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3 pages, 175 KiB

Open AccessEditorial

Special Issue on Advances in High-Performance Fiber-Reinforced Concrete

by Chao-Wei Tang

Appl. Sci. 2022, 12(17), 8723; https://doi.org/10.3390/app12178723 - 31 Aug 2022

Cited by 1 | Viewed by 952

Abstract

With the advancement of science and technology, scholars have developed a cement composite material with tensile strain hardening, called high-performance fiber-reinforced concrete (HPFRC) [...] Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

Research

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20 pages, 4142 KiB

Open AccessArticle

Experimental Study on Axial Stress–Strain Behaviour of Steel Fibre-Reinforced Steel Slag Micropowder UHPC

by Xianyuan Tang, Binbing He, Bai Yang and Junhua Chen

Appl. Sci. 2023, 13(15), 8807; https://doi.org/10.3390/app13158807 - 30 Jul 2023

Cited by 2 | Viewed by 646

Abstract

To investigate the toughening effect and stress–strain relationship of steel fibre-reinforced steel slag micropowder ultra-high-performance concrete (UHPC), nine sets of specimens with coarse aggregate and steel fibre contents were prepared for axial compression and elastic modulus tests. This study examines the variations in [...] Read more.

To investigate the toughening effect and stress–strain relationship of steel fibre-reinforced steel slag micropowder ultra-high-performance concrete (UHPC), nine sets of specimens with coarse aggregate and steel fibre contents were prepared for axial compression and elastic modulus tests. This study examines the variations in compressive strength and peak strain of the steel slag micropowder UHPC specimens to determine the corresponding characteristics of the stress–strain relationship. The results indicate that the experimental groups mixed with 1%, 1.5%, and 2% steel fibre increased the peak strain by about 20.3%, 25.3%, and 26.2%, respectively, compared to the non-steel fibre specimens. It can be seen that the toughening effect of UHPC with steel fibre and slag micro powder is good. With a fixed steel fibre content, the compressive strength and peak strain of steel slag micropowder UHPC initially increase and then decrease as the coarse aggregate content increases. The maximum compressive strength is achieved when the steel fibre content is 1.5% and the coarse aggregate content is 20%. A constitutive equation suitable for steel fibre-reinforced steel slag micropowder UHPC was derived through curve fitting based on the experimentally obtained stress–strain curves. The calculated values from the equation show deviations within 10% of the measured values, indicating a good fit. Nonlinear analysis of the entire compression process of prismatic specimens using the finite element method confirms the rationality of the constitutive equation, as the simulated curve closely aligns with the experimental curve. This research findings provide a reference for the engineering application of steel slag micropowder UHPC. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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21 pages, 8690 KiB

Open AccessArticle

Enhancing the Performance of Asphalt Mastic with Natural Fiber Reinforcement: Basalt and Bamboo Fibers

by Tingting Xie, Wenjuan Ren, Yifang Chen, Jiajia Sheng and Linbing Wang

Appl. Sci. 2023, 13(13), 7946; https://doi.org/10.3390/app13137946 - 06 Jul 2023

Cited by 2 | Viewed by 1046

Abstract

Incorporating fibers into asphalt mixtures as additives and stabilizers can significantly enhance the performance of asphalt pavements. This study aimed to analyze the impact of using basalt and bamboo fibers as modifiers on the properties of asphalt mastics. The effects of different types [...] Read more.

Incorporating fibers into asphalt mixtures as additives and stabilizers can significantly enhance the performance of asphalt pavements. This study aimed to analyze the impact of using basalt and bamboo fibers as modifiers on the properties of asphalt mastics. The effects of different types of fibers on rutting resistance, fatigue resistance, elastic recovery, and low-temperature cracking performance were tested using frequency scanning, linear amplitude scanning (LAS), multiple stress creep and recovery (MSCR), elastic recovery, and bending beam rheometer (BBR) experiments. The study results suggest that adding fibers into asphalt mastics can effectively improve their stiffness, and the higher the fiber content, the better the stiffness enhancement. Moreover, the characteristic flow index of asphalt mastics grows gradually with the rise in temperature, indicating that these materials exhibit near-Newtonian fluid behavior at elevated temperatures. Furthermore, incorporating fibers significantly enhances the high-temperature rutting resistance of asphalt mastics. However, the addition of fibers did not demonstrate any appreciable benefits in terms of fatigue resistance. The elasticity of asphalt mastics cannot be significantly changed by fiber content without compromising their elastic recovery. Surprisingly, the study’s findings showed that adding basalt fibers to asphalt mastics did not improve their resistance to low-temperature cracks. On the other hand, it was discovered that the ability of asphalt mastics to resist cracking at low temperatures could be made up for by the use of bamboo fibers as a modifier together with a raised temperature. Overall, it was discovered that bamboo fibers performed better than basalt fibers at improving the performance of modified asphalt mastics. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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17 pages, 4900 KiB

Open AccessArticle

An Explorative Study into the Influence of Different Fibers on the Spalling Resistance and Mechanical Properties of Self-Compacting Concrete after Exposure to Elevated Temperatures

by Xiliang Ning, Jianfeng Li and Yuanyuan Li

Appl. Sci. 2022, 12(24), 12779; https://doi.org/10.3390/app122412779 - 13 Dec 2022

Cited by 6 | Viewed by 1461

Abstract

This study aims to explore the impact of different fibers on the explosive spalling resistance, residual compressive strength, residual flexural tensile strength, and mass loss of self-compacting concrete (SCC) after heating to elevated temperatures. The fiber types, fiber contents, and target temperatures are [...] Read more.

This study aims to explore the impact of different fibers on the explosive spalling resistance, residual compressive strength, residual flexural tensile strength, and mass loss of self-compacting concrete (SCC) after heating to elevated temperatures. The fiber types, fiber contents, and target temperatures are selected as the tested variables. Steel fibers (SF), polypropylene fibers (PF), and their combination are used to improve the fire resistance of SCC. Then, the specimens are tested after exposure to different target temperatures varying from 200 °C to 1000 °C and cooling down to room temperature naturally. The obtained results reveal that PF can effectively prevent explosive spalling in the SCC. Moreover, it was found that the temperature of 400 °C is a critical temperature for the residual compressive strength of fiber-reinforced SCC. Regarding the flexural tensile strength, the temperature of 200 °C was found to be a changing point of the SCC after heating to elevated temperatures. A sharp decrease in the compressive strength is observed when the target temperature exceeds 400 °C. For temperatures below 400 °C, the compressive strength is enhanced slightly with the increase of the target temperature. Moreover, incorporating a fiber cocktail is an effective way to improve the explosive spalling resistance and residual mechanical properties in the case of fire. Finally, the regression analysis was performed and the proposed correlations between the residual strengths and elevated temperatures are compared with equations in the literature. Good accuracy of the proposed correlation is achieved for fiber-reinforced SCC. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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19 pages, 4813 KiB

Open AccessArticle

Effect of Adding Waste Polyethylene and GGBFS on the Engineering Properties of Cement Mortar

by Chang-Chi Hung, Jung-Nan Chang, Her-Yung Wang and Fu-Lin Wen

Appl. Sci. 2022, 12(24), 12665; https://doi.org/10.3390/app122412665 - 10 Dec 2022

Cited by 3 | Viewed by 1086

Abstract

The recycling of waste materials has become an important topic worldwide. Wastes can be effectively used in concrete to improve its characteristics. This study aimed to research cement mortar’s physical properties, mechanical properties, and durability. In a cement mortar with a fixed water-to-binder [...] Read more.

The recycling of waste materials has become an important topic worldwide. Wastes can be effectively used in concrete to improve its characteristics. This study aimed to research cement mortar’s physical properties, mechanical properties, and durability. In a cement mortar with a fixed water-to-binder ratio (W/B) of 0.5, waste polyethylene (PE) was added at sand volume ratios of 0%, 1%, 2%, 3%, and 4%. Cement was replaced with 0%, 10%, and 20% ground granulated blast furnace slag (GGBFS). The results showed that the slump and flow of mortar tended to decline as the added amount of waste PE increased, but they also increased with the increased replaced amount of GGBFS. The setting time of mortar was shortened as the waste PE increased but delayed as the amount of GGBFS increased. In terms of mechanical properties, the compressive strength of mortar declined as the replaced amount of waste PE increased. Using the GGBFS to replace part of the cement can improve the later mortar strength. This study found that when the added waste PE was within 2% and the replacement amount of GGBFS was 10%, the goal of recycling waste was reached most effectively, while maintaining the concrete’s mechanical properties. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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13 pages, 4610 KiB

Open AccessArticle

Investigation into the Flexural Toughness and Methods of Evaluating Ductile Concrete

by Yonggang Ding, Yunfei Li, Xiangyang Zhao, Jie Dai and Hualong Xu

Appl. Sci. 2022, 12(23), 12313; https://doi.org/10.3390/app122312313 - 01 Dec 2022

Cited by 2 | Viewed by 980

Abstract

The main purpose of this study was to investigate the flexural behavior of high-ductility fiber-reinforced concrete (HDC) and propose a suitable method for evaluating flexural toughness. The flexural strength, deformation, and toughness of HDC were investigated through four-point bending tests with specimens of [...] Read more.

The main purpose of this study was to investigate the flexural behavior of high-ductility fiber-reinforced concrete (HDC) and propose a suitable method for evaluating flexural toughness. The flexural strength, deformation, and toughness of HDC were investigated through four-point bending tests with specimens of 40 × 40 × 160 mm. The test parameters were fiber volume fractions (0%, 1%, 1.5%, and 2%), water–binder ratios (0.24, 0.26, 0.29, and 0.32), and ages (28 d and 56 d). The experimental results showed that polyvinyl alcohol (PVA) fibers led to significant improvement in the flexural behavior of HDC due to its strain-hardening behavior and excellent crack dispersion capacity. The ultimate flexural strength of HDC with 2% PVA fibers of about 15.32 MPa showed an increase of up to 221%. The deformation and flexural toughness ratios were 23 times and 1.43 times higher, respectively, than the specimens without fibers. A simple and practical method for evaluating the flexural toughness of HDC was proposed, which solved many problems with the existing methods. This method made full use of the peak load, which overcame the difficulty of identifying the initial crack information, solved the insufficient deflection limit, and provided a more comprehensive and accurate evaluation by selecting characteristic points evenly distributed throughout the loading process. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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14 pages, 5426 KiB

Open AccessArticle

Application of Self-Compacting Steel Fiber Reinforced Concrete for Pervious Frames Used for River Revetment

by Haibin Geng, Xinxin Ding, Hao Du, Jiaxin Shi, Changyong Li and Xiaoke Li

Appl. Sci. 2022, 12(20), 10457; https://doi.org/10.3390/app122010457 - 17 Oct 2022

Cited by 4 | Viewed by 1283

Abstract

Aimed at improving the production efficiency of tetrahedron-like pervious frames for the river revetment, self-compacting steel fiber reinforced concrete (SFRC) was applied to strengthen the tensile resistance of concrete to remove conventional steel bars used as reinforcement. The workability and mechanical properties of [...] Read more.

Aimed at improving the production efficiency of tetrahedron-like pervious frames for the river revetment, self-compacting steel fiber reinforced concrete (SFRC) was applied to strengthen the tensile resistance of concrete to remove conventional steel bars used as reinforcement. The workability and mechanical properties of self-compacting SFRC were experimentally studied with the volume fraction of steel fiber changed from 0.4% to 1.2%, and the rational volume fraction of 0.8% was determined for producing the pervious frames. Based on the flow-induced orientation of the steel fibers in the fresh mix, the casting process of self-compacting SFRC was optimal from one inclined rod to other two inclined rods and the horizontal rods of the pervious frame. The loading capacities of pervious frames during lifting and stacking were respectively detected by the simulation tests on the testing machine, which ensure the safety of pervious frames lifted six layers together and stacked for nineteen layers. By testing groups of pervious frames throwed in and then salvaged from the river, the quality of pervious frames without any damage was observed. Finally, the pervious frames were successfully applied in an engineering project for the river revetment. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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21 pages, 7156 KiB

Open AccessArticle

Methodology for Predicting the Structural Response of RPC-Filled Steel Tubular Columns under Blast Loading

by Zhizhong Jiang, Qin Rong, Xiaomeng Hou, Zhonghui Zhao and Enyuan Yang

Appl. Sci. 2022, 12(18), 9142; https://doi.org/10.3390/app12189142 - 12 Sep 2022

Cited by 9 | Viewed by 1502

Abstract

Reactive powder concrete-filled steel tube (RPC-FST) is a critical supporting component of large-span, high-rise, and heavy-load structures. The collapse of RPC-FST may occur under explosive load. Therefore, investigation of the dynamic response is essential for understanding the mechanisms of collapse. In this article, [...] Read more.

Reactive powder concrete-filled steel tube (RPC-FST) is a critical supporting component of large-span, high-rise, and heavy-load structures. The collapse of RPC-FST may occur under explosive load. Therefore, investigation of the dynamic response is essential for understanding the mechanisms of collapse. In this article, the numerical simulation of reactive powder concrete (RPC) adopted the modified Holmquist–Johnson–Cook (HJC) model and the modified Karagozian and Case (K&C) model. The dynamic response of RPC-FST columns under explosive load is analyzed based on arbitrary Lagrange–Euler (ALE) method. The proposed model is verified by experimental results. Results show that the modified HJC model and modified K&C model can be applied to simulate the dynamic response of RPC-FST columns under explosive load. As compared with the modified HJC model, the modified K&C model has more accurate results. This phenomenon mainly accounts for the lack of ultimate strain of RPC (EFMIN). To analyze the reliability sensitivity of RPC-FST, an efficient probability analysis method is proposed based on the Kriging model and Monte Carlo simulation (MCS). The proposed method considers five nonlinear factors, including weight and distance of TNT, height and section diameter of RPC-FST, and steel tube thickness. Finally, the sensitivity of each factor is evaluated. Results show that TNT weight greatly influences the reliability of the RPC-FST, followed by TNT distance, RPC-FST height, RPC-FST section diameter, and steel tube thickness. In addition, the RPC-FST dynamic response analysis method based on the Kriging model and MCS can improve the calculation efficiency by more than 200 times compared with the ALE method. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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13 pages, 2563 KiB

Open AccessArticle

Performance-Based Fibre Design for Ultra-High Performance Concrete (UHPC)

by Jan-Paul Lanwer and Martin Empelmann

Appl. Sci. 2022, 12(17), 8559; https://doi.org/10.3390/app12178559 - 26 Aug 2022

Cited by 4 | Viewed by 1366

Abstract

The paper presents a method to establish a performance-based fibre design of high-strength micro steel fibres for ultra-high-performance concrete (UHPC). The performance-based fibre design considers effects of fibre layout, fibre orientation, and type of loading (quasi-static and cyclic) and expands the current approach [...] Read more.

The paper presents a method to establish a performance-based fibre design of high-strength micro steel fibres for ultra-high-performance concrete (UHPC). The performance-based fibre design considers effects of fibre layout, fibre orientation, and type of loading (quasi-static and cyclic) and expands the current approach using experiences and suitability testing results. The performance-based fibre design is based on a so-called utilization rate, which is determined via pullout tests of high-strength micro steel fibres in UHPC under quasi-static as well as high cyclic loading with varying orientations and embedment depths. The utilization rate for a straight fibre pullout is 0.27 on average considering the measured tensile strength of the fibre and 0.50 considering the manufacturers specifications. For inclined fibres, additional bending stresses occur at the exit point of the fibre channels, leading to a significant increase in local tensile stress. Therefore, the utilization rate of inclined fibres under quasi-static loading is approximately 60–70% higher than in the case of straight embedded fibres (comparing it to the measured tensile strength). Comparing the utilization rate to the manufacturer’s specification, it increases to approximately 1.00. Under cyclic loading, the additional bending stresses in inclined fibres result in a local increase of the load amplitude, leading to a reduced fatigue resistance and premature fibre rupture, underlining the feasibility of a performance-based fibre design. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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19 pages, 7271 KiB

Open AccessArticle

Susceptibility to Expansive Reactions of a Greener UHPC: Micro to Macro-Scale Study

by Ana Mafalda Matos

Appl. Sci. 2022, 12(12), 6252; https://doi.org/10.3390/app12126252 - 20 Jun 2022

Cited by 3 | Viewed by 1472

Abstract

Nowadays, in Europe, several infrastructures, such as bridges, viaducts, and maritime structures, are in an advanced state of degradation. Therefore, novel repair/rehabilitation techniques are sought. Recent advances in ultra-high-performance fibre-reinforced cement-based composites (UHPFRC) represent a significant step towards resilient structures. In addition to [...] Read more.

Nowadays, in Europe, several infrastructures, such as bridges, viaducts, and maritime structures, are in an advanced state of degradation. Therefore, novel repair/rehabilitation techniques are sought. Recent advances in ultra-high-performance fibre-reinforced cement-based composites (UHPFRC) represent a significant step towards resilient structures. In addition to their remarkable mechanical properties (compressive strength > 150 MPa), they present extremely low permeability and, as a premise, very high durability. Despite their relatively high cost, UHPFRC can be a competitive solution for rehabilitation/strengthening applications where smaller volumes are needed. UHPFRC applied in thin layers (with or without reinforcement) can replace carbonated and/or cracked concrete acting as a protective watertight and/or strengthening layer. The structural capacity increases (stiffness, ultimate strength), and the durability is expected to improve significantly while keeping cross-sectional dimensions. Additional advantages are expected, such as reduced intervention time, fewer maintenance routines, reduced life-cycle cost, and longer service life. Although much of the focus on UHPFRC has centred on mechanical and/or structural performance, durability is inevitably linked with mechanical properties. The current work evaluated the durability of non-property and greener UHPC concerning expansive reactions, alkali-silica reactions and expansion due to external sulphates, by macro and micro-scale integrative study. Linear expansion tests were performed in UHPC specimens according to ASTM C 1260 and LNEC E−364. At the macro level, no deleterious expansion due to ASR or external sulphate occured. Expansion due to ASR was 0.0018% after 14 days of immersion in an alkali-rich environment, and no expansion was recorded regarding sulphate attack. However, SEM analysis reveals reactive products of ASR and sulphate attack, namely, ASR gel and ettringite, respectively, in UHPC specimens. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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15 pages, 6058 KiB

Open AccessArticle

Study on Microwave Deicing of Carbon-Fiber-Modified Concrete under Multi-Factor Coupling Effect

by He Huang, Jinyu Xu, Ao Yao, Wei Xia, Erlei Bai and Yipeng Ning

Appl. Sci. 2022, 12(11), 5551; https://doi.org/10.3390/app12115551 - 30 May 2022

Cited by 6 | Viewed by 1288

Abstract

To explore the law of microwave deicing of carbon-fiber-modified concrete under the action of multiple factors and improve its application in pavement, in this study, we designed a test of the heat absorption and deicing effect of concrete under the action of multiple [...] Read more.

To explore the law of microwave deicing of carbon-fiber-modified concrete under the action of multiple factors and improve its application in pavement, in this study, we designed a test of the heat absorption and deicing effect of concrete under the action of multiple factors. We found that the law of heat absorption and deicing of CFRP is influenced by the coupling effect of fiber length and dosage, height (straight-line distance between the microwave receiving surface and bell component), initial temperature and ice cover. The temperature rises fastest when the fiber dosage is 0.2% and fiber length is 6 mm without ice. Further analysis of other factors shows that the deicing effect is optimal when the height is 40 mm, and the presence of ice on fiber-reinforced concrete weakens the microwave deicing efficiency, although the reduction is small. The test results of these two factors are in agreement with the simulation results and conform to expectations. The initial temperature has a considerable influence on the deicing efficiency. In practical applications, the deicing time should be adjusted according to the initial temperature in order to prevent the phenomenon of secondary icing when the heating time is too long. Based on heat generation and heat dissipation, the four stages of microwave deicing were analyzed, and the relationship with the temperature increase rate was deduced. It was proven that carbon fiber affected the deicing efficiency by changing the microwave absorption and reflection effect of concrete. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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19 pages, 5916 KiB

Open AccessArticle

Study on Impact Compression Performance and Constitutive Model of Aluminum Oxide Fiber-Reinforced Concrete

by Ao Yao, Jinyu Xu, Wei Xia, He Huang and Yipeng Ning

Appl. Sci. 2022, 12(10), 4909; https://doi.org/10.3390/app12104909 - 12 May 2022

Cited by 4 | Viewed by 1296

Abstract

In order to explore the impact compression performance of aluminum oxide fiber concrete, the impact compression test of aluminum oxide fiber concrete with different contents is carried out by using the split Hopkinson pressure bar (SHPB) comprehensive test system with a diameter of [...] Read more.

In order to explore the impact compression performance of aluminum oxide fiber concrete, the impact compression test of aluminum oxide fiber concrete with different contents is carried out by using the split Hopkinson pressure bar (SHPB) comprehensive test system with a diameter of 100 mm. Our intent was to explore the influence law of different contents of aluminum oxide fiber on the impact compression performance of concrete matrixes, and to optimize and establish a constitutive model based on damage theory and stress residue. The results show that adding alumina short-cut fiber to concrete changes its mechanical properties of impact compression to a certain extent. When the volume content of fiber is 0.2%, the characteristics of strength, deformation, and energy are the best, and the excess aluminum oxide fiber reduces the original performance due to agglomeration and other factors; the strength characteristics, peak deformation characteristics, and energy characteristics of aluminum oxide fiber concrete are significantly affected by strain rate and impact velocity. Based on the Zhu-Wang-Tang non-linear viscoelastic model (ZWT model), the complexity coefficient is optimized and the residual stress term is added to construct the prediction model of aluminum oxide fiber concrete. The parameters in the model have a good prediction effect on the stress-strain curve under different strain rates. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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16 pages, 4360 KiB

Open AccessArticle

Study on Dynamic Constitutive Model of Polypropylene Concrete under Real-Time High-Temperature Conditions

by Rui Li, Lei Liu, Huaming An and Ya Wang

Appl. Sci. 2022, 12(3), 1482; https://doi.org/10.3390/app12031482 - 29 Jan 2022

Cited by 5 | Viewed by 2035

Abstract

Polypropylene (PP) concrete, a kind of high-performance fiber-reinforced concrete, is widely used in large concrete structures. Studies on the dynamic mechanical properties of polypropylene concrete under temperature–impact load can provide a theoretical basis for research on the structural stability of concrete structures during [...] Read more.

Polypropylene (PP) concrete, a kind of high-performance fiber-reinforced concrete, is widely used in large concrete structures. Studies on the dynamic mechanical properties of polypropylene concrete under temperature–impact load can provide a theoretical basis for research on the structural stability of concrete structures during fires, explosions, and other disasters. The purpose of this paper was to study the dynamic mechanical properties of polypropylene concrete under real-time high-temperature conditions and to establish a dynamic damage constitutive model for polypropylene concrete under real-time high-temperature conditions. In this paper, Split Hopkinson Pressure Bar (SHPB) equipment was used to test the dynamic mechanical properties of polypropylene concrete with different high strain rates under different real-time high temperatures (room temperature, 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C). A modified “Z-W-T” model was used to determine the recursion of the dynamic damage constitutive model of polypropylene concrete under different temperature–impact loads, and the model was compared with the experimental data. The results show that the thermal conditions influenced the chemical composition and microstructure of the polypropylene fiber concrete, which was why the high temperatures had a strong influence on the dynamic mechanical properties of polypropylene concrete. When the heating temperature exceeded 300 °C, although the polypropylene concrete specimen was still able to maintain a certain strength, the dynamic mechanical properties showed a deterioration trend as the temperature increased. The comparation between the experimental data and the fitting curve of the dynamic damage constitutive model showed that the dynamic stress–strain curves could be well matched with the fitting curves of the dynamic damage constitutive model, meaning that this model could describe the dynamic mechanical properties of polypropylene concrete under different real-time high temperatures well. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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9 pages, 1995 KiB

Open AccessArticle

Electrical Conductivity and Compressive Strength of Cement Paste with Multiwalled Carbon Nanotubes and Graphene Nanoplatelets

by Kwang Mo Lim and Joo Ha Lee

Appl. Sci. 2022, 12(3), 1160; https://doi.org/10.3390/app12031160 - 23 Jan 2022

Cited by 10 | Viewed by 2049

Abstract

Many studies have been conducted using carbon-based nanomaterials (CBNs) for improving the electrical conductivity and mechanical properties of cementitious composites, but their practical use is yet to be achieved. Several methods have been attempted to secure the dispersibility in the cementitious composite matrix [...] Read more.

Many studies have been conducted using carbon-based nanomaterials (CBNs) for improving the electrical conductivity and mechanical properties of cementitious composites, but their practical use is yet to be achieved. Several methods have been attempted to secure the dispersibility in the cementitious composite matrix of CBNs, such as multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). In this study, MWCNTs and GNPs were noncovalently functionalized using melamine, a low-cost chemical, and ball milling, a simple process commonly used in industrial fields. Additionally, MWCNTs and GNPs having one- and two-dimensional shapes were mixed with the cement paste to examine their effect on electrical conductivity and compressive strength. Following the experiment, it was shown that the electrical conductivity was improved via the noncovalent functionalization of MWCNT and GNP. The compressive strength increased up to approximately 0.30–0.60% of the CBNs content; however, for CBN content higher than 0.60%, the compressive strength decreased. The hybrid MWCNT and GNP mixture had a negligible effect on the electrical conductivity and compressive strength. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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21 pages, 5303 KiB

Open AccessArticle

Mix Design and Engineering Properties of Fiber-Reinforced Pervious Concrete Using Lightweight Aggregates

by Chao-Wei Tang, Chiu-Kuei Cheng and Lee-Woen Ean

Appl. Sci. 2022, 12(1), 524; https://doi.org/10.3390/app12010524 - 05 Jan 2022

Cited by 12 | Viewed by 2668

Abstract

The main purpose of this study was to investigate the mix design and performance of fiber-reinforced pervious concrete using lightweight coarse aggregates instead of ordinary coarse aggregates. There were two main stages in the relevant testing work. First, the properties of the matrix [...] Read more.

The main purpose of this study was to investigate the mix design and performance of fiber-reinforced pervious concrete using lightweight coarse aggregates instead of ordinary coarse aggregates. There were two main stages in the relevant testing work. First, the properties of the matrix were tested with a rheological test and then different amounts of lightweight coarse aggregate and fine aggregate were added to the matrix to measure the properties of the obtained lightweight pervious concrete (LPC). In order to greatly reduce the experimental workload, the Taguchi experimental design method was adopted. An orthogonal array L₉(3⁴) was used, which was composed of four controllable three-level factors. There were four test parameters in this study, which were the lightweight coarse aggregate size, ordinary fine aggregate content, matrix type, and aggregate/binder ratio. The research results confirmed that the use of suitable materials and the optimal mix proportions were the key factors for improving the mechanical properties of the LPC. Due to the use of silica fume, ultrafine silica powder, and polypropylene fibers, the 28-day compressive strength, 28-day flexural strength, and 28-day split tensile strength of the LPC specimens prepared in this study were 4.80–7.78, 1.19–1.86, and 0.78–1.11 MPa, respectively. On the whole, the mechanical properties of the prepared LPC specimens were better than those of the LPC with general composition. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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15 pages, 10341 KiB

Open AccessArticle

Experimental Study of the Thermal and Dynamic Behaviors of Polypropylene Fiber-Reinforced Concrete

by Liu Lei, Lizhe Dong, Huaming An, Yuqing Fan and Ya Wang

Appl. Sci. 2021, 11(22), 10757; https://doi.org/10.3390/app112210757 - 15 Nov 2021

Cited by 4 | Viewed by 1630

Abstract

The wide use of high-performance concrete (HPC) makes it essential to study its dynamic and thermal behavior. In this study, polypropylene fiber-reinforced high-performance concrete was developed and a series of tests were carried out to obtain its mechanical and thermal properties. Since high-strength [...] Read more.

The wide use of high-performance concrete (HPC) makes it essential to study its dynamic and thermal behavior. In this study, polypropylene fiber-reinforced high-performance concrete was developed and a series of tests were carried out to obtain its mechanical and thermal properties. Since high-strength HPC has previously been studied intensively, only low-strength HPC—i.e., C30, C40, and C50—was studied in this research. The split Hopkinson pressure bar (SHPB) was employed to carry out the dynamic tests of the HPC under various loading rates and the principles of the SHPB were introduced in detail. Then, the polypropylene fiber-reinforced HPCs were heated to various high temperatures and measures were taken to keep the temperatures relatively constant. It was found that at temperatures lower than 100 °C, the specimen could still be kept in its entirety, although many fractures were produced in the HPC specimen under dynamic loading conditions. However, it was found that at temperatures higher than 200 °C, all the HPC samples were smashed into fragments. In addition, the HPC’s compressive strength was found to be significantly influenced by the temperature. At temperatures lower than 300 °C, the HPC’s compressive strength was found to increase with increases in temperature. At temperatures higher than 300 °C, the HPC’s compressive strength was found to decrease with increases in temperature. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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19 pages, 6082 KiB

Open AccessArticle

Experimental Study on Mechanical Properties of Steel-Polyvinyl Alcohol Fibre-Reinforced Recycled Concrete

by Haicheng Niu, Lei Wang, Jianhua Li and Jiakun Ji

Appl. Sci. 2021, 11(22), 10550; https://doi.org/10.3390/app112210550 - 09 Nov 2021

Cited by 4 | Viewed by 1528

Abstract

Research on the utilization of recycled concrete in civil engineering applications is gaining popularity world-wide due to the increased efforts to promote preservation of the environment and sustainable development. Recycled concrete is, however, presently still limited to nonstructural applications. This is due to [...] Read more.

Research on the utilization of recycled concrete in civil engineering applications is gaining popularity world-wide due to the increased efforts to promote preservation of the environment and sustainable development. Recycled concrete is, however, presently still limited to nonstructural applications. This is due to the poor mechanical properties of recycled concrete, which make it difficult to cope with complex mechanical environments. Therefore, an experimental work is presented to investigate the mechanical behaviour of recycled concrete, focusing on the cube, flexural, and uniaxial compressive mechanical properties of steel-polyvinyl alcohol fibre-doped specimens. The test results showed that the compressive strength and the flexural strength of the recycled concrete increased by 6.0% and 55.2%, respectively, when steel fibre was single-incorporated. The cubic compressive strength of the recycled concrete decreased by 14.1% when polyvinyl alcohol fibre was single-incorporated, but there was a 47.9% increase in the flexural strength of recycled concrete. Based on these tests, the elastic modulus, the Poisson’s ratio, and the uniaxial compression toughness were digitised to derive mathematical expressions that provided a theoretical understanding of the mechanical properties of steel-polyvinyl alcohol fibre-reinforced recycled concrete. Moreover, combining the characteristics of the uniaxial compressive stress–strain curve of fibre-reinforced recycled concrete, an equation for the uniaxial compressive stress–strain curve of recycled concrete associated with the fibre characteristic value was established, which agreed well with the test results. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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21 pages, 6331 KiB

Open AccessArticle

Effect of Fiber Reinforcement on the Compression and Flexural Strength of Fiber-Reinforced Geopolymers

by Michał Łach, Bartłomiej Kluska, Damian Janus, Dawid Kabat, Kinga Pławecka, Kinga Korniejenko, Martin Duarte Guigou and Marta Choińska

Appl. Sci. 2021, 11(21), 10443; https://doi.org/10.3390/app112110443 - 06 Nov 2021

Cited by 15 | Viewed by 2593

Abstract

This work aimed to determine the effect of the addition of different types of reinforcing fibers on the strength properties of geopolymers such as flexural and compressive strength. Geopolymers are an attractive alternative to conventional binders and building materials; however, one of the [...] Read more.

This work aimed to determine the effect of the addition of different types of reinforcing fibers on the strength properties of geopolymers such as flexural and compressive strength. Geopolymers are an attractive alternative to conventional binders and building materials; however, one of the main problems of their widespread use is their low resistance to brittle fracture. To improve the mechanical properties, reinforcement in the form of glass, carbon, and basalt fibers (as grids) was applied to geopolymers in the following work. Additionally, composites with these fibers were produced not only in the matrix of pure geopolymer but also as a hybrid variant with the addition of cement. Furthermore, basalt grids were used as reinforcement for geopolymers not only based on ash but also metakaolin. An additional variable used in the study was the molar concentration of the alkali solution (5 M and 10 M) for the different types of geopolymer samples. The mechanical properties of geopolymer materials and geopolymer–cement hybrids are the highest when reinforcement in the form of carbon fiber is used. Strength values for geopolymers reinforced with basalt mats depend on the number of reinforcement layers and the concentration of the alkaline solution used. All produced composites were tested for compressive strength and bending strength. When using basalt mesh, it was possible to achieve a bending strength of 12 MPa. The highest compressive strength that was achieved was the value of 66 MPa, while for samples not reinforced with fibers, only about 40 MPa was achieved. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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21 pages, 7184 KiB

Open AccessArticle

Properties of Fibre-Reinforced High-Strength Concrete with Nano-Silica and Silica Fume

by Arash Karimipour, Mansour Ghalehnovi, Mahmoud Edalati and Jorge de Brito

Appl. Sci. 2021, 11(20), 9696; https://doi.org/10.3390/app11209696 - 18 Oct 2021

Cited by 17 | Viewed by 2206

Abstract

This study intends to assess the influence of steel fibres (SF) and polypropylene fibres (PPF) on the hardened and fresh state properties of high-strength concrete (HSC). For this purpose, 99 concrete mixes were designed and applied. SF and PPF were used at six-volume [...] Read more.

This study intends to assess the influence of steel fibres (SF) and polypropylene fibres (PPF) on the hardened and fresh state properties of high-strength concrete (HSC). For this purpose, 99 concrete mixes were designed and applied. SF and PPF were used at six-volume replacement contents of 0%, 0.1%, 0.2%, 0.3%, 0.4% and 0.5%. Moreover, nano-silica (NS) was used at three contents, 0%, 1% and 2%, and silica fume powder (SP) was also used at three weight ratios (0%, 5% and 10%). The slump, compressive and tensile strength, elasticity modulus, water absorption and the electric resistivity of concrete specimens were examined. The results showed that using 1% NS and 10% SP together with 0.5% PPF improved the compressive strength of HSC by about 123%; however, the effect of SF on tensile strength is more significant and adding 0.5% SF with both 2% NS and 10% SP increased the tensile strength by 104%. Moreover, increasing the SF content reduces the electric resistivity while using PPF improves this property especially when 1% NS was employed, and it was enhanced by about 68% when 0.5% SF and 1% NS were utilized with 10% SP. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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14 pages, 6628 KiB

Open AccessArticle

Fundamental Investigations on the Performance of Micro Steel Fibres in Ultra-High-Performance Concrete under Monotonic and Cyclic Tensile Loading

by Jan-Paul Lanwer and Martin Empelmann

Appl. Sci. 2021, 11(20), 9377; https://doi.org/10.3390/app11209377 - 09 Oct 2021

Cited by 6 | Viewed by 1603

Abstract

Ultra-high-performance fibre-reinforced concrete (UHPFRC) can preferably be used for lean and thin-walled structures due to its very high compressive strength. Based on the adverse relation between the increased load bearing capacities and the condensed dead weight of UHPFRC-structures, the impact of live loads [...] Read more.

Ultra-high-performance fibre-reinforced concrete (UHPFRC) can preferably be used for lean and thin-walled structures due to its very high compressive strength. Based on the adverse relation between the increased load bearing capacities and the condensed dead weight of UHPFRC-structures, the impact of live loads in the design gets bigger and, in case of traffic loads, the effects of a cyclic loading have to be considered in more detail. In this context, this study investigated the material behaviour of UHPFRC, especially the tensile fatigue behaviour of high-strength micro steel fibres and the bond behaviour between those fibres and plain UHPC. The test programme included once tensile tests of high-strength micro steel fibres under monotonic and cyclic loading. Based on the test results, an S/N-curve was set up with the characteristic values. Furthermore, the test programme included pullout tests of fibre groups with different embedded lengths and orientations under monotonic and cyclic loading. It was observed that some fibres rupture under certain test configurations like the angle of orientation and the load amplitude. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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29 pages, 10704 KiB

Open AccessArticle

Experimental Study of the Compressive Strengths of Basalt Fiber-Reinforced Concrete after Various High-Temperature Treatments and Cooling in Open Air and Water

by Huaming An, Yushan Song, Lei Liu and Xiang Meng

Appl. Sci. 2021, 11(18), 8729; https://doi.org/10.3390/app11188729 - 18 Sep 2021

Cited by 5 | Viewed by 1893

Abstract

The rapid development of modern society has increased the demand for high-performance geo-materials. As an advanced cementitious composite, fiber-reinforced concrete has attracted much attention and has been widely applied to various buildings and civil infrastructure. A basalt fiber-reinforced concrete is proposed as an [...] Read more.

The rapid development of modern society has increased the demand for high-performance geo-materials. As an advanced cementitious composite, fiber-reinforced concrete has attracted much attention and has been widely applied to various buildings and civil infrastructure. A basalt fiber-reinforced concrete is proposed as an advanced geo-material and the mechanical and thermal properties were investigated in this study. The basalt fiber-reinforced concrete was compared with ordinary concrete to confirm its superiority by determination of the physical parameters, static compressive test, and dynamic compressive test. The static compressive test was performed using the YAW-2000C constant stress pressure experimental machine under different heating temperatures and cooling methods, while the dynamic compressive test was performed using the 75-mm split-Hopkinson pressure bar under different loading rates, heating temperatures, and cooling methods. For the basic physical parameters, it was found that the mass loss and wave velocity of concrete decrease with the increase of the temperature. In the static compressive test, the static compressive strength for both the ordinary concrete and the fiber-reinforced concrete decreased with the increase of the temperature, and greater strength was observed with the air-cooled compared to the water-cooled method. It was found that the strength of basalt fiber-reinforced concrete is greater than that of ordinary concrete. In the dynamic compressive test, the strength increased with an increasing loading rate and descended with an increasing temperature, while for the same heating temperature and loading rate, water cooling produced more irregular and smaller fragments than air cooling. The dynamic compressive strength of basalt fiber-reinforced concrete was bigger than that of ordinary concrete. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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14 pages, 5060 KiB

Open AccessArticle

Experimental Study on Mechanical Properties of High Performance Hybrid Fiber Concrete for Shaft Lining

by Qian Zhang, Wenqing Zhang, Yu Fang, Yongjie Xu and Xianwen Huang

Appl. Sci. 2021, 11(17), 7926; https://doi.org/10.3390/app11177926 - 27 Aug 2021

Cited by 4 | Viewed by 1518

Abstract

In order to solve the problem of highly brittle shaft lining under dynamic loading, a combination of hybrid fiber concrete mixed with steel and polypropylene fiber is proposed to make shaft lining. C60, the concrete commonly used in shaft lining, was selected as [...] Read more.

In order to solve the problem of highly brittle shaft lining under dynamic loading, a combination of hybrid fiber concrete mixed with steel and polypropylene fiber is proposed to make shaft lining. C60, the concrete commonly used in shaft lining, was selected as the reference group. The static mechanical properties, dynamic mechanical properties, and crack failure characteristics of the hybrid fiber concrete were experimentally studied. The test results showed that compared to the reference group concrete, the compressive strength of the hybrid fiber-reinforced concrete did not significantly increase, but the splitting tensile strength increased by 60.4%. The split Hopkinson compression bar results showed that the optimal group peak stress and peak strain of the hybrid fiber concrete increased by 58.2% and 79.2%, respectively, and the dynamic toughness increased by 68.1%. The strain distribution before visible cracks was analyzed by the DIC technology. The results showed that the strain dispersion phenomenon of the fiber-reinforced concrete specimen was stronger than that of the reference group concrete. By comparing the crack failure forms of the specimens, it was found that compared to the reference group concrete, the fiber-reinforced concrete specimens showed the characteristics of continuous and slow ductile failure. The above results suggest that HFRC has significantly high dynamic splitting tensile strength and compressive deformation capacity, as well as a certain anti-disturbance effect. It is an excellent construction material for deep mines under complex working conditions. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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12 pages, 4836 KiB

Open AccessArticle

Characteristics of Restrained Drying Shrinkage on Arched Steel Fiber-Reinforced Concrete

by Dae-Jin Kim, Sun-Hee Kim and Won-Chang Choi

Appl. Sci. 2021, 11(16), 7537; https://doi.org/10.3390/app11167537 - 17 Aug 2021

Cited by 5 | Viewed by 1958

Abstract

The volumetric changes of concrete, including drying shrinkage, are effectively controlled in steel fiber-reinforced concrete (SFRC) mixtures due to the action of the included steel fiber. The current code provision in ANSI/SDI C-2017 allows a minimum steel fiber content of 0.2% of the [...] Read more.

The volumetric changes of concrete, including drying shrinkage, are effectively controlled in steel fiber-reinforced concrete (SFRC) mixtures due to the action of the included steel fiber. The current code provision in ANSI/SDI C-2017 allows a minimum steel fiber content of 0.2% of the volume fraction of concrete to control drying shrinkage and to manage cracking in the slab. Limited research has addressed replacing the shear reinforcement in concrete beams with steel fiber. In this study, we used newly developed arched steel fiber to evaluate shrinkage characteristics, including free-drying shrinkage and restrained drying shrinkage, of SFRC and scaled-down deck slab elements. We compared the measured drying shrinkage test results to predicted results obtained from models found in the literature. We confirmed that, overall, the number, width, and length of cracks were reduced significantly at the surface of SFRC slabs when arched steel fiber at 0.2% volume fraction was included in the mixture. Full article

(This article belongs to the Special Issue Advances in High-Performance Fiber-Reinforced Concrete)

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