Optimum Fiber Content Research Articles

Influence of Wood Fiber on the Laboratory Road Performance of Recycled Asphalt Pavement (RAP) Asphalt Mixture

The influence of wood fiber content on the road performance of asphalt mixture with high recycled asphalt pavement (RAP) content was studied based on the Marshall test, high temperature rutting test, low temperature crack resistance test and water stability test. And the optimum wood fiber content in RAP asphalt mixture with high RAP content was recommended. The results show that the dynamic stability and low temperature bending strain of RAP asphalt mixture increased and then decreased with the increase of wood fiber content. When the content of wood fiber is 0.3 %, the road performance of RAP asphalt mixture is the best. Compared with RAP asphalt mixture without wood fiber, the Marshall stability and low temperature flexural tensile strain of RAP asphalt mixture with 0.3% wood fiber increase by 7.1% and 4.6%, respectively, and the high temperature rutting resistance and water stability decreases.

Assessment of Moisture Susceptibility for Asphalt Mixtures Modified by Carbon Fibers

Moisture induced damage in asphaltic pavement might be considered as a serious defect that contributed to growth other distresses such as permanent deformation and fatigue cracking. This paper work aimed through an experimental effort to assess the behaviour of asphaltic mixtures that fabricated by incorporating several dosages of carbon fiber in regard to the resistance potential of harmful effect of moisture in pavement. Laboratory tests were performed on specimens containing fiber with different lengths and contents. These tests are: Marshall Test, the indirect tensile test and the index of retained strength. The optimum asphalt contents were determined based on the Marshall method. The preparation of asphaltic mixtures involved three contents of carbon fiber namely (0.10%, 0.20%, and 0.30%) by weight of asphalt mixture and three lengths including (1.0, 2.0 and 3.0) cm. The results of this work lead to several conclusions that mainly refer to the benefits of the contribution of carbon fibers to improving the performance of asphalt mixtures, such as an increase in its stability and a decrease in the flow value as well as an increase in voids in the mixture. The addition of 2.0 cm length carbon fibers with 0.30 percent increased indirect tensile strength ratio by 11.23 percent and the index of retained strength by 12.52 percent. It is also found that 0.30 % by weight of the mixture is the optimum fiber content for the three lengths.

Mechanical Behaviors of Natural Sand Soils and Modified Soils in Heavy‐Haul Railway Embankment

The addition of chemical or mechanical materials, such as fibers or stabilizers, is frequently utilized in geotechnical engineering to improve the mechanical properties of problematic soils. In this study, great efforts have been made to obtain insight into the mechanical properties of the natural, fiber, and chemical additive‐stabilized soil in heavy‐haul railway embankment. A series of triaxial compression tests are conducted on the stabilized samples of different preparation conditions, including water content, compaction degree, confining pressure, fiber content, fiber length, stabilizer content, and curing time. Results show that the shear strength of natural soils shows a distinct increase after adding fiber and chemical additive stabilization. The optimum fiber content and length for fiber stabilization are 0.2% and 12 mm, respectively. The initial tangential modulus and failure stress of chemical stabilized samples increase with the increase of additive dosage or curing time. Meanwhile, a brittle characteristic is observed. In the process of determining the reinforcement methods in practical projects, several other considerations are included, such as equipment and time available, especially for stabilized soils. The fiber‐reinforced soils and stabilized soils are efficient for increasing the shear strength and changing of the brittleness character of the heavy‐haul railway embankment. The results of this study could provide a valuable reference for geotechnical engineers dealing with soil problems, especially for the heavy‐haul railway embankment.

Strength and Micromechanism Analysis of Microbial Solidified Sand with Carbon Fiber

Microbially induced calcite precipitation (MICP) is an effective and ecofriendly technology that utilizes the microbes‐induced mineralization to improve foundation soils of the transportation infrastructure. The carbon fiber can be used along with the MICP in order to reduce the brittleness of microbial solidified soil. This paper investigated the strength of carbon fiber‐reinforced sand with different mass fractions through a series of unconfined compression tests. The effect of fiber content on the solidification of carbon fiber‐reinforced sand was quantitatively analyzed using calcium carbonate content test and penetration test. The microsolidification mechanism was investigated by micrographs from the optical and scanning electron microscope (SEM). The test results showed that unconfined compressive strength generally increased first and then decreased with the increase of the fiber content. The optimal fiber content in the silica and calcareous sand was 0.2% and 0.1%, respectively. The bulging deformation of the fiber‐reinforced sand sample was gradually developed along with the fiber breakage during loading.

Crack Resistance and Mechanical Properties of Polyvinyl Alcohol Fiber‐Reinforced Cement‐Stabilized Macadam Base

A series of tests were carried out to evaluate crack resistance and mechanical properties of polyvinyl alcohol fiber‐reinforced cement‐stabilized macadam, which is widely used as pavement base or subbase composite material. Three series of cement‐stabilized macadam mixtures with cement content of 3.2%, 3.6%, and 4.0% were prepared by incorporating four various contents (0, 0.6, 0.9, and 1.2 kg/m3) and lengths (12, 18, 24, and 30 mm) of polyvinyl alcohol fiber. The optimum polyvinyl alcohol fiber content, fiber length, and cement content were determined based on the mechanical properties of cement‐stabilized macadam mixtures. Then, unconfined compressive strength test, compressive resilience modulus test, splitting strength test, flexural tensile strength test, drying shrinkage test, and temperature shrinkage test were carried out in this study. The results show that polyvinyl alcohol fiber‐reinforced cement‐stabilized prepared by optimum proportions (cement 3.6%, fiber content 0.9 kg/m3, and fiber length 24 mm) has good crack resistance. The incorporation of polyvinyl alcohol fiber can effectively improve compressive strength and splitting strength, while its effect on CRM of cement‐stabilized macadam is not remarkable. The anti‐dry‐shrinkage property and anti‐temperature‐shrinkage property of the specimens are also drastically improved due to the reinforcement effect of polyvinyl alcohol fiber. Moreover, the crack resistance index is proposed to evaluate the crack resistance of materials. The crack resistance of PVA fiber‐reinforced cement‐stabilized macadam prepared by optimum proportions is improved by 44.4%. Consequently, the mechanical properties and crack resistance of cement‐stabilized macadam are obviously improved by adding polyvinyl alcohol fiber.

Study on Damage Characteristics of Fiber Concrete under Acid Rain Erosion

Concrete structure will be corroded under acid rain scouring and soaking for a long time, which has a great influence on its durability life. In order to further study the damage characteristics of fiber reinforced concrete under acid rain erosion, the formation mechanism of acid rain and its influence on the corrosion and deterioration of concrete and fiber materials were analyzed in this paper. Taking basalt fiber concrete as an example, the characteristics such as porosity, compressive strength and mechanical indexes were studied and analyzed. Moreover, the reasons for the optimal fiber content was briefly analyzed. The results show that the inner structure of basalt concrete mixed with 0.1% fiber was the most stable and the corrosion resistance was the most satisfying.This conclusion has certain reference significance for the corrosion damage research of fiber reinforced concrete.

Flexural Behavior of Lightweight Concrete Beams Reinforced with GFRP Bars and Effects of the Added Micro and Macro Fiber

This study evaluated the effect of macro steel fiber (SF), micro glass fiber (GF) and micro polypropylene fiber (PF) in lightweight aggregate concrete, (LWAC) beams reinforced with glass fiber reinforced polymer (GFRP) bars. Firstly, concrete mixtures with different volume fractions of GF, PF and SF were tested up to compressive strength, then determine the optimum fiber content GF, PF and SF added into LWAC mix by 0.3%, 0.8% and 0.25% by the volume of concrete, respectively. Meanwhile, eight rectangular cross-section beams with 100 mm (width) × 200 mm (depth) × 1500 mm (length) were tested by four-point bending beam test up to the ultimate load. The GFRP bars were used to reinforce all beams. The failure modes, load-deflection behavior, ductility, flexural capacity and energy absorption were compared in the test results. The experimental results shown added fibers into LWAC improved the flexural capacity, ductility and energy absorption also enhanced moment capacity by 10.07% to 110%. The results indicated that failure modes of GF and PF specimens were in good consistency with the ACI 440.1R-06 predicted failure modes, but for SF specimens, only concrete crushing failure modes accrued. At the end step, the correction factor ( ) obtained from calculated of the experimental results with the flexural capacity according to the ACI 440.1R-06 and ISIS design manual No. 3.

Experimental study on the effect of basalt fiber on the shear behavior of cemented sand

In this study, a series of triaxial tests was performed on a cemented sand improved by adding various contents of basalt fiber. The binding and interfacial interaction between the fiber and cemented sand matrix and the failure model of the interfacial interaction at the sliding surface were examined using scanning electron microscopy (SEM). The triaxial tests show that as the fiber content was increased, the cohesion and residual cohesion first increased and then decreased and the brittleness index decreased, whereas the internal friction angle and residual internal friction angle exhibited no clear variation patterns. Under the optimum fiber content of 0.75%, the cohesion is 406.1 kPa, and the residual cohesion is 145.4 kPa. Compared with cemented sand, the increase is 74.6% and 148.0%, respectively. The SEM tests show that the failure model of the interfacial interaction on the sliding surface included essentially the sliding and pull-out of fibers. The fiber was found to improve shear behavior through the interfacial effect and to affect the failure model through its bridging effect in binding sand particles.

Reactive Powder Concrete Mix Ratio and Steel Fiber Content Optimization under Different Curing Conditions.

In this paper, a practical reactive powder concrete mixture ratio is created on the basis of an orthogonal experiment. Previous studies have combined the compressive and splitting tensile strengths of four categories of reactive powder concrete (RPC) for major materials. These categories include water/binder ratio, silica fume volume content, sand/binder ratio, and dosage of fly ash volume. The optimal mixing proportion of each factor was determined by analyzing the compressive strength of the RPC matrix. For this purpose, steel fiber was used as a reinforcing agent. The compressive and splitting tensile strength test results of steel fiber RPC were analyzed by comparing compound, standard, and natural curing. This was conducted to explore the improvement effect of different steel fiber contents on compressive performance, especially tensile strength of the RPC matrix. According to the results, the optimal steel fiber content was found to be 4% under the three curing conditions. The effect of compound curing on early strength was found to be greater in RPC than by natural or standard curing. However, the effect of late improvement is not obvious. Although standard curing is slightly stronger than natural curing, the performance under the latter can still meet engineering requirements.

Mechanical Properties of Carbon-Fiber–Reinforced Concrete

Abstract Fibers are used to improve the properties of concrete. This article investigates the mechanical properties of chopped carbon-fiber–reinforced concrete (CFRC). The properties examined include workability, compressive strength, splitting tensile strength, and flexural strength. The fibers were added at the volume fractions of 0.5, 1.0, 1.5, and 2.0 %. Adding carbon fiber to the concrete decreased the workability of concrete. The compressive strength of CFRC increases when more carbon fiber is added to the mixture, up to a certain percentage, after which increasing fiber content becomes unbeneficial. This optimum fiber content is found to be 1 %, with a strength effectiveness of 13.65 %. The splitting tensile strength of CFRC improved linearly when more fiber was added to the mixture, and the strength effectiveness ranged from 18.37 to 132.6 %. The flexural strength of CFRC improved linearly with increased fiber content, and the strength effectiveness ranged from 3.26 to 13.82 %. Relationships for compressive strength, splitting tensile strength, and flexural strength of CFRC are introduced and explained.

Analysis of strength characteristics of carbon fiber–reinforced microbial solidified sand

Microbial solidified sand effectively enhances the strength of the soil, but it will cause brittle failure. In order to reduce the impact of microbial solidification sand brittleness, an improved method for adding carbon fiber to microbial solidified sand is proposed. The qualitative analysis was based on unconfined compressive strength test, calcium carbonate content determination, and penetration test. The results show that the addition of fiber in the microbial solidified sand can significantly increase the unconfined compressive strength of the sample. The unconfined compressive strength of the sample increases first and then decreases with the increase of fiber addition. The addition of fibers during the soil process enhances the toughness of the specimen and causes plastic damage during the failure of the specimen. Based on the analysis of the microstructure of the sample, the effect of fiber bundles on the strength characteristics of the sample is discussed when the fiber content is higher than the optimal fiber content. The addition of carbon fiber to microbial solidified sand can greatly improve the strength of the sample and increase the toughness, which plays a positive role in improving the safety and stability of the project.

The use of natural fiber from oil palm empty fruit bunches for soft soil stabilization

The use of natural fiber as a construction material, especially soil stabilization continues to grow. This paper focuses on the use of natural fiber to increase shear strength and bearing capacity of soft soil. The fiber used is obtained from oil palm empty fruit bunches (EFB) as a by-product of palm oil mills. Soft soil mixed with fiber with a composition of 5, 6, 7, and 8% fiber in the mixture. Some tests such as the standard compaction test, unconfined compression test, laboratory vane test, and California Bearing Ratio test were carried out. The results show that the soft soil used in this study can be compacted at fiber content higher than 5%. The maximum density obtained is 0.92 g/cm3 at 7% fiber content. The compacted soil-EFB mixtures successfully increase the shear strength and bearing capacity of the soft soil shown by the results of the UCT, laboratory vane, and CBR tests. The soil consistency changes from soft to medium soil. The maximum qu, su, and CBR obtained are 0.8 kg/cm2, 0.65 kg/cm2, and 6%, respectively at optimum fiber content of 6 to 7%.

Evaluation of Fiber Type and Water-Binder Ratio Influence on Concrete Properties

This paper enumerates the experimental study on workability and strength properties of concrete containing different dosage of polypropylene fiber from 0.1% to 0.6% and 1.0% to 3.5% of steel fiber. Water – binder ratio, fiber type and fiber dosage influence on flow behaviour, compressive strength, flexural strength and brittleness ratio were analysed. Experimental results were substantiated by linear regression analysis considering 95% confidence level. Reference mixes with 0.34 and 0.36 water- binder were prepared for results comparison with polypropylene and steel fiber reinforced concretes. Test results showed comparatively higher workability reduction in polypropylene fiber reinforced concrete. Compressive strength test results of fiber reinforced concrete indicted an optimum fiber content of 0.30% of polypropylene fiber and 2.50% of steel fiber. Steel fiber reinforced concrete displayed continuous increase in flexural strength with 44.46% average increase. Brittleness ratio, which was the ratio of flexural strength and compressive strength showed maximum value of 0.24 for concrete with 3.5 % steel fiber and 0.36 w/B ratio. Linear regression analysis revealed good correlation of flow properties with w/B ratio irrespective of fiber type. Though the compressive strength had low correlation with fiber type and w/B ratio, steel fiber reinforced concrete indicated up to 0.987 coefficient of determination with flexural strength.

A More Realistic Study on the Mechanical Properties of CFRC Composite Grouting Material under a Long-Term Water Immersion Process

The long-term effect of water immersion on the mechanical properties of CFRC composite grouting materials was studied by using five different carbon fiber contents (0, 0.25%, 0.50%, 0.75%, and 1.00%). The direct shear and long-term immersion tests were performed based on the specified and optimum values of carbon fiber content, respectively. The results showed the following: (1) the application of carbon fiber significantly improved the shear resistance of CRFC composite grouting material by using “reinforcing” and “anchoring” actions. The shear strength of the specimen was increasing by 5.66%∼43.41% when the carbon fiber content increased from 0.25% to 1.00%. After a comprehensive analysis, the optimum carbon fiber content was found to be 0.75%. (2) The degradation in the compressive and tensile strength of CRFC composite specimens exhibited a consistent trend (i.e., a steep gradient was gradually followed by a gentle slope) under a long-term water immersion process. About 90% of the total degradation in the compressive and tensile strength has occurred in 90 immersion days (i.e., 16.05% and 18.45%, respectively). In comparison, the degradation in the tensile strength (20.05%) was slightly higher than the compressive strength (18.16%). (3) Under the long-term water immersion process: the properties of the specimens were gradually deteriorating, the carbon fibers were gradually reaching a fatigue stage, and the bonding properties of carbon fiber was decreasing, which resulted in a reduction in the compressive and tensile strength. The uniaxial compression failure mode changed from brittle to ductile, and the development of local failure was very noticeable. Based on the findings of this paper, groundwater has a significant impact on the mechanical properties of grouted rock mass such as dam foundations and abutments. Therefore, the degradation in the grouting materials has to be considered in practical cases.

Effect on Compressive Strength of Concrete by Addition of Polypropylene Fiber in M20 Grade of Concrete

The paper deals with the effects of addition of various proportions of polypropylene fiber on the properties of high strength concrete m20 mixes. An experimental program was carried out to explore its effects on compressive strength under different curing condition. the main aim of the investigation program is to study the effect of polypropylene fiber mix by varying content such as 0%, 0. 5%, 1%, 1. 5%, 2% and find the optimum polypropylene fiber content. the concrete specimen were tested at different age level for mechanical properties of concrete name compressive strength of the concrete. a detailed study was carried out of curing conditions. the increase were compressive strength

Properties of biocemented, basalt-fibre-reinforced calcareous sand

Basalt fibres and biocement were used to improve the mechanical properties of calcareous sand. The biocement was produced through a microbial-induced calcium carbonate precipitation (MICP) process. The unconfined compressive strength (UCS), tensile strength and permeability of the biocemented and fibre-reinforced calcareous sand were evaluated. The calcium carbonate content of each sample was also measured. The microstructure of the biocemented calcareous sand was observed using scanning electron microscopy (SEM). The SEM results indicated that the fibre facilitated the MICP process by bridging the pores in the calcareous sand. As a result, the fibre reduced the brittleness and increased the failure strains of the biocemented calcareous sand. Compared with biocemented calcareous sand without fibre, for all fibre lengths except 4 mm, the UCS, tensile strength and calcium carbonate content of the biocemented calcareous sand increased gradually with an increase in fibre content up to a fibre content of 1%; the optimum fibre content and fibre length were found to be 1% and 8 mm, respectively. The UCS and tensile strength of the biocemented calcareous sand at the optimum fibre content and fibre length increased by 717% and 115%, respectively.

Designing the organoplastics based on aromatic polyamide, study of their operational properties and applicability

Polymeric composite materials that are reinforced with organic fibers are characterized by great possibilities in terms of improving the durability of friction nodes in machines and mechanisms. These composites successfully compete with non-ferrous metals and their alloys and, in some cases, outperform polymeric and metallic analogs by their properties. In this regard, we have studied the influence of the organic fiber lola on operational characteristics of the aromatic polyamide phenylone, brand C-1, and on possibilities to apply the developed polymeric composite materials. Experimental studies have confirmed that the reinforcement of phenylone with the organic fiber lola in the amount of 5–15 % by weight improves its operational characteristics. This is predetermined by the arrangement of the supramolecular structure of the basic polymer due to the introduction of organic fiber. Thus, at the interface phenylone-filler one clearly observes the transformation of the binder's globular structure into fibrillar one. That leads to a positive effect: there is an increase in destruction energy (by 1.5 times) and chemical resistance (by 1.1–1.36 at aging in 5 % HCl, and by 1.27–1.6 ‒ in 10 % HCl). It should be noted that the developed organoplastics are stable at a temperature of 673 K, while the starting polymer begins to destroy intensively at 400 K. Specifically, it was determined that at a further increase in the mass fraction of the filler these indicators deteriorate, due to insufficient adhesion between the filler and the binder. Using the organic fiber lola (in the amount of 5–15 % by weight) makes it possible to obtain composites with improved operational characteristics: enhanced thermal and chemical parameters, high resistance to impact loads. Thus, there is reason to argue about the prospects of using the fiber lola as a filler for composites. Organoplastic with an optimum fiber content (15 % by weight) is recommended for manufacturing the components of tribological nodes for modern equipment instead of non-ferrous metals and their alloys due to sufficiently high operational properties.

Experimental study on effect of fiber length and fiber content on tensile and flexural properties of bamboo fiber/epoxy composite

PurposeThe purpose of this paper is to study the effects of fiber length and content on properties of E-glass and bamboo fiber reinforced epoxy resin matrices. Experiments are carried out as per ASTM standards to find the mechanical properties. Further, fractured surface of the specimen is subjected to morphological study.Design/methodology/approachComposite samples were prepared according to ASTM standards and were subjected to tensile and flexural loads. The fractured surfaces of the specimens were examined directly under scanning electron microscope.FindingsFrom the experiment, it was found that the main factors that influence the properties of composite are fiber length and content. The optimum fiber length and weight ratio are 15 mm and 16 percent, respectively, for bamboo fiber/epoxy composite. Hence, the prediction of optimum fiber length and content becomes important, so that composite can be prepared with best mechanical properties. The investigation revealed the suitability of bamboo fiber as an effective reinforcement in epoxy matrix.Practical implicationsAs bamboo fibers are biodegradable, recyclable, light weight and so on, their applications are numerous. They are widely used in automotive components, aerospace parts, sporting goods and building industry. With this scenario, the obtained result of bamboo fiber reinforced composites is not ignorable and could be of potential use, since it leads to harnessing of available natural fibers and their composites rather than synthetic fibers.Originality/valueThis work enlists the effect of fiber length and fiber content on tensile and flexural properties of bamboo fiber/epoxy composite, which has not been attempted so far.

Mechanical behavior of fiber-reinforced, chemically stabilized dredged sludge

In order to improve the mechanical properties of dredged sludge, short polypropylene fibers were used as physical reinforcement, while cement and fly ash were used as chemical stabilizers. Different mass percentages of fiber (i.e., 0%, 0.05%, 0.1%, 0.2%, 0.4%, and 0.8%), cement (i.e., 15%, 20%, and 25%), and fly ash (i.e., 15% and 30%) were added to dredged sludge at two initial high water contents (i.e., 92% and 120%) and evaluated using physical experiments. The unconfined compression test was performed on samples after curing them for 28 days. The results show that inclusion of cement and fly ash can significantly increase the dry density and reduce the water content of dredged sludge after curing, consequently enhancing the unconfined compressive strength (UCS). It is found that chemical stabilization can increase the stiffness and brittleness of dredged sludge. However, excessively high fly ash fraction in the mix inhibits strength development in cement-stabilized dredged sludge. The inclusion of fiber decreases the initial stiffness and enhances the UCS, strain at failure, and residual strength of dredged sludge. The UCS increases with fiber content and then decreases slightly, with the optimal fiber content being 0.1%. Fiber reinforcement generates a distinct transition zone in the stress–strain curve, which enlarges with increasing fiber content. The contribution of fiber reinforcement to the strength of dredged sludge is more pronounced at relatively lower water content. The inclusion of fiber can temper the brittleness of chemical-stabilized dredged sludge with more ductile behavior by inducing a ‘bridging’ effect. This effect helps in reducing loading-induced cracking of the stabilized sludge.

Investigating the Effects of Chopped Basalt Fiber on the Performance of Porous Asphalt Mixture

Porous asphalt mixture is a type of asphalt mixture with good drainage. However, it has poor tensile strength performance and durability. Chopped basalt fibers (CBF) have been proved to be an effective additive to improve the mechanical and fatigue performance of asphalt mixtures, but little attention has been paid on porous asphalt mixture. This paper examined the effect of chopped basalt fibers with different lengths (nonfiber, 3 mm, 6 mm, 9 mm, and 12 mm) and contents (3% and 4%) on the performance of the porous asphalt mixture. A series of tests were conducted to figure out the optimum fiber length and content, including draindown test, cantabro abrasion test, freeze-thaw split tensile test, wheel tracking test, low-temperature cracking resistance test, and four-point bending beam test. Thereafter, indirect tensile tests at different temperatures were conducted to investigate the tensile strength properties of porous asphalt mixtures with optimum fiber length and content. Besides, the macroscopic and microscopic morphology of fracture sections of the samples after indirect tensile tests were studied by using a single-lens reflex (SLR) camera and scanning electron microscopy (SEM) so as to further explore the reinforced mechanism of chopped basalt fibers. The results show that the addition of chopped basalt fibers can generally improve the performance of porous asphalt mixture since chopped basalt fibers form a three-dimensional network structure in the porous asphalt mixture.