Effect Of Carbon Fiber Research Articles

Effect of carbon fiber on mechanical properties of reactive powder concrete exposed to elevated temperatures

An ultra-high-performance cement-based composite like reactive powder concrete (RPC) achieves its exceptional engineering properties due to a dense and homogenous microstructure. To improve the ductility and fire-resistance, RPC is often reinforced with a high volume of steel fibers (SF). Due to the issues of high density, low durability, and high conductivity; there is a need to study RPC with lightweight and durable fibers. In this research, the mechanical properties of RPC are studied with a single and hybrid fiber mixture of carbon fiber (CF) and conventional SF. The mechanical properties of plain and fiber-reinforced RPC were examined after exposure to 200oC, 400oC, 600oC, and 800oC temperatures for the 2 h. The results showed that CFRPC mechanically performs up to 85–90% potential of conventional SFRPC. Hybridization of 1.5% SF and 0.5% CF produced synergistic effects on the mechanical properties of RPC at both normal and elevated temperatures. After exposure to 800oC, CFRPC showed about 2, 4, and 5 times higher residual compressive, tensile, and flexural strength than plain RPC, respectively. Compressive strength-per-unit weight of CFRPC was notably higher than SFRPC.

Effect of Carbon Fiber on Microwave Deicing Efficiency of Pavement Concrete

Snow and icing on roads in winter will bring serious consequences to traffic safety. Microwave deicing, as a new type of environmentally friendly road surface deicing method, has the characteristics of environmental protection, pollution-free, and high ice removal rate, but its low deicing efficiency limits its use. Carbon fiber has good electrical and thermal conductivity, wear resistance, etc., and can provide a new composite material for road surface deicing. Taking carbon fiber concrete as the research object, the effect of different carbon fiber length on the microwave heat absorption efficiency of concrete is studied. The results found that: as the length of carbon fiber increases, the temperature rise at the same time increases exponentially, the higher the efficiency of carbon fiber concrete for absorbing and heating.

Strengthening Prestressed Concrete Bridge Girders and Building Beams with Carbon Fiber Reinforced Polymer Sheets

The effect of Carbon Fiber Reinforced Polymer (CFRP) retrofitting and concrete type on the flexural strength of prestressed concrete I-section girders used in bridges and beams in buildings is investigated. Non-linear moment-curvature relationships are predicted using an iterative algorithm for both non-retrofitted and CFRP-retrofitted prestressed concrete girder and beam cross-sections with various concrete types. Two different CFRP-retrofitting schemes are analyzed for comparing their effectiveness. It is found that although non-retrofitted beam section exhibits greater ductility, the use of CFRP retrofitting in both tension and compression regions simultaneously results in a significant increase in flexural strength. It is also found that the higher the ultimate concrete strength, the higher is the influence of CFRP-retrofitting on increasing flexural strength.

Study on Splitting Tensile Mechanical Properties of Carbon Fiber/Polymer Latex Powder Composite Modified Concrete

The effects of carbon fiber and polymer latex powder on the split tensile mechanical properties of concrete in single and compound mixing conditions are studied. The results show that both carbon fiber or polymer latex powder can improve the split tensile strength and peak strain of concrete. When the carbon fiber content is 0.2%, the split tensile mechanical properties of carbon fiber reinforced concrete (CFRC) are the best. When the amount is 8%, the mechanical properties of polymer modified concrete (PMC) in split tension are the best. When the carbon fiber content is 0.3% and the polymer latex powder content is 0.8%, the splitting tensile mechanical properties of the carbon fiber/polymer latex powder composite modified concrete (CFRPMC) specimens are the best, and are better than CFRC specimens and PMC specimens.

Performance Improvement of Carbon Fiber Reinforced Epoxy Composite Sports Equipment

This study is to explore the changes in the performance of sports equipment under the action of carbon fiber reinforced epoxy composites. This paper studies the effects of carbon fiber reinforced epoxy composites in pole vault, bicycle, and tennis. The research results show that the performance of sports equipment based on carbon fiber reinforced epoxy composite materials has been greatly improved, with outstanding effects in terms of thermal properties, interface properties, mechanical properties, and fatigue resistance. Carbon fiber reinforced epoxy composite material damage expansion is divided into five stages: matrix cracking, interfacial degumming, delamination, fiber fracture, fracture. Therefore, carbon fiber reinforced epoxy composite materials are comprehensive for the improvement of sports equipment, which has greatly promoted the further development of sports. Carbon fiber reinforced epoxy composite materials can be promoted in other fields, thereby obtaining greater progress with help of high technology. The study of carbon fiber reinforced epoxy composites in this paper has a positive effect on subsequent research.

Effects of carbon fibers on the microstructure and properties of laser cladding 24CrNiMoY alloy steel

24CrNiMoY alloy steel is widely used as a raw material for manufacturing wear-resistant parts, but its low microhardness can’t meet the service requirements of the surface working layer of the parts. Therefore, laser cladding technology was used to prepare carbon fibers (CFs) reinforced alloy steel samples with different CFs content (0−1 wt.%). The results showed that as the CFs content increased, the microstructure of the samples gradually changed from lath bainite (LB) to lath martensite (LM), and finally to plate martensite (PM). The microhardness and tensile strength of samples showed a trend of increasing first and then decreasing. When the CFs content was 0.8 wt.%, the microhardness was 835 HV0.2, reaching the peak value, which was 133.9 % higher than that of 24CrNiMoY alloy steel. Besides, when the CFs content was 0.6 wt.%, the comprehensive mechanical properties were the best. Compared with 24CrNiMoY alloy steel, the average microhardness and tensile strength increased by 113.2 % and 29.4 %, respectively, reaching 761 HV0.2 and 1061.14 MPa. The research results indicated that the microhardness and wear resistance of 24CrNiMoY alloy steel were significantly enhanced by adding a small number of CFs, which provides a reference for laser cladding parts with high microhardness surface working layer.

USING CARBON FIBER STRIPS IN JOINTS STRENGTHING OF BOX SEGMENTAL SELF-COMPACTING CONCRETE BEAMS

The main objective of this research is to study the effect of carbon fibers used to strengthen the joints of the box segmental beams. For this research, four beams were produced and tested. One of these beams, monolithically, was cast as a reference beam and the three others were segmental beams. All beams were produced with Self-Compact Concrete (SCC) and box cross section. Each segmental beam consisted of three precast concrete segments were connected by post tensioning tendons. The three segmental beams have same characteristics, but different in joint types between the segments. The types of joints used were (dried, epoxied and dried strengthen by CFRP sheets). All beams were tested under static two point loads up to failure. For each test, deflections at mid-span location were recorded for each (5kN). Also, first cracking, mode of failure and ultimate loads values were recorded as well as the concrete surface strains at the specified locations for both loadings.

Role of smart concrete in strain sensing and structural properties of reinforced concrete beam

AbstractPresent work demonstrates the experimental investigation on four large scale reinforced concrete (RC) beams cast with and without smart concrete to study strain and damage sensing properties (for health monitoring), effect of carbon fiber (CF) on ultimate strength, crack pattern, and stiffness response under monotonically increased loading. A total of four beams, one without and three with smart concrete (CF‐based concrete) having similar dimensions, similar percentage of reinforcement, similar aspect ratio, same grade of steel but having variable strengths of concrete were cast and tested for evaluating above said properties. Micro CFs were placed only in mid‐span region for a length of 350 mm and a depth of 55.5 mm at top and bottom surface of the beam from economical point of view for health monitoring. From obtained experimental results, it was found that RC beam embedded with smart concrete can be used for structural health monitoring (SHM) and obtained fractional change in resistance of smart concrete can be corelated with compressive strain in concrete and tensile strain in steel up to good extent. Along with strain and damage sensing properties, the effect of smart concrete on structural properties is also reported and it was found that, apart from showing positive results for SHM, it also increases ultimate strength carrying capacity of the same RC beam. Also the experimentally obtained ultimate strength values were compared with theoretical predicted values using IS456‐2000, ACI 318–11, and CSA A23.3–04 codes.

Mode-I fracture toughness of glass/carbon fiber reinforced epoxy matrix polymer composite

Abstract Advanced polymer composites such as continuous fiber-hybrid reinforced composites results in significant increase in fracture toughness and strength when compared with conventional composites. In this recent research plane strain or mode-I (tensile) fracture toughness of the glass fiber reinforced polymer matrix composite, carbon fiber reinforced polymer matrix composite and hybrid polymer composite (with glass and carbon fiber reinforcements to epoxy matrix) along with its interlaminar shear strength and flexural strength has been evaluated and discussed. Scanning electron microscopic images were also used to analyze the fracture behavior of these composites. The obtained results are analyzed to evaluate: (i) effect of glass fiber and its influence on the flexural strength, interlaminar shear strength and mode-I fracture toughness, (ii) effect of carbon fiber and its influence on the flexural strength, interlaminar shear strength and mode-I fracture toughness, and (iii) finally, properties of hybrid composite. The results thus obtained have revealed that the mode-I or plane fracture toughness is significantly enhanced with the reinforcement of carbon fibers. In hybrid composite fracture toughness is greater when compared with their bulk and monolithic counter parts.

Influence of chemically treated carbon fibers on the electromagnetic shielding of ultra-high-performance fiber-reinforced concrete

The effects of carbon fiber and its surface treatment through chemical solutions on the mechanical properties and electromagnetic (EM) shielding of ultra-high-performance fiber-reinforced concrete (UHPFRC) were analyzed. Three types of carbon fibers chemically treated with sodium hydroxide, nitric acid, and ammonia solutions were evaluated, along with a plain carbon fiber control sample, at two different concentrations of 0.1% and 0.3% by weight. The surface of carbon fiber was oxidized by chemical solutions. The conductivity of UHPFRC increased with increasing the carbon fiber content, and slightly better conductivity was obtained using the chemically treated carbon fibers than plain fibers at the lower content of 0.1 wt%. Both steel and carbon fibers were effective at improving the shielding effectiveness of ultra-high-performance concrete, and a higher shielding effectiveness was achieved for higher carbon fiber content. Surface treatment using the nitric acid solution was the most effective at enhancing the tensile performance and EM shielding effectiveness, and the best shielding effectiveness (49.0 dB at 1 GHz) was achieved for UHPFRC with 0.1 wt% nitric acid treated carbon fibers. The shielding effectiveness was found to be generally proportional to the electrical conductivity, although its increase was minor relative to that of the conductivity.

Numerical Investigation on Dynamic Response of RC T-Beams Strengthened with CFRP under Impact Loading

To precisely evaluate the retrofitting effectiveness of Carbon Fiber Reinforced Plastic (CFRP) sheets on the impact response of reinforced concrete (RC) T-beams, a non-linear finite element model was developed to simulate the structural response of T-beams with CFRP under impact loads. The numerical model was firstly verified by comparing the numerical simulation results with the experimental data, i.e., impact force, reaction force, and mid-span displacement. The strengthening effect of CFRP was analyzed from the section damage evaluation. Then the impact force, mid-span displacement, and failure mode of CFRP-strengthened RC T-beams were studied in comparison with those of un-strengthened T-beams. In addition, the influence of the impact resistance of T-beams strengthened with FRP was investigated in terms of CFRP strengthening mode, CFRP strengthening sizes, CFRP layers and FRP material types. The numerical simulation results indicate that the overall stiffness of the T-beams was improved significantly due to external CFRP strips. Compared with the un-strengthened beam, the maximum mid-span displacement of the CFRP-strengthened beam was reduced by 7.9%. Additionally, the sectional damage factors of the whole span of the CFRP-strengthened beam were reduced to less than 0.3, indicating that the impact resistance of the T-beams was effectively enhanced.

Effect of carbon fiber on properties of concrete with different W/C and its air‐entraining models

AbstractThe addition of carbon fiber can change plain concrete (PC) to a quasi‐ductile material and improve its flexural properties through sharing the tensile stress transduced from concrete matrix. However, the influence rule and its mechanism of air entrained by carbon fiber on properties of concrete with different water to cement ratios (W/C) is not clear at present. Therefore, this research aims to explore this influence rule and mechanism. Eighteen kinds of concrete samples with W/C of 0.25, 0.3, and 0.45 including 216 specimens in total were studied. Their mechanical and permeability‐related properties were tested, and carbon fiber's air‐entraining models were established. The results show that carbon fiber has effect of improving the flexural strength, compressive strength, and impermeability of concrete with W/C of 0.25, but when W/C increases, the effect of carbon fiber on improving the flexural strength, reducing the compressive strength and impermeability of concrete increases. The calculation results of the air‐entraining models suggest that one possible air‐entraining mechanism of carbon fiber can be summarized as that carbon fiber entrains more air into concrete as W/C increases, and another one can be summarized as that the air entrained by carbon fiber increases the connectivity of the pore structure of concrete.

Effect of carbon fiber on the braking performance of copper-based brake pad under continuous high-energy braking conditions

The braking performance of copper-based brake pads containing different carbon fiber (CF) content was evaluated on a reduced scale dynamometer. The results show that the introduction of CF has a pronounced impact on the microhardness and plastic deformation resistance of the tribo-film. Compared with graphite, nano CFs has higher specific surface energy and is easy to react with iron to form cementite. On the one hand, the cementite containing iron particles in the sub-friction surface has high strength, which plays a strong supporting role on the friction surface; on the other hand, the cementite participating in the formation of the tribo-film also strengthens the tribo-film and reduces the oxidation degree of iron. All of those contribute to the formation of tribo-film with high plastic deformation resistance, which imparts the low transfer rate of tribo-film in the process of high-energy braking, so as to stabilize the friction coefficient and reduce the wear loss. In the range of 0–1.2 wt% CF, the 0.4 wt% CF can make the copper-based brake pad exhibit the best wear resistance and the most stable friction coefficient (0.357–0.372) during continuous high-speed emergency braking.

Effects of Carbon Fibre on Performance Properties of Asphalt Mixtures

In this study, the effects of carbon fibre on improving the performance characteristics of asphalt mixtures were investigated. To this end, four percentages of carbon fibre (0%, 0.3%, 0.5%, and 0.7% by weight of bitumen) were used as an additive in asphalt mixtures. The mechanical properties of prepared mixture specimens were investigated using tests such as Marshall Stability and flow, Indirect Tensile Stiffness Modulus, Creep Stiffness, Indirect Tensile Strength, and moisture resistance. The results of tests applied to asphalt mixtures showed that the carbon fibre additive increased the resistance to shear stress by 25%, the fatigue life by 51% at 40 °C and the permanent deformation resistance by 2.25 times at 60 °C. It also improved the resistance of mixtures to moisture damage by increasing the durability and cohesion of asphalt mixtures. Experimental results indicated that the carbon fibre provided a positive contribution to the performance properties of asphalt pavements.

A nanoindentation based study to evaluate the effect of carbon nanofibers on the mechanical properties of SiC composites

ABSTRACT An advanced high-speed nanoindentation technique is employed to analyze the combined benefit of the particulate and continuous fiber’s reinforcing effect of carbon fibers in the SiC matrix. Spray freeze granulated well-dispersed carbon nanofibers (CNF) containing precursor SiC-CNF (1 wt%) composite powder was used as a base matrix in which continuous carbon fibers were introduced in a systematic laying pattern to produce hybrid composite tubes with 10–12 mm wall thickness. Thin tubes with a wall thickness of 1–2 mm were produced with SiC, SiC-CNF composite powder. The two types of tubes with various lengths were cold isostatically pressed and pressureless sintered at 2150°C/1hour under Argon (Ar). The surface properties of the sintered tubes were further enhanced by coating with a dense SiC layer by adopting a CVD technique. The properties of the fiber-matrix interface and coating-matrix interfaces of the tube samples were evaluated using conventional processes as well as the nanoindentation techniques and compared at different length scales. Attempts have been made to correlate the structure-property relations of complex multi-phase of SiC composites employing high-speed nanoindentation mapping as well as XRD, Digital optical, SEM, and TEM analysis.

Economical and Technical Study on the Effect of Carbon Fiber with High Strength on Hot Mix Asphalt (HMA)

In this article by adding different percentages of carbon fiber with high strength and doing the necessary Marshall tests, it was observed that the Marshall Resistance and its Flow increased. Due to their armed properties, the carbon fibers have a positive effect on Marshall Resistance. According to the results, in-creasing the percentage of fibers, reduces the resistance, so that the resistance of the sample containing 1.5% of carbon fiber is almost 32% more than the resistance of the sample without fiber. According to the results, the increased resistance compared to the previous researches and other fibers stems from the kind of fiber used in it and its high resistance. After increasing the fiber percentage to 3, a 12% decrease in the resistance was seen. On the other hand, by changing the percentage of the fibers added to the aggregates, the Flow will change, so that the sample containing 3% of fiber is almost 189% more Flow than the base sample. The economic analysis was used for a three-lane road. The results showed that economically speaking, due to their high price, these types of fibers are recommended to be used in restricted and optimal areas.

Effect of CFRP strengthening systems on the fatigue limit of reinforced concrete beams

This paper aims to study the effect of Carbon Fiber Reinforced Polymer (CFRP) strengthening techniques on the fatigue limit of Reinforced Concrete (RC) beams. An accelerated fatigue method was utilized to find the fatigue limit based on the hypothesis of linear cumulative damage as determined by the Palmgren-Miner rule. Six RC beams with dimensions of 152.4 × 152.4 × 1,520 mm were tested under monotonic and cyclic loading using a four-point bending configuration: two non-strengthened RC beams, two RC beams strengthened with Near Surface Mounted (NSM) CFRP rods, and two RC beams strengthened with Externally Bonded (EB) CFRP sheets. Strengthened RC beams had less stiffness degradation and more energy dissipation when compared to the non-strengthened RC beam. The NSM CFRP technique demonstrated a better monotonic flexural strength than the EB CFRP technique. NSM CFRP rods and EB CFRP sheets increase the fatigue limit when compared to the non-strengthened RC beam by 19% and 33%, respectively.

Bond performance between substrate concrete and repair mortar: Effect of carbon fibre and expansive agent

This study aims to investigate the impact of an expansive agent and carbon fibre in repair mortar (overlay) on the bond strength at different water-to-binder ratios (w/b). Measurements of the flexural and compressive strengths, drying shrinkage, and mercury intrusion porosimetry (MIP) were used to evaluate the properties of the overlays, and the compressive strength, drying shrinkage, and splitting tensile strength were adopted to evaluate the properties of substrate. The exposure surface after splitting a cube into two halves was used as repair surface of substrate. The bond strength was evaluated by a splitting tensile test, and backscattered electron images were acquired to observe micro-cracks of the repair bond. The experimental results indicated that the drying shrinkage of the repair mortar was reduced by the carbon fibre and expansive agent. The total porosity of the repair mortar was increased and the compressive strength was decreased by the expansive agent. Interface failure accompanied by partial substrate failure and repair mortar failure accounted for 85.7% of bond failures. The incorporation of the expansive agent and carbon fibre in the repair mortar resulted in growth rates of 25.18% and 33.56%, respectively, for the splitting tensile bond strength at w/b of 0.30. This enhancement decreased as the w/b decreased. The repair effectiveness improved as the compressive strength ratio (repair mortar/substrate concrete) increased with a certain range (no more than 1.45). Therefore, the expansive agent and carbon fibre have the potential to improve the bond strength when the strengths of the substrate and of the repair material are equivalent and the repair bond under splitting tensile stress.

The mechanical properties and microstructure of carbon fibers reinforced coral concrete

In this paper, the effect of carbon fibers (CFs) on the mechanical properties and microstructure of carbon fibers reinforced coral concrete (CFRCC) were experimentally investigated. Eighteen CFRCC mixtures were designed considering concrete strength grade (C20, C30, C40) and CFs content (0.0%, 0.3%, 0.6%, 1.0%, 1.5%, 2.0%) as variables, and a total of 414 specimens were poured. The cube compressive strength, axial compressive strength, splitting tensile strength, elastic modulus, and Poisson's ratio of CFRCC were obtained by test. Moreover, the microstructure of coral aggregates (CAs) and CFRCC was also observed by X-ray diffractometer, digital microscope, and scanning electron microscope (SEM). The experimental results show that the addition of CFs can improve the compressive strength and splitting tensile strength. The optimum content of CFs is about 1.5% by weight of the binder. However, the effect of CFs on the elastic modulus and Poisson's ratio is not significant. Furthermore, the microstructure investigation reveals that the CAs have a porous structure, and the interfacial transition zone (ITZ) does not be the weak zone in CFRCC. It is also observed from SEM that there are two failure patterns of CFs in CFRCC, namely fiber pull-out and fiber breakage.

Analysis of the Effect of Nanometer Silica on Cement Modification

The purpose of this study was to explore the effect of nano-scale silica on cement modification. In this study, nano-SiO2 particle materials were prepared, and then the properties of the nano-materials were analyzed by monofilament pull-out test and different amounts of SAE and PE in the preparation of nano-SiO2. Through the research, it was found that the appearance of the new nanomaterials was characterized by that the contact interface between the carbon fiber modified by nano-silica and the cement-based was dense, and the pores were not observed. Moreover, the interface was strongly bonded and the scratches were very obvious. This result indicates that the biosensor was successfully constructed; in the analysis of the influence of different content of SAE and PE on nanomaterials, it was found that the maximum increase in flexural strength was achieved when the content was 3% at 28d in the flexural strength study; in the study of compressive strength, it was found that the adulterate amount of 6% was a cutoff point for the decrease of compressive strength; when PE content was 3%, the flexural strength and compressive strength were increased to the maximum. In the load-displacement curve analysis of carbon fiber monofilament pull-out test, the modified fiber and cement matrix formed greater physical adsorption force and chemical adhesive force. The experiment showed that the critical length of cement can be significantly reduced after nano and modified research, so as to improve the strengthening effect of carbon fiber in cement matrix. Although there are some deficiencies in the research process, it also provides a basis for the future direction of new materials in the construction industry.