Fiber Content Ratio Research Articles

Study on betel nut fiber enhancing water stability of asphalt mixture based on response surface method

In recent years, there has been an increasing interest in waste fiber reinforced asphalt mixes. Waste betel nut fiber (BNF) can improve the tensile strength of asphalt mixture, while the hydrophilic groups on its surface can reduce its water stability. Therefore, this study investigated the effect of alkali-treated BNF on the water stability performance of asphalt mixtures. The effects of shear time, fiber content, and asphalt aggregate ratio on the water stability of BNF-enhanced asphalt mixtures were investigated separately by response surface methodology (RSM). The road performance of the RSM method with optimal solution and without fiber, fiber without alkali treatment, and fiber without shear was also compared. The results showed that under the AC13 gradation, the optimal solutions of multi response variables are fiber content of 0.2561%, fiber shear time of 12.78 min and asphalt aggregate ratio of 5.82%. The corresponding predicted Rdry value is 1.48 MPa, Rsaturated value is 1.27 MPa and TSR value is 88.41%. The final test results are within the 95% confidence interval, and the prediction model has good reliability. The optimal solution has the best low-temperature flexural strength and water stability. This study helps to promote the application and promotion of BNF in road construction.

Effect of fiber dispersion, content and aspect ratio on tensile strength of PP fiber reinforced soil

The present study was conducted to investigate the tensile strength characteristics of polypropylene (PP) fiber reinforced soil with different fiber dispersion, content and aspect ratio. In order to investigate this, the experimental programme was comprised by the test with a wide range of fiber content (0.35%, 0.60%, 0.85%), fiber aspect ratio (150, 225, 350), and mix patterns (discrete or random distribution). The results indicated that increases in fiber content caused an increment in the tensile strength whether discrete or random distribution. The increasing extent of tensile strength was different with increase of fiber aspect ratio under different fiber mix patterns. From experimental data, a genetic programming (GP) model was proposed for analyzing tensile strength contrast of the two mix patterns. In addition, the sensitive analysis of three inputs showed that aspect ratio has the greatest influence on the forecasting model. The effectiveness of the GP model was validated by the test results, and the robust model developed would provide a theoretical support for roadbase designing and construction which were reinforced with PP fibers.

Characteristic evaluation and finite element analysis of glass fiber/recycled polyester thermoplastic composites by cross-sectional shape of glass fiber

In this paper, properties of glass fiber-reinforced thermoplastic polymers (GFRTP) were evaluated using recycled polyester (rPET) for injection molding bicycle frame. The effect on thermal and mechanical properties of rPET reinforced glass chop fiber according to fiber cross section and fiber content ratio were studied. The crystallization temperature of glass fiber (GF)/rPET, a glass fiber added thermoplastic composite, was higher than the crystallization temperature of rPET pellet without a glass fiber, and the shape of the exothermic curve was sharper. Mechanical characteristics of a GF/rPET thermoplastic composites has been increased by increasing fiber contents, than above a certain level did not longer increased. And mechanical properties of flat glass fiber reinforced rPET with low void volume were most excellent. In order to prove the validity of the experimental results, finite element analysis of thermoplastic composite was performed by Digimat and Abaqus to compare the experimental values according to the cross sectional shape and volume fraction of glass fiber. The results of finite element analysis showed a similar tendency between the experimental results and the analysis results.

Investigation on the dynamic shear modulus of fiber-reinforced sand

As a new type of composite material, fiber-reinforced soil has attracted much attention due to its good dispersibility, mechanical properties and durability. Based on the dynamic triaxial test, the dynamic characteristics of polypropylene fiber-reinforced sand were studied, and the effects of fiber content (w), fiber length (lf ), and cyclic stress ratio (CSR) on the dynamic shear modulus (G) of polypropylene fiber-reinforced sand were systematically analyzed. The results showed that the curves of dynamic shear modulus ratio (G/G0 ) and cycles ratio (N/NL ) had piecewise linear characteristics. The slope of the curves was small before the segment point, whereas was large after the segment point. The G/G0 decreased with the increasing of the CSR, whereas the effect of w, lf and CSR on the curve was not significant. The curves of G/G0 and dissipated energy per unit volume ratio (W/WL ) also had piecewise linear characteristics. The G/G0 decreased rapidly as the increasing of W/WL until it was close to 0, and then kept stable. The decreasing rate of G/G0 at low CSR was greater than that at high CSR, which indicated that high CSR had great affect on the G.

Influence of concrete strength, fiber content and aspect ratio in the residual flexural strength of steel fiber reinforced self-compacting concrete

Abstract Steel Fiber Reinforced Self-Compacting Concrete (SFRSCC) is a material that combines the benefits of self-compacting concrete in the fresh state and the greater durability, with the gains of fiber- reinforced concrete in the hardened state, especially the gains in residual flexural strength. Results are presented in this paper of residual flexural strengths on 48 prenotched prisms conducted in accordance with RILEM TC 162 TDF for the Steel Fiber Reinforced Self-Compacting Concretes (SFRSCC). This article presents equations to estimate residual flexural stresses in SFRSCC. For this, SFRSCC prisms of two compressive strength classes, 20 MPa and 40 MPa, were produced with 3 different types of steel fibers with the contents volume of 0.5% and 1.0%. Based on the test results, equations were proposed to determine the residual flexural stresses established through regression analysis, which were, then, further validated with concretes produced in this work and results available in the literature. The equations found, despite showing an indication of the residual flexural strengths that will be achieved, obtained a relatively high error. In order for the equations to be applied in a technical way, further studies for a larger sample need to be carried out, seeking to optimize the equations.

WITHDRAWN: Effect of polypropylene fibre on swelling behaviour of black cotton soil

Abstract This paper discusses the laboratory study of performance on expansive soil reinforced with polypropylene fiber and demonstrates that discrete and randomly distributed polypropylene fiber is useful in restraining the swelling tendency of expansive soils. Swelling characteristics of remoulded expansive soil specimens reinforced with varying fiber content (f = 0.2%, 0.3%, 0.4% and 0.5%) and aspect ratio (l/b = 15, 30 and 45) were studied. One dimensional swell-consolidation tests were conducted on consolidometer specimens. Reduction in heave and swelling pressure was the maximum at low aspect ratios at both the fibers contents of 0.2%, 0.3%, 0.4%, and 0.5%. Finally, the mechanism by which discrete and randomly distributed polypropylene fiber restrain swelling of expansive soil is explained with the help of soil-fiber interaction.

Experimental study on compressive properties of SFRC under high strain rate with different fiber content and aspect ratio

The dynamic mechanical properties of steel fiber reinforced concrete (SFRC) depend largely on the content and size of steel fibers. This paper presents an experimental study on mechanical properties of SFRC under high strain-rate compressive loading. In order to explore the co-effect of the fiber content and aspect ratio on the dynamic performance of SFRC, the SFRC specimens with three kinds of fiber aspect ratio (30, 50, 60, respectively) and six kinds of fiber content (0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5% in volume fraction) were tested by Split Hopkinson Pressure Bar (SHPB) device with a diameter of 75 mm. The test strain rate ranged from 30 s−1 to 370 s−1. Test results show that SFRC has obvious strain rate effect. With the same fiber aspect ratio, the optimum fiber content of SFRC shows strain rate sensitivity. And with the increase of fiber content, the dynamic increase factor (DIF) of SFRC decrease gradually. With the same fiber content, SFRC with a fiber aspect ratio of 50 shows the maximum compressive strength at different strain rates. In addition, the study also proposed the expression of DIF, strain rate and fiber content of SFRC to each fiber aspect ratio.

Fiber-Reinforced Cemented Paste Backfill: The Effect of Fiber on Strength Properties and Estimation of Strength Using Nonlinear Models.

This experimental investigation was conducted to research the properties of polypropylene (PP) fiber-reinforced cemented paste backfill (CPB). The unconfined compressive strength (UCS) of the fiber-reinforced CPB showed a significant improvement with average UCS increase ratios of 141.07%, 57.62% and 63.17% at 3, 7 and 28 days, respectively. The macroscopic failure mode and SEM analysis indicated that fibers prevented the formation of large tensile and shear cracks during the pull-out and pull-off failure modes. A linear fitting function for the UCS at a curing time of 3 days and two polynomial fitting functions for the UCS at curing times of 7 and 28 days were established to characterize the relationship between the UCS of the fiber-reinforced and unreinforced CPB. Moreover, based on composite mechanics, nonlinear models related to the UCS and fiber reinforcement index were obtained. The estimated functions containing the fiber reinforcement index λ, which consists of the fiber content and aspect ratio of fiber, could evaluate the UCS. Furthermore, the fiber reinforcement index λ quantifies the enhancement by the fibers. Both estimation results indicated that the UCS values were estimated accurately at curing times of 3, 7 and 28 days in this study. Additionally, the estimation models could be used to guide the strength design of fiber-reinforced CPB. Besides this, the results showed that fiber-reinforced CPB can be used more widely in mine backfills and meets the requirements of controlled low-strength material (CLSM) for broader applications.

EXPERIMENTAL CHARACTERIZATION OF COMPRESSION PERFORMANCE OF CARBON-BASALT HYBRID FILAMENT WOUND PIPES BEFORE AND AFTER IMPACT

This paper describes the effects of different stacking sequences and fiber content ratios on the compression and the compression-after-impact (CAI) behavior of hybrid carbon�basalt (C�B) fiber-reinforced polymer pipes. Hybrid composite pipes composed of eight layers of ± 55°/90°2/± 55°/90°2 were manufactured utilizing the filament winding technique. A series of axial compression tests were carried out on the composite pipes based on ASTM D3410 standard for the nonimpacted and impacted specimens at 100-J impact energy. Residual compressive strength, damage tolerance and failure modes were examined and analyzed for different composite pipe configurations before and after an impact. The results showed that the specimens with fiber content ratio 50:50 C�B fibers exhibited better impact resistance as compared with specimens of fiber content ratio 75:25 C�B fibers, under the same conditions of impact energy. Furthermore, despite carbon fiber sustaining highest compressive force among nonimpacted samples, it exhibited the highest percentage reduction in residual compressive force after impact, at 62%, as such having the worst impact damage tolerance for a given energy level. Specimens with basalt fiber on the outer surface (i.e., Nos. 3 and 6) and alternative fiber specimens (i.e., Nos. 5 and 8), which showed a good response to the impact, sustain high values of the compressive loads for both content ratios. © 2020 by Begell House, Inc.

Analysis and Prediction of Compressive Properties for Steel Fiber‐and‐Nanosilica‐Reinforced Crumb Rubber Concrete

The disposal of waste tire rubber has gained more attention from the viewpoint of green, environmental protection, and sustainability. Numerous attempts have been stated on the properties of crumb rubber concrete (CRC) and observed that there is a large reduction of compressive strength and elastic modulus of CRC with the increase of the rubber substitution rate. Based on the CRC with the crumb rubber volume content of 5%, the steel fibers and nanosilica were added to CRC to make steel fiber‐and‐nanosilica‐reinforced crumb rubber concrete (SFNS‐CRC) in this paper. The effects of the steel fiber volume content and nanosilica content on the compressive properties of SFNS‐CRC were studied, including compressive strength, elastic modulus, peak strain, compression toughness, and failure pattern. The test results indicated that the modulus of elasticity and compressive strength of SFNS‐CRC have the increasing tendency with the addition of steel fibers and nanosilica. Moreover, the peak strains have a significant increase with the increase of the steel fiber content and nanosilica replacement ratio. The compressive stress‐strain curves of SFNS‐CRC gradually plump with the increase of the steel fibers and nanosilica. Finally, the prediction formulas for the compressive strength, elastic modulus, and peak strain of SFNS‐CRC were set up. A simple predicted model of the stress‐strain curve for SFNS‐CRC was proposed, which considers the effect of steel fibers and nanosilica.

Mechanical response of fiber-reinforced sand under cyclic loading

Based on the consolidated undrained test under cyclic loading, the mechanical response of fiber-reinforced sand under cyclic loading was studied by varying fiber content (0.2% and 0.4%), fiber length (7 mm and 13 mm), and cyclic stress ratio (0.22, 0.24 and 0.26), and the effects of fiber content and fiber length on the excess pore water pressure, dynamic strength and dynamic shear modulus were discussed. The results showed that with the increasing of fiber content, the dynamic strength and liquefaction resistance increased, whereas the accumulation rate of excess pore water pressure decreased. The reduction rate of dynamic shear modulus decreased with the increasing of fiber length, and the dynamic strength decreased with the increasing of cyclic stress ratio, which indicated that the dynamic characteristics of fiber-reinforced sand were better than that of unreinforced sand.

Experimental Study of High‐Strength Steel Fiber Lightweight Aggregate Concrete on Mechanical Properties and Toughness Index

In this paper, three different kinds of steel fibers, being micro (M), end‐hooked (H), and corrugated (C), commonly used in engineering applications, are added to high‐strength lightweight aggregate concrete (HLAC) to study the effects of steel fiber and volume content ratio of fiber on the compressive, splitting tensile, and flexural strength of HLAC. The range of steel fiber volume content fraction studied is 0.5% to 2.0%. The research shows that different types of steel fiber have different effects on the mechanical properties and toughness of HLAC. M steel fibers have the best reinforcing performance on the mechanical properties. The study also shows that the toughness of M steel fibers is the best with the same fiber content. The toughening effect of H and C steel fibers can only reach 2/3 and 1/2 of M steel fibers, respectively. At the end of this paper, the unified strength formula and toughness index of these three kinds of high‐strength steel fiber lightweight aggregate concrete (HSLAC) with different fiber contents are given to provide a reference for engineering practice and design.

Prediction of Shear Behavior of Fiber Reinforced Concrete Beams Using Artificial Neural Networks

Due to the shortage of clear equations in the building codes that explain shear strength for fiber reinforced concrete (FRC) beams; there is a need to develop a numerical approach that can be used to predict shear behavior in FRC. The main objective of this research is to develop an artificial Neural Network (ANN) that can predict shear strength and simplify its use through developing a Graphic User Interface (GUI). Moreover, shear behavior in fiber reinforced concrete beams (FRCBs) is quantified by compressive strength of concrete, longitudinal steel, size effect, fiber's type, content and aspect ratio. The research methodology is based on collecting experimental results of technical investigations carried out to predict shear behavior in FRCBs. ANN aims at reducing the amount of computing time required in the numerous iterations involving structural analysis and experimental work. For this, two back-propagation neural networks have been experimented by MATLAB program; their types have been fitting (1st network) and pattern recognition (2nd network) which are used to classify failure of FRC beams into 6 categories. Through simulation study, the optimum architectures for the individual ANNs have been determined. The training algorithms used feed forward back propagation. The ANNs model has been assessed in comparison with exact values and deduces a good correlation with it. Finally, a software program is developed as an evaluation system for predicting resistance of FRC beams to shear forces, and to expect the failure pattern in order to avoid its occurrence.

Medium-strain dynamic behavior of fiber-reinforced sand subjected to stress anisotropy

A comprehensive database is established to investigate the behavior of polypropylene fiber reinforced sands under anisotropic stress state in a wide range of strain amplitudes from about 4 × 10−4% to 1.4 × 10−1%. A fixed-partly fixed Hardin-type resonant column which has a system that allows the specimen to be tested in resonance while maintaining an anisotropic loading path, is utilized. The results show important influence of the fiber content as well as the anisotropic stress state on the normalized modulus reduction and damping increase curves of the reinforced soils. Specifically, the increase of fiber content and stress ratio tend to increase the linearity in the normalized modulus reduction curves. On the other hand, the inclusion of fiber leads to the damping increase curves to shift to greater values, while the stress ratio has an opposite effect. An expression is proposed to predict the normalized shear modulus, as a function of mean effective confining pressure, stress ratio, coefficient of uniformity of the host sand and fiber content. The damping ratio, in a normalized form, is correlated with the normalized shear modulus reduction.

Effect of Molding Condition on Lap Joint of Glass Fiber Reinforced Plastic.

In this study, materials with each different fiber content ratio and fiber orientation state were used in the study for the decision of molding condition of GFRP and the condition of lap joint. Clarify joint strength and lap joint efficiency during high temperature and compression press lap joint molding of GFRP and research data regarding the lap length of the joint part was presented. Thus, the purpose of this study is to contribute to the substitution of existing products as well as usage development in the non-automobile field and also to find out precise dynamic characteristics as designing data of structures. In press lap joint molding of GFRP, tensile stress and lap joint connection efficiency was increased according to the increase of lap length L. However, as the increase of compression ratio and fiber content ratio per unit area was higher in impact test, it has caused the deterioration of lap joint efficiency after joint molding of GFRP.

Experimental Investigation on Compressive Toughness of the PVA-Steel Hybrid Fiber Reinforced Cementitious Composites

In order to achieve the whole process control of crack formation of engineered cementitious composites (ECC) under loading and improve the mechanical properties of ECC, PVA-steel hybrid fiber reinforced cementitious composites (HyFRCC) was proposed by mixing steel fibers with traditional ECC. And the key parameters to affect the HyFRCC performance are PVA fiber content, steel fiber content and aspect ratio of steel fiber. In order to investigate the mechanical properties of PVA-steel HyFRCC such as the compressive toughness, 15 PVA-steel HyFRCC specimens with different volume fraction of steel fiber and PVA fiber, together with 1 non-fibrous cementitious composites specimen and 3 ECC specimens with PVA fiber only for comparison were designed and uniaxial compression tests were conducted. Furthermore, the effect of fiber content, fiber type and fiber geometrical characteristic on the compressive toughness of HyFRCC were analyzed. The results show that PVA fiber content, steel fiber content and aspect ratio of steel fiber have little impact on the uniaxial compressive strength of the PVA-steel HyFRCC, while the peak strain, compressive toughness and the post-peak ductility of PVA-steel HyFRCC are improved significantly due to fiber hybridization. The formation of large scale cracks of ECC specimens after post-peak loading is restrained effectively with the addition of steel fiber. The mixture of PVA and steel fiber has a remarkable effect on the improvement of ECC compression toughness and crack control. It indicates that the energy dissipation and damage control capacity of the structural component with PVA-steel HyFRCC under seismic loading will be enhanced.

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

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

Impacts of the inclusion of various fruit pomace types on the expansion of corn starch extrudates

Effects of pomace chemical composition and physical properties (hydration, density, particle size distribution, crystallinity), inclusion level (0, 50, 150, and 300 g/kg), and extrusion processing parameters including, moisture content (150 and 200 g/kg), and screw speed (150, 200, and 250 rpm) of selected fruit (cranberry, blueberry, grape, and apple) pomace-corn starch mixtures, on the expansion of extrudates were studied. All factors had significant main and interaction effects on expansion. Expansion values of pomace were observed in the following order from high to low: apple > cranberry > blueberry > grape at 200 g/kg moisture content. Total dietary fiber and insoluble dietary fiber content of pomace were negatively correlated (p < 0.01) with the expansion. However, a positive correlation between soluble fiber content and expansion ratio was found at 300 g/kg pomace level (p < 0.05). At 300 g/kg pomace level, sugar might have aided to increase the expansion ratio significantly (p < 0.01), suggesting interactions between the fiber, and other components present in the pomace with the starch during expansion. Higher crystallinity might result in a lower expansion (p < 0.01). These results show the presence of positive active interactions between the pomace components and the starch molecules.

Effects of Carbon Fiber Hybridization on the Compressive Strength of Glass-Carbon/Epoxy Hybrid Composite Pipes before and after Low Velocity Impact

In this paper, the effect of carbon fiber hybridization on the compressive strength of glass-carbon/epoxy hybrid filament wound pipes before and after low velocity impact was investigated experimentally. Specifically, the effects of different stacking sequence and fiber content ratio on the compression and compression after impact (CAI) behavior of hybrid glass-carbon fiber reinforced polymer pipes were analyzed. Hybrid composite pipes composed of eight layers of / reinforced with thin HDPE liner were manufactured utilizing filament winding technique. A series of axial compressive tests were carried out on the composite pipes for the non-impacted and impacted specimens under 100 J of impact energy. Residual compressive strength, damage tolerance and failure modes were examined and analyzed for different pipe configurations, before and after the impact. The failure modes of non-impacted and impacted composite pipes under compressive loading were analyzed visually. The results show that, under the same conditions of impact energy, specimens with alternative fibers exhibited better impact resistance regardless of fiber content ratio. Moreover, carbon fiber reinforced epoxy specimens exhibited the worst impact damage tolerance for a given impact energy level although having the highest compressive strength before impact among the samples, with the highest percentage reduction of 62% in residual compressive force after impact.

A Nondestructive Method for Determining Fiber Content and Fiber Ratio in Concretes Using a Metamaterial Sensor Based on a V-Shaped Resonator

A micro sensor based on a V-shaped resonator (VSR) is implemented for the purpose of determining fiber content and ratio in construction materials as a nondestructive method. Concrete is investigated as the construction material in the study. First, electrical properties of concretes reinforced by different fiber types and ratios are investigated using the Nicolson-Ross-Weir technique. These values are used to design a nondestructive sensor based on microwave transmission line methods. At the resonance frequency, the VSR has a dense electric field. Construction material which is positioned within range of the VSR can change the distribution of the electric field, thus affecting the resonance response and transmission magnitude in the operating frequency. Since construction materials having various contents have different complex dielectric permittivity and loss tangent values, the resonance frequency, transmission magnitude and bandwidth of VSR shift correspondingly. Alterations in the resonance frequency and magnitude of transmission values which are related to the permittivity of the construction materials enable us to detect characteristics of the content in construction materials. The proposed technique is not only capable of sensing the type of content in the construction material which is positioned within range of the VSR, but it is also capable of determining the percentage of this content. Results show that the proposed microwave-based VSR sensor provides a cost-efficient and nondestructive solution for sensing the type and percentage of the contents in fiber-reinforced concretes.