• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.115-123
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• 2007

For investigating self-diagnosis applicability, a method based on monitoring the changes in the electrical resistance of carbon fiber reinforced concrete has been tested. Then after examining change in the value of electrical resistance at each flexural weight-stage of carbon fiber in CFGFRP (carbon fiber and glass fiber reinforcing plastic) with new type rib and carbon sheet for concrete reinforcing, the correlations of electrical resistance and load as a function of strain, deflection were analyzed. As the results, it is clarified that when carbon fiber rod, rib and sheet fracture, the electrical resistance of it increase largely, and specially in case of CFGFRP, afterwards glass fiber tows can be resist the load due to the presence of the hybrid (carbon and glass) reinforced fiber. Therefore, it can be recognized that reinforcing bar and new type rib of CFGFRP and sheet of CF could be applied for self-diagnosis of fracture in reinforced FRP concrete.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.601-608
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• 1992

We investigated the influence of several processes, including the preparation of slurry and preform and the heat-treatment of the preform, on the properties of composites to fabricate the carbon-fiber reinforced glass composites having good mechanical properties. Cerander was determined to be the best binder among Cerander, Rhoplex and Elvacite 2045 by the dipping test and the binder within a preform could be completely eliminatd by burning out the specimen under 10-6 Torr at 400$^{\circ}C$ for more than 1h. The fracture behavior of a composite was largely dependent on the uniformity of carbon-fiber distribution within the composite and the heat-treatment condition of the composite. The higher the glass content, the more difficult to obtain uniform distribution of carbon-fiber. As the hot-pressing temperature increased, the densification process of the composite and the formation of pore due to oxidation of carbon fiber occurred competitively. But, above 1000$^{\circ}C$ the latter played a predominant role. We could fabricated the densest 15 vol.% carbon-fiber-content glass composite having the highest toughness and flexural strength of 250 MPa by hot-pressing under 15 MPa at 900$^{\circ}C$ for 30 min.

• International Journal of Highway Engineering
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• v.18 no.1
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• pp.57-62
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• 2016

PURPOSES : Reflection cracking has been one of the major causes of distress when asphalt pavement is laid on top of concrete pavement. This study evaluated the reflection cracking resistance of asphalt mixtures reinforced with asphalt embedded glass fiber and carbon fiber using a Texas Transportation Institute (TTI) overlay tester. METHODS : Different asphalt mixtures such as polymer-modified mastic asphalt (PSMA) and a dense graded asphalt mixture were reinforced with asphalt-embedded carbon fiber and glass fiber. For comparison purposes, two PSMA asphalt mixtures and one dense graded asphalt mixture were evaluated without fiber reinforcement. Two different overlay test modes, the repeated overlay test (R-OT) and monotonic overlay test (M-OT), were used to evaluate the reflection cracking resistance of asphalt mixtures at $0^{\circ}C$. In the R-OT test, the number of repeated load when the specimen failed was obtained. In the M-OT test, the tensile strength at the peak load and tensile strain were obtained. RESULTS : As expected, the fiber-reinforced asphalt mixture showed a higher reflection cracking resistance than the conventional nonreinforced asphalt mixtures based on the R-OT test and M-OT test. The dense graded asphalt mixture showed the least reflection cracking resistance and less resistance than the PSMA. CONCLUSIONS : The TTI overlay tester could be used to differentiate the reflection cracking resistance values of asphalt mixtures. Based on the R-OT and M-OT results, the carbon-fiber-reinforced asphalt mixture showed the highest reflection cracking resistance among the nonreinforced asphalt mixtures and glass-fiber-reinforced asphalt mixture.

• Advances in materials Research
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• v.13 no.1
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• pp.63-86
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• 2024

Asphalt concrete (AC), is a mixture of bitumen and aggregates, which is very sensitive in the design of flexible pavement. In this study, the Marshall stability of the glass and carbon fiber bituminous concrete was predicted by using Artificial Neural Network (ANN), Support Vector Machine (SVM), Random Forest (RF), and M5P Tree machine learning algorithms. To predict the Marshall stability, nine inputs parameters i.e., Bitumen, Glass and Carbon fibers mixed in 100:0, 75:25, 50:50, 25:75, 0:100 percentage (designated as 100GF:0CF, 75GF:25CF, 50GF:50 CF, 25GF:75CF, 0GF:100CF), Bitumen grade (VG), Fiber length (FL), and Fiber diameter (FD) were utilized from the experimental and literary data. Seven statistical indices i.e., coefficient of correlation (CC), mean absolute error (MAE), root mean squared error (RMSE), relative absolute error (RAE), root relative squared error (RRSE), Scattering index (SI), and BIAS were applied to assess the effectiveness of the developed models. According to the performance evaluation results, Artificial neural network (ANN) was outperforming among other models with CC values as 0.9147 and 0.8648, MAE values as 1.3757 and 1.978, RMSE values as 1.843 and 2.6951, RAE values as 39.88 and 49.31, RRSE values as 40.62 and 50.50, SI values as 0.1379 and 0.2027 and BIAS value as -0.1 290 and -0.2357 in training and testing stage respectively. The Taylor diagram (testing stage) also confirmed that the ANN-based model outperforms the other models. Results of sensitivity analysis showed that the fiber length is the most influential in all nine input parameters whereas the fiber combination of 25GF:75CF was the most effective among all the fiber mixes in Marshall stability.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.409-416
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• 2007

In accordance with the increased usage of reinforcing materials such as carbon fibers and glass fibers, delamination detection between concrete and the reinforcing material is needed as such delaminations may be a major cause for strength reduction or failure of a structure. In this work, 15 GHz center frequency with 10 GHz band width horn antenna was used to detect delamination between concrete and carbon fibers or glass fibers. The specimens measured $600\;(length)\;{\times}\;600\;(width)\;{\times}\;100\;(thickness)\;mm$, and glass fibers and carbon fibers with a thickness of 1.5 mm were attached on the specimens' surfaces using epoxy. In addition, artificial delaminations of size $50\;(length)\;{\times}\;50\;(width)\;mm$ were placed in the middle of the specimen with thickness of 2, 4, 6 mm respectively together with a 2 mm delamination projecting upwards from the surface of the concrete. Therefore a total of 8 specimens were used, 4 specimens for glass fiber reinforced concrete and 4 for carbon fiber reinforced concrete, containing delaminations as described above. The experiment results were derived by using the difference of area under the curved graph. According to experimental results artifical delaminations were identified in both fiber reinforced and carbon reinforced specimens and these results could contribute to further development of delamination detection technology.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.499-507
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• 2002

The carbon nanotube emitters for field emission displays were fabricated by using screen printing techniques. The pastes for screen printing are composed of organic binders, carbon nanotubes (multiwalled or singlewalled), and some additive materials. The pastes were printed on Cr-coated/Ag-printed soda-lime glass substrates. From the I-V characteristics, the turn-on field of SWNT was lower than that of MWNT. The decrease in the mesh size of screen masks (i.e. increase in the opening size of the screen mesh) resulted in decreasing the turn-on field and increasing the electron emission current. When the carbon nanotubes were mixed with silver pastes, silver powders appeared to contribute to the vertically aligning of carbon nanotubes on a glass.

• Composites Research
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• v.16 no.2
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• pp.48-53
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• 2003

This paper presents a study on the permittivities of the I-glass fabric/epoxy composite laminates containing carbon black dispersions at microwave frequency. Measurements were performed at the frequency band of 5 GHz∼18 GHz. The results showed that the complex permittivities of the composites depend strongly on the natures and concentrations of the carbon black dispersion. A new scheme is proposed to obtain a mixing law for the estimation of the complex permittivities of the composite laminates as a function of concentration of carbon black. Simultaneously, the complex permittivity of carbon black itself was also calculated by the scheme. The experimental values of the complex permittivities of the composites were compared to those calculated.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.570-575
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• 2006

In this paper, we have investigated thermal properties by changing the content of carbon nanotube, which is component part of semiconductive shield in underground power transmission cable. Heat capacity (${\Delta}H$), glass transition temperature (Tg) and melting temperature (Tm) were measured with the samples of eight, through DSC (Differential Scanning Calorimetry), and the measurement ranges of temperature selected from $-100[^{\circ}C]\;to\;100[^{\circ}C]$ with heating temperature selected per $4[^{\circ}C/min]$ Also, high temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis) in the temperature from $0[^{\circ}C]\;to\;700[^{\circ}C]$ with rising temperature of $10[^{\circ}C/min]$. As a result, the Glass transition temperatures of the sample were showed near $-20[^{\circ}C]{\sim}25[^{\circ}C]$, and the heat capacity and melting temperature from the DSC was increased according to increasing the content of carbon nanotube, while, thermal diffusivity was increased according to increasing the content of carbon nanotube. Also, heat degradation initiation temperature from the TGA results was increasing according to increasing the content of carbon nanotube with CNT/EEA. Therefore, heat stabilities of EVA, which contained the we VA (vinyl acetate), showed the lowest.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.3
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• pp.53-59
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• 2021

In vibration-free vehicles such as limousine buses, the vibration is minimized by installing an air spring instead of the leaf spring used in the existing freight cars to prevent the damage to the loaded cargo from shocks generated during movement. In the existing vehicles, steel structures support the air spring system. This study was aimed at replacing the steel structures used in the Z-spring by carbon fiber and glass fiber reinforced plastics. In addition, the mechanical properties (elastic modulus, tensile strength, and shear strength) of carbon fiber and glass fiber prepreg were derived using specimens molded with the corresponding prepreg. The final goal was to develop a material lighter than the conventional steel material but with enhanced mechanical properties. Although the CF prepreg exhibited excellent mechanical properties, the production cost was extremely high. To overcome this limitation, hybrid composites with GF prepreg were examined, which are expected to be promising future materials.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.9-17
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• 1999

Viscoelastic characteristics of cured phenolic resin/carbon fiber composite materials were investigated through glass transition and degradation reaction processes in the high temperature region up to $400^{\circ}C$. A typical glass transition of the cross-linked thermoset polymer was followed by irreversible degradation reactions, which were exhibited by the increasing storage modulus and loss modulus peak. A degradation master curve was constructed by using the vertical and horizontal shift factors, both of which complied well with the Arrhenius equation in light of the kinetic expression of degradation rate constants. Using an analogy to the Havriliak-Negami equation in dielectric relaxation phenomena, a viscoelastic modeling methodology was developed to characterize the frequency- and temperature-dependent complex moduli of the degrading thermoset polymer composite systems. The temperature-dependent relaxation time of the degrading composites was determined in a continuous fashion and showed a minimum relaxation time between the glass transition and degradation reaction regions. The capability of the developed modeling methodology was demonstrated by describing the complex behavior of the viscoelastic complex moduli of reacting phenolic resin composite systems.