP strengthening technique effectively increased the load-bearing capacity of the initially imperfect RC two-way slab by nearly 50%. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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16 pages, 3342 KiB

Open AccessArticle

Dynamic Monitoring of CFRP Strengthened Bridges: A Distributed Sensing Approach Under Bridge–Vehicle Coupling

by Bitao Wu, Sicheng Fu, Yan Gong, Yanchao Shao, Zhenwei Zhou and Haitao Wang

Buildings 2025, 15(1), 76; https://doi.org/10.3390/buildings15010076 - 29 Dec 2024

Viewed by 586

Abstract

To achieve a rapid assessment of reinforced bridges without interrupting traffic, the method and influence parameters for evaluating prestressed CFRP (Carbon Fiber Reinforced Polymer) plate-strengthened bridges were investigated based on distributed sensing while considering the bridge–vehicle coupling. Firstly, based on the principle of [...] Read more.

To achieve a rapid assessment of reinforced bridges without interrupting traffic, the method and influence parameters for evaluating prestressed CFRP (Carbon Fiber Reinforced Polymer) plate-strengthened bridges were investigated based on distributed sensing while considering the bridge–vehicle coupling. Firstly, based on the principle of distributed monitoring, the strain influence line equation for prestressed CFRP plate-strengthened bridges under moving vehicle loads was derived. An evaluation index and method for assessing strengthening effectiveness based on distributed strain monitoring was proposed. Numerical simulation experiments were conducted for verification, in which a simulation method for solving the bridge–vehicle coupling vibration response based on the displacement contact method was studied. Relevant example verifications were carried out to prove the correctness of this method. On this basis, a dynamic performance analysis of the bridge before and after strengthening under bridge–vehicle coupling was performed. Finally, a study on influencing parameters was conducted to investigate the impact of different prestress levels of CFRP plates, different vehicle speeds, and different vehicle axle loads on the evaluation method. The results demonstrate that the bridge–vehicle coupling calculation model based on the displacement contact method can effectively simulate the dynamic response of the bridge after reinforcement. The evaluation method based on distributed sensing monitoring is unaffected by the speed and axle load of the vehicle, enabling the assessment of the condition and stress state of the strengthened bridge. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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22 pages, 7295 KiB

Open AccessArticle

Effect of Fiber Type and Length on Strength, Fracture Energy, and Durability Properties of Microwave-Cured Fiber-Reinforced Geopolymer Mortars

by Adil Gultekin

Buildings 2024, 14(12), 3723; https://doi.org/10.3390/buildings14123723 - 22 Nov 2024

Viewed by 829

Abstract

Microwave curing can be an alternative curing method for geopolymer production. Although many properties of microwave-cured geopolymer composites have been investigated, the effect of microwave curing on the strength and durability properties of fiber-reinforced geopolymers remains a topic that requires investigation. In this [...] Read more.

Microwave curing can be an alternative curing method for geopolymer production. Although many properties of microwave-cured geopolymer composites have been investigated, the effect of microwave curing on the strength and durability properties of fiber-reinforced geopolymers remains a topic that requires investigation. In this study, the effect of fiber type and length on the properties of microwave-cured metakaolin-based geopolymers was investigated. For this purpose, PVA (6, 12 mm) and polymer (15, 30 mm) fibers were utilized. Compressive and flexural strength, fracture energy, abrasion resistance, high-temperature resistance, water absorption capacity and rate of capillary water absorption tests were conducted and the microstructure was examined using scanning electron microscopy. For curing, a household microwave oven was used at a power level of 300 watts. With the fibers’ inclusion, fracture energies could be increased by up to 1150%, ductility was enhanced, flexural strengths were increased and compressive strengths decreased. Moreover, the rate of capillary water absorption decreased by up to 13%, while water absorption values increased by between 5% and 12%. The results suggested that microwave curing could be an alternative curing method for the production of fiber-reinforced geopolymer composites, offering shorter curing times and lower energy consumption. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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19 pages, 5141 KiB

Open AccessArticle

Numerical Modeling of Distributed Macro-Synthetic Fiber and Deformed Bar Reinforcement to Resist Shear

by Benedikt Fadel Farag, Travis Thonstad and Paolo Martino Calvi

Buildings 2024, 14(10), 3247; https://doi.org/10.3390/buildings14103247 - 14 Oct 2024

Cited by 1 | Viewed by 968

Abstract

Macro-synthetic fibers are increasingly used in concrete as secondary reinforcement to control temperature and shrinkage cracks, improving durability by limiting crack widths. However, their impact on the shear strength of structural elements remains underexplored, particularly when used in combination with traditional steel reinforcement. [...] Read more.

Macro-synthetic fibers are increasingly used in concrete as secondary reinforcement to control temperature and shrinkage cracks, improving durability by limiting crack widths. However, their impact on the shear strength of structural elements remains underexplored, particularly when used in combination with traditional steel reinforcement. To address this knowledge gap, this study developed and calibrated a non-linear numerical model to simulate the shear response of macro-synthetic fiber-reinforced concrete (PFRC) elements, using finite element software VecTor2. The model was calibrated with experimental data from PFRC panels subjected to pure shear loading, incorporating a custom concrete tension-softening model to capture the contribution of fibers. Validation against a broad range of PFRC beam experiments from the literature demonstrated the model’s accuracy, achieving an average predicted-to-experimental shear strength ratio of 0.99 (COV = 5.5%). Additionally, the model successfully replicated key response characteristics such as deformation patterns, crack propagation, and residual strength. The proposed modeling approach provides valuable insights into the interaction between fiber volume and transverse reinforcement. It also serves as a powerful tool for future numerical studies, addressing the existing data gap on PFRC behavior and exploring the synergistic effects of macro-synthetic fibers and steel reinforcement on shear strength. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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20 pages, 11570 KiB

Open AccessArticle

An Experimental Study and Result Analysis on the Dynamic Effective Bond Length of a Carbon Fiber-Reinforced Polymer Sheet Attached to a Concrete Surface

by Dong Li, Xinrui Wang, Jiangxing Zhang, Liu Jin and Xiuli Du

Buildings 2024, 14(10), 3245; https://doi.org/10.3390/buildings14103245 - 13 Oct 2024

Cited by 1 | Viewed by 1500

Abstract

A carbon fiber-reinforced polymer (CFRP) is a common material utilized for the enhancement in reinforced concrete (RC) constructions. Previous research indicates that the bonding performance between a CFRP sheet and concrete determines whether the bonding of CFRP material is effective. However, the majority [...] Read more.

A carbon fiber-reinforced polymer (CFRP) is a common material utilized for the enhancement in reinforced concrete (RC) constructions. Previous research indicates that the bonding performance between a CFRP sheet and concrete determines whether the bonding of CFRP material is effective. However, the majority of existing research on the bonding performance of the CFRP–concrete interface is concentrated on static loading conditions. In order to clarify the effect of dynamic load on the bonding performance of the CFRP sheet–concrete interface, this study adopts the double-sided shear test method to carry out dynamic experimental research. The test findings reveal that the damage pattern of the CFRP sheet–concrete interface remains consistent across different loading rates. The ultimate bearing capacity increases as the strain rate increases. As the strain rate increases from 10⁻⁵ s⁻¹ to 10⁻² s⁻¹, the effect of bond length on ultimate bearing capacity increases by about 7%. As the strain rate increases, both the maximum strain of CFRP and the maximum interfacial shear stress demonstrate a corresponding increase, with respective increase rates of 60% and 20%. The effective bond length decreases by about 20% when the strain rate rises from 10⁻⁵ s⁻¹ to 10⁻² s⁻¹. Finally, a formula for calculating the dynamic effective bond length of a CFRP sheet, grounded in the Chen and Teng formula, has been proposed and verified. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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16 pages, 7455 KiB

Open AccessArticle

Bond Behavior of CFRP–Concrete Bonded Joints with Additional GFRP Layer: Effect of Bonding Sequence

by Hao Zhou, Jiahao Zhao, Yan Yang, Fengling Tan, Ya Ou, Yi Wang and Chao Li

Buildings 2024, 14(9), 2936; https://doi.org/10.3390/buildings14092936 - 17 Sep 2024

Cited by 1 | Viewed by 1293

Abstract

Existing studies have shown that bonding a ±45° biaxial GFRP under CFRP laminate can significantly improve the load-carrying capacity and ultimate deformation of CFRP–concrete bonded joints. In such a bonding configuration, the GFRP interlayer is wider than the CFRP laminate so that the [...] Read more.

Existing studies have shown that bonding a ±45° biaxial GFRP under CFRP laminate can significantly improve the load-carrying capacity and ultimate deformation of CFRP–concrete bonded joints. In such a bonding configuration, the GFRP interlayer is wider than the CFRP laminate so that the interfacial stress can be redistributed to achieve a higher fracture work; however, the effect of the bonding sequence,—specifically, the position of the GFRP layer—on the bond behavior is not yet clear. In this study, considering the same CFRP and GFRP usage, three types of CFRP–concrete bonded joints with CFRP bonded under, above, and between GFRP layers were prepared and tested under single-shear loading. Digital image correlation (DIC) was used to measure the deformation of the bonded joints during the test. Afterward, the failure mode, load–displacement behavior, and principal strain distribution were analyzed. The experimental results show that the dominant failure mode is the combined cohesion failure mode within the concrete and GFRP delamination, which is not affected by the bonding sequence. Compared to conventional CFRP–concrete bonded joints, bonding the CFRP laminate above, under, and between the GFRP layers achieved a 157.6%, 175.0%, and 177.2% increase in load-carrying capacity, respectively. Accordingly, the ultimate deformation also recorded an 83.0%, 103.6%, and 86.3% increase. However, the bonding sequence showed a slight influence on the initial stiffness of the load–displacement curve with a maximum difference of 16.1%, taking the minimum as a reference, which could be attributed to the differences in the strength and stiffness between the CFRP–concrete and CFRP–GFRP–concrete interfaces. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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15 pages, 6699 KiB

Open AccessArticle

Evaluation of the Strengthening Effects on Prestressed Carbon-Fiber-Reinforced-Polymer-Strengthened Steel Beam Bridges Using Macro-Strain Influence Lines

by Bitao Wu, Qingquan Xia, Yan Gong, Sicheng Fu, Haitao Wang and Zhongzhao Guo

Buildings 2024, 14(8), 2535; https://doi.org/10.3390/buildings14082535 - 17 Aug 2024

Cited by 1 | Viewed by 992

Abstract

Effectively evaluating the effectiveness of bridge strengthening is a necessary means to ensure the normal operation of existing strengthened bridges, especially when evaluating the effectiveness of bridge strengthening without interrupting normal traffic. Based on a distributed long-gauge Fiber Bragg Grating (FBG) sensor, this [...] Read more.

Effectively evaluating the effectiveness of bridge strengthening is a necessary means to ensure the normal operation of existing strengthened bridges, especially when evaluating the effectiveness of bridge strengthening without interrupting normal traffic. Based on a distributed long-gauge Fiber Bragg Grating (FBG) sensor, this paper derived the macro-strain influence line (MSIL) formula for a simply supported beam bridge under a moving vehicle load, studied the changes in the MSIL at the bottom of the beam under the vehicle load before and after the prestressed CFRP plate strengthening, and proposed a rapid evaluation method for the strengthening effect based on the amplitude of the MSIL as the evaluation index for the strengthening effect. Finally, the prestressed CFRP-strengthened steel beam was tested under the moving vehicle load. The theoretical analysis and the experimental results confirm that under the load of moving vehicles, the macro-strain–time history amplitude of the strengthened steel beams under different prestressed tensioning conditions is different. The amplitude of the macro-strain time history of the strengthened bridge is reduced compared to before strengthening, and the local strengthening effect of the bridge can be monitored by the amplitude change in a single sensor. The change in global stiffness can be evaluated by monitoring the MSIL obtained from multiple long-gauge strain sensors. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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14 pages, 6095 KiB

Open AccessArticle

The Effect of Volcanic Stone and Metakaolin on the Compressive Properties of Ultrahigh-Performance Concrete Cubes

by Yushi Yin and Zeyu Ma

Buildings 2024, 14(7), 2024; https://doi.org/10.3390/buildings14072024 - 2 Jul 2024

Cited by 4 | Viewed by 1601

Abstract

Over the past few decades, ultrahigh-performance concrete (UHPC) has been widely studied and applied because of its outstanding mechanical properties, such as its high strength and notable durability. However, because of its high cost and easy shrinkage cracking during early pouring in mass [...] Read more.

Over the past few decades, ultrahigh-performance concrete (UHPC) has been widely studied and applied because of its outstanding mechanical properties, such as its high strength and notable durability. However, because of its high cost and easy shrinkage cracking during early pouring in mass concrete construction, to reduce the cost of UHPC and reduce the cracks caused by early pouring, volcanic stone was used as a new type of UHPC coarse aggregate, while metakaolin (MK) was added to the system at the same time, and then two parameters, namely the volcanic rock particle size group and the MK dispersion ratio, were set. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric (TG) microanalysis methods were used to reveal the influence of changes in the material microstructure, phase composition, material composition and crystallinity of the mineral composition on the compressive properties of the UHPC cubes. The results show that the mechanical “lock-in effect” of the structure formed by the volcanic rock holes and mortar can effectively improve the shear resistance of the UHPC–volcanic rock interface, and the compressive strength of the UHPC cubes increases with the volcanic stone’s particle size. When the MK dispersion ratio is less than 4%, the cube compressive strength of the UHPC and the contents of CaCO₃ crystals, C-S-H gel and travertine in the UHPC increase with an increasing MK dispersion ratio. At an age of 28 days, compared with the addition of 1% MK, the addition of 4% MK increases the production of C-S-H gel and travertine in the UHPC matrix by 24.82%. When the MK dispersion ratio is 4%, the crystallinity values of the C-S-H gel, travertine and limestone in the UHPC are greater. Adding MK at a 4% dispersion ratio can promote the crystallization of limestone into a large amount of calcite, which can increase the strength of UHPC. On the one hand, the addition of volcanic coarse aggregate results in the retention of more free water and bound water; on the other hand, it also makes it difficult to crystallize CaCO₃. The combined action of MK at a 4% dispersion ratio and volcanic rock significantly inhibits CaCO₃ crystallization. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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16 pages, 4483 KiB

Open AccessArticle

Tensile Mechanical and Stress-Strain Behavior of Recycling Polypropylene Fiber Recycled Coarse Aggregate Concrete

by Jianchao Wang, Jiahe Liang, Yucheng Li and Wei Hou

Buildings 2024, 14(4), 1116; https://doi.org/10.3390/buildings14041116 - 16 Apr 2024

Cited by 1 | Viewed by 1586

Abstract

To effectively recycle waste petroleum products and construction waste, recycling polypropylene fiber (RPF) and recycled aggregate can be mixed into concrete to make RPF recycled coarse aggregate (RCA) concrete. In this study, the RPF recycled from a polypropylene (PP) packaging belt was used [...] Read more.

To effectively recycle waste petroleum products and construction waste, recycling polypropylene fiber (RPF) and recycled aggregate can be mixed into concrete to make RPF recycled coarse aggregate (RCA) concrete. In this study, the RPF recycled from a polypropylene (PP) packaging belt was used as the test material and manually cut into the shape required for the experiment. The effects of RCA and RPF on the tensile mechanical behavior of concrete are researched. The failure modes and constitutive relationship of the specimens under axial tension and splitting tension are further investigated. The results show that the axial tensile strength of RPF RCA concrete first increased and then decreased with the increase in fiber volume content, and was the largest when the fiber volume content was 1.5%, and its strength increased by 21.14% compared with that of recycled concrete. Its lifting rate relative to recycled concrete is between 13.14–21.41%. The change trend of axial tensile strength with the substitution rate of RCA is that it decreases with the increase in substitution rate, and the substitution rate decreases by 9.64% when the substitution rate is 100% compared with 0%.The peak strain first increased and then decreased with the increase in fiber volume content, and the maximum fiber volume content was 1.5%, which increased by 28.19% compared with that of recycled concrete. The peak strain first increased and then decreased with the increase in fiber length-diameter ratio, and the maximum length-diameter ratio was 47.85, which increased by 18.22% compared with that of recycled concrete. The peak strain increased with the increase in the replacement rate of RCA, and the peak strain at 30%, 60% and 100% was 96.22%, 102.45% and 118.09% when the replacement rate was 0%, respectively. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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18 pages, 6775 KiB

Open AccessArticle

Experimental Study on the Effect of Steel Reinforcement Ration on the Cracking Behaviour of FRP-Strengthened RC Elements

by Andrea Armonico, Laurent Michel, Mohamed Saidi and Emmanuel Ferrier

Buildings 2024, 14(4), 950; https://doi.org/10.3390/buildings14040950 - 30 Mar 2024

Cited by 7 | Viewed by 1362

Abstract

This paper examines the cracking behaviour of reinforced concrete beams strengthened by externally bonded fiber-reinforced polymer. The crack opening of RC structures is a key parameter for the durability of concrete structures. It is of vital importance for designers to be able to [...] Read more.

This paper examines the cracking behaviour of reinforced concrete beams strengthened by externally bonded fiber-reinforced polymer. The crack opening of RC structures is a key parameter for the durability of concrete structures. It is of vital importance for designers to be able to make correct estimations of the crack opening values of strengthened structures. FRP strengthening affects the cracking behaviour of RC beams with different steel percentages. Beams have been tested under four-point bending mechanical tests until failure with three steel ratios and two layers of externally bonded wet carbon fibers (CFRP). In order to measure the crack opening during loading, Digital Image Correlation is used to obtain the crack opening along the beam during load functioning. The results allow for a comparison of the RC beams with and without FRP and enhance the effect of FRP on crack opening. The crack width was compared with the theoretical values obtained based on the relation proposed by Eurocode 2 (EC2). The comparison enhanced the need to propose a modified relation. Subsequently, an empirical model was established as a modification of EC2, considering the presence of a CFRP system. The corresponding results were compared and discussed to validate the model. For the same level of loads, the crack opening can be reduced by 20 to 50% depending on the level of steel ratio. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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17 pages, 10757 KiB

Open AccessArticle

Effect of Textile Layers and Hydroxypropyl Methylcellulose on Flexural Behavior of TRLC Thin Plates

by Jiyang Wang, Dan Yu, Chen Zeng, Xiaohua Ji, Lingpeng Ye, Pinghuai Zhou and Senlin Zhao

Buildings 2024, 14(4), 924; https://doi.org/10.3390/buildings14040924 - 28 Mar 2024

Cited by 2 | Viewed by 1019

Abstract

To examine the flexural toughness characteristics of textile-reinforced lightweight aggregate concrete (TRLC), a four-point bending test was conducted to assess the impact of varying numbers of textile layers and the inclusion of hydroxypropyl methylcellulose on the ultimate load-bearing capacity and deformation capacity of [...] Read more.

To examine the flexural toughness characteristics of textile-reinforced lightweight aggregate concrete (TRLC), a four-point bending test was conducted to assess the impact of varying numbers of textile layers and the inclusion of hydroxypropyl methylcellulose on the ultimate load-bearing capacity and deformation capacity of TRLC thin plates. Six groups of specimens were prepared for the experiment, and the bending capacity of the thin plates in each group was evaluated. The flexural toughness index was utilized to quantify the bending performance of TRLC thin plates. The findings revealed that increasing the number of textile layers improved the initial cracking load, initial cracking deflection, ultimate load, ductility, and flexural toughness of the thin plates. For the specimens without HPMC, the initial cracking load was increased by up to 36.1%, the ultimate load by up to 40.9%, and the flexural toughness index by up to 292% as the number of textile layers was increased. For specimens doped with HPMC, the initial cracking load was increased by up to 61.7%, the ultimate load by up to 246.7%, and the flexural toughness index by up to 65%. The TRLC thin plate containing hydroxypropyl methylcellulose exhibited a reduced initial cracking load yet displayed a stronger matrix consistency and good flexural toughness. Moreover, the enhancement in the ultimate load of TRLC thin plates with hydroxypropyl methylcellulose was more pronounced with an increased number of textile layers, resulting in a significantly higher number of cracks compared to TRLC without hydroxypropyl methylcellulose and an 11.40-fold increase in the flexural toughness index. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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17 pages, 4623 KiB

Open AccessArticle

Study on the Stress Threshold of Preventing Interfacial Fatigue Debonding in Concrete Beams Strengthened with Externally-Bonded FRP Laminates

by Xinzhe Min, Dong Yang, Shoutan Song and Xing Li

Buildings 2024, 14(2), 430; https://doi.org/10.3390/buildings14020430 - 4 Feb 2024

Cited by 2 | Viewed by 1389

Abstract

Externally-bonded FRP laminate is widely used in structural strengthening due to the many advantages of FRP materials. Further enhancement of the strengthening effect can be achieved by inducing prestress into the FRP laminate. However, FRP debonding is still a main issue of this [...] Read more.

Externally-bonded FRP laminate is widely used in structural strengthening due to the many advantages of FRP materials. Further enhancement of the strengthening effect can be achieved by inducing prestress into the FRP laminate. However, FRP debonding is still a main issue of this strengthening method, especially the Intermediate Crack-induced debonding (IC debonding). To better understand the impact of FRP debonding on the strengthening effect, a series of parameter analyses were conducted in this study based on the fatigue life prediction model proposed by the authors. The proposed model involves the fatigue damage accumulation of components of the beam, the mutual interaction between each component, and the impact of FRP fatigue debonding. As a result, a stress threshold for preventing FRP fatigue debonding in strengthening the concrete beam was proposed, which aimed to avoid safety hazards caused by IC debonding in practical engineering. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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18 pages, 8585 KiB

Open AccessArticle

Parametric Study on Mechanical Properties of Basalt Fiber-Reinforced Pea Gravel Concrete

by Jiming Li, Bu Wang, Peng Zhang, Zhenyu Wang and Meng Wang

Buildings 2024, 14(2), 380; https://doi.org/10.3390/buildings14020380 - 1 Feb 2024

Cited by 5 | Viewed by 1347

Abstract

Basalt fiber-reinforced pea gravel concrete (BFRPGC) has remarkable potential for use as the retrofitting covers for masonry walls. However, a quantitative understanding of the mechanical properties of the BFRPGC material is still a perceived gap in the current literature. In this study, the [...] Read more.

Basalt fiber-reinforced pea gravel concrete (BFRPGC) has remarkable potential for use as the retrofitting covers for masonry walls. However, a quantitative understanding of the mechanical properties of the BFRPGC material is still a perceived gap in the current literature. In this study, the role of basalt fibers in pea gravel concrete was evaluated by a comprehensive experimental investigation involving compressive strength tests and splitting tensile tests. Fiber length and volume fraction were selected as the key parameters. Two fiber lengths of 6 mm and 12 mm were considered, while the volume fraction corresponding to each of the fiber lengths was increased from 0.3% to 0.8%, with a step of 0.1%. The measured strengths were not simply proportional to the fiber volume fraction. The reason behind this phenomenon, i.e., the coupling effect of the bridging role of basalt fibers on concrete microcracks and the fiber agglomeration in concrete, was analyzed. The best performance of the BFRPGC material was achieved by incorporating 12-millimeter-length fibers with a volume fraction of 0.4%. Compared to that of the reference pea gravel concrete, a significant increase of up to 44.5% in compressive strength was recorded in this case. Furthermore, the failure mechanism of basalt fibers in pea gravel concrete was disclosed via the scanning electron microscope observations. In addition, the uniaxial compressive stress–strain model of the BFRPGC material was established. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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32 pages, 43577 KiB

Open AccessArticle

Improved Bond Stress-Slip Relationships for Carbon Fibre-Reinforced Polymer-Strengthened Masonry Triplets

by Seyyed Motasam Hashemi and Ashraf Ayoub

Buildings 2024, 14(1), 257; https://doi.org/10.3390/buildings14010257 - 17 Jan 2024

Cited by 3 | Viewed by 1453

Abstract

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical [...] Read more.

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical studies of their structural behaviour. Walls, being fundamental components in masonry construction, play a crucial role in transferring both horizontal and vertical lateral forces. This study investigates the enhancement of masonry wall behaviour through the reinforcement of CFRP. CFRP reinforcement increases ductility and strength, reducing the risk of failure under shear conditions. Additionally, CFRP composites present a practical solution to strengthening masonry structures compared to traditional reinforcement. However, brick, mortar, and CFRP have not been thoroughly investigated. Experimental tests on the bond behaviour of different configurations of CFRP-retrofitted masonry triplets have not been performed before and are therefore presented in this paper. Triplet specimens, comprising three bricks and two mortar joints, both with and without CFRP strengthening, were subjected to bond testing. The study affirms that masonry triplets strengthened with CFRP under shear loads exhibit strength levels at least four to six times greater than those without CFRP. The experimental work was carried out with eight different CFRP configurations on triplet masonry, and each test was repeated four times. Further, the bond stress-slip relationship in the case of masonry triplets with and without CFRP was predicted with new mathematical equations based on the conducted test results. These equations were included in the commercial finite element software ANSYS and used to conduct simulations of CFRP-reinforced masonry triplets. The numerical results indicate good agreement between the finite element model and the test results. The outcome of this research improves the current knowledge on the use of CFRP to reinforce masonry walls with brick and mortar, which will contribute to the understanding of the effect of CFRP on masonry structures. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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14 pages, 3174 KiB

Open AccessArticle

Nonlinear Coupled Vibration Behavior of BFRP Cables on Long-Span Cable-Stayed Bridges under Parametric Excitation

by Yaqiang Yang, Zixian Zhou, Yanlin Guan, Jianzhe Shi, Qiwei Zhan, Mohamed F. M. Fahmy and Bitao Wu

Buildings 2023, 13(12), 3082; https://doi.org/10.3390/buildings13123082 - 11 Dec 2023

Cited by 2 | Viewed by 1393

Abstract

Based on the cable-stayed beam model, this paper studies the nonlinear coupled vibration behavior of basalt fiber-reinforced polymer (BFRP) cables on long-span cable-stayed bridges under parametric excitation. Considering the sag, damping of BFRP cables, and the coupled interactions between stayed cables and the [...] Read more.

Based on the cable-stayed beam model, this paper studies the nonlinear coupled vibration behavior of basalt fiber-reinforced polymer (BFRP) cables on long-span cable-stayed bridges under parametric excitation. Considering the sag, damping of BFRP cables, and the coupled interactions between stayed cables and the main girder, the nonlinear coupling vibration model of the BFRP cable–beam composite structure has been established. Taking the longest cable of Sutong Bridge as a case study, the nonlinear coupled vibration behavior of BFRP cables under parametric excitation has been numerically analyzed using the finite difference method. The analysis results indicate that (1) under parametric excitation, the large amplitude nonlinear vibration of the BFRP cable will be induced with an evident “beat” phenomenon. (2) Under the same parametric excitation, the nonlinear coupling vibration response and the beta frequency of the BFRP cable were both smaller than that of the traditional steel cable. (3) The nonlinear coupling vibration response of the BFRP cable increased with an increment in excitation amplitude and a decrement in cable force. With the increase in the excitation frequency, weight per unit length, and axial stiffness, the nonlinear vibration response of the BFRP cable increased first and then decreased. Meanwhile, the damping ratio of the BFRP cable had no significant influence on the nonlinear coupling vibration. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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Review

Jump to: Editorial, Research

29 pages, 7068 KiB

Open AccessReview

A Review on Research Advances and Applications of Basalt Fiber-Reinforced Polymer in the Construction Industry

by Sheng-Jie Duan, Ru-Ming Feng, Xin-Yan Yuan, Liang-Tao Song, Gen-Shu Tong and Jing-Zhong Tong

Buildings 2025, 15(2), 181; https://doi.org/10.3390/buildings15020181 - 9 Jan 2025

Viewed by 1545

Abstract

Compared to glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP), basalt fiber-reinforced polymer (BFRP) offers distinct advantages, including the relatively lower cost and superior creep resistance. As a result, its application in the construction industry has been gaining growing attention. This paper [...] Read more.

Compared to glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP), basalt fiber-reinforced polymer (BFRP) offers distinct advantages, including the relatively lower cost and superior creep resistance. As a result, its application in the construction industry has been gaining growing attention. This paper begins by providing an overview of the fundamental background, as well as the mechanical and microscopic properties, of BFs. By exploring various application types, including one-dimensional (e.g., bars, cables), two-dimensional (e.g., grids, sheets), and three-dimensional (e.g., profiles) applications, the research progress of BFRP products in the construction industry is comprehensively summarized. Research has demonstrated the effectiveness of BFRP in a variety of structural applications, such as reinforcing existing structures (e.g., concrete or masonry) using BFRP bars, grids, or sheets, and the development of novel design concepts that integrate BFRP products with existing structural systems. Furthermore, this paper identifies unresolved challenges and proposes potential research directions, intending to promote BFRP’s broader adoption as a standardized and innovative material in the construction industry. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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