Variation In Fiber Content Research Articles

Experimental study on flexural mechanical properties of steel fiber reinforced alkali-activated slag concrete beams

As an environmentally friendly alternative to ordinary concrete, slag concrete is subject to limitations such as drying shrinkage and micro-cracking during its promotion and application. In order to address these challenges, steel fibers, known for their excellent tensile, shear, crack-resistance, and toughness properties, have been introduced to enhance the ductility of alkali-activated slag concrete. This study utilized steel fiber content as a variable and produced eight steel fiber-reinforced alkali-activated slag concrete beams to investigate their flexural mechanical properties. By exploring the influence of steel fiber content variation on the mechanical behavior of alkali-activated slag concrete beams and conducting validation through finite element analysis, the study unveiled the impact of steel fibers on the performance of alkali-activated slag concrete beams. The research findings demonstrate a significant enhancement in the flexural mechanical properties of alkali-activated slag concrete beams with the addition of steel fibers, leading to a reduction in surface cracking and an improvement in the durability of the elements. The outcomes of this study hold crucial theoretical implications for the widespread application of steel fiber-reinforced alkali-activated slag concrete.

Mechanical properties and energy damage evolution mechanism of fiber-reinforced cemented sulfur tailings backfill under uniaxial compression.

This paper studies mechanical properties and energy damage evolution of fiber-reinforced cemented sulfur tailings (CSTB) backfill. The effects of fiber length and fiber content on the stress, toughness and failure properties of the CSTB were systematically revealed. In addition, the energy index evolution law was studied, and the energy damage evolution mechanism of CSTB was revealed. The results show that the deformation failure of fiber-reinforced CSTB mainly goes through four stages: initial crack compaction, linear elastic deformation, yield failure and post-peak failure. The peak stress and residual stress of the CSTB firstly increase and then decrease with the increase of fiber content and the addition of fiber can promote the change from brittle failure to ductile failure of the CSTB. Adding appropriate amount of fiber can improve the toughness of CSTB, and the influence degree of fiber length on the toughness index of CSTB is 6mm>12mm>3mm. The total strain energy increases linearly along the variation of fiber content, while the elastic strain energy and dissipated energy increase exponentially at the peak stress point. In the process of CSTB deformation and failure, "gentle-linear growth-slow growth-rapid decline" is for elastic strain energy, while "gentle-slow growth-rapid growth-linear growth" is for dissipation energy. The damage and failure of CSTB mainly experienced four stages: initial damage, slow growth of damage, accelerated damage and damage failure, and the damage evolution curve also showed the changing characteristics of "gentle-slow growth-rapid growth-linear growth". The CSTB without added fiber showed obvious "Y-type" and "linear-type" shear failure characteristics and the phenomenon of shear cracks penetrating the backfill appeared. No big shear crack occur when it is damaged, showing that the fiber addition restrain the crack growth and improve the overall crack resistance of the CSTB. Hydration products are obviously distributed on the surface of the fiber, which indicates that the fiber will be evenly dispersed in the CSTB and form a certain bonding force with the cement-tailings matrix, thus improving the overall mechanical properties of the CSTB.

Effects of steel fibers on the dynamic properties and failure process of ultra-high performance concrete

In the building area, an increasing number of applications have been made of ultra-high performance concrete (UHPC) because of its excellent properties. The steel fiber, as one of the popular admixtures of UHPC, can have a significant impact on the properties and failure process of UHPC under dynamic loading. A series of dynamic compression and Brazilian split tests were performed on UHPC specimens with six steel fiber contents based on the split Hopkinson pressure bar (SHPB) to investigate the effects of varying fiber content on the dynamic performance of UHPC. The digital image correlation (DIC) system equipped with a high-speed camera was incorporated to assist an in-depth knowledge of the UHPC failure process. Diverse experimental results were obtained and demonstrated that the presence of steel fibers can enhance the strength and toughness of UHPC, but the crack resistance of UHPC was unremarkable when the steel fiber content was 0.5%. Over the studied range, an increase in tensile strain rate of 10 s −1 resulted in a 36% growth of tensile dynamic increase factor (DIF t ) and the variation of fiber content had little effect on the growth ratio of DIF t . While with a 100 s −1 increase in compressive strain rate, the compressive dynamic increase factor (DIF c ) increased within 27% and higher fiber content decreased this value obviously. Based on the test data, logarithmic models for compressive and tensile dynamic increase factors were proposed in which the effects of strain rate and fiber content were both incorporated. DIC analysis revealed that the inclusion of steel fibers allowed for a larger peak strain of the specimen and slower macro-crack evolution after cracking. This research facilitates further understanding of the dynamic behaviors and damage mechanisms of UHPC. • The effects of steel fiber on dynamic behaviors of UHPC and corresponding mechanisms were analyzed. • DIF models incorporating the effects of strain rate and fiber content were proposed. • The crack evolution was explored in terms of strain field and the cracking speed was evaluated. • Inclusion of steel fibers allowed for greater deformation before failure and restrained the expansion of macro-cracks after failure.

Effect of Chemical and Physical Treatments on Mechanical Properties of Diss Fibers-Based Biocomposites Materials

ABSTRACT This work highlights the exploitation of fibers from a promising plant, commonly called Diss, in polymer matrix reinforcement. In this context, various untreated and treated (with acetic acid, silane, NaOH, thermal) Diss fibers were used to reinforce a thermoplastic matrix, polypropylene (PP). The effect of fiber treatments was evaluated at a ratio of 10% (by mass) of fiber, using mechanical, microstructural and physical characterization. A fiber content optimization study was carried out after choosing the fiber treatment by varying the fiber content from 10% to 40%. The microstructure observations showed a multi-layer structure for the biocomposites studied. The particular morphology of Diss fibers, with the presence of thorns, seems to improve the mechanical adhesion between the two phases. For 10% fiber content composites, the incorporation of the different fibers in the PP matrix led to improvements in most mechanical properties. The biocomposite reinforced with NaOH treated fibers (NPP-10%) showed the best mechanical performance with an improvement of 30%, 22% and 9% in tensile modulus, bending modulus and bending stress, respectively. For the fiber content variation, the NPP was retained, and an enhancement in the tensile modulus was found when the fiber content was below 20%.

Stress-Strain Relationship of High-Performance Fiber-Reinforced Concrete using Silica Fume and Steel Fiber

Disaster mitigation in the world of civil engineering can do by improving the performance of construction materials using High-Performance Fiber-Reinforced Concrete (HPFRC). The increasing performance of concrete materials positively affects the physical and mechanical properties of the concrete produced, including the modulus of elasticity. Many equations develop to calculate the distribution of stress-strain of concrete material, such as the Madrid Parabola Formula, Desay & Khrisnan Formula, Majewski Formula, Wang & Hsu Formula, and Saenz Formula. The purpose of this study is to investigate a stress-strain distribution equation and the elastic modulus of elasticity of HPFRC using Portland Pozzolana Cement (PPC) with variations in the composition of silica fume and steel fiber and also investigate the formula of the HPFRC stress-strain distribution. The study conduct using f 15 cm x 30 cm cylindrical specimens. The materials are PPC, sand, gravel, water, silica fume additives, superplasticizers, and Dramix @ 3D steel fiber. Silica fume used varies from 0.0% to 15.0% of the weight of cement. While the steel fiber varies from 0.2% to 1.4% of the volume of the concrete mixture. The compressive strength test carries out refers to ASTM C39/C39M-03, 2003. The stress-strain relationship of HPFRC is obtained from the axial deformation measurement using an extensometer. The results of the study compare with some well-known stress-strain relationship equation. From this study, the stress-strain relationship formula of Desay-Khrisnan is rather suitable for the concrete with W/B ratio variation, but not suitable for silica fume and steel fiber content variation.

Theoretical and Numerical Contribution for Prediction of the Mechanical Properties of a Randomly Distributed Reinforcement in the Matrix

Today, the construction industry is trying to reduce its energy consumption and to move towards more environmentally friendly materials, including renewable materials such as straw earth. In order to promote its use, a consideration of a model to predict its behavior in the constructive system is necessary. Objectives for homogenization of the straw earth composite material, variation in fiber content and random fiber distribution are taken into account. The digital model relies on the generation of the reinforcement’s random positions in the field while controlling its filling rate in the matrix. The model created is implemented in the Ansys Mechanical APDL software for numerical simulation. All the parameters obtained from the straw-earth composite using a numerical method, including the Young module and the Poisson ratio, are explicitly modelled as a theoretical model. The results of this work have been validated by theoretical analysis and have been compared to the experimental results listed in the bibliography.

Effect of Crack Initiation and Life Prediction of Polyacrylonitrile-Reinforced Gussasphalt Surfacing over Steel Bridge Deck under Fiber Content Variation

The crack initiation and life prediction of fiber-reinforced asphalt concrete (FRAC) surfacing for steel bridge decks under a cyclic vehicle load are analyzed from the perspective of damage mechanics. The damage field and the stress and strain field evolution rule of a composite beam in fatigue test are studied, and a fatigue failure criterion is proposed for steel deck FRAC surfacing. Bending fatigue tests are performed on composite beams composed of a steel deck and polyacrylonitrile (PAN)-fiber-reinforced Gussasphalt (GA), i.e., GA-PAN, concrete surfacing under different fiber content and temperature conditions. The damage evolution characteristics of GA-PAN concrete surfacing over the steel deck with different fiber lengths and volume ratios are predicted by analyzing the fatigue life equations. The results show that the steel bridge deck FRAC surfacing model can reflect the comprehensive influence of the fiber content and length on the fatigue performance of steel bridge AC. Specifically, a lower temperature results in the fiber more synergistically affecting the fatigue resistance of AC. Theoretically, the service performance of asphalt concrete increases with the increase of fiber length and content. The optimum fiber length and volume ratio of GA-PAN are found to be 9 mm and 0.46–0.48%, respectively, considering the construction workability.

Effect of fiber content variation on the strength of the weakest section in Strain Hardening Cementitious Composites (SHCC)

Fiber dispersion, especially the variation of fiber content among different sections of a member, is a major factor that influences the mechanical properties of fiber composites. In this study which focuses on Strain Hardening Cementitious Composites (SHCC), a numerical approach is proposed to compute the bridging laws in various sections of a specimen with varying content of randomly distributed fibers. Through the analysis, the weakest plane which governs the ultimate strength and saturated crack spacing is determined. This weakest plane is then investigated for members of different sizes, and a size effect is revealed.

Dietary Fiber Analysis of Four Pulses Using AOAC 2011.25: Implications for Human Health.

Chickpeas, common beans, dry peas, and lentils are pulse crops that have been a cornerstone of the human diet since the inception of agriculture. However, the displacement of pulses from the diet by low fiber protein alternatives has resulted in a pervasive deficiency referred to as the dietary fiber gap. Using an analytical method American Association of Analytical Chemists (AOAC) 2011.25 that conforms to the Codex Alimentarius Commission consensus definition for dietary fiber, the fiber content of these pulse crops was evaluated in seed types used for commercial production. These pulse crops have 2 to 3 times more fiber per 100 g edible portion than other dietary staples. Moreover, there is marked variation in fiber content among cultivars of the same crop. We conclude that pulse crop consumption should be emphasized in efforts to close the dietary fiber gap. The substantial differences in fiber content among currently available cultivars within a crop can be used to further improve gains in fiber intake without the need to change dietary habits. This provides a rationale for cultivar-based food labeling.

Evaluating the Effect of Fiber Reinforcement on the Anisotropic Undrained Stiffness and Strength of Peat

AbstractThis paper presents the results of an investigation into the role of peat fibers in the development of anisotropic stiffness and strength within peat samples taken from below three Canadian National Railway embankments across Canada. These sites include two from northern Alberta on the Edson and Lac-La-Biche subdivisions and one from the Levis subdivision in southern Quebec. The peat samples were collected in Shelby tubes and were subjected to a program of consolidated undrained triaxial testing. These samples represented a wide variation in fiber content and degree of humification. The measured pore-pressure response during undrained loading indicated that the peat samples were undergoing an anisotropic elastic response to loading. This pore-pressure response was similar in the peat from all three sites, with an anisotropic pore-pressure parameter, a, of approximately 0.3. The stiffness and strength of the different peats were also similar, with an elastic modulus of approximately 1.7–2.2 MPa and...

Effect of coir fiber content and compatibilizer on the properties of unidirectional coir fiber/polypropylene composites

The main objective of this research was to study the effect of fiber content variation and stearic acid (SA) treatment on the fundamental properties of unidirectional coir fiber (CF) reinforced polypropylene (PP) composites. Several percentages of filler contents were used (10–40 wt %) in order to gain insights into the effect of filler content on the properties of the composites. Coir/PP composites were fabricated by compression molding, and the properties of composites were studied by physico-mechanical and thermal properties. The results from mechanical properties such as tensile strength (TS), tensile modulus (TM) and impact strength (IS) of the CF/PP composites were found to be increased with increasing fiber content, reached an optimum and thereafter decreased with further increase in fiber content. Treatment of the coir with SA as the coupling agent enhanced the mechanical properties, crystallization temperature and crystallinity of virgin PP and water desorption of the resulting composites, resulting from the improved adhesion between the CF and PP matrix. Scanning electron micrographs (SEM) of the tensile fractured samples showed improved adhesion between fiber and matrix upon treatment with SA. Interfacial shear strength (IFSS) of the composites was measured by single fiber fragmentation test (SFFT).

Tensile and Impact Properties of Sugarcane Bagasse/Poly(vinyl Chloride) Composites

Sugarcane bagasse is divided into two main components, pith and rind, with “pith” representing the inner part of the sugarcane bagasse and “rind” as the outer part. In this study, the tensile and impact properties of untreated pith/ poly(vinyl chloride) composites were compared to that of untreated rind composites using the same matrix with variation of fibre content. It was observed that the tensile strength and modulus of rind/PVC composites are higher than the unfilled PVC at composite fibre contents of 30% and 40%. Additionally, the rind composites exhibited superior strength and stiffness in comparison with the pith composites.

Flexural properties of sugarcane bagasse pith and rind reinforced poly(vinyl chloride)

Sugarcane bagasse is divided into two major components. They are pith and rind. Pith is the inner part of sugarcane bagasse while rind is the outer part of it. In this study, the flexural properties of pith reinforced poly (vinyl chloride) composites were compared to that of rind composites with the same matrix in variation of fibre content. The composites were produced by compression moulding method. The fibre contents were 10%, 20%, 30%, 40%, and 50% in weight. Three-point bending tests were carried out to measure the flexural properties of the composites. It has been found that, in general, the addition of fibre improved the flexural modulus of the materials. Meanwhile, the rind composites were of superior flexural properties compared to the pith composites.

Renewable resource based biocomposites from natural fiber and polyhydroxybutyrate-co-valerate (PHBV) bioplastic

Abstract Renewable resource based green biocomposites were prepared using a bacterial polyester i.e., poly(hydroxybutyrate-co-valerate) (PHBV) and natural bamboo fiber. Fabrication of the biocomposites was carried out by injection molding following extrusion compounding of PHBV and bamboo fiber with 30 or 40 wt.% fiber. The mechanical, thermo-mechanical and morphological properties of the biocomposites were evaluated. Little variation in the thermo-mechanical and impact properties was observed when the fiber content was varied. The tensile modulus of biocomposites at 40 wt.% fiber improved by 175% as compared to that of neat PHBV. The theoretical tensile modulus of the biocomposites was calculated using Christensen’s equations and compared with the experimental results. It was found to be in near approximation to the experimental data. The storage modulus was affected slightly by the variation of fiber content from 30 to 40 wt.% in biocomposites. The heat deflection temperature of PHBV increased by 9 °C at 40 wt.% of fiber reinforcement. Morphological aspects and thermal stability were studied using scanning electron microscopy and thermo-gravimetric analysis, respectively. In addition, a comparative analysis of bamboo fiber–PHBV with wood fiber–PHBV biocomposites was performed. Statistical analysis of both biocomposites was carried out by performing a two-way ANOVA on their tensile and flexural moduli in order to evaluate the effect of fiber type and content in the PHBV matrix.

Flexural and Torsional Properties of Pultruded Fiber Reinforced Plastic I-Profiles

Experimental determination of the full section flexural and torsional properties of pultruded fiber reinforced plastic I-profiles is described. Based on beam theory approximations, test configurations for determining the various section properties are established. Tests were conducted on three different I-profiles with a range of span-to-depth ratios. Major and minor axis flexural rigidities and flexural moduli, determined from three- and four-point bending tests, show close correlation. Major and minor axis transverse shear rigidities and shear moduli show significant variation, due to differing effective areas of the cross section resisting transverse shear and differing fiber content and orientation in the web and flanges. St. Venant torsional shear moduli, determined from uniform torsion tests, are consistent but significantly greater than the transverse shear moduli, which may be due to variations in fiber content, orientation, and lay up. Warping torsional rigidities, determined from nonuniform tors...

Differential dietary effects on colonic and small bowel neoplasia in C57BL/6J Apc Min/+ mice.

The effects of fiber on colon cancer are controversial. Twenty 5-week old C57BL/6J Apc Min/+ mice were fed for 60 days with a commercial mouse diet (Teklad LM-485) and eight semidefined diets containing 5-10% various fibers and 20% soybean oil. Ten additional C57BL/6J congenic litter-mates were fed each diet to assay colonic SCFA. SCFA, stool bulk, and colonic tumor incidence differed only slightly among the semidefined diets despite variations in fiber content and source. However, food consumption, caloric intake, stool bulk, and SCFA were substantially increased by the Teklad diet compared with all other groups. The Teklad diet significantly increased the number of mice with colonic tumors, average number of tumors/mouse, total tumor burden, colonic atypical hyperplasia, and small bowel tumors. Mice fed high-fat, no-fiber diets had more small bowel tumors (29.8 +/- 3.1) than mice fed diets with fiber (8.2 +/- 2.1) or with low fat and no fiber (18.1 +/- 3.4) (P < 0.05 for each group). These studies suggest that fat predisposes to and fiber protects against small bowel tumors but not colon tumors in these mice. Thus, diets high in fiber or yielding high colonic luminal SCFA may not necessarily protect against colonic cancer. Furthermore, the effects of dietary fiber in Teklad appear overshadowed by some other biologically active factors in this animal model.

Polymer composites with dual gradient structure

AbstractFunctionally dual gradient type of carbon fiber reinforced epoxy composites, in which crosslinking density of epoxies and content of carbon fibers are gradually varied through the thickness, were fabricated by using centrifugal force. The spatial variation of fiber content and the crosslinking density change of epoxies were confirmed by checking densities and glass transition temperatures, respectively, along the thickness. The mechanical properties of the polymer composites were also measured.

An Investigation of Tensile Properties and a Simple Constitutive Model for a Random Continuous Fiber Thermoplastic Composite

The tensile properties of a commercially available, random continuousfiber thermoplastic composite material are investigated at various strain rates and elevated temperatures. The material utilizes polypropylene (PP) for the matrix material, with random continuous E-glass fiber reinforcement. Tensile modulus, tensile strength, strain to peak stress, and strain energy are experimentally determined at strain rates varying from 0.000167 sec-1 to 0.0334 sec-5 and temperatures varying from 20 to 120'C. The material properties are found to have large scatter caused by local variations in fiber content and orientation. The tensile properties are independent of the strain rate but depend on the temperature. A model for the material response based on a simple power law equation is presented.

Dietary fiber composition of selected foods in the People's Republic of China

The content of dietary fiber and its components in food items commonly consumed in China were analyzed using more recently developed methods. These foods were collected as part of an epidemiologic study designed to investigate the relationship between diet and disease. Five hundred and twenty-seven food samples were analyzed for total dietary fiber (TDF), neutral-detergent fiber (NDF) including its constituents, hemicelluloses, cellulose, and lignin, and soluble dietary fiber. The content (% dry weight) of TDF was 1.2 to 17 for cereals, 16 to 52 for legumes, 7.7 to 37 for tubers and roots, 20 to 56 for cucurbits and fruits, and 27 to 55 for leafy vegetables. Samples of 15 of these foods were replicated in 14 or more counties permitting assessment of geographic variation for the same food. Considerable variation in fiber content was observed indicating that nutrient contents of specific foods published in composition tables are likely to be considerably more variable than generally appreciated even though replicates may be collected and analyzed at the same time of year.

Effects of Fiber on Digestibility and Transit Time in Dogs

This study examines effects of variations in fiber content on nutrient assimilation, fecal output, and gastrointestinal transit time in the dog. Four normal Beagles were fed four diets in a randomized block design. The basal diet was a canned, balanced, meat-based dog food (Alpo Trio®) to which was added 3, 6, and 9% by weight of alpha cellulose (Solka Flok®). Food intake and fecal outputs were recorded for 5-day periods. Samples of diets and fecal collections were analyzed for dry matter, nitrogen, fat, carbohydrate and ash; digestibilities were calculated. Transit times were measured by a radiographic marker technique. Fecal weight and water increased linearly; digestibility of dry matter decreased from 90 to 70% and ash from 43 to 32% with added fiber. Responses of protein, carbohydrate and fat were less pronounced but were regular; regressions of their digestibilities on added fiber were significant. Regression estimate of true digestibility for α-cellulose was 6%. Intestinal transit time decreased from a mean of 37.4 to 28.7 hours with added fiber. Decreased intestinal transit time would contribute to depression of dry matter digestibility. Increased fecal water output probably also reflected retention by fiber.α-cellulose digestibility nutrient assimilation transit time dogs