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X-ray computed tomography (CT) was used to investigate the fatigue crack growth behavior of continuous SiC fiber reinforced Ti alloy (SiCf/Ti). Based on the three-dimensional morphology of the fatigue crack and the tortuosity of the SiC fibers, we investigated the fatigue crack growth behavior and their dependence on the tortuosity of the fibers. The results revealed that the fatigue crack tends to intersect fibers with higher tortuosity compared to their straighter counterparts, which could explain the crack initiation position and its propagation behavior in continuous fiber reinforced composites. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effect of fiber reinforcement materials on the magnitude of stresses in a critical part of the maxillary denture base under thermal and occlusal load. Thermal stress analyses of the models were carried out using the finite element method. The models consisted of bone, soft tissue, interface gap, and maxillary dentures with and without reinforcements. A concentrated occlusal load of 230 N was applied bilaterally on the molar teeth. A 36 °C reference and 0 °C, 36 °C, and 70 °C variable ambient temperatures were applied to the models. CrCo, unidirectional and woven carbon/epoxy, unidirectional and woven glass/epoxy, and unidirectional and woven Kevlar/epoxy were used as reinforcing materials in the maxillary denture base made of PMMA (polymethyl methacrylate). Stress distributions on the maxillary denture's midline and lateral line direction were evaluated. Maximum stresses in the incisal notch and the labial frenal notch of the maxillary denture were determined. Failure analysis of reinforcement materials used in maxillary dentures was carried out using the Tsai-Wu index criterion. The results obtained show that the thermal properties of reinforcement materials should be considered as an important criterion in their selection. [ABSTRACT FROM AUTHOR]

In the classical literature devoted to the study of orthotropic materials under large strains, a lot of emphasis is given to strain invariants, obscuring the association of finite strain constitutive relations with wellestablished small strains constitutive relations. In this work, this association is established through the comparison of 8 orthotropic models (3 classical and 5 new) for hyperelastic orthotropic materials using the Flory's decomposition. This is done transforming the initial formalism of different models into complete quadratic polynomials written in terms of the Right-Cauchy-Green stretch and a volumetric control that guaranties the growth condition. A tailoring fiber-reinforced solid model - in which discrete fibers are immersed into continuous matrix - is also presented and used to establish numerical tests, generating basic elastic constants for comparisons. The 5 proposed models are implemented in an in-house FEM code and comparisons among their mechanical behavior are presented. From these comparisons one of the proposed models is selected to successfully simulate a biological tissue, opening the possibilities for future studies. [ABSTRACT FROM AUTHOR]

Using recycled waste for soil improvement is a sustainable strategy that can reduce resource consumption. In this paper, recycled polyester fiber (RPF) is proposed to improve the engineering performance of red mud- improved volcanic ash (RV). A series of mechanical test were performed for RVs with five different content of RPF. And the microstructure was also investigated using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and mercury intrusion porosimetry (MIP) tests. Results show that RPF significantly reinforces the mechanical strength and toughness of RV and the optimum content of RPF is 0.9%. The Unconfined compressive strength (UCS), cohesion (c) and internal friction angle (φ) of reinforced soil enhanced by up to 122%, 40% and 8% compared to untreated soil at the optimum incorporation and optimum water content, respectively. The failure model of RPF-reinforced RV is converted from brittle to ductile, and the toughness parameters are significantly improved. Microscopic investigations reveal that RPF forms a complex three-dimensional structure within the reinforced soil. Adhesion and friction interactions at the fiber-matrix interface are the main reasons for the enhancement of strength and toughness. However, the performance of composites does not continue increasing with RPF content. Excessive fibers gather and twist to form weak zones, reducing the strength and stiffness of material. In practice, the optimal fiber content needs to be controlled to ensure the best mechanical properties. This eco-friendly soil improvement can promote the harmless utilization of red mud and waste polyester materials contributing to ground improvement techniques in volcanic areas. [ABSTRACT FROM AUTHOR]

Three-dimensional concrete printing (3DCP) technology with solid wastes has significant potential for sustainable construction. However, the hardened mechanical properties of components manufactured using 3DCP technology are affected by weak interlayer interfaces, limiting the widespread application of 3DCP technology. To address the inherent limitations of 3DCP technology, conventional improvement strategies, such as external reinforcement and the optimization of material properties, lead to increased production costs, complex fabrication, and decreased automation. This study proposes an innovative spatial path optimization method to enhance the mechanical performance of 3D-printed, cement-based components. The novel S-path design introduces additional printed layers in the weak interlayer regions of the printed samples. This design improves the spatial distribution of fiber-reinforced filaments in continuous weak zones, thus enhancing the functional efficiency of fibers. This approach improves the mechanical performance of the printed samples, achieving compressive strengths close to those of cast samples and only a 20% reduction in average flexural strength. Compared to using a conventional printing path, the average compressive strength and flexural strength are improved by 30% and 55%, respectively, when the S-path layout is employed in 3DCP. Additionally, this method significantly reduces the anisotropy in compressive and flexural strengths to 26% and 28% of samples using conventional printing paths, respectively. Therefore, the proposed method can improve the mechanical properties and stability of the material, reducing the safety risks of printed structures. [ABSTRACT FROM AUTHOR]

This study examined the mechanical characteristics of 3D printed concrete utilized in sculpture materials, with an emphasis on the incorporation of wood fibers. A series of experiments were conducted to probe into the wood fiber-reinforced 3D printed concrete sculpture materials. Through mechanical and microscopic examinations, the role of flexible fibers in enhancing the bearing capacity of concrete 3D printed components was investigated. The results indicated that an optimal amount of wood fiber addition significantly improved the mechanical properties of the concrete sculpture materials. At the interlayer interface, wood fibers exhibited elongation, thereby mitigating the specimen damage. However, beyond a certain threshold, the mechanical properties tended to decline due to either the agglomeration or direct dislodgment of wood fibers at the interlayer interface, which resulted in an absence of notable deformation. This scenario thereby failed to impede crack propagation. Hydrophobic performance assays revealed an elevation in surface hydrophobicity of 3D printed concrete sculpture materials with the inclusion of wood fibers. Yet, an excessive amount of wood fibers caused a gradual reduction in the contact angle, implying a decrease in the hydrophobicity of the material surface. [ABSTRACT FROM AUTHOR]

In order to improve the strength and brittleness of ceramsite concrete, polypropylene fiber was added to ceramsite concrete in this study. A total of 180 polypropylene fiber-reinforced ceramsite concrete specimens were prepared, and cube compressive test, splitting tensile test, axial compressive test and elastic modulus test were carried out. The results show that polypropylene fiber can effectively improve the splitting tensile strength and tension-compression ratio of ceramsite concrete, and has little effect on compressive strength and elastic modulus. Based on the experimental results, the conversion relationship model between splitting tensile strength and cube compressive strength, axial compressive strength and cube compressive strength, and the numerical model of elastic modulus of polypropylene fiber-reinforced ceramsite concrete were proposed. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A concrete slab is one of the chief structural members in buildings, considered the most prominent member consuming concrete. Structural engineers are challenged to work on the new trend introduced using different slabs. One-way ribbed slabs are commonly used in construction due to their efficiency in spanning long distances while maintaining a low overall depth and giving the least possible number of columns. The main limitation of slab design in the construction of a reinforced concrete structure is the span between columns; a greater span between columns necessitates more supported beams or increased slab thickness; these requirements lead to an increase in the structure weight due to other concrete and steel which make the structure more costly. On the other hand, any increase in the structure’s self-weight limits the horizontal slab’s span, increases the structure’s stress, and raises the inertia forces that must be resisted. Lightweight aggregate concrete has been effectively utilized for structural applications for a long time. The density of lightweight concrete (LWC) is sometimes more essential than its strength in structural applications. The dead load is reduced for structural design and foundations when the density is lower for the same strength level. Reinforced concrete ribbed slabs have become increasingly popular in industry construction as an alternative to solid slabs in building structures. The incorporation of steel fibers facilitates flexural softening, which takes longer than sudden brittle failure, indicating its ability to increase energy absorption and improve crack behavior. Designing structures requires materials with higher strength-to-weight ratios. Ribs and LWCs are two leading sustainable assets. The world is moving toward sustainability by reducing the amount of concrete used and the overall weight of the unit. Studies have shown that the drop in compressive strength was about 4.85–65.55%. The structural performance of lightweight fiber-reinforced concrete slabs is influenced by the concrete mix ratio, fiber type and content, reinforcement detail, and rib geometry. The study provides valuable insights into the properties and performance of key effects on the structural behavior of fiber-reinforced LWC-ribbed slabs. It provides recommendations for future research and advancement of sustainable building methods.

The preparation of fused silica glass with microstructural patterns has attracted considerable interest, and the process chain of using nano-silica powders mixed with organic polymers to prepare composites for molding, degreasing, and sintering provides a good solution. However, the potential negative effects of organic residues cannot be avoided. In this study, a pattern stencil replication method with silica gel using high-purity quartz fibers as reinforcement is proposed for preparing micropatterned fused silica glass. The microscopic morphology and mechanical properties before and after silica gel drying and the optical properties of fused silica glass obtained by sintering were evaluated via transmission electron microscopy), three-point bending strength test, scanning electron microscopy, X-ray diffraction spectrum analysis, ultraviolet–visible and infrared measurements. The results showed that quartz fiber as a reinforcer could shorten the drying time of the gel and did not degrade the quality of the fused silica glass obtained by sintering. Laser confocal test results showed that microlens arrays were generated by template replication, demonstrating the feasibility of molding fused silica lens arrays with small feature sizes and providing new ideas for the preparation of bulk fused silica glass or micropatterned glass. [ABSTRACT FROM AUTHOR]

Stepped repair, scarf patch repair, and patch repair are important in terms of repair techniques. The composite plate repair process starts after damage zone determination either by the unaided eye or nondestructive testing (NDT) techniques. This study investigates design cases for the stepped repairs of damaged fiber-reinforced composite materials. Before preparing steps for repair, the material around the damage zone is removed. In the stepped repair, it needs extra care to ensure that the repair plies overlap each other properly in the cut. Different cases are performed considering different step sizes. 5, 10, and 15 mm step sizes are used. The damages are given to the produced fiber-reinforced composite laminates using the Quasi-static indentation (QSI) method. Using QSI high-velocity impact simulation can be done. To get damage characteristics well-known damage test method is issued. Different span-to-punch diameter ratio (SPR) values were also used to compare different damage sizes. As a result, High ratio strength recovery was obtained using the longer step size. Maximum penetration force was reduced by nearly % 6-7 and maximum stress reduction was obtained by nearly % 8-9 for the 15 mm step size repaired composites. Among the all cases, case-1 has the highest strength recovery and case-5 has the lowest. For SPR 2, The average ultimate force value of specimens repaired with case-1 was maintained at nearly 94%. For SPR 4, repairs carried out using case-1 maintain more than 95% of damage resistance. [ABSTRACT FROM AUTHOR]

Highlights The goal of this project was to recycle the waste forming in the production of a flexible, multilayer food packaging film. The film consists of five layers, two polyamides containing three different polymers, a polyethylene and two adhesive layers of maleated polyethylene. The type of the components and the exact composition are not disclosed because they represent proprietary information. The key to recycling is the selection of an appropriate strategy and target product. In this case, glass fiber reinforced PA composites were produced with an acceptable property profile. The properties of the recycled product are comparable to those of commercial composites available on the market. The crucial question was the selection of the glass fiber grade with the appropriate sizing. The selection was further complicated by the possible interaction of the functionalized polymer with the sizing of the fiber. The implementation of the solution is feasible technologically, the properties of the product are comparable to those available on the market, and its price is very advantageous. An engineering material can be produced from flexible multilayer packaging waste. The properties of the recycled product are comparable with those on the market. The selection of the glass fiber is crucial for mechanical properties. The solution is feasible technologically and the final price is competitive. [ABSTRACT FROM AUTHOR]

The continued global urbanization of the world is driving the development of the construction industry. In order to protect the environment, intensive research has been carried out in recent years on the development of sustainable materials and ecological construction methods. Scientific research often focuses on developing building materials that are renewable, energy-efficient, and have minimal impact on the environment throughout their life cycle. Therefore, this article presents research results aimed at developing a concrete mixture using cement with reduced CO2 emissions. In the context of increasing ecological awareness and in line with European Union policy, the development of a mixture based on environmentally friendly cement is of key importance for the future development of the construction industry. The article compares the physical properties of two mixtures, their foaming possibilities, and the influence of the added polypropylene (PP) fibers on the strength properties of the produced composites. It was found that bending strength and compressive strength were highest in the material with silica fume and aluminum powder at 5.36 MPa and 28.76 MPa, respectively. Microscopic analysis revealed significant pore structure differences, with aluminum foamed samples having regular pores and hydrogen peroxide foamed samples having irregular pores. Optimizing aluminum powder and water content improved the materials' strength, crucial for maintaining usability and achieving effective 3D printing. The obtained results are important in the development of research focused on the optimization of 3D printing technology using concrete. [ABSTRACT FROM AUTHOR]

Industrial solid waste (mine tailings) management has emerged as the key universal ecological challenge as a result of the unceasing creation of rising waste by-products. Employing tailings makes mine fill production economical and assists resolve disposal problems. Foamed cement-based tailings backfill (FCTB) is a mine fill consisting of tailing, cement, water, and foaming agents. It provides certain advantages such as lightweight, good fluidity, and thermal insulation yet is relatively weak in strength. Additionally, FCTB's strength properties can be intensely improved by adding fibers. A total of three diverse fibers: polypropylene (PP), glass (G), and basalt (B) as well as dodecyltrimethylammonium bromide (DTAB) as a foaming agent were used to prepare fiber-reinforced foamed cementitious tailings backfill (FR-FCTB). The mechanical properties, energy evolution, ductility, and microstructure of FR-FCTB were elaborately investigated by uniaxial compression tests (UCS) and SEM. Laboratory findings demonstrate the reinforcing effect of three fibers on FCTB specimens: glass > polypropylene > basalt. FR-FCTB showed the best strength features as a fiber content of 0.3% was adopted in FCTB. At this time, the UCS performance of glass fiber-reinforced FCTBs was 0.85 MPa increased by 18.1%. The addition of fibers can increase the fill's energy storage limit, slow down the discharge of elastic strain energy within the backfill, and enhance the fill's ductility and toughness. The ductility factor evaluates the degree of deterioration of filling in terms of post-peak drop, with all FR-FCTB values being greater than CTB. FR-FCTB's chief hydration product is the C-S–H gel. Fiber's bridging effect significantly rallies crack extension and thus fill's strength features. Lastly, the study's main results are instructive for the industrial application of FR-FCTB used in metallic mines. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) have gained significant attention due to their potential in soft robotics and adaptive structures. However, their performance is often limited by their in-plane strain distribution and limited mechanical stability. We introduce a novel design utilizing fiber reinforcement to address these challenges. The fiber reinforcement provides enhanced mechanical integrity and improved strain distribution, enabling efficient energy conversion and out-of-plane displacement. We discuss an analytical model and the fabrication process, including material selection, to realize fiber-reinforced DEAs. Numerical simulations and experimental results demonstrate the performance of the fiber-reinforced equibiaxial DEAs and characterize their displacement and force capabilities. Actuators with four and eight fibers are fabricated with 100 μ m and 200 μ m dielectric thicknesses. A maximal out-of-plane displacement of 500 μ m is reached, with a force of 0.18 N, showing promise for the development of haptic devices. [ABSTRACT FROM AUTHOR]

In this study, an inhomogeneous Cosserat rod theory is introduced and compared to the conventional homogeneous rod for modeling soft manipulators. The inhomogeneity is addressed by considering the pressure actuation as part of the rod's constitutive laws, resulting in shifting the neutral axis. This shift is investigated for a soft manipulator with three parallel fiber-reinforced actuators. Furthermore, a fiber-reinforced actuator is modeled using nonlinear continuum mechanics to extract the effect of radial pressure on axial deformation and is combined with Cosserat model. Finally, several numerical methods are employed to solve the proposed model and validated by a series of experiments. [ABSTRACT FROM AUTHOR]

In the aerospace industry, lightweight can reduce the weight of the engine and improve the thrust-weight ratio of the engine. Ceramic matrix composites have attracted widespread attention in the industry due to their much lower density compared to high-temperature alloys and excellent high-temperature performance. SiC fiber-reinforced SiC ceramic matrix composites are the most outstanding representatives, but their long manufacturing cycle and high manufacturing costs limit their widespread use. Ti 2 AlC is a new type of ceramic material with the characteristics of low density, high melting point, high-temperature resistance, oxidation resistance, and corrosion resistance of ceramic materials, as well as the conductivity and machinability of metals. However, its mechanical properties are slightly inadequate. The use of chopped fibers for toughening can compensate for these deficiencies to a certain extent and improve mechanical properties. This article first explored the influence of various process parameters on the mechanical properties of pure-phase Ti 2 AlC ceramic materials in SPS preparation technology and then prepared Ti 2 AlC composites reinforced with 10 vol%, 20 vol%, and 30 vol% Al 2 O 3 chopped fibers. The results showed that the samples prepared at 1300 °C, 40 MPa, and 10 min had a flexural strength of 697 MPa and a fracture toughness of 9.83 MPa m1/2 when the volume ratio of the reinforcement phase was only 10 vol%, which was the same as that of the continuously fiber-reinforced SiC f /SiC composites. This study showed that the MAX phase matrix composites reinforced with chopped fibers have the potential to become high-temperature structural materials by adjusting the composite composition and optimizing the preparation process. [ABSTRACT FROM AUTHOR]

This paper explores the grain-size composition effect on flexural and micro-structural features of fiber reinforced cementitious tail-rock fill (FRCTRF). The FRCTRF mixes considered contained a stationary solid concentration of 70 wt% and a cement/tail rate of 1:6, and were cured for an age of 7-day for strength tests and microstructure. Three-point bending test shows that FRCTRF’s bending property is upgraded by totaling gravel rock. Adding fiber to FRCTRF’s bottom can enhance its peak deflection. With rising gravel particle size/dosage, FRCTRF’s peak deflection displays a trend of falling first and then growing. Accumulating polypropylene fiber could advance FRCTRF’s post-peak strength features as well. FRCTRF sample containing gravel has a large stress drop, and adding gravel rock could essentially boost FRCTRF’s post-peak brittle-ability. In conclusion, this study provides a strong scientific and theoretical underpinning for optimizing artificial false roofs employed recently in modern underground metalliferous mining operations.

Starch cryogel is a strong, yet light and porous material with various applications. Neat starch cryogel often suffers from suboptimal mechanical properties. In this study, we investigate the effects of additives on the material properties of starch-based cryogels. Cellulose fibre and glycerol were selected as reinforcing agent and plasticizer, respectively, to formulate starch-based hydrogels, which were freeze-dried into cryogels. Cryogels were characterized in terms of moisture content, density, microstructure, and mechanical properties. Our results show that adding cellulose fibres improves the Young's modulus and structural stability of composite materials. Conversely, adding glycerol significantly enhanced the ductility of the composite materials (i.e., higher maximum flexural strain) without compromising on their Young's modulus. We attributed these results to the impact of the additives on ice formation in the hydrogels during freezing and the structural stability of the matrix during freeze drying, which yielded in distinct microstructures of glycerol-containing samples. This study shows edible composite materials with a large range of material properties can be obtained with the aid of additives, to substitute engineering materials with equivalent properties for various applications.

In this research, the effect of soil stabilization with cement at the same time as its reinforcement with fibers has been studied on the shear strength of sandy soil exposed to freeze-thaw cycles. In order to achieve this goal, laboratory studies were carried out with the help of unconfined compressive strength tests (UCS tests) on different compounds obtained from mixing cement, fibers, and sandy soil. More than 336 cylindrical laboratory models with dimensions including 3.6cm in diameter and 8cm in length have been made. Various modes have been observed during the failure of the samples, including shear, tensile, plastic yielding, and composite failure modes. The fibers used in the present research are waste products of tire factories known as DTY. Percentages of 2, 4, and 6 for cement and 0, 0.5, and 1 for fibers with lengths of 0.5, 1, and 1.5 cm were used relative to the weight of dry sandy soil in making the samples. Uniaxial cylindrical samples were tested for unconfined compressive strength after 7 and 28 days of curing time and under 0, 1, 2, and 3 freeze-thaw cycles. The results show that the act of stabilizing the soil with cement, along with reinforcing it to a certain amount of fibers, improves the uniaxial compressive strength before and after freezing and thawing cycles. This amount depends on the percentage of cement and the curing period. Also, adding cement in a certain curing time increases the unconfined compressive strength before and after applying the cycle, increases stiffness, reduces the ductility and toughness of the sample, and brittle failure when breaking occurs in the soil. Also, the addition of fibers, to some extent, improves the weaknesses caused by soil stabilization, such as reducing the failure axial strain, decreasing the residual strength, and the toughness of the materials in the conditions before and after freezing and thawing.

With the development of miniaturized wearable electronics，flexible energy storage devices with soft，flexible，small size，and high energy density have attracted widespread attention. Aramid nanofibers (ANF) were utilized as fiber reinforcement and pillared structure materials to prepare MXene/ANF flexible self-supporting electrode through vacuum filtration, which were subsequently assembled into all-solid-state symmetric supercapacitors.With the increase of ANF content to 15%，the mechanical properties of MXene/ANF self-supporting electrode increase to 151.5 MPa，while the conductivity decrease to 1371.1 S/cm. The MXene/ANF Self-supporting electrode shows a high specific capacitance of 432.7 F/g at the current density of 1 A/g. The assembled symmetric all-solid-state supercapacitors exhibit excellent mechanical flexibility and remarkable cycling stability,with an energy density of 25.7 Wh/kg at the power density of 523.1 W/kg and about 88.9% capacitance retention over 10000 cycles.

AbstractThis study investigated the rheological and compression–permeability attributes of dredged slurry reinforced using waste rice straws. Recognizing the potential of natural waste fibers in geotechnical applications, this study aimed to elucidate the effects of fiber length and pretreatment processes on the relocation dynamics of the cemented slurry. A series of laboratory evaluations were conducted to gauge critical parameters such as flow consistency, viscosity, one-dimensional compression, and hydraulic conductivity. Results indicated that straw lengths greater than 0.075 mm significantly increased slurry slump flow due to altered surface area and water adsorption. Dynamic viscosity decreased with increasing straw length, yet overall performance improved with straw inclusion. The influence of immersing straws in pure water emerged as a determinant in the study. A 24-h pretreatment duration influenced the flowability, viscosity, and the structural integrity of the fibers. Based on the observations, the study deduces that straw powder finer than 0.075 mm, subjected to a 24-h immersion in pure water, optimally bolsters the flow properties of cemented waste slurry. While the benefits associated with elongated straw fibers necessitate exploration and validation, this work underscores the potential of rice straw as a sustainable reinforcement material in geotechnical endeavors, promoting waste recycling and reducing environmental impact. [ABSTRACT FROM AUTHOR]

Soil stabilization using polymers and fibers has been widely investigated in recent years. This study introduces an innovative approach by integrating synthetic polymer (AH polymer) with natural fibers (sisal fiber) for sand stabilization. A comprehensive experimental framework was established to assess the impact of varying polymer content (1%, 2%, 3%, and 4%) and fiber content (0.2%, 0.4%, 0.6%, and 0.8%, by the mass of dry sand), and densities, on the mechanical properties of stabilized sand, including compressive strength (UCS), tensile strength (TS), and flexural strength (FS). The synergistic stabilization effects of the polymer and fibers were elucidated through SEM. The findings indicate that the synergistic application of AH polymer and sisal fibers significantly enhances the structural integrity of sand. Notably, the UCS, TS, and FS exhibited a well-linear relationship with both the polymer and fiber content. The strengthening effect of fiber was particularly pronounced in samples with higher polymer content. According to the strength increase rate, the optimal polymer content is 2%, and optimal fiber content is 0.6% for the UCS, 0.4% for the TS and 0.8% for the FS. An increase in density was observed to linearly augment the UCS and FS. For sand with 2% polymer and 0.8% fiber, the TS increased linearly with the increment in density, however, for sand with 4% polymer and 0.4% fiber, TS kept a non-monotonic relationship with density. The study also revealed that augmenting the content of polymer and fibers diminishes the brittleness of the stabilized sand, whereas an increase in density has the opposite effect. Furthermore, the incorporation of polymer and fibers resulted in an elevated deformation modulus. The polymer functions as an adhesive, binding fibers to sand particles, while the fibers create a network-like structure that amplifies the effective contact area among sand particles, thereby substantially improving the mechanical properties of the sand. [ABSTRACT FROM AUTHOR]

Fiber-reinforced cement composites, particularly those incorporating natural fibers like cellulose, have gained attention for their potential towards more sustainable construction. However, natural fibers present inherent deficiencies in mechanical properties and can benefit from hybridization with carbon fibers. This study focuses on the incorporation of cellulose and carbon fibers, in varying contents, into fibrocement composites, employing a Response Surface Methodology (RSM) to optimize the material characteristics. The methodology involves testing, encompassing flexural tensile, compression, and fracture toughness tests. The results indicate an increasing trend in flexural strength for higher carbon fiber content, peaking near 5%. A plateau in flexural strength is observed between 1.2% and 3.6% carbon fiber content, suggesting a range where mechanical properties stabilize. Compressive strength shows a plateau between 1.2 and 3.6% and reaches its highest value (≈33 MPa) at a carbon fiber content greater than 4.8%, and fracture toughness above 320 MPa·m1/2 is achieved with carbon fiber content above 3.6%. This study offers insights into optimizing the synergistic effects of cellulose and carbon fibers in fibrocement composites. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sustainability and limitations in embedded reinforcement are the main obstacles in digital fabrication with concrete. This study proposed a 3D printable fiber-reinforced calcined clay-limestone-based cementitious material (FR-LC3). The binder systems incorporating calcined clay (CC) and limestone filler (LF) were optimized by determining the flow characteristics and water retention ability of the paste. The effect of fiber volume on the key fresh and mechanical properties of the fiber-reinforced mortars made with the optimized binder was evaluated. A combination of offline assessments and inline printing were employed to investigate the printability of the FR-LC3 with various binder systems and viscosity-modifying admixture (VMA) dosages. The results revealed that the binary system with 20% CC and the ternary system containing 30% CC and 15% LF were highly advantageous, with enhanced packing density, robustness, and water retention ability. Incorporating 2% 6-mm steel fiber contributed to the highest 28-day compressive and flexural strengths and toughness without significantly compromising the fluidity. Finally, the developed FR-LC3 mixtures were successfully printed using an extrusion-based 3D printer. The LF addition in the ternary system decreased the maximum buildable height of a single-wall printed object while reducing the SP/VMA ratio significantly increased the height due to enhanced yield stress and thixotropy. [ABSTRACT FROM AUTHOR]

The use of 3D printers is expanding across various industries. The incorporation of reinforcing fibers and structures, such as negative Poisson, has the potential to enhance the mechanical properties of three-dimensional products. In this study, a specialized nozzle is developed for 3D Fused Deposition Modeling (FDM) printers dedicated to the production of continuous fiber-reinforced thermoplastic (CFRT) composites. The primary objective is to enhance the tensile strength and impact resistance of 3D-printed samples. It is achieved through the investigation of strategies such as fiber reinforcement, variation in the number of fibers within the reinforcing yarn, and the creation of samples featuring an internal structure with a negative Poisson's ratio (NPRS). In this regard, four types of 3D samples are prepared including polymer only, polymer with a negative Poisson's ratio structure, polymer reinforced with continuous fibers (glass and carbon fibers), and polymer reinforced with continuous fibers featuring a negative Poisson's ratio structure. The mechanical properties of these samples, including tensile strength and impact resistance, are also compared. The results indicate that incorporating fibers as reinforcement can enhance the mechanical properties of 3D-printed products. Moreover, continuous fibers with more fibers within the same yarn count have an increased strengthening effect. The use of negative Poisson structures significantly improves impact resistance but adversely affects tensile strength. [ABSTRACT FROM AUTHOR]

An aluminum silicate fiber/alumina aerogel (ASF/AA) composite was prepared via the sol-gel method and atmospheric drying (APD) method using coal gangue (CG) solid waste from Xingxian county, Shanxi Province, as the aluminum source. Utilizing N2 adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermal conductivity meters, researchers examined the microstructure, composition, pore structure, and thermal insulation performance of ASF/AA composites. The thermal conductivity mechanism of the composite was analyzed. The experimental results show that most of the aluminum in CG is used. More importantly, in the process of aerogel synthesis, the atmospheric pressure drying method is used to obtain similar properties to supercritical drying. The composite material exhibits a low thermal conductivity of 0.047 W/(m·K), a high specific surface area of 416 m2/g, and a low density of 0.26 g/cm3 at room temperature. After heating at 1200 °C for 2 h, the thermal conductivity was as low as 0.071 W/(m·K). This strategy can not only effectively achieve a reduction in the harmfulness of solid waste coal gangue, but also alleviate the shortage of related energy and resources in our country. [ABSTRACT FROM AUTHOR]

This study aims to investigate the influence of different fiber types, lengths, and contents on their performance in freeze-thaw environments. Indoor freeze-thaw tests were conducted to evaluate the flexural strength, compressive strength, and mass loss of fiber-reinforced geopolymer materials. Additionally, SEM and XRD analyses were performed to examine the internal structure of the geopolymer composites. The results demonstrated that the incorporation of different fibers significantly improved various properties, particularly the flexural strength of the specimens. With an increasing number of freeze-thaw cycles, surface cracks became more prominent in the geopolymer specimens, leading to a gradual decrease in frost resistance. However, the addition of an appropriate amount of fiber effectively enhanced frost resistance. Following freeze-thaw exposure, an increase in fiber content initially resulted in a decrease and subsequently an increase in relative flexural strength, compressive strength, and mass loss. Notably, studies revealed that polypropylene fibers with a length of 9 mm and a content of 0.9 % exhibited minimal mass and strength loss. SEM analysis indicated uniform distribution of fibers within the geopolymer matrix, contributing to improved flexural strength and enhanced frost resistance in fiber-reinforced structures. XRD results indicate that red mud-slag based geopolymers produce high-strength hydrated calcium (aluminosilicate) silicate and hematite phases, which enhances the mechanical properties and durability of the specimens. In conclusion, this study highlights that incorporating suitable fibers can enhance the durability and performance of red mud-slag based geopolymers under freeze-thaw conditions. The findings provide valuable insights for optimizing fiber type, length, and content to achieve superior mechanical properties and frost resistance in geopolymer composites.

Failure behavior is the key property needed to be characterized in asphalt concrete at low temperature, which is one of the major influence factors for service life of asphalt pavement. In this study, the reinforcing effect of glass fiber on failure process of asphalt concrete under indirect tension (IDT) test at − 10 ℃ was investigated using acoustic emission (AE) and digital image correlation (DIC) techniques. Control asphalt concrete (CAC) with no fibers was also carried out for comparison. The evolutions of AE parameters including amplitude, count, duration, rise time and corresponding cumulative ones were obtained and analyzed to characterize the failure processes of fiber reinforced asphalt concretes (FRACs) and control one, which were compared with the results from static displacement and strain data obtained through DIC. The effect of fiber length was also investigated to better understand the reinforcing mechanism and determine the proper reinforcing fibers. The test results revealed that low temperature failure processes of CAC and FRAC could be effectively classified according to the variations of AE parameters and corresponding cumulative ones. Three and five failure stages were identified for CAC and FRACs, respectively, which could clearly reflect the reinforcing effect of glass fiber. Cumulative AE parameters presented better identification effect on fiber reinforcement than displacement or strain, while stain data exhibited favorable performance for microcrack initiation. As for the fiber length effect on damage failure process of FRAC, evolutions of cumulative AE parameters before final failure of specimen became more stable with the increase of fiber length within 6–20 mm. AE technique presented great potential for failure behavior analysis and explanation of fiber reinforcing mechanism in asphalt concrete, which also provided promising method for real-time monitoring of cracking in asphalt pavement.

The purpose of this study was to determine the effect of fiber reinforcement materials on the magnitude of stresses in a critical part of the maxillary denture base under thermal and occlusal load. Thermal stress analyses of the models were carried out using the finite element method. The models consisted of bone, soft tissue, interface gap, and maxillary dentures with and without reinforcements. A concentrated occlusal load of 230 N was applied bilaterally on the molar teeth. A 36 °C reference and 0 °C, 36 °C, and 70 °C variable ambient temperatures were applied to the models. CrCo, unidirectional and woven carbon/epoxy, unidirectional and woven glass/epoxy, and unidirectional and woven Kevlar/epoxy were used as reinforcing materials in the maxillary denture base made of PMMA (polymethyl methacrylate). Stress distributions on the maxillary denture’s midline and lateral line direction were evaluated. Maximum stresses in the incisal notch and the labial frenal notch of the maxillary denture were determined. Failure analysis of reinforcement materials used in maxillary dentures was carried out using the Tsai-Wu index criterion. The results obtained show that the thermal properties of reinforcement materials should be considered as an important criterion in their selection.

Pull-out strength tests conducted on screw anchors in uncracked concrete substrates of the C25/30 class are presented in this article. The destructive force for anchor–concrete fasting was tested, and in the next step, the average pull-out strengths of screw anchors in concrete substrates with and without the addition of steel fiber were determined. Currently, the pull-out strengths of anchors in fiber-reinforced concrete substrates are defined as for unreinforced concrete substrates. Therefore, pull-out tests were performed for screw anchors in fiber-reinforced concrete substrates. Fiber contents of 10, 20, 30, and 50 kg/m3 were used. An increase in the load capacity of screw anchors in a fiber-reinforced concrete substrate was demonstrated in a pull-out test compared to base samples without fibers. The coefficient related to the actual fastening behavior of a screw anchor in the fiber-reinforced concrete substrate was determined. It was assumed that a coefficient of 13.10 should be adopted. This was the lowest value obtained for the load capacity in this study for screw anchors in a fiber-reinforced concrete substrate. [ABSTRACT FROM AUTHOR]

To evaluate properties of fiber-reinforced-composites (FRC) containing Bis-EMA/UDMA monomers but identical dispersed phase (60% wt BaSi glass power +10% wt E-glass fibre). A control (Group A), monomer mixture comprising 60% Bis-GMA, 30% TEGDMA, and 10% PMMA (typical FRC monomers) was used. The following monomer mass fractions were mixed: 50% bis-GMA plus 50% of different ratios of Bis-EMA+UDMA to produce consistent formulations (Groups B-E) of workable viscosities was also studied. Flexural strength (FS), fracture toughness (K IC), water sorption (SP), solubility (SL) and hygroscopic expansion (HE) were measured. FS and K IC specimens were stored for 1, 7 d, and 30 d in water at 37 °C. SP/SL specimens were water-immersed for 168d, weighed at intervals, then dried for 84 d at 37 °C. To analyze differences in FS, and K IC , a two-way ANOVA and Tukey post-hoc tests (α = 0.05) were conducted. For SP/SL, and HE, one-way ANOVA with subsequent Tukey post-hoc tests (α = 0.05) were utilized. FS and K IC for groups A, D, E decreased progressively after 1 d. Groups B and C (highest amounts of Bis-EMA) did not decrease significantly. The modified matrix composites performed significantly better than the control group for SP and HE. The control group outperformed the experimental composites only for SL with up to 250% higher SL for group E (6.9 μg/mm) but still below the maximum permissible threshold of 7.5 μg/mm. Significance: composites with highest amounts of Bis-EMA showed improved hydrolytic stability and overall enhancement in several clinically-relevant properties. This makes them potential candidates for alternative matrices to a semi-interpenetrating network in fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

In recent years, composite resin materials have been the most frequently used materials for direct restorations of posterior teeth. These materials have some clinically relevant limitations due to their lack of fracture toughness, especially when used in larger cavities with high volume factors or when utilized as direct or indirect overlays or crown restorations. Recently, short-fiber-reinforced composite materials have been used in bi-structure restorations as a dentine substituting material due to their superior mechanical properties; however, there is no scientific consensus as to whether they can be used as full restorations. The aim of our review was to examine the available literature and gather scientific evidence on this matter. Two independent authors performed a thorough literature search using PubMed and ScienceDirect up until December 2023. This study followed the PRISMA guidelines, and the risk of bias was assessed using the QUIN tool. The authors selected in vitro studies that used short-fiber-reinforced composite materials as complete restorations, with a conventional composite material as a comparison group. Out of 2079 potentially relevant articles, 16 met our inclusion criteria. All of the included studies reported that the usage of short-fiber-reinforced composites improved the restoration's load-bearing capacity. Fifteen of the included publications examined the fracture pattern, and thirteen of them reported a more favorable fracture outcome for the short-fiber-reinforced group. Only one article reported a more favorable fracture pattern for the control group; however, the difference between groups was not significant. Within the limitations of this review, the evidence suggests that short-fiber-reinforced composites can be used effectively as complete restorations to reinforce structurally compromised teeth. [ABSTRACT FROM AUTHOR]

Modern materials used in civil engineering should fulfill the numerous of requirements connected building standards, but not only. They should also be ecological and durable. Geopolymers are characterized by very good mechanical properties, high resistance against acids, chlorides and sulfates, high thermal resistance, and other properties confirmed by previous research. There is still a few amount of research connected with resistance, this materials for different environmental conditions, especially a lack of investigation connected with foamed geopolymers in this area. The main objective of the article is to analyze the possibilities of the development of new foamed geopolymer composites to increase durability, especially against degradation in corrosive water environments. This paper presents the influence on the mechanical properties of foamed geopolymer composites on the water environment. As raw materials, fly ash from the coal power plant 'Skawina' (located in: Skawina, Lesser Poland, Poland) and metakaolin (Czech Republic) were used. The chemical composition of the fly ash is typical for class F. Additionally, the composites were reinforced by flax fiber. Solid and foam samples were prepared. As a foaming agent, hydrogen peroxide (H 2 O 2) was applied. The following research methods were applied: compressive strength, flexural strength, porosity measurements, water absorption in fresh and salt water. The results show that, however, environmental conditions have a significant influence on the mechanical properties of geopolymer composites; the geopolymer composites can be successfully produced with the addition of natural fibers and have good strength parameters even after long-term use (materials were tested after 360 days). [ABSTRACT FROM AUTHOR]

This study evaluated the feasibility of using polypropylene fiber (PF) as reinforcement in improving tensile strength behavior of cement-stabilized dredged sediment (CDS). The effects of cement content, water content, PF content and length on the tensile strength and stress–strain behavioral evolutions were evaluated by conducting splitting tensile strength tests. Furthermore, the micro-mechanisms characterizing the tensile strength behavior inside PF-reinforced CDS (CPFDS) were clarified via analyzing macro failure and microstructure images. The results indicate that the highest tensile strengths of 7, 28, 60, and 90 d CPFDS were reached at PF contents of 0.6%, 1.0%, 1.0%, and 1.0%, exhibiting values 5.96%, 65.16%, 34.10%, and 35.83% higher than those of CDS, respectively. Short, 3 mm, PF of showed the best reinforcement efficiency. The CPFDS exhibited obvious tensile strain-hardening characteristic, and also had better ductility than CDS. The mix factor (CCa/Cwb) and time parameter (qt0(t)) of CDS, and the reinforcement index (kt-PF) of CPFDS were used to establish the tensile strength prediction models of CDS and CPFDS, considering multiple factors. The PF "bridge effect" and associated cementation-reinforcement coupling actions inside CPFDS were mainly responsible for tensile strength behavior improvement. The key findings contribute to the use of CPFDS as recycled engineering soils. [ABSTRACT FROM AUTHOR]

Composite materials have an ever-increasing demand for their application in numerous applications such as aerospace, automobile, petroleum, etc. These materials vary according to their chemical composition, properties, manufacturing techniques, etc. Natural fiber-reinforced composites are the composites where natural fibers such as plant, animal, and mineral fibers are used as reinforcement material. Reinforcement of these fibers yields composite material with extensive properties such as high strength, durability, reliability, etc. These properties lead them to commercial applications in several areas. Therefore, this paper describes various characteristics of the matrix, reinforcement, and resin used for natural fiber composite materials. Also, multiple parameters that affect the growth of these composites are investigated. The tribological behavior of natural fiber composites is focused mainly on friction, wear, and lubrication. Furthermore, the material's mechanical performance and metallurgical behavior are also given significant importance. These materials' application in various fields is explored separately, and multiple conclusions are drawn. [ABSTRACT FROM AUTHOR]

At present, concrete blocks serve as the primary construction material in civil engineering due to their convenient material selection and impressive compressive strength. However, their limitations in terms of low tensile strength, poor toughness, and susceptibility to cracking hinder their progress. To enhance the flexibility and resilience of concrete, incorporating fibers is a viable method to develop a composite material. Pine needles is a promising material for reinforcing concrete blocks, pavers, and kerbstones. It has been shown to enhance a wide range of concrete valuables, containing tensile strength compressive strength, flexural strength, toughness indices, and energy absorption. In current study mix design of 1:4:2:0.8 (cement: sand: aggregate: water) is used for preparing PC. Pine needle fibres lengths of 37 mm are used for preparation of pine needle reinforced concrete. Improvement observed in compressive energy absorption by 2.25 times, toughness index 3.05 times, maximum deformation up to 13 mm and decrease in compressive strength observed by 23%. Ductile behaviour also observed with respect to the reference specimens. In general, pine needles are effective in utilization in concrete structure has the potential to be used in cement concrete composites for different structural. The current investigation focuses on to develop low cost-efficient concrete keeping compressive performance. [ABSTRACT FROM AUTHOR]

Reducing the environmental footprint of the construction industry in general and concrete in particular is essential. The addition of synthetic and natural fibers to concrete mixes at appropriate dosages enhances durability and strength and extends the lifespan of concrete infrastructures. This study reviews the geometric and mechanical properties of selected fibers such as steel, basalt, polypropylene, polyvinyl alcohol, polyethylene, glass, carbon, and natural fibers and their impact on concrete fresh, mechanical, and durability properties when combined in different configurations. The study focuses on the effect of blending fibers with concrete mixes that use alkali-activated binders based on recycled industrial byproducts such as slag and fly ash and thereby contribute to reduction of CO2 contribution through complete or partial replacement of Ordinary Portland cement (OPC). As a result, the effect of binder content, binder composition, alkaline activator concentration, and water-to-binder (w/b) ratio on fresh properties, mechanical strength, and durability of concrete with blended fibers is also evaluated in this study. The properties of fiber-reinforced concrete with alkali-activated binder and conventional OPC binders are compared. Fiber-reinforced concrete with alkali-activated binders that are based on industrial byproducts may represent sustainable alternatives to conventional concrete and offers competitive fresh and mechanical properties when fiber properties, fiber content, w/b ratio, binder type, and dosage are carefully considered in concrete mix design. [ABSTRACT FROM AUTHOR]

Türkiye has approximately 50.000 acres of banana plantations. Banana cultivation produces a huge amount of waste that has no commercial value. The main purpose of this study is to investigate the possibilities of using waste banana fiber in natural pozzolan-based geopolymer mortar to increase its ductile fracture behavior. The effects of fiber content and length on physical and mechanical properties were experimentally carried out. The optimum banana fiber content and length were found to be 1.5% and 20 mm, respectively. Above this limit, fibers made it difficult to obtain a workable matrix and generated fiber agglomeration. Although increasing the fiber content from 0.5% to 1.5% and length above 20 mm led to a decrease in the ultrasound pulse velocity, modulus of elasticity and compressive strength due to the higher porosity of the matrix, the increasing ratios of the flexural strength and toughness were consistent. Furthermore, banana fiber-reinforced geopolymer mortars have adequate porosity (22.87%), water absorption ratio (9.25%), swelling thickness (0.58%), saturation coefficient (78%), drying shrinkage (195x10–6), water vapor diffusion resistance index (5.73), flexural strength (6.88 MPa), compressive strength (8.75 MPa), and comply with the performance requirements of the related standards. By considering the adequate physical, mechanical and ductile fracture performance of the material, waste banana fiber can be utilized in the production of geopolymers. [ABSTRACT FROM AUTHOR]