Materials

Research

Jump to: Review

22 pages, 6230 KiB

Open AccessArticle

Investigating Optimal Confinement Behaviour of Low-Strength Concrete through Quantitative and Analytical Approaches

by Mujahid Ali, Sheraz Abbas, Bashir Salah, Javed Akhter, Waqas Saleem, Sani Haruna, Shah Room and Isyaka Abdulkadir

Materials 2021, 14(16), 4675; https://doi.org/10.3390/ma14164675 - 19 Aug 2021

Cited by 20 | Viewed by 3064

Abstract

Reinforced concrete is used worldwide in the construction industry. In past eras, extensive research has been conducted and has clearly shown the performance of stress–strain behaviour and ductility design for high-, standard-, and normal-strength concrete (NSC) in axial compression. Limited research has been [...] Read more.

Reinforced concrete is used worldwide in the construction industry. In past eras, extensive research has been conducted and has clearly shown the performance of stress–strain behaviour and ductility design for high-, standard-, and normal-strength concrete (NSC) in axial compression. Limited research has been conducted on the experimental and analytical investigation of low-strength concrete (LSC) confinement behaviour under axial compression and relative ductility. Meanwhile, analytical equations are not investigated experimentally for the confinement behaviour of LSC by transverse reinforcement. The current study experimentally investigates the concrete confinement behaviour under axial compression and relative ductility of NSC and LSC using volumetric transverse reinforcement (VTR), and comparison with several analytical models such as Mander, Kent, and Park, and Saatcioglu. In this study, a total of 44 reinforced-column specimens at a length of 18 in with a cross-section of 7 in × 7 in were used for uniaxial monotonic loading of NSC and LSC. Three columns of each set were confined with 2 in, 4 in, 6 in, and 8 in c/c lateral ties spacing. The experimental results show that the central concrete stresses are significantly affected by decreasing the spacing between the transverse steel. In the case of the LSC, the core stresses are double the central stress of NSC. However, increasing the VTR, the capacity and the ductility of NSC and LSC increases. Reducing the spacing between the ties from 8 in to 2 in center to center can affect the concrete column’s strength by 60% in LSC, but 25% in the NSC. The VTR and the spacing between the ties greatly affected the LSC compared to NSC. It was found that the relative ductility of the confined column samples was almost twice that of the unrestrained column samples. Regarding different models, the Manders model best represents the performance before the ultimate strength, whereas Kent and Park represents post-peak behaviour. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

12 pages, 2938 KiB

Open AccessArticle

Mechanical and Durability Properties of Latex-Modified Hybrid Fiber-Reinforced Roller-Compacted Rapid-Set Cement Concrete for Pavement Repair

by Su-Jin Lee, Hyung-Jin Shin and Chan-Gi Park

Materials 2021, 14(14), 3981; https://doi.org/10.3390/ma14143981 - 16 Jul 2021

Cited by 3 | Viewed by 2104

Abstract

This study evaluated the mechanical properties and durability performance of latex-modified hybrid fiber-reinforced roller-compacted rapid-set cement concrete (LMHFRCRSC) for emergency repair of concrete pavement. Experimental parameters included the blend ratio of the hybrid fiber, which comprised natural jute fiber (0–0.2 vol.%) and structural [...] Read more.

This study evaluated the mechanical properties and durability performance of latex-modified hybrid fiber-reinforced roller-compacted rapid-set cement concrete (LMHFRCRSC) for emergency repair of concrete pavement. Experimental parameters included the blend ratio of the hybrid fiber, which comprised natural jute fiber (0–0.2 vol.%) and structural synthetic fiber (0–2 vol.%). The mechanical performance of LMHFRCRSC of various blend ratios was evaluated in terms of compressive, flexural, and splitting tensile strength. Durability assessment included chlorine ion penetration and abrasion resistance measurements. Compressive and flexural strength values of 21 and 3.5 MPa, respectively, were the set targets after 4 h of curing; a compressive strength of 35 MPa, a flexural strength of 4.5 MPa, a splitting tensile strength of 4.2 MPa, and chloride ion penetration of 2000 C or less were required after 28 days of curing. Our test results confirmed that all mix proportions satisfied the target values, regardless of the blend ratio of the hybrid fiber. Specifically, the mechanical performance of the concrete improved as the blend ratio of the structural synthetic fiber increased. With regard to durability, a greater amount of jute fiber, a hydrophilic fiber, enhanced the concrete’s durability. Additionally, incorporating jute fiber of 0.6 kg/m³ provided excellent chlorine ion penetration resistance. The optimal blend ratio for the hybrid fiber was natural jute fiber at 0.6 kg/m³ and structural synthetic fiber at 13.65 kg/m³ (mix: J0.6 + P13.65); with this mix proportion, a chloride ion penetration amount of 1000 C or less and maximum mechanical performance were achieved. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

12 pages, 4668 KiB

Open AccessArticle

Effects of the Replacement Length of Concrete with ECC on the Cyclic Behavior of Reinforced Concrete Columns

by Jung-Hwan Hyun, Jin-Wook Bang, Bang-Yeon Lee and Yun-Yong Kim

Materials 2021, 14(13), 3542; https://doi.org/10.3390/ma14133542 - 25 Jun 2021

Cited by 5 | Viewed by 1920

Abstract

This paper presents an experimental investigation on the effects of the replacement length of concrete with engineered cementitious composites (ECC) on the cyclic behavior of a reinforced concrete (RC) column. A conventional RC column specimen and two RC composite columns designed with ECC [...] Read more.

This paper presents an experimental investigation on the effects of the replacement length of concrete with engineered cementitious composites (ECC) on the cyclic behavior of a reinforced concrete (RC) column. A conventional RC column specimen and two RC composite columns designed with ECC were fabricated. To investigate the cyclic behavior of each specimen, a series of cyclic loading tests was performed under a reversed cyclic loading condition with a constant axial load. Test results showed that ECC columns exhibited higher cyclic behavior in terms of load carrying capacity, ductility, and energy dissipation capacity compared to the RC column. It was also found that when applying ECC to the column specimen with a length of 3.6d or more, the energy dissipation capacity was greatly increased. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

18 pages, 7837 KiB

Open AccessArticle

Experimental Study on the Performance of Graded Glass Fiber Reinforced Concrete (G-GRC) Based on Engineering Application

by Qingbiao Wang, Hongxu Song, Yue Li, Fuqiang Wang, Zhongjing Hu, Shumei Lou and Zhenyue Shi

Materials 2021, 14(5), 1149; https://doi.org/10.3390/ma14051149 - 28 Feb 2021

Cited by 11 | Viewed by 2660

Abstract

An important way to improve concrete performance is the use of alkali-resistant glass fibers (ARGFs) as reinforcement. This paper is based on the problems of the cracking of the partition wall and lining seepage in Laoshan Tunnel, Qingdao, China. Two types of ARGFs [...] Read more.

An important way to improve concrete performance is the use of alkali-resistant glass fibers (ARGFs) as reinforcement. This paper is based on the problems of the cracking of the partition wall and lining seepage in Laoshan Tunnel, Qingdao, China. Two types of ARGFs were selected as reinforcement materials for the partition wall and lining concrete: high dispersion (HD) and high performance (HP); and the compressive strength (CS), tensile strength (TS), flexural strength (FS), and impervious performance (IP) of concrete with different gradations of the two types of fibers were investigated. The results show that although the CS of graded glass fiber reinforced concrete (G-GRC) is slightly decreased, the TS, FS, and IP of G-GRC are significantly improved. When the densities of the ARGFs of HD and HP are 0.6 and 5 kg/m³, respectively, G-GRC performs best; additionally, compared with ordinary concrete, the TS, FS, and IP of G-GRC are increased by 15.86%, 14.90%, and 31.58%, respectively. Meanwhile, the tension–compression ratio is increased by 22.29%, and the mechanical properties of concrete are remarkably enhanced. The research results were successfully applied to the construction of the Laoshan tunnel, and good engineering results were obtained. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

22 pages, 5338 KiB

Open AccessArticle

Structural Behavior of Fibrous-Ferrocement Panel Subjected to Flexural and Impact Loads

by Gunasekaran Murali, Mugahed Amran, Roman Fediuk, Nikolai Vatin, Sudharshan N. Raman, Gundu Maithreyi and Arunachalam Sumathi

Materials 2020, 13(24), 5648; https://doi.org/10.3390/ma13245648 - 11 Dec 2020

Cited by 22 | Viewed by 4249

Abstract

Ferrocement panels, while offering various benefits, do not cover instances of low and moderated velocity impact. To address this problem and to enhance the impact strength against low-velocity impact, a fibrous ferrocement panel is proposed and investigated. This study aims to assess the [...] Read more.

Ferrocement panels, while offering various benefits, do not cover instances of low and moderated velocity impact. To address this problem and to enhance the impact strength against low-velocity impact, a fibrous ferrocement panel is proposed and investigated. This study aims to assess the flexural and low-velocity impact response of simply supported ferrocement panels reinforced with expanded wire mesh (EWM) and steel fibers. The experimental program covered 12 different ferrocement panel prototypes and was tested against a three-point flexural load and falling mass impact test. The ferrocement panel system comprises mortar reinforced with 1% and 2% dosage of steel fibers and an EWM arranged in 1, 2, and 3 layers. For mortar preparation, a water-cement (w/c) ratio of 0.4 was maintained and all panels were cured in water for 28 days. The primary endpoints of the investigation are first crack and ultimate load capacity, deflection corresponding to first crack and ultimate load, ductility index, flexural strength, crack width at ultimate load, a number of impacts needed to induce crack commencement and failure, ductility ratio, and failure mode. The finding revealed that the three-layers of EWM inclusion and steel fibers resulted in an additional impact resistance improvement at cracking and failure stages of ferrocement panels. With superior ultimate load capacity, flexural strength, crack resistance, impact resistance, and ductile response, as witnessed in the experiment program, ferrocement panel can be a positive choice for many construction applications subjected to repeated low-velocity impacts. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

13 pages, 2765 KiB

Open AccessArticle

Pullout Behavior of Recycled Waste Fishing Net Fibers Embedded in Cement Mortar

by Jun Kil Park, Min Ook Kim and Dong Joo Kim

Materials 2020, 13(18), 4195; https://doi.org/10.3390/ma13184195 - 21 Sep 2020

Cited by 15 | Viewed by 2816

Abstract

In this study, recycled waste fishing net (WFN) short fibers were proposed to be used as short fiber reinforcements. The pullout resistance of WFN short fibers embedded in cement mortar was investigated by conducting fiber pullout tests. Three types of WFN short fibers [...] Read more.

In this study, recycled waste fishing net (WFN) short fibers were proposed to be used as short fiber reinforcements. The pullout resistance of WFN short fibers embedded in cement mortar was investigated by conducting fiber pullout tests. Three types of WFN short fibers and two types of commercial polypropylene (CP) fibers were investigated. To quantitatively compare the pullout resistance of WFN short fibers and CP fibers, pullout parameters, including peak pullout load (peak bond strength), peak fiber stress, slip at peak load, and pullout energy (equivalent bond strength) of the pullout specimens, were analyzed. In addition, the analysis of fiber images, captured by using a stereoscopic digital microscope, before and after pullout tests, elucidated the different mechanisms of fiber pullout corresponding to the type of fibers. The bundled structures of the WFN fibers generated mechanical interaction between fiber and matrix during fiber pullout; consequently, they produced higher bond resistance and more damage on the surface of fibers after the pullout. Therefore, the bundled WFN fibers showed comparable pullout resistance with CP fibers. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

22 pages, 8390 KiB

Open AccessArticle

An Experimental Study on the Ductility and Flexural Toughness of Ultrahigh-Performance Concrete Beams Subjected to Bending

by In-Hwan Yang, Jihun Park, The Quang Bui, Kyoung-Chul Kim, Changbin Joh and Hyungbae Lee

Materials 2020, 13(10), 2225; https://doi.org/10.3390/ma13102225 - 12 May 2020

Cited by 40 | Viewed by 3725

Abstract

Ultrahigh-performance concrete (UHPC) and high-strength concrete (HSC) are currently widely used because of their distinct superior properties. Thus, a comprehensive comparison of the flexural behavior of UHPC and HSC beams is presented in this study. Nine UHPC beams and three HSC beams were [...] Read more.

Ultrahigh-performance concrete (UHPC) and high-strength concrete (HSC) are currently widely used because of their distinct superior properties. Thus, a comprehensive comparison of the flexural behavior of UHPC and HSC beams is presented in this study. Nine UHPC beams and three HSC beams were subjected to pure bending tests to investigate the effect of various reinforcement ratios and steel fiber volume contents on the cracking and failure patterns, load-deflection behavior, ductility, and flexural toughness of these beams. The addition of steel fibers in the UHPC improved the energy absorption capacity of the beams, causing the UHPC beams to fail via rebar fracture. The deflection and curvature ductility indices were determined and compared in this study. The ductility indices of the HSC beam tended to decrease sharply as the rebar ratio increased, whereas those of the UHPC beam did not show a clear trend with respect to the rebar ratio. In addition, a comparison between the results in this study and the results from previous studies was performed. In this study, the addition of steel fiber contents up to 1.5% in UHPC increased the load capacity, ductility, and flexural toughness of the UHPC beams, whereas the addition of a steel fiber content of 2.0% did not significantly increase the ductility or flexural toughness of the UHPC beams. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

15 pages, 2551 KiB

Open AccessArticle

Engineering Properties of Basalt Fiber-Reinforced Bottom Ash Cement Paste Composites

by Mohamad Hanafi, Ertug Aydin and Abdullah Ekinci

Materials 2020, 13(8), 1952; https://doi.org/10.3390/ma13081952 - 21 Apr 2020

Cited by 26 | Viewed by 4972

Abstract

Extinction of natural resources builds up pressure on governments to invest in research to find more sustainable resources within the construction sector. Earlier studies on mortar and concrete show that bottom ash and basalt fiber are independently alternative binders in the concrete sector. [...] Read more.

Extinction of natural resources builds up pressure on governments to invest in research to find more sustainable resources within the construction sector. Earlier studies on mortar and concrete show that bottom ash and basalt fiber are independently alternative binders in the concrete sector. This study aims to use bottom ash and basalt fiber blends as alternative novel-based composites in pure cement paste. The strength and durability properties of two different percentages of bottom ash (40% and 50%) and three volume fractions of basalt fiber (0.3%, 0.75%, and 1.5%) were used at three curing periods (7, 28, and 56 days). In order to measure the physical properties of the basalt-reinforced bottom ash cement paste composites flowability, dry unit weight, porosity, and water absorption measurements at 7, 28, and 56 days of curing were performed. Furthermore, the mechanical properties of composites were determined by unconfined compressive strength and flexural strength tests. Finally, to assess the durability, sulfate-resistance and seawater-resistance tests have been performed on composites at 28 and 56 days of curing. Results showed that the addition of basalt fiber improves the physical, mechanical, and chemical stability properties of paste up to a limiting basalt fiber addition (0.3% volume fraction) where, above, an adverse effect has been monitored. It is clear that observed results can lead to the development of sustainability strategies in the concrete industry by utilizing bottom ash and basalt fiber as an alternative binder. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

16 pages, 2303 KiB

Open AccessArticle

Carbon-Fiber Enriched Cement-Based Composites for Better Sustainability

by Mohamad Atiyeh and Ertug Aydin

Materials 2020, 13(8), 1899; https://doi.org/10.3390/ma13081899 - 17 Apr 2020

Cited by 32 | Viewed by 4941

Abstract

Damage caused by global warming is rapidly increasing, and its adverse effects become more evident with each passing day. Although it is known that the use of alternative binder materials in concrete would decrease this negative effect, reluctance to use such new composites [...] Read more.

Damage caused by global warming is rapidly increasing, and its adverse effects become more evident with each passing day. Although it is known that the use of alternative binder materials in concrete would decrease this negative effect, reluctance to use such new composites continues. Waste plays a vital role in sustainability studies. In this study, pure cement paste was prepared and enriched with carbon fiber. This study also investigated the wide range of volume fraction of carbon fiber in cement-based composites. Two different types of industrial waste, i.e., marble dust and bottom ash, were chosen and mixed with cement and four different (0.3%, 0.75%, 1.5%, and 2.5%) carbon fiber volume fractions. Based on physical, mechanical, and durability tests at 7, 28, and 56 days of curing, the composites were resistant to sulfate and seawater attacks. The 0.75% carbon fiber addition seems to be an optimum volume percentage, beyond which both physical and mechanical properties were adversely affected. The composites with 0.75% carbon fiber reached 48.4 and 47.2 MPa at 56 days of curing for marble dust and bottom ash mixture groups, respectively. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Graphical abstract

18 pages, 5353 KiB

Open AccessArticle

Research on Bonding and Shrinkage Properties of SHCC-Repaired Concrete Beams

by Penggang Wang, Maopeng Jiao, Chunhong Hu, Li Tian, Tiejun Zhao, Dongyi Lei and Hua Fu

Materials 2020, 13(7), 1757; https://doi.org/10.3390/ma13071757 - 9 Apr 2020

Cited by 13 | Viewed by 2704

Abstract

Traditional cement-based repair materials are brittle and prone to cracking. The failure of more than half of repaired concrete structure is due to the re-cracking of the repair material itself or delamination and peeling from the concrete matrix. Thus, a second repair is [...] Read more.

Traditional cement-based repair materials are brittle and prone to cracking. The failure of more than half of repaired concrete structure is due to the re-cracking of the repair material itself or delamination and peeling from the concrete matrix. Thus, a second repair is required in a short period, increasing the maintenance cost. To reduce cracking, Strain Hardening Cement-based Composite (SHCC), with strain hardening and multiple cracking property, is prepared to study the influence of interface roughness and repair layer thickness on the shrinkage, cracking and delamination modes of SHCC-repaired concrete beams. The results show that under the shrinkage stress, multiple fine cracks instead of local fractures occur in the SHCC repair layer, and the interfacial delamination is effectively controlled. Interfacial bonding property is the main factor that affects the shrinkage and deformation coordination of SHCC-repaired beams. When the interface roughness is different, the crack width of the SHCC repair layer is similar. However, it has a greater influence on the interfacial delamination length and maximum delamination height of the repaired beam. With the increase of interface roughness, the delamination length and height of the repaired beam are greatly reduced. Therefore, before using SHCC to repair the existing structures or components, the bonding surface should be roughened to improve the bond strength between SHCC and the old concrete. With the increase of the repair layer thickness, the cracking and delamination of the repair layer tend to be alleviated. Although the crack width of the repair layer can be effectively controlled after cracking, the overlarge shrinkage (985.35 × 10⁻⁶, about twice the shrinkage value of ordinary concrete) of the SHCC prepared in this research results in the cracking of the repair layer and the delamination of the repair interface under the restraint of concrete; thus, SHCC fails to repair the concrete efficiently. In terms of shrinkage deformation control, materials with high toughness and low shrinkage are required to repair the existing concrete structures. The implication of this research may provide a theoretical basis for the preparation and application of SHCC with high toughness and low shrinkage. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

15 pages, 13730 KiB

Open AccessArticle

Pullout Behavior of Bundled Aramid Fiber in Fiber-Reinforced Cementitious Composite

by Toshiyuki Kanakubo, Saki Echizen, Jin Wang and Yu Mu

Materials 2020, 13(7), 1746; https://doi.org/10.3390/ma13071746 - 9 Apr 2020

Cited by 9 | Viewed by 2814

Abstract

The tensile performance of fiber-reinforced cementitious composite (FRCC) after first matrix cracking is characterized by a tensile stress–crack width relationship called the bridging law. The bridging law can be obtained by an integral calculus of forces carried by individual bridging fibers considering the [...] Read more.

The tensile performance of fiber-reinforced cementitious composite (FRCC) after first matrix cracking is characterized by a tensile stress–crack width relationship called the bridging law. The bridging law can be obtained by an integral calculus of forces carried by individual bridging fibers considering the effect of the fiber inclination angle. The main objective of this study is to investigate experimentally and evaluate the pullout behavior of a single aramid fiber, which is made with a bundling of original yarns of aramid fiber. The bundled aramid fiber has a nonsmooth surface, and it is expected to have good bond performance with the matrix. The test variables in the pullout test are the thickness of the matrix and the inclined angle of the fiber. From the test results, the pullout load–slip curves showed that the load increases lineally until maximum load, after which it decreases gradually. The maximum pullout load and slip at the maximum load increase as the embedded length of the fiber becomes larger. The pullout load–crack width relationship is modeled by a bilinear model, and the bridging law is calculated. The calculated result shows good agreement with the experimental curves obtained by the uniaxial tension test of aramid–FRCC. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

17 pages, 4508 KiB

Open AccessArticle

Impact of Reinforcement Ratio on Shear Behavior of I-Shaped UHPC Beams with and without Fiber Shear Reinforcement

by Altug Yavas and Cumali Ogun Goker

Materials 2020, 13(7), 1525; https://doi.org/10.3390/ma13071525 - 26 Mar 2020

Cited by 40 | Viewed by 3511

Abstract

In the presented paper, the impacts of steel fiber use and tensile reinforcement ratio on shear behavior of Ultra-High Performance Concrete (UHPC) beams were investigated from the point of different tensile reinforcement ratios. In the scope of the experimental program, a total of [...] Read more.

In the presented paper, the impacts of steel fiber use and tensile reinforcement ratio on shear behavior of Ultra-High Performance Concrete (UHPC) beams were investigated from the point of different tensile reinforcement ratios. In the scope of the experimental program, a total of eight beams consisting of four reinforcement ratios representing low to high ratios ranged from 0.8% to 2.2% were casted without shear reinforcement and subjected to the four-point loading test. While half of the test beams included 30 mm end-hooked steel fibers (SF-UHPC) with 2.0 vol%, the remaining beams were produced without the fiber to show possible effectiveness of the fiber use. The shear performances were discussed in terms of the load—deflection response, cracking pattern and failure mode, first cracking load and ultimate shear strength. In this sense, all the non-fiber beams were failed by shear with a dramatic load drop, regardless of the tensile reinforcement amount, before the yielding of reinforcement and they produced no deflection capability. The test results showed that while the inclusion of steel fibers to the UHPC mixture with low reinforcement ratios changed the failure mode from the shear to flexure, it significantly enhanced the ultimate shear strength in the case of higher reinforcement ratio through the SF-UHPC’ superior mechanical properties and fibers’ crack-bridging ability. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

16 pages, 12316 KiB

Open AccessArticle

Synergistic Influences of Stearic Acid Coating and Recycled PET Microfibers on the Enhanced Properties of Composite Materials

by Dang Mao Nguyen, Thi Nhung Vu, Thi Mai Loan Nguyen, Trinh Duy Nguyen, Chi Nhan Ha Thuc, Quoc Bao Bui, Julien Colin and Patrick Perré

Materials 2020, 13(6), 1461; https://doi.org/10.3390/ma13061461 - 23 Mar 2020

Cited by 27 | Viewed by 5180

Abstract

This study aims to produce novel composite artificial marble materials by bulk molding compound processes, and improve their thermal and mechanical properties. We employed stearic acid as an efficient surface modifying agent for CaCO₃ particles, and for the first time, a pretreated, [...] Read more.

This study aims to produce novel composite artificial marble materials by bulk molding compound processes, and improve their thermal and mechanical properties. We employed stearic acid as an efficient surface modifying agent for CaCO₃ particles, and for the first time, a pretreated, recycled, polyethylene terephthalate (PET) fibers mat is used to reinforce the artificial marble materials. The innovative aspects of the study are the surface treatment of CaCO₃ particles by stearic acid. Stearic acid forms a monolayer shell, coating the CaCO₃ particles, which enhances the compatibility between the CaCO₃ particles and the matrix of the composite. The morphology of the composites, observed by scanning electron microscopy, revealed that the CaCO₃ phase was homogeneously dispersed in the epoxy matrix under the support of stearic acid. A single layer of a recycled PET fibers mat was pretreated and designed in the core of the composite. As expected, these results indicated that the fibers could enhance flexural properties, and impact strength along with thermal stability for the composites. This combination of a pretreated, recycled, PET fibers mat and epoxy/CaCO₃-stearic acid could produce novel artificial marble materials for construction applications able to meet environmental requirements. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Graphical abstract

20 pages, 4889 KiB

Open AccessArticle

Experimental Study on Basic Mechanical Properties of Basalt Fiber Reinforced Concrete

by Hao Zhou, Bin Jia, Hui Huang and Yanling Mou

Materials 2020, 13(6), 1362; https://doi.org/10.3390/ma13061362 - 17 Mar 2020

Cited by 118 | Viewed by 7702

Abstract

Blending a certain proportion of basalt fiber into concrete improves the toughness of concrete, which prevents cracking and avoids the brittle behaviors. In this paper, the compressive, tensile, and flexural tests of concrete with different basalt fiber contents were carried out. Then the [...] Read more.

Blending a certain proportion of basalt fiber into concrete improves the toughness of concrete, which prevents cracking and avoids the brittle behaviors. In this paper, the compressive, tensile, and flexural tests of concrete with different basalt fiber contents were carried out. Then the test phenomena, failure modes, and mechanical properties were compared and analyzed to derive the relationship between the basalt fiber contents and mechanical properties. The toughness and crack resistance performance of basalt fiber reinforced concrete were evaluated by the fracture energy, advanced toughness parameters, and characteristic length proposed by Hillerborg. The correlation coefficient of basalt fiber was introduced to establish the calculation formula for mechanical properties of basalt fiber reinforced concrete. The results indicated that basalt fiber significantly improved the toughness and crack resistance performance of concrete. The enhancing effect of the basalt fiber on the compressive strength of concrete is lower than that of tensile strength and flexural strength. Moreover, the improvement effect was the highest with the basalt fiber content was 0.3% and 0.4%. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

15 pages, 2150 KiB

Open AccessArticle

A Comparative Study on the Effects of Three Nano-Materials on the Properties of Cement-Based Composites

by Chao Fu, Chunyan Xie, Jing Liu, Xiuli Wei and Dake Wu

Materials 2020, 13(4), 857; https://doi.org/10.3390/ma13040857 - 13 Feb 2020

Cited by 24 | Viewed by 3065

Abstract

The application of nano-materials to modify construction materials has become a research hotspot in recent years, but often different scholars use different research methods and reach different conclusions about the same material, which is not conducive to the performance comparison between different materials. [...] Read more.

The application of nano-materials to modify construction materials has become a research hotspot in recent years, but often different scholars use different research methods and reach different conclusions about the same material, which is not conducive to the performance comparison between different materials. In this paper, nano-SiO₂, carbon nanotubes (CNTs) and nanocrystalline cellulose (NCC) were used as raw materials to prepare cement-based composites to compare the effects of the three nanomaterials on the mechanical and water absorption properties under the same experimental conditions, and their principles were investigated via The scanning electron microscope (SEM), X-Ray Diffraction (XRD) and other microscopic analysis testing methods. At the same time, strength benefit indexes are introduced to comprehensively evaluate the economics of the strength improvement provided by the three kinds of nanomaterial. The results show that doping with nano-SiO₂, CNTs and NCC can promote the hydration process of cement effectively. The composite material exhibits excellent mechanical properties at the macro level because of the nucleation and filling effect of nano-SiO₂, and the bridging and strengthening effects of CNTs and NCC. The compressive strength increased by 45.13%, 28.31% and 44.19% at 7d, and 23.09%, 18.40% and 23.40% at 28d. The flexural strength of 7d increased by 31.00%, 36.22 and 54.81%, and 14.91%, 22.23% and 30.46% at 28d. The water absorption is SiO₂ < NCC < CNTs, and the nano-SiO₂ is lower than the other two materials at least 15.54%. CNTs group has the lowest compressive strength benefit, which is 16.91 yuan/m³, and the lowest flexural strength benefit is NCC, which is 3.59 yuan/m³. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

20 pages, 52940 KiB

Open AccessArticle

Properties of Lightweight Aggregate Concrete Reinforced with Carbon and/or Polypropylene Fibers

by Hui Wei, Tao Wu and Xue Yang

Materials 2020, 13(3), 640; https://doi.org/10.3390/ma13030640 - 31 Jan 2020

Cited by 26 | Viewed by 4326

Abstract

The impact of carbon and polypropylene fibers in both single and hybrid forms on the properties of lightweight aggregate concrete (LWAC), including the slump, density, segregation resistance, compressive strength, splitting tensile strength, flexural strength, and compressive stress–strain behavior, were experimentally investigated. The toughness [...] Read more.

The impact of carbon and polypropylene fibers in both single and hybrid forms on the properties of lightweight aggregate concrete (LWAC), including the slump, density, segregation resistance, compressive strength, splitting tensile strength, flexural strength, and compressive stress–strain behavior, were experimentally investigated. The toughness ratio and ductility index were introduced for quantitatively evaluating the energy-absorbing capacity and post-peak ductility. A positive synergistic effect of hybrid carbon and polypropylene fibers was obtained in terms of higher tensile strength, toughness, and ductility. The toughness ratio and ductility index of hybrid fiber-reinforced LWAC were increased by 26%–37% and 12%–27% compared with plain LWAC, respectively. The fiber in both single and hybrid forms had a smaller effect on the linearity ascending branch of the stress–strain curves, whereas the post-peak patterns in terms of the toughness and ductility for the hybrid fiber-reinforced LWAC were significantly improved when the fiber in hybrid form. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

13 pages, 4739 KiB

Open AccessArticle

Hybrid-Fiber-Reinforced Concrete Used in Frozen Shaft Lining Structure in Coal Mines

by Zhishu Yao, Xiang Li, Taoli Wu, Long Yang and Xiaohu Liu

Materials 2019, 12(23), 3988; https://doi.org/10.3390/ma12233988 - 2 Dec 2019

Cited by 9 | Viewed by 2605

Abstract

To address the cracking and leaking of concrete in frozen shaft linings in deep and thick topsoil layers in coal mines, hybrid-fiber-reinforced concrete (HFRC) was developed. First, the composition of the reference concrete was obtained by investigating high-strength concrete commonly used in shaft [...] Read more.

To address the cracking and leaking of concrete in frozen shaft linings in deep and thick topsoil layers in coal mines, hybrid-fiber-reinforced concrete (HFRC) was developed. First, the composition of the reference concrete was obtained by investigating high-strength concrete commonly used in shaft linings, and two dosages of polyvinyl alcohol fiber (PVAF) and polypropylene plastic steel fiber (PPSF) were obtained by the mixing test. Then, tests of early cracks of concrete were conducted; results showed that HFRC could almost avoid early cracks, exhibiting an advantage in early crack resistance. Thus, HFRC can play a significant role in improving the durability of frozen shaft linings in complex underground environments. Furthermore, a series of mechanical property tests were carried out. The results showed that the compressive strength of HFRC was similar to that of the reference concrete, but the tensile and flexural strength of HFRC was 42.7% and 35.1% higher than that of the reference concrete, respectively. Finally, an analog simulation model test of shaft linings was conducted. The new type of shaft lining structure containing hybrid fibers (HFs) exhibited plastic deformation characteristics under load, and the maximum hoop strain was −3562 με. It addressed the problem of high brittleness of frozen shaft lining structures of ordinary high-strength concrete and improved the toughness and crack resistance. HFRC is an ideal material for frozen shaft lining structures in deep and thick topsoil. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

16 pages, 2091 KiB

Open AccessArticle

Analysis of the Versatility of Multi-Linear Softening Functions Applied in the Simulation of Fracture Behaviour of Fibre-Reinforced Cementitious Materials

by Alejandro Enfedaque, Marcos G. Alberti and Jaime C. Gálvez

Materials 2019, 12(22), 3656; https://doi.org/10.3390/ma12223656 - 6 Nov 2019

Cited by 5 | Viewed by 2107

Abstract

Fibre-reinforced cementitious materials (FRC) have become an attractive alternative for structural applications. Among such FRC, steel- and polyolefin fibre-reinforced concrete and glass fibre-reinforced concrete are the most used ones. However, in order to exploit the properties of such materials, structural designers need constitutive [...] Read more.

Fibre-reinforced cementitious materials (FRC) have become an attractive alternative for structural applications. Among such FRC, steel- and polyolefin fibre-reinforced concrete and glass fibre-reinforced concrete are the most used ones. However, in order to exploit the properties of such materials, structural designers need constitutive relations that accurately reproduce FRC fracture behaviour. This contribution analyses the suitability of multilinear softening functions combined with a cohesive crack approach for reproducing the fracture behaviour of the FRC mentioned earlier. The performed implementation accurately simulated fracture behaviour, while being versatile, robust, and efficient from a numerical point-of-view. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

10 pages, 6549 KiB

Open AccessArticle

Deformation and Compressive Strength of Steel Fiber Reinforced MgO Concrete

by Feifei Jiang, Zhongyang Mao, Min Deng and Dawang Li

Materials 2019, 12(21), 3617; https://doi.org/10.3390/ma12213617 - 4 Nov 2019

Cited by 13 | Viewed by 3329

Abstract

To reduce the cracking caused by shrinkage and avoid the brittle behavior of concrete, MgO expansion agent and steel fibers were used in this paper. Firstly, the effect of MgO and steel fibers on the compressive strength of concrete was compared. The results [...] Read more.

To reduce the cracking caused by shrinkage and avoid the brittle behavior of concrete, MgO expansion agent and steel fibers were used in this paper. Firstly, the effect of MgO and steel fibers on the compressive strength of concrete was compared. The results showed that the compressive strength of steel fibers reinforced concrete (SC) and steel fiber reinforced MgO concrete (SMC) was significantly improved. Compared with ordinary concrete (OC), SMC’s 28 days compressive strength increased by 19.8%. Secondly, the influence of MgO and steel fibers with different contents on the self-volumetric deformation of concrete was compared through the experiment. The results showed that as a result of the hydration expansion of MgO, MC and SMC both showed obvious expansion, and their 190 days expansion was 335

μ ε

and 288

μ ε

, respectively. Lastly, through a scanning electron microscope (SEM) test, it was found that the constraint effect of steel fibers changed the expansion mode of MgO from outward expansion to inward extrusion, thus improving the interfacial bond strength of concrete. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

13 pages, 4407 KiB

Open AccessArticle

Mechanical Properties of Carbon Fiber-Reinforced Polymer Concrete with Different Polymer–Cement Ratios

by Gao-Jie Liu, Er-Lei Bai, Jin-Yu Xu and Ning Yang

Materials 2019, 12(21), 3530; https://doi.org/10.3390/ma12213530 - 28 Oct 2019

Cited by 16 | Viewed by 4345

Abstract

To study the effect of redispersible polymer emulsion powder on the mechanical properties of carbon fiber-reinforced polymer concrete (CFRPC), the compressive, flexural, and splitting tests of CFRPC specimens with different polymer–cement ratios (polymer–cement mass ratios) were performed in this study. The modification effect [...] Read more.

To study the effect of redispersible polymer emulsion powder on the mechanical properties of carbon fiber-reinforced polymer concrete (CFRPC), the compressive, flexural, and splitting tests of CFRPC specimens with different polymer–cement ratios (polymer–cement mass ratios) were performed in this study. The modification effect of emulsion powder on CFRPC was analyzed from the perspectives of the strength and deformation properties of the specimens. The results show that the static properties of CFRPC increased first and then decreased with the increase of the polymer–cement ratio, in which the splitting tensile strength had the most significant increase; the flexural strength took second place and the compressive strength had a slight increase. When the polymer–cement ratio was 8%, the flexural and splitting tensile strength of the CFRPC specimens increased significantly by 36% and 61%, respectively. According to electron microscopy images, adding emulsion powder can effectively improve the structure of fiber–matrix transition zones and enhance the bond property between fibers and the matrix. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

15 pages, 2824 KiB

Open AccessArticle

Strain-Hardening and High-Ductile Behavior of Alkali-Activated Slag-Based Composites with Added Zirconia Silica Fume

by Jeong-Il Choi, Se-Eon Park, Huy Hoàng Nguyễn, Sang Lyul Cha and Bang Yeon Lee

Materials 2019, 12(21), 3523; https://doi.org/10.3390/ma12213523 - 27 Oct 2019

Cited by 14 | Viewed by 3099

Abstract

This paper presents an experimental study on the effects of zirconia silica fume on the composite properties and cracking patterns of fiber-reinforced alkali-activated slag-based composites. Four mixtures were prepared with added zirconia silica fume and varying water-to-binder ratio. Polyethylene fiber was used as [...] Read more.

This paper presents an experimental study on the effects of zirconia silica fume on the composite properties and cracking patterns of fiber-reinforced alkali-activated slag-based composites. Four mixtures were prepared with added zirconia silica fume and varying water-to-binder ratio. Polyethylene fiber was used as a reinforcing fiber for all the mixtures at a volumetric ratio of 2.0% cubic specimens and uniaxial tensile specimens were prepared to evaluate their density, compressive strength, and tensile behavior. The test results demonstrated that the compressive strength, tensile strength, and tensile strain capacity of the composite can be simultaneously improved by incorporating zirconia silica fume. A mixture incorporating zirconia silica fume showed high-ductile behavior of 26.5% higher tensile strength, and 13.7% higher tensile strain capacity than the mixture without zirconia silica fume. The composite with added zirconia silica fume also showed excellent cracking patterns, i.e., narrow crack spacing and crack width. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

13 pages, 1627 KiB

Open AccessArticle

Thin Slabs Made of High-Performance Steel Fibre-Reinforced Cementitious Composite: Mechanical Behaviour, Statistical Analysis and Microstructural Investigation

by Paulo Roberto Ribeiro Soares Junior, Priscila Souza Maciel, Richard Rodrigues Barreto, João Trajano da Silva Neto, Elaine Carballo Siqueira Corrêa and Augusto Cesar da Silva Bezerra

Materials 2019, 12(20), 3297; https://doi.org/10.3390/ma12203297 - 11 Oct 2019

Cited by 6 | Viewed by 2986

Abstract

The present study evaluated the mechanical behaviour of thin high-performance cementitious composite slabs reinforced with short steel fibres. For this purpose, slabs with 1%, 3% and 5% vol. of steel fibres were moulded using the slurry infiltration method. Fibres concentrated in the region [...] Read more.

The present study evaluated the mechanical behaviour of thin high-performance cementitious composite slabs reinforced with short steel fibres. For this purpose, slabs with 1%, 3% and 5% vol. of steel fibres were moulded using the slurry infiltration method. Fibres concentrated in the region subjected to traction during bending stresses. After curing for 28 days, all slabs underwent flexural testing. The slabs with 5% fibre showed significantly higher flexural strength, deflection and toughness compared to those of the control group without reinforcement. The dense fibre distribution, resulting from the production process, led to profiles with multiple random cracks in the region of failure of the slabs as the fibre content increased. The results of the statistical analysis showed the intensity of the correlation between the variables and revealed that the increase of the fibre content significantly influenced the parameters of mechanical behaviour (load, flexural strength, deflection, toughness and toughness factor). Images obtained by optical microscopy aided in understanding the fibre–matrix interface, showing the bonding surface between the constituents of the composite. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

17 pages, 8148 KiB

Open AccessArticle

Effects of Vehicle-Induced Vibrations on the Tensile Performance of Early-Age PVA-ECC

by Xiaodong Zhang, Shuguang Liu, Changwang Yan, Xiaoxiao Wang and Huiwen Wang

Materials 2019, 12(17), 2652; https://doi.org/10.3390/ma12172652 - 21 Aug 2019

Cited by 9 | Viewed by 2881

Abstract

Polyvinyl alcohol-engineering cementitious composites (PVA-ECCs) have been widely applied in bridge deck repairing or widening, and a common practice is that a portion of the bridge is left open to traffic while the closed portion is constructed, which exposes the early-age PVA-ECC to [...] Read more.

Polyvinyl alcohol-engineering cementitious composites (PVA-ECCs) have been widely applied in bridge deck repairing or widening, and a common practice is that a portion of the bridge is left open to traffic while the closed portion is constructed, which exposes the early-age PVA-ECC to vehicle-induced vibrations. However, whether vehicle-induced vibrations affect the performance of early-age PVA-ECC remains unknown. The purpose of this study was to conduct laboratory test programs to investigate to what extent vehicle-induced vibrations soon after installation affects the tensile performance of the PVA-ECC. A self-improved device was used to simulate the vehicle-induced vibrations, and after vibrating with the designed variables, both a uniaxial tensile test and a grey correlation analysis were performed. The results indicated that the effects of vehicle-induced vibrations on the tensile performance of early-age PVA-ECCs were significant, and they generally tended to be negative. In particular, for all of the vibrated PVA-ECC specimens, the most negative effects occurred when vibration occurred during the period between the initial set and the final set. We concluded that although vehicle-induced vibrations during the setting periods had no substantial effects on the inherent strain-hardening characteristics of PVA-ECCs, the effects should not be ignored. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Graphical abstract

15 pages, 3395 KiB

Open AccessArticle

Probabilistic Analysis for Strain-Hardening Behavior of High-Performance Fiber-Reinforced Concrete

by Seung-Won Choi, Jongkwon Choi and Seong-Cheol Lee

Materials 2019, 12(15), 2399; https://doi.org/10.3390/ma12152399 - 27 Jul 2019

Cited by 27 | Viewed by 3497

Abstract

The practical application of fiber-reinforced concrete (FRC) in structural components has gained growing interest due to structural advantages such as improved tensile strength, distributed load transfer, crack width control, as well as superior durability. To this end, reliable structural assessment techniques and analytical [...] Read more.

The practical application of fiber-reinforced concrete (FRC) in structural components has gained growing interest due to structural advantages such as improved tensile strength, distributed load transfer, crack width control, as well as superior durability. To this end, reliable structural assessment techniques and analytical models have been developed, placing emphasis on tension-softening behavior owing to the bond and pull-out mechanisms of fibers at a local crack. However, these models could not be directly applicable to evaluate the multiple cracking mechanisms of high-performance fiber-reinforced concrete (HPFRC), which exhibits strain-hardening behavior. To overcome this challenge, this paper presents a probabilistic analytical technique. This approach has employed the simplified diverse embedment model (SDEM). Then, an HPFRC member was modeled with multiple segments considering the most probable number of cracks. It was assumed that material properties had a normal probability distribution and were randomly assigned to each segment. To have reliable results, 10,000 analyses were performed for each analysis case and validated using experimental test data. Based on the analysis results, the actual strain-hardening tensile behavior of an HPFRC member could be reasonably predicted with the number of segments chosen on the basis of the fiber length. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

16 pages, 3391 KiB

Open AccessArticle

Shear Behaviors of RC Beams Externally Strengthened with Engineered Cementitious Composite Layers

by Guan Wang, Caiqian Yang, Yong Pan, Fawang Zhu, Kai Jin, Kefeng Li and Antonio Nanni

Materials 2019, 12(13), 2163; https://doi.org/10.3390/ma12132163 - 5 Jul 2019

Cited by 22 | Viewed by 3342

Abstract

The shear behaviors of reinforced concrete (RC) beams externally strengthened with engineered cementitious composite (ECC) layers were studied and the strengthening effect was evaluated based on a truss and arch model. The beams were designed without web reinforcement in the middle part and [...] Read more.

The shear behaviors of reinforced concrete (RC) beams externally strengthened with engineered cementitious composite (ECC) layers were studied and the strengthening effect was evaluated based on a truss and arch model. The beams were designed without web reinforcement in the middle part and ECC was sprayed onto both sides of the beams to the designed thicknesses, which were 20 mm and 40 mm. A series of four-point bending experiments were conducted and analyzed. The development of the shear strain in each side of the beams was recorded by strain rosettes formed with three fiber Bragg grating (FBG) sensors. The thickness of ECC layers, reinforcement ratios, and shear span-to-depth ratios were considered and analyzed. This is an effective way to shear strengthen RC beams with ECC layers. The ultimate load of the strengthened specimen can be improved by 89% over the control specimen. Strengthening an RC beam into an under-reinforced beam should be avoided. The FBG sensors are suitable to measure and monitor the development of shear strain in the side of the strengthened specimen. Based on the truss and arch model, an evaluation of the shear strengthening effect was established and the results agree well with the experimental results. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

12 pages, 2280 KiB

Open AccessArticle

Investigation of the Match Relation between Steel Fiber and High-Strength Concrete Matrix in Reactive Powder Concrete

by Guangyao Yang, Jiangxiong Wei, Qijun Yu, Haoliang Huang and Fangxian Li

Materials 2019, 12(11), 1751; https://doi.org/10.3390/ma12111751 - 29 May 2019

Cited by 18 | Viewed by 2913

Abstract

This study investigated the strength and toughness of reactive powder concrete (RPC) made with various steel fiber lengths and concrete strengths. The results indicated that among RPC samples with strength of 150 MPa, RPC reinforced with long steel fibers had the highest compressive [...] Read more.

This study investigated the strength and toughness of reactive powder concrete (RPC) made with various steel fiber lengths and concrete strengths. The results indicated that among RPC samples with strength of 150 MPa, RPC reinforced with long steel fibers had the highest compressive strength, peak strength, and toughness. Among the RPC samples with strength of 270 MPa, RPC reinforced with short steel fibers had the highest compressive strength, and peak strength, while RPC reinforced with medium-length steel fibers had the highest toughness. As a result of the higher bond adhesion between fibers and ultra-high-strength RPC matrix, long steel fibers were more effective for the reinforcement of RPC with strength of 150 MPa, while short steel fibers were more effective for the reinforcement of RPC with strength of 270 MPa. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

14 pages, 1724 KiB

Open AccessArticle

Multi-Objective Optimization Design and Test of Compound Diatomite and Basalt Fiber Asphalt Mixture

by Yongchun Cheng, Liding Li, Peilei Zhou, Yuwei Zhang and Hanbing Liu

Materials 2019, 12(9), 1461; https://doi.org/10.3390/ma12091461 - 6 May 2019

Cited by 41 | Viewed by 2999

Abstract

This study focuses on improving the performance of asphalt mixture at low- and high- temperature and analyzing the effect of diatomite and basalt fiber on the performance of the asphalt mixture. Based on the L₁₆(4⁵) orthogonal experimental design (OED), [...] Read more.

This study focuses on improving the performance of asphalt mixture at low- and high- temperature and analyzing the effect of diatomite and basalt fiber on the performance of the asphalt mixture. Based on the L₁₆(4⁵) orthogonal experimental design (OED), the content of diatomite (D) and basalt fiber (B) and the asphalt-aggregate (A) ratio were selected as contributing factors, and each contributing factor corresponded to four levels. Bulk volume density (γ_f), volume of air voids (VV), voids filled with asphalt (VFA), Marshall stability (MS) and splitting strength at −10 °C (S_b) were taken as the evaluation indexes. According to the results of the orthogonal experiment, the range analysis and variance analysis were used to study the effect of the diatomite content, basalt fiber content and asphalt-aggregate ratio on the performance of the asphalt mixture, and the grey correlation grade analysis (GCGA) was used to obtain the optimal mixing scheme. Furthermore, the performance tests were conducted to evaluate the performance improvement of asphalt mixtures with diatomite and basalt fibers, and the scanning electron microscopy (SEM) tests were carried out to analyze the mechanism of diatomite and basalt fibers in asphalt mixtures. The results revealed that the addition of diatomite and basalt fiber can significantly increase the VV of asphalt mixture, and reduce γ_f and VFA; the optimal performance of the asphalt mixture at high- and low-temperature are achieved with 14% diatomite, 0.32% basalt fibers and 5.45% asphalt-aggregate ratio. Moreover, the porous structure of diatomite and the overlapping network of basalt fibers are the main reasons for improving the performance of asphalt mixture. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

16 pages, 5091 KiB

Open AccessArticle

Stress–Strain Properties and Gas Permeability Evolution of Hybrid Fiber Engineered Cementitious Composites in the Process of Compression

by Zhenbo Wang, Jianping Zuo, Chang Liu, Zishan Zhang and Yudong Han

Materials 2019, 12(9), 1382; https://doi.org/10.3390/ma12091382 - 28 Apr 2019

Cited by 14 | Viewed by 3096

Abstract

Polyvinyl alcohol (PVA)-steel hybrid fiber reinforced engineered cementitious composites (ECC) characterized by optimal combination of high strength and high ductility were developed recently. These composites exhibit even tighter crack width than normal ECC, showing great potential for lower permeability in cracked state, and [...] Read more.

Polyvinyl alcohol (PVA)-steel hybrid fiber reinforced engineered cementitious composites (ECC) characterized by optimal combination of high strength and high ductility were developed recently. These composites exhibit even tighter crack width than normal ECC, showing great potential for lower permeability in cracked state, and consequently improving the durability of ECC structures. In addition, the wide variety of promising applications in underground or hydraulic structures calls for knowledge on the mechanical behavior and corresponding permeability properties of strained ECC under multiaxial stress, as they are essential for structural analysis and durability design. Experimental investigations into the compressive properties and the in-situ gas permeability of PVA-steel hybrid fiber ECC were performed in this study, with special focus on the impact of additional steel fiber content and confining pressure. The test results show that the presence of a low confinement level allows ECC to attain a substantial improvement on compressive behavior but impairs the enhancement efficiency of additional steel fiber. The permeability evolution of strained ECC corresponds to the variation of radial strains, both of which experience little change below the threshold stress but a rapid increase beyond the peak axial strain. Apart from exhibiting low permeability at relatively small strains in the pre-peak stage, ECC can also exhibit low permeability at higher levels of compressive strain up to 2.0%. However, unlike the case in tensile loading, impermeability of cracked ECC in compression would be weakened by additional steel fibers, especially in the post-peak stage. The present research is expected to provide insight into performance-based durability design of structures made of or strengthened with ECC. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Graphical abstract

Review

Jump to: Research

36 pages, 4194 KiB

Open AccessReview

Fibre-Reinforced Foamed Concretes: A Review

by Mugahed Amran, Roman Fediuk, Nikolai Vatin, Yeong Huei Lee, Gunasekaran Murali, Togay Ozbakkaloglu, Sergey Klyuev and Hisham Alabduljabber

Materials 2020, 13(19), 4323; https://doi.org/10.3390/ma13194323 - 28 Sep 2020

Cited by 115 | Viewed by 7627

Abstract

Foamed concrete (FC) is a high-quality building material with densities from 300 to 1850 kg/m³, which can have potential use in civil engineering, both as insulation from heat and sound, and for load-bearing structures. However, due to the nature of the [...] Read more.

Foamed concrete (FC) is a high-quality building material with densities from 300 to 1850 kg/m³, which can have potential use in civil engineering, both as insulation from heat and sound, and for load-bearing structures. However, due to the nature of the cement material and its high porosity, FC is very weak in withstanding tensile loads; therefore, it often cracks in a plastic state, during shrinkage while drying, and also in a solid state. This paper is the first comprehensive review of the use of man-made and natural fibres to produce fibre-reinforced foamed concrete (FRFC). For this purpose, various foaming agents, fibres and other components that can serve as a basis for FRFC are reviewed and discussed in detail. Several factors have been found to affect the mechanical properties of FRFC, namely: fresh and hardened densities, particle size distribution, percentage of pozzolanic material used and volume of chemical foam agent. It was found that the rheological properties of the FRFC mix are influenced by the properties of both fibres and foam; therefore, it is necessary to apply an additional dosage of a foam agent to enhance the adhesion and cohesion between the foam agent and the cementitious filler in comparison with materials without fibres. Various types of fibres allow the reduction of by autogenous shrinkage a factor of 1.2–1.8 and drying shrinkage by a factor of 1.3–1.8. Incorporation of fibres leads to only a slight increase in the compressive strength of foamed concrete; however, it can significantly improve the flexural strength (up to 4 times), tensile strength (up to 3 times) and impact strength (up to 6 times). At the same time, the addition of fibres leads to practically no change in the heat and sound insulation characteristics of foamed concrete and this is basically depended on the type of fibres used such as Nylon and aramid fibres. Thus, FRFC having the presented set of properties has applications in various areas of construction, both in the construction of load-bearing and enclosing structures. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Concrete Composites)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Advanced Fiber-Reinforced Concrete Composites

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (29 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI