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The purpose of the study was to evaluate selected mechanical properties and structural characteristics of samples manufactured using composite filament fabrication (CFF) technology from Onyx material, whichwas filled with continuous glass fiber. Selected mechanical properties were correlated with the density of the resulting composite to determine the specific strength of the fabricated parts. The test specimens were manufactured on a Mark Two Enterprise machine (Markforged, USA) using composite filament fabrication (CFF) technology. The material used was polyamide 6.6 with a 20% short carbon fiber content with the trade name Onyx. Continuous glass fiber was used to reinforce the fabrication. The density of the manufactured samples was determined using a hydrostatic method. Methanol was used as the liquid. By determining the density of the samples, it was possible to estimate through appropriate calculations what specific strength and specific modulus the obtained composites would have. Determination of tensile and flexural strengths was carried out in accordance with ISO 527-1:2012 and ISO 178:2003. Determination of the impact tensile strength of the samples was carried out in accordance with ISO 8256, the beams were tested using the A method. Due to the high impact tensile strength, two 1 mm notches with an angle of 45°were made on the specimens. The image of the sample structure obtained by the CFF method was recorded using a CT scanner. A thermogravimetric test (TG) of the Onyx matrix material was carried out. The samples were tested approximately 72 hours after fabrication. Filling the samples with continuous glass fiber above 50% leads to a slight increase in impact resistance. The density of the composite increased by only 16% relative to the reference samples, resulting in a 389% increase in the maximum average flexural strength. Despite significant discontinuities in the structure of the produced composite, it was possible to record an increase in tensile strength and Young's modulus by 606% and 370%, respectively. [ABSTRACT FROM AUTHOR]

The use of fibres applied to concrete in order to improve its properties is widely known. Nowadays, research is not only focused on improving mechanical properties but also on the environmental implications. The aim of this research was a mechanical and environmental comparison between different types of fibres. For this purpose, commercial fibres of three materials were used: low carbon steel, modified polyolefins, and glass fibre. In order to improve the sustainability of the sector, we also analysed and compared the performance of using a waste product, such as fibres from machining operations on lathes. For the evaluation of the mechanical properties, compression and flexural tests were carried out. The results show that the use of low carbon steel fibres increases the flexural strength by 4.8%. At the environmental level, and in particular for impact categories such as the Global Warming Potential (GWP), lathe waste fibres prove to be the most suitable. For instance, compared to glass fibres, CO2 emissions are reduced by 14.39%. This is equivalent to a total of 38 kg CO2 emissions per m3 of reinforced concrete. In addition to avoiding the consumption of 482 MJ/m3 of fossil fuels, the results of the research indicate the feasibility of using waste fibres as a substitute for commercial fibres, contributing to an improved environmental balance without losing mechanical performance. [ABSTRACT FROM AUTHOR]

Objective: To measure the flexural strength (FS) of bulk-fill resin composites and assess their long-term water absorption and solubility properties with and without the inclusion of short glass fibres. Methods: One resin composite, everX Flow with fibres, and four commercially available bulk-fill composites without fibres, namely, PALFIQUE, Activa, SDR Plus, and Filtek Bulk Fill One, were tested. Six specimens (2 × 2 × 25 mm) were fabricated for each material and stored in water for 1 day and 30 days to measure the flexural strength using a three-point bending test. To evaluate water absorption and solubility, circular disks measuring 15 × 2 mm (n = 5) were immersed in water for 60 days, and their weights were recorded periodically. After 60 days, the specimens were dried for an additional 21 days to determine solubility. Results: Flexural strength values ranged from 101.7 to 149.1 MPa. Significant distinctions were observed among the resin composites at the onset of the study (p < 0.05). The highest FS value was identified in everX Flow, while ACT exhibited the lowest (p < 0.05). However, the flexural strength values exhibited a significant decrease with increased storage time (p < 0.05), except for ACT, which demonstrated a noteworthy increase. Concerning water absorption and solubility, ACT displayed the highest absorption, while the range of solubility varied from −0.88 to 5.8 μg/mm3. ACT also had the highest solubility, whereas everX Flow exhibited negative solubility. Significance: The addition of short fibres, along with potential differences in matrix composition, enhanced the flexural strength of everX Flow. However, the substantial reduction in flexural strength observed in everX Flow and SDR following exposure to water corroborates the manufacturers' recommendation to apply a conventional resin composite cap on these materials. [ABSTRACT FROM AUTHOR]

Polymethylmethacrylate (PMMA) has been the most-widely used denture base material in prosthetic dentistry for the last 80 years. It is still one of the best alternatives when new methods are inapplicable. Due to the lack of some physical inadequacies occurring during cyclic use and accidental situations, various reinforcement strategies such as using nanoparticles, wires, fibers, and meshes have been investigated and reported. In this study, it was aimed to conduct a comparative investigation of the effect of fiber additives with different characteristics on the flexural properties of heat-cured PMMA denture base resins. Glass fibers (GFs), polypropylene fibers (PPFs), and carbon fibers (CFs) having 3, 6, and 12 mm lengths and 0.25, 0.50, and 1.0% concentrations (v/v) were used for the reinforcement of PMMA denture base resins. The flexural properties (flexural strength, flexural modulus, and maximum deformation) were determined using a three-point bending test, and three-way ANOVA analyses with Bonferroni corrections were performed on the test results. The morphologies of the fracture surfaces were analyzed using scanning electron microscopy. All three fibers exhibited reinforcement in the flexural strength (p < 0.001) and flexural modulus (p < 0.001) regardless of their length and concentration. The group with 1.0% 12 mm CF-reinforced PMMA exhibited the greatest flexural strength (94.8 ± 8.8 MPa), and that with 1.0% 3 mm GFs displayed the lowest flexural strength (66.9 ± 10.4 MPa) among the fiber-reinforced groups. The greatest value of the flexural modulus was displayed by the 1.0% 3 mm CF-reinforced resin (3288.3 ± 402.1 MPa). Although the CF-reinforced groups exhibited better flexural properties, CFs are not favorable for use as reinforcement in practice due to the dark gray discoloration of the denture base resin. It was concluded that PPF is a promising material for the reinforcement of heat-cured PMMA denture base resins. [ABSTRACT FROM AUTHOR]

Mechanical properties considerably reduce in wood-plastic composites (WPCs) due to the use of wood particles, so the structural applications of these composites are scarce. Thus, embedding continuous fibers is considered the most reliable method for increasing mechanical properties, although there are still challenges in employing this method on a large scale. In this study, an elaborated, special modular die with the capability of adjusting 14 rovings of continuous fibers was designed, manufactured, and implemented to simultaneously embed continuous glass fibers into the extruded WPC profile. More precisely, it was aimed to investigate the arrangement of fiber rovings into the desired positions in a WPC profile of 70 wt% wood content. Also, the effect of the glass bundle tex (at three level, 1200,2400 and 4800) and the fiber position (at four levels, 0, 2, 4, and 6 mm of relative movement of the guides) on the mechanical properties of WPCs was evaluated. According to the results, the flexural strength of reinforced specimens for 1200, 2400, and 4800 texes increased by 85.8, 107, and 159.7%, respectively, compared with the non-reinforced composite. Theoretical values were calculated and compared with experimental outcomes. Based on the results, The failure mode was non-catastrophic, which means the specimens were able to carry partial loading; a desirable characteristic for the structural applications. [ABSTRACT FROM AUTHOR]

In this article, two kinds of carbon/glass fiber hybrid rod with the sandwich structures were designed and developed through the pultrusion technology, including the fiber random hybrid (RH) mode with multi-layer sandwich structure and fiber core-shell hybrid (CH) mode with single-layer sandwich structure. The hybrid sandwich-structure plates were prepared from the rod and immersed in bending loading, temperature alternating and sustained water immersion as long as 360 days. The effect of fiber hybrid mode/sandwich structure on the degradation mechanism of mechanical properties was revealed through the digital image correlation and thermogravimetric analysis. Through the fiber hybrid design, the strength improvement percentages of RH plates with multi-layer sandwich structure were up to ∼50% (tensile strength), 30 ∼ 40% (flexural strength) and 18% (in-plane shear strength) compared to CH plates with single-layer sandwich structure. Higher bending loading level brought about the decrease of flexural strength and in-plane shear strength close to 18% and 19%, respectively. During the immersion, microcracks or microvoids formed and expanded in the resin tensile area under the bending loading and water diffusion, leading to the uncoordinated stress concentration for single-layer sandwich-structure CH plate. By uniformly dispersing carbon fibers into glass fibers, the uneven interface stress concentration can be effectively alleviated for multi-layer sandwich-structure RH plates. The comparison of mechanical properties with the others' work showed the interface shear strength was more sensitive to the bending loading and immersion temperature. The long-term life prediction showed the maximum increase percentages of mechanical properties of multi-layer sandwich structure were 435.4% (tensile strength) and 149.2% (flexural strength) and 110.7–114.2% (shear strength) compared to the single-layer sandwich structure. [ABSTRACT FROM AUTHOR]

The use of glass fiber reinforced concrete (GFRC) in the construction industry is increasing due to its mechanical and physical properties. Waiting time of concrete in the mold and the removal of the mold at the right time are important in terms of strength. In conventional concretes, maturity models are widely used as a non-destructive method for early strength estimate. In this study, it is aimed to develop an estimate model of flexural and compressive strength in GFRCs using the maturity index method. In this context, glass fiber reinforced concretes were produced at the rates of 0%, 1%, 2% and 3%. Calcined kaolin and acrylic polymer were used as modification materials in the mixtures. Properties such as compressive, flexural, hardness, and shrinkage of specimens were investigated at different ages. The maturity-strength relationships of mixtures at different ages were examined by weighted maturity and Nurse-Saul methods. At the end of the study, two new models were developed to estimate the compressive and flexural strengths of GFRCs, taking into account all the data. The suggested models have been confirmed by examining them on all mix-age groups and comparing them with the literature. [ABSTRACT FROM AUTHOR]

Owing to its enhanced strength, ductility, and resistance to harsh environments, increasing research attention has been paid to alkali-resistant glass fiber reinforced concrete (ARGFRC). This paper presents experimental studies concerning the effects of fiber content on the mechanical properties and microstructural characteristics of ARGFRC. The amount of glass fiber was considered at levels of 0.0, 0.3, 0.5, 0.8, 1.0, 1.3, and 1.5% of the concrete volume. The compression, flexural, impact resistance, scanning electron microscopy, and energy dispersive spectroscopy tests were conducted. The flexural load-deflection curve, flexural strength, flexural toughness index, flexural fracture energy, postcracking stiffness, postpeak stiffness, and impact resistance energy absorption were obtained. Then the changing law affected by fiber content on these mechanical properties was further analyzed, and the corresponding equation was fitted. When fiber content was 1.5%, the flexural toughness index I5, I10, and I20 values were 4.0, 5.9, and 8.9, respectively, and increased by 3.0∼7.9 times. Glass fiber incorporation could increase the ductility and delay the brittle failure when the fiber content reached 0.8%. The largest postcracking stiffness was calculated at 36.174 kN/mm with a fiber content of 0.8%. The higher the fiber content, the larger the postpeak stiffness of the tested beams. Impact resistance test results demonstrated that the optimum fiber content was 1.3%. As the fiber content increased, the effect of the concrete grout on the fiber packaging decreased, according to the scanning electron microscopy analysis. The energy dispersive spectroscopy observation proved that adding a certain fiber content did not affect the concrete hydration reaction. [ABSTRACT FROM AUTHOR]

The growing demand for polymer composites and their widespread use is inevitably accompanied by the need to know their degradation behavior over a sufficiently long period of time. This study focuses on commercial glass fiber rovings, which were stored in the indoor environment for up to 11 years. Fibers with different storage times, from fresh up to the oldest, were used to produce unidirectional fiber-reinforced polyester composites that were characterized to determine their shear and flexural properties dependent on fiber storage time. A significant decrease in shear strength was observed throughout the aging of the fibers, down to a decrease of 33% for the oldest fibers. An important finding, however, was that the significant decrease in shear strength was only partially reflected in the flexural strength, which corresponded to a decrease of 18% for the oldest fibers at consistent flexural modulus. [ABSTRACT FROM AUTHOR]

For enhancing impact characteristics, woven glass fiber epoxy laminates are reinforced with short fibers. The 6‐mm‐long slender fillers, when added up to 4% in the matrix, exhibit no influence on the flexural modulus, but at 2% they maximize the laminate's flexural strength. While the dissipation energy continues to increase up to 30 J of impact, the laminates' post‐impact load bearing capacity gets significantly affected beyond 20 J. The reinforced laminates exhibit better elastic response and enhanced damage resistance with as high as 50% reduction in the visible damage area as well as up to 35% increase in the damage initiation force. The degree of damage shows excellent correlation with the visible damage area. The distinct through thickness conical region, diverging from the impact site, is attributed to the presence of microcracks oriented along the fiber directions. The cone boundary, from where the interlaminar failure initiates, is largely the manifestation of transverse matrix cracks. While the damage cone with greater divergence indicates reduced impact resistance of the laminate, the orientation of transverse matrix cracks remains unaffected by the impact energy or the filler content. At low impact energies, the failure initiated from the fiber/matrix interfaces, coalesce to form the matrix cracks, which act as a precursor to the interlaminar failure. However, at high energy levels, several failure mechanisms simultaneously develop with no clear indication of the order of damage evolution. The short fibers enhance the laminate's impact resistance either by arresting the cracks or by developing tortuous crack path with high energy dissipation. [ABSTRACT FROM AUTHOR]

The present study is focused on investigating the mechanical properties of hybrid polymer composites. The reinforcement materials are animal bone (ox) particulate and E-glass fiber. The matrix material is epoxy resin. The following combinations are considered for investigation: (a) bone particulate weight percent (20%, 30%, and 40%), (b) E-glass fiber weight percent (20%, 30%, and 40%), and (c) bone particulate (10%, 20%, and 30%) and E-glass fiber (30%, 20%, and 10%) with epoxy resin 60% by weight percent. The test specimens are prepared as per the required ASTM standard for tensile, compressive, and flexural tests. The test results show that maximum tensile and compressive strength observed in 40% of E-glass fiber with 60% of epoxy matrix, correspondingly, is 254.964 MPa and 37.52 MPa. The maximum flexural strength observed in E-glass fiber reinforced composites is 250.43 MPa. [ABSTRACT FROM AUTHOR]

• Fibers improve mechanical properties of a resin modified glass ionomer cement (RMGIC). • Mechanical properties with RMGIC matrix are improved over GIC matrix. • Braided long fibers give higher flexural strength than discontinuous short fibers. • Resin pre-impregnation of braided long fibers greatly enhanced the flexural strength. • Pre-impregnation of the short glass fibers had no effect on mechanical properties. Understand how discontinuous short glass fibers and braided long fibers can be effectively used to reinforce a resin modified glass ionomer cement (RMGIC) for carious lesion restorations. Two control groups (powder/liquid kit and capsule) were prepared from a light cured RMGIC. Either discontinuous short glass fibers or braided polyethylene fiber ribbons were used as a reinforcement both with and without pre-impregnation with resin. For the former case, the matrix was the powder/liquid kit RMGIC, and for the latter case the matrix was the capsule form. Flexural strength was evaluated by three-point beam bending and fracture toughness was evaluated by the single-edge V-notch beam method. Compressive strength tests were performed on cylindrical samples. Results were compared by analysis of variances and Tukey's post-hoc test. Flexural strength data were analyzed using Weibull statistical analysis. The short fiber reinforced RMGIC both with and without pre-impregnation showed a significant increase of ∼50% in the mean flexural strength and 160–220% higher fracture toughness compared with the powder/liquid RMGIC control. Reinforcement with continuous braided fibers gave more than a 150% increase in flexural strength, and pre-impregnation of the braided fibers with resin resulted in a significant flexural strength increase of more than 300% relative to the capsule control. However, for the short fiber reinforced RMGIC there was no significant benefit of resin pre-impregnation of the fibers. The Weibull modulus for the flexural strength approximately doubled for the fiber reinforced groups compared to the control groups. Finally, compressive strength was similar for all the groups tested. By using a RMGIC as a matrix, higher flexural strength was achieved compared to reported values for short fiber reinforced GICs. Additionally, the short fibers provided effective toughening of the RMGIC matrix by a fiber bridging mechanism. Finally, continuous braided polyethylene fibers gave much higher flexural strength than discontinuous glass fibers, and their effectiveness was enhanced by pre-impregnation of the fibers with resin. [ABSTRACT FROM AUTHOR]

A novel strategy of multi‐walled carbon nanotubes‐montmorillonite (MWCNTs‐Mt)‐modified glass fiber fabrics (GFf) was used here to reinforce interlaminar regions of epoxy composites. One/two‐dimensional MWCNTs‐Mt hybrids with different mass ratios of MWCNTs and Mt were combined with the GFf, respectively, prior to a resin injection process. Making use of this strategy, uniformly dispersed MWCNTs and highly exfoliated Mt at the fiber/matrix interface could be achieved; meanwhile, mechanical and interfacial properties of resultant composites were greatly enhanced. Under a mass ratio of MWCNTs:Mt (0.2:1), the interlaminar shear, tensile, and flexural strengths of resultant composites were improved by 31.0%, 26.0%, and 21.9%, respectively; the storage modulus increased by 23.6%, compared with the composite without MWCNTs‐Mt. Also, the work of fracture obtained from interlaminar load‐displacement curves and peak loss moduli of resultant composites were significantly enhanced, indicating the synergistic toughening effect of MWCNTs and Mt. [ABSTRACT FROM AUTHOR]

Utilization of recycled aggregate from the construction and demolition waste as a partial substitution of natural aggregate in the concrete has been increased in the recent times in order to minimize the consumption of natural resources and the harmful effects to the environment. The present investigation mainly focuses on the influence of different fibers on mechanical and other properties of concrete made with 50% of recycled coarse aggregate (RCA) as well as concrete with 100% natural aggregate. Three types of fibers such as Woolen fibers (WF), Glass fibers (GF), and Steel fibers (SF) were used in both normal and recycled aggregate concrete mixes. The workability, compressive strength, split tensile and flexural strengths, modulus of elasticity, density, water absorption and volume of voids, and ultrasonic pulse velocity (UPV) properties of all the mixes were investigated. From the experimental findings it was observed that the fibers significantly improve the mechanical properties of both normal and recycled aggregate concretes. Further among the WF, GF, and SF, SFs had shown more positive impact on the properties of concrete. [ABSTRACT FROM AUTHOR]

As the progress of using materials for making concrete is growing, a lot of research has been done to make concrete with a variety of materials to get concrete performing well. The compressive strength and split concrete are influenced by what materials are used. This study conducted an experiment to make fibrous concrete using a mixture of fiberglass material type Chopped Strand Mat (CSM), CSM was cut to a size of 1 cm x 4 cm then CSM was described by pulling CSM from the webbing. The cylindrical specimens measuring 150 mm x 300 mm, the compressive strength of the plan 20 Mpa with 4 kinds of mixed variations of 0 %, 0.25 %, 0.5 %, and 0.75 % of the weight of cement used. Compressive and split strength testing of concrete aged 7, 14, and 28 days. The results of slump test results showed that the greater the percentage of Fiberglass the lower the slump produced. The compressive strength test results obtained 0 % at the age of 28 days obtained compressive strength of 20.2 MPa, while the highest addition of fiberglass compressive strength at 28 days the addition of fiberglass by 0.25 % 24.6 MPa. The highest tensile strength at 0.75 % fiber addition was 3.9 MPa, and the maximum flexural strength at 0.75 % fiber addition was 2.889 MPa. From the results of this study it was concluded that with the addition of 0.25 % fiberglass it was found to be strong the highest compressive strength is 24.6 MPa and the splitting strength of 3.9 MPa is produced from the addition of 0.75 % fiber, and the flexural strength of 2.889 MPa is produced from the addition of 0.075 % fiber. with the addition of a certain percentage of fiberglass can add compressive strength, tensile strength and flexural strength in concrete. [ABSTRACT FROM AUTHOR]

The un-stiffened fiber reinforced polymer (FRP) beams under three-point bending often fail at compression web-flange junction due to low inter-laminar shear and transverse compressive strengths of web. Therefore, the objective of the present work is to study the effect of different stiffening elements on the flexural response of FRP I-beams. Various stiffening elements such as glass fiber reinforced polymer (GFRP) cover plates, cover angles, and bearing stiffeners are connected to the beam separately to examine their effect on the strength, stiffness and failure modes. This study also includes the strengthening of web-flange junction of FRP I-beams using carbon fiber layers with adhesive. It is observed that replacing the chopped strand mats with 45° and 90° unidirectional rovings increases the crushing strength of the beam. Strengthening of web-flange junction using carbon fiber layers or stiffening with short length bearing stiffeners under loading is observed to be most effective in preventing the failure of web-flange junction of FRP I-beams. Beams stiffened with short length bearing stiffeners have higher failure load than other stiffened beams. Strengthening of web-flange junction using wet carbon fiber layers is noted to be more effective than stiffening with GFRP cover angles. Since the stress concentration produced due to the sudden change in the cross-section of beams strengthened with carbon fiber reinforced polymer (CFRP) laminated cover angle is less than that for beams stiffened with GFRP cover angles. • Web-flange junction strength of FRP beams without imperfection is higher than beams with imperfection. • Short length bearing stiffeners avoid the failure at tension web-flange junction of FRP I-beams. • Strengthening using wet (adhesive) carbon fiber layers is more effective than stiffening with cover angles. • Delamination of web-flange junction of I-beams can be avoided by strengthening of web-flange junction with carbon fiber layers. • Flexural strength of beams with short bearing stiffeners under web-flange junction is higher than other stiffening elements. [ABSTRACT FROM AUTHOR]

This paper explores the fracture properties of a novel and sustainable glass-fiber reinforced composite, the matrix for which is formed through the aqueous, anoxic, room-temperature carbonation of (waste) metallic iron powder along with other minor ingredients. A comparison of the properties of this binder with Ordinary Portland Cement pastes, which constitutes one of the most common and economic ceramic matrices is also provided. The iron-based binder system exhibits fracture parameters (fracture toughness, K IC S and critical crack tip opening displacement, CTOD C , determined using two parameter fracture model, TPFM) that are significantly higher when compared to those of the OPC systems in both the unreinforced and glass fiber reinforced states. The beneficial influence of the unreacted metallic iron particles of large aspect ratio, on the fracture parameters of iron-based binders are elucidated. The strain energy release rates show trends that are in line with the fracture parameters from TPFM. The elastic and inelastic components of strain energy release rate are separated in an effort to capture the fundamental toughening mechanisms in these systems. The fracture parameters determined using a non-contact, digital image correlation technique are found to relate well to those obtained from TPFM. [ABSTRACT FROM AUTHOR]

Highlights: [•] We suggested a section of a new module that would apply a large section. [•] We developed a new FRP composite girder that is filled with concrete. [•] It was confirmed the composite effect from confining concrete. [ABSTRACT FROM AUTHOR]

[Display omitted] • The macro mechanical strength and microstructures were conducted. • Combined fiber-reinforced effect was obvious in the cemented tailings backfill (CTB). • The fiber has a positive effect on improving the flexural strength of CTB. The brittleness of the cemented tailings backfill (CTB) can easily cause collapse, which seriously threatens the safety of underground mining workers and equipment. Studies have shown that fibers can improve the ductility of the CTB. However, there are still few existing studies on the mechanical behavior of combined fibers. In this study, glass (G) fiber and polypropylene (PP) fiber were adopted to prepare fiber-reinforced CTB (FRCTB) specimens. The three-point bending and scanning electron microscopy (SEM) tests were adopted to investigate the mechanical properties of CTB and FRCTB. The main conclusions were shown that: the flexural strength (FS) values of FRCTB specimens first decreased and then increased with the glass fiber content decreased. However, the residual FS values of all FRCTB were larger than those none fiber-reinforced CTB. The average flexural modulus of all the FRCTB first decreased and then increased with the content of glass fiber decreased. The average toughness index (ATI) values of all FRCTB specimens were larger than those none fiber-reinforced CTB. Indicating that the addition of fibers can improve the bending performance of the CTB specimens. The failure patterns of the CTB were mainly the tensile failure along the loading direction. The main hydrate products were still AFt and C-S-H gels. The combined fibers had an impeding effect on crack propagation. The results of this study can provide references for elaboration combined fiber-reinforced mechanism of FRCTB and serve the industrial application. [ABSTRACT FROM AUTHOR]

The static and dynamic mechanical properties of banana and glass woven fabric-reinforced polyester composites have been determined with special reference to the effect of fiber volume fraction, layering pattern, and the weaving architecture. Even though articles related to natural fiber composites are abundant in the literature, work on natural fiber textile composites is found to be rare. Composites with high tensile strength can be obtained using banana and glass in the fabric form, using two layers of the fabric. The impact strength of the composites increases with the number of layers and the fiber volume fraction. By incorporating the fabric, the G′ curve shows an improved rubbery plateau indicating that the incorporation of the fabric induces reinforcing effects in the polyester matrix. The storage modulus has been found to be the highest for composites with four layers of the fabric. In all the composite samples, the relaxation peak of polyester is visible as peak in G″ at about 98°C. In the case of composites with four layers of the fabric, two peaks and one shoulder are seen. Increase in the number of layers made a second relaxation peak visible. The damping peaks have been found to be lowered by the incorporation of more number of layers. [ABSTRACT FROM AUTHOR]

Due to the sharp and corrosion-prone features of steel fibers, there is a demand for ultra-high-performance concrete (UHPC) reinforced with nonmetallic fibers. In this paper, glass fiber (GF) and the high-performance polypropylene (HPP) fiber were selected to prepare UHPC, and the effects of different fibers on the compressive, tensile and bending properties of UHPC were investigated, experimentally and numerically. Then, the damage evolution of UHPC was further studied numerically, adopting the concrete damaged plasticity (CDP) model. The difference between the simulation values and experimental values was within 5.0%, verifying the reliability of the numerical model. The results indicate that 2.0% fiber content in UHPC provides better mechanical properties. In addition, the glass fiber was more significant in strengthening the effect. Compared with HPP-UHPC, the compressive, tensile and flexural strength of GF-UHPC increased by about 20%, 30% and 40%, respectively. However, the flexural toughness indexes I5, I10 and I20 of HPP-UHPC were about 1.2, 2.0 and 3.8 times those of GF-UHPC, respectively, showing that the toughening effect of the HPP fiber is better. [ABSTRACT FROM AUTHOR]

Novel combinations of mechanical and biological properties are required when developing new polymer-based restorative dental composites. This study reports a promising strategy to develop preventive and restorative dental materials by synthesizing multifunctional dental composites reinforced with chitosan integrated halloysite nanotubes (CHI-HNTs). An enhanced dispersion capability of CHI-HNTs in the urethane-dimethacrylate/triethyleneglycol-dimethacrylate based dental composite is obtained by a sonication-supported chitosan integrating process, resulting in increased mechanical properties such as flexural strength, modulus, and breaking energy of the composites (2 wt% CHI-HNTs, 45 wt% glass particle, 5 wt% glass fiber) up to 8.1%, 17.2%, and 9.8% compared to control composites without CHI-HNT. Microscopic fractography of the fracture surface reveals that highly dispersed CHI-HNTs contribute to the increased mechanical strength of the composites. This is achieved via a dispersion-strengthening mechanism such as nanotube pinning and bridging/pull-out reinforcements. The highly dispersed CHI-HNTs in the composites also have antibacterial capability against Streptococcus mutans. With 2 wt% of CHI-HNTs in the composites, the viability of S. mutans biofilm decreases by approximately 39%. The positively charged amine groups (-NH 3 +) of chitosan are involved in improving the dispersion effect of HNTs and antibacterial activity of the CHI-HNTs reinforced dental composites. These findings open the route for developing advanced dental composites and engineered biomaterials with well-controlled HNTs dispersion. Image 1 [ABSTRACT FROM AUTHOR]

Hessian fibre-reinforced gypsum, known as fibrous plaster, is a common material used for the manufacture of decorative features, including ceilings and walls in historic buildings, such as theatres and ballrooms, since the mid 19th century. It is still fabricated with modern materials for the decoration of new buildings in the UK, the Middle East and elsewhere. Following several recent failures of historic fibrous plaster ceilings in England, there is an urgent need to understand how these materials perform. There is no previous scientific investigation into the physical and mechanical properties of this material. As an initial experimental study, the microstructure of low and high density gypsum plaster were evaluated together with traditional hessian fabrics and modern glass fabrics, which are supplementing or replacing hessian fabrics. The chemical and physical characteristics were evaluated by X-ray diffraction, mercury intrusion porosimetry and dynamic vapour sorption. For the hessian, fibre density was measured and single filament strength measured to ascertain the effect of long-term ageing in new and historic material. Flexural tests were performed on gypsum plaster reinforced with different configurations of hessian and glass fabric reinforcements. Single filaments from historic hessian were weaker than filaments from new hessian and the larger scatter in strength was demonstrated using a Weibull distribution function. High density gypsum absorbed less moisture (0.2%) than low density gypsum (1%), as expected, but the jute fibres in the hessian absorbed more than 20% of the moisture. High density gypsum was considerably stronger than low density material, and random glass mats as reinforcement resulted in the highest flexural strengths and ability to yield to higher strains, due to enhanced interfacial bonding. This work will have high impact by providing a much needed basis for understanding the long-term degradation of fibrous plaster systems. [ABSTRACT FROM AUTHOR]