The Experts below are selected from a list of 1836 Experts worldwide ranked by ideXlab platform
Jing Zhou - One of the best experts on this subject based on the ideXlab platform.
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indirect Microwave Curing process design for manufacturing thick multidirectional carbon fiber reinforced thermoset composite materials
Applied Composite Materials, 2019Co-Authors: Jing Zhou, Yingguang Li, Libing Cheng, Linglin ZhangAbstract:Recently, indirect Microwave Curing technology was developed to process multidirectional carbon fiber reinforced composite materials with high efficient and energy saving purpose. The aim of this paper is to solve the problem of large mid-plane heat generation in manufacturing this kind of materials with large thickness. The difference between the traditional thermal Curing and indirect Microwave Curing processes was analyzed. A Multiphysics model was constructed to reflect the composite Curing behavior in a cost-effective manner, which agreed well with the experimental results. On this basis, a new indirect Microwave Curing cycle was designed, and relevant process parameters were determined. Compared with the manufacturer’s recommended cycle, the degree of mid-plane heat generation was greatly relieved, and a reduction of 34.6% in composite residual strains was achieved. Moreover, the Curing cycle was reduced by 38%, while the interlaminar shear strength of the composite was improved by 1.38 times. Corresponding reinforcement mechanisms were explored through the observation of composite cross-sections with optical microscopes.
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Microwave Curing of multidirectional carbon fiber reinforced polymer composites
Composite Structures, 2019Co-Authors: Jing Zhou, Qiang ChengAbstract:Abstract Composite Microwave Curing technologies have been researched and given great expectations for decades to cutting down the long Curing cycle and enormous energy consumption during traditional Curing process. However, this good vision was stopped since the Microwave can hardly penetrate and heat multidirectional carbon fiber reinforced polymer composites. In this paper, the mechanism that multidirectional composite can hardly be heated was revealed. New method was found to stimulate Vertical Penetrating Microwave (VPM) by using metal strips, and the multidirectional carbon fiber reinforced polymer composites can be heated directly. The theory and model of VPM’s heating depth of multidirectional composite were established and verified. The results indicated that 2.3 mm thickness multidirectional composite can be cured effectively by using the VPM.
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a multi pattern compensation method to ensure even temperature in composite materials during Microwave Curing process
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Jing Zhou, Libing Cheng, Shuting Liu, Shaochun Sui, James GaoAbstract:Abstract Microwave Curing technologies have many advantages in manufacturing fiber reinforced polymer composite materials used in aerospace products, compared with traditional autoclave Curing technologies. However, the uneven electromagnetic field of Microwave in the cavity of the Curing chamber results in uneven temperature on the surface of composite laminates during Curing, which has been a major obstacle in industrial applications worldwide. Existing methods attempted to solve the problem by the random superposition of uneven electromagnetic fields, but the results were still not satisfactory to meet the high quality requirements of aerospace parts. This paper reveals the one-to-one correspondence between heating patterns of composite parts and Microwave Curing system settings, and reports a new concept to solve this problem by continuously monitoring and compensating the uneven temperature distribution in real-time. Experimental results from both fiber optical fluorescence sensors and infrared thermal imagers showed significant improvement in temperature uniformity compared with existing methods.
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Anisotropic Dielectric Properties of Carbon Fiber Reinforced Polymer Composites during Microwave Curing
Applied Composite Materials, 2018Co-Authors: Linglin Zhang, Jing ZhouAbstract:Microwave cuing technology is a promising alternative to conventional autoclave Curing technology in high efficient and energy saving processing of polymer composites. Dielectric properties of composites are key parameters related to the energy conversion efficiency during the Microwave Curing process. However, existing methods of dielectric measurement cannot be applied to the Microwave Curing process. This paper presented an offline test method to solve this problem. Firstly, a kinetics model of the polymer composites under Microwave Curing was established based on differential scanning calorimetry to describe the whole Curing process. Then several specially designed samples of different feature cure degrees were prepared and used to reflect the dielectric properties of the composite during Microwave Curing. It was demonstrated to be a feasible plan for both test accuracy and efficiency through extensive experimental research. Based on this method, the anisotropic complex permittivity of a carbon fiber/epoxy composite during Microwave Curing was accurately determined. Statistical results indicated that both the dielectric constant and dielectric loss of the composite increased at the initial Curing stage, peaked at the maximum reaction rate point and decreased finally during the Microwave Curing process. Corresponding mechanism has also been systematically investigated in this work.
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CSCWD - Temperature Distribution Optimization during Composites Microwave Curing Using Time - varying Electromagnetic Field
2018 IEEE 22nd International Conference on Computer Supported Cooperative Work in Design ((CSCWD)), 2018Co-Authors: Libing Cheng, Jing ZhouAbstract:Compared with autoclave Curing process, Microwave can cure the composite with high quality, short time and low cost. However, the temperature distribution of the composite is uneven during Microwave heating, which seriously hampers the industrial application of the Microwave Curing technology. In order to solve the problem, this paper presents a method for improving the temperature distribution of the composite during Microwave Curing using time-varying electromagnetic field. The method can achieve a real-time and automatic power adjustment of multiple Microwave sources via LabVIEW program, and generate a large number of electromagnetic field modes in the high-performance Microwave cavity. The temperature distribution is improved by the compensation effect between the heating patterns corresponding to different kinds of resonant states during Microwave Curing. Experimental results show that the time-varying electromagnetic field in the Microwave cavity can effectively improve the temperature distribution of the composite. Compared with rotating tray adjustment, the method proposed can greatly improve the temperature distribution.
James Gao - One of the best experts on this subject based on the ideXlab platform.
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a multi pattern compensation method to ensure even temperature in composite materials during Microwave Curing process
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Jing Zhou, Libing Cheng, Shuting Liu, Shaochun Sui, James GaoAbstract:Abstract Microwave Curing technologies have many advantages in manufacturing fiber reinforced polymer composite materials used in aerospace products, compared with traditional autoclave Curing technologies. However, the uneven electromagnetic field of Microwave in the cavity of the Curing chamber results in uneven temperature on the surface of composite laminates during Curing, which has been a major obstacle in industrial applications worldwide. Existing methods attempted to solve the problem by the random superposition of uneven electromagnetic fields, but the results were still not satisfactory to meet the high quality requirements of aerospace parts. This paper reveals the one-to-one correspondence between heating patterns of composite parts and Microwave Curing system settings, and reports a new concept to solve this problem by continuously monitoring and compensating the uneven temperature distribution in real-time. Experimental results from both fiber optical fluorescence sensors and infrared thermal imagers showed significant improvement in temperature uniformity compared with existing methods.
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A new process control method for Microwave Curing of carbon fibre reinforced composites in aerospace applications
Composites Part B: Engineering, 2017Co-Authors: John Jelonnek, Guido Link, James GaoAbstract:Abstract For the fabrication of carbon fibre reinforced composites used in aerospace industry, Microwave Curing technologies are more effective than traditional thermal Curing technologies. However, the manufacturer's recommended cure cycles used in traditional autoclave Curing are directly adopted into current Microwave Curing technologies without thorough validation. Here, a new cyclic heating and cooling methodology for Microwave Curing process control of composite is proposed by analyzing mechanisms of heat conduction, stress generation and Curing kinetics. The results of the experiment carried out show significant reductions in residual strain, warpage, total Curing time and energy consumption, compared with both traditional thermal Curing and current Microwave Curing technologies. The mechanical properties of samples cured by the new process are compared with the autoclave cured ones.
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analysis and optimization of temperature distribution in carbon fiber reinforced composite materials during Microwave Curing process
Journal of Materials Processing Technology, 2014Co-Authors: Xiang Hang, James GaoAbstract:Abstract Vacuum assisted Microwave Curing technologies and modified optical sensing systems have been employed to investigate the influence of ply orientation and thickness on through-thickness temperature distribution of carbon fiber reinforced composite laminates. Two different types of epoxy systems have been studied. The results demonstrated that the ply orientation did not affect the temperature distribution of composite materials. However, the thickness was an important influencing factor. Nearly 10 °C temperature difference was found in 22.5 mm thick laminates. Through analyzing the physical mechanisms during Microwave Curing, the temperature difference decreased when the heat-loss in surface laminates was reduced and the absorption of Microwave energy in the center laminates was improved. The maximum temperature difference of the samples formed using the modified Microwave Curing technologies in this research could be reduced by 79% to 2.1 °C. Compared with the 5.29 °C temperature difference of laminates using thermal heating process, the maximum temperature difference in laminates using modified Microwave Curing technologies was reduced by 60%, and the Curing time was cut down by 25%.
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tooling design and Microwave Curing technologies for the manufacturing of fiber reinforced polymer composites in aerospace applications
The International Journal of Advanced Manufacturing Technology, 2014Co-Authors: James GaoAbstract:The increasing demand for high-performance and quality polymer composite materials has led to international research effort on pursuing advanced tooling design and new processing technologies to satisfy the highly specialized requirements of composite components used in the aerospace industry. This paper reports the problems in the fabrication of advanced composite materials identified through literature survey, and an investigation carried out by the authors about the composite manufacturing status in China’s aerospace industry. Current tooling design technologies use tooling materials which cannot match the thermal expansion coefficient of composite parts, and hardly consider the calibration of tooling surface. Current autoclave Curing technologies cannot ensure high accuracy of large composite materials because of the wide range of temperature gradients and long Curing cycles. It has been identified that Microwave Curing has the potential to solve those problems. The proposed technologies for the manufacturing of fiber-reinforced polymer composite materials include the design of tooling using anisotropy composite materials with characteristics for compensating part deformation during forming process, and vacuum-pressure Microwave Curing technology. Those technologies are mainly for ensuring the high accuracy of anisotropic composite parts in aerospace applications with large size (both in length and thickness) and complex shapes. Experiments have been carried out in this on-going research project and the results have been verified with engineering applications in one of the project collaborating companies.
Xiaozhong Hao - One of the best experts on this subject based on the ideXlab platform.
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enhanced interlaminar fracture toughness of carbon fiber bismaleimide composites via Microwave Curing
Journal of Composite Materials, 2017Co-Authors: Jing Zhou, Xiaozhong HaoAbstract:Carbon fiber-reinforced polymer composites have been widely used in the aerospace industry. However, they are extremely sensitive to crack initiation, propagation and interlaminar delamination which severely reduce their service life. This paper demonstrated that the Mode-I interlaminar fracture toughness could be significantly improved in carbon fiber/bismaleimide composites using a Microwave Curing process. An increase of about 53.5% in critical load and an increase of approximately 133.5% and 61.2% in fracture toughness and fracture resistance have been achieved, respectively. The Microwave manufacturing cycle for composites was cut to 44% of the thermal processing cycle. Dynamic mechanical thermal analysis was performed to investigate the enhanced interfacial strength in Microwave-cured composites. The improvement in fracture toughness was attributed to a better interfacial adhesion between resin and fiber, which was investigated by the observation of fracture surfaces with optical microscopes.
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effects of temperature profiles of Microwave Curing processes on mechanical properties of carbon fibre reinforced composites
Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2017Co-Authors: Xiang Hang, Xiaozhong Hao, Youyi WenAbstract:The Microwave Curing of composites is a promising technology to manufacture the composite components faster than conventional thermal Curing. But how the shortened temperature profiles, which determine the duration of Microwave Curing processes, will affect the outcome of cured parts is still not clear. In this study, the effects of Microwave Curing processes governed by different temperature profiles on the mechanical properties of carbon fibre–reinforced composite material have been experimentally investigated. The results showed that Microwave-cured composites have similar Curing kinetics as the conventional thermally cured ones, and they were better in interlaminar shear and flexural strengths than thermally cured ones, while slightly lower in tensile and compressive strengths. The increase in heating rates in the temperature profiles enhanced the compressive and flexural strengths of the composites within a certain range, but moderately compromised the tensile and interlaminar strengths; the reductio...
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Tool-part interaction in composites Microwave Curing: Experimental investigation and analysis:
Journal of Composite Materials, 2017Co-Authors: Wu Xiaochun, Xiaozhong HaoAbstract:The tool-part interaction of composite materials during Microwave Curing is different from conventional thermal heating, mainly because of the rapid and selective heating mechanism of Microwave. Novel measurement and analysis approaches of Microwave Curing induced tool-part shear stresses were established and verified in this article. The optical fiber sensors were placed in the groove of tool surface to measure the strain values, which were converted to the tool-part shear stresses. A comprehensive friction coefficient was calculated by the shear stresses, and it was presented by considering the thermal expansion mismatch of composite/tool and the chemical shrinkage of resin. In order to validate the accuracy of model, the shape dimension of Microwave cured scaling down leading edge of the composite part was measured to compare with simulation model. The results exhibited that the presented model can significantly decrease the prediction error of composite deformation compared with other methods during m...
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Enhanced interlaminar fracture toughness of carbon fiber/bismaleimide composites via Microwave Curing
Journal of Composite Materials, 2017Co-Authors: Jing Zhou, Nanya Li, Yingguang Li, Xiaozhong HaoAbstract:Carbon fiber-reinforced polymer composites have been widely used in the aerospace industry. However, they are extremely sensitive to crack initiation, propagation and interlaminar delamination which severely reduce their service life. This paper demonstrated that the Mode-I interlaminar fracture toughness could be significantly improved in carbon fiber/bismaleimide composites using a Microwave Curing process. An increase of about 53.5% in critical load and an increase of approximately 133.5% and 61.2% in fracture toughness and fracture resistance have been achieved, respect- ively. The Microwave manufacturing cycle for composites was cut to 44% of the thermal processing cycle. Dynamic mechanical thermal analysis was performed to investigate the enhanced interfacial strength in Microwave-cured com- posites. The improvement in fracture toughness was attributed to a better interfacial adhesion between resin and fiber, which was investigated by the observation of fracture surfaces with optical microscopes.
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drilling delamination and thermal damage of carbon nanotube carbon fiber reinforced epoxy composites processed by Microwave Curing
International Journal of Machine Tools & Manufacture, 2015Co-Authors: Jing Zhou, Xiaozhong HaoAbstract:Abstract The drilling-induced delamination and thermal damage of carbon fiber reinforced epoxy composite materials are serious problems especially for high value components of the aviation industry. To suppress the delamination and drilling ablation, an innovative approach was employed in this study. The multiwalled carbon nanotubes (MWCNTs) were introduced to the matrix resin to improve the interlaminar strength and thermal conductivity. The as-prepared composite was processed by Microwave Curing to enhance the interface strength between carbon fiber and the carbon nanotubes modified matrix. During the drilling processes, optical fiber Bragg grating sensors were utilized to precisely measure the drilling temperature. Experimental results indicated that the interlaminar fracture toughness was increased by more than 66% compared to that of the traditional thermal cured samples without MWCNTs. And the delamination factor was decreased by 16% according to the computerized tomography scanning results. The maximum drilling temperature of the MWCNTs reinforced composite was below the glass transition temperature of the matrix resin and declined by 23 °C compared to traditional composites. With this novel method of carbon nanotube modification and Microwave Curing, we provide the capability of reducing the drilling delamination and thermal damage of carbon fiber composites simultaneously, and explored the possibility of manufacturing and machining integration.
Freddy Yin Chiang Boey - One of the best experts on this subject based on the ideXlab platform.
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Microwave Curing of an epoxy–amine system: effect of Curing agent on the glass-transition temperature
Polymer Testing, 2001Co-Authors: Freddy Yin Chiang BoeyAbstract:Abstract Increasing demands on industrial applications in the microelectronics industries have led to the need for accelerated Curing of high-performance structural adhesive systems like epoxies. The Curing of such thermoset systems has become the bottleneck of the whole production process. Recently, Microwave Curing has been shown to be a viable alternative as an accelerated Curing system. This paper investigates the effect of using different Curing agents in Microwave Curing of an epoxy system on the final cured glass-transition temperature ( T g ). Microwave radiation and thermal heating were performed on a diglycidyl ether of bisphenol-A (DGEBA). The three Curing agents used were 4,4′-diaminodiphenylsulfone (DDS), 4,4′-diaminodiphenylmethane (DDM) and meta -phenylene diamine (mPDA). The use of different Curing agents resulted in different glass-transition properties for the Microwave Curing of the three epoxy–amine systems. Whilst all three systems exibited a shorter Curing time to reach the maximum percentage cure and T g , the actual maximum values achieved for both percentage cure and T g were significantly lower than for thermal Curing. Evidently, during Microwave Curing, whilst a faster rate was obtained, the existence of the highly electron-attracting SO 2 functional group appeared to induce a delay in the reactivity of the amine functions sufficient to entrap them in the crosslink network, effectively inhibiting further Curing. In contrast, both the DDM and the mPDA systems, having different electron-donating fuctional groups, were able to achieve maximum percentage cure and T g values equal to those for thermal Curing, at significantly shorter Curing times, due principally to a greater reduction in the effective cure time than in the lag time. Microwave Curing seemed to be more effective in reducing the overall cure time for the mPDA system.
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Microwave Curing of an epoxy amine system effect of Curing agent on the glass transition temperature
Polymer Testing, 2001Co-Authors: Freddy Yin Chiang BoeyAbstract:Abstract Increasing demands on industrial applications in the microelectronics industries have led to the need for accelerated Curing of high-performance structural adhesive systems like epoxies. The Curing of such thermoset systems has become the bottleneck of the whole production process. Recently, Microwave Curing has been shown to be a viable alternative as an accelerated Curing system. This paper investigates the effect of using different Curing agents in Microwave Curing of an epoxy system on the final cured glass-transition temperature ( T g ). Microwave radiation and thermal heating were performed on a diglycidyl ether of bisphenol-A (DGEBA). The three Curing agents used were 4,4′-diaminodiphenylsulfone (DDS), 4,4′-diaminodiphenylmethane (DDM) and meta -phenylene diamine (mPDA). The use of different Curing agents resulted in different glass-transition properties for the Microwave Curing of the three epoxy–amine systems. Whilst all three systems exibited a shorter Curing time to reach the maximum percentage cure and T g , the actual maximum values achieved for both percentage cure and T g were significantly lower than for thermal Curing. Evidently, during Microwave Curing, whilst a faster rate was obtained, the existence of the highly electron-attracting SO 2 functional group appeared to induce a delay in the reactivity of the amine functions sufficient to entrap them in the crosslink network, effectively inhibiting further Curing. In contrast, both the DDM and the mPDA systems, having different electron-donating fuctional groups, were able to achieve maximum percentage cure and T g values equal to those for thermal Curing, at significantly shorter Curing times, due principally to a greater reduction in the effective cure time than in the lag time. Microwave Curing seemed to be more effective in reducing the overall cure time for the mPDA system.
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Microwave Curing of epoxy amine system effect of Curing agent on the rate enhancement
Polymer Testing, 1999Co-Authors: Freddy Yin Chiang Boey, L H L ChiaAbstract:Increasing application in the aerospace and microelectronics industries have led to the demand for accelerated Curing of high performance structural adhesive systems like epoxy. Particularly for the microelectronics industry, the Curing of such thermoset systems have become the bottleneck of the whole production process. Alternative accelerated Curing systems like Ultra Violet light, Gamma rays and Electron Beams have been limited by their respective disadvantages. More recently Microwave Curing has been shown to be a viable alternative as an accelerated Curing system. This paper investigates the effect of different Curing agents in Microwave Curing for an epoxy system. Microwave radiation and thermal heating were performed on the epoxy Araldite GY6010, which is a resin of di-glycidyl ether of bisphenol-A (DGEBA). The three types of Curing agents used were 4,4'-Diamino-di-phenyl-sulfone (DDS), 4,4'Diamino-diphenyl-methane (DDM) and meta-Phenylene-diamine (mPDA). Thermal cure temperatures were determined between the onset and midway to the peak temperature of the freshly prepared epoxy/amine systems of the DSC exotherm curves. Microwave Curing of the epoxy/amine systems was carried out with a 1.1 kW variable power generator with a 2.45 GHz magnetron coupled to a multimodal cavity through a wave guide. Curing was done between 200 W and 600 W Microwave power. The Curing was strongly dependent on the Curing agent used. A low degree of cure at a relatively low Microwave power was observed in DGEBA/DDS system, and has been attributed to the sluggish reaction of DDS with epoxy, resulting in the entrapment of the functional group in the cross-link network. DDM and mPDA were more reactive than DDS and gave relatively faster full Curing times than DDS.
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Microwave Curing of epoxy-amine system — effect of Curing agent on the rate enhancement
Polymer Testing, 1999Co-Authors: Freddy Yin Chiang Boey, L H L ChiaAbstract:Increasing application in the aerospace and microelectronics industries have led to the demand for accelerated Curing of high performance structural adhesive systems like epoxy. Particularly for the microelectronics industry, the Curing of such thermoset systems have become the bottleneck of the whole production process. Alternative accelerated Curing systems like Ultra Violet light, Gamma rays and Electron Beams have been limited by their respective disadvantages. More recently Microwave Curing has been shown to be a viable alternative as an accelerated Curing system. This paper investigates the effect of different Curing agents in Microwave Curing for an epoxy system. Microwave radiation and thermal heating were performed on the epoxy Araldite GY6010, which is a resin of di-glycidyl ether of bisphenol-A (DGEBA). The three types of Curing agents used were 4,4'-Diamino-di-phenyl-sulfone (DDS), 4,4'Diamino-diphenyl-methane (DDM) and meta-Phenylene-diamine (mPDA). Thermal cure temperatures were determined between the onset and midway to the peak temperature of the freshly prepared epoxy/amine systems of the DSC exotherm curves. Microwave Curing of the epoxy/amine systems was carried out with a 1.1 kW variable power generator with a 2.45 GHz magnetron coupled to a multimodal cavity through a wave guide. Curing was done between 200 W and 600 W Microwave power. The Curing was strongly dependent on the Curing agent used. A low degree of cure at a relatively low Microwave power was observed in DGEBA/DDS system, and has been attributed to the sluggish reaction of DDS with epoxy, resulting in the entrapment of the functional group in the cross-link network. DDM and mPDA were more reactive than DDS and gave relatively faster full Curing times than DDS.
Yaning Kong - One of the best experts on this subject based on the ideXlab platform.
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Effect of Microwave Curing on the hydration properties of cement-based material containing glass powder
Construction and Building Materials, 2018Co-Authors: Yaning Kong, Peiming Wang, Shuhua Liu, Zhiyang Gao, Meijuan RaoAbstract:Abstract The effects of Microwave Curing on the hydration of cement-based materials containing coarse glass powder were studied by performing compressive strength, XRD, TG-DSC, SEM-EDS and MIP analysis. The results showed that Microwave Curing could effectively improve the early-age compressive strength of mortar prepared with composite binder containing coarse glass powder. Microwave Curing accelerated the hydration of cement particles by dissolution of Na + from glass powder and thermal effect. Although Microwave Curing increased the porosity slightly at the early age, the porosity of pores larger than 50 nm did not increase, which has little effect on the decrease of compressive strength. Additionally, Microwave Curing increased the connection of aggregate, CH, hydrated glass powder and cement particles by reticular C–S–H, leading to a denser microstructure of the interfacial transition zone of mortar. The adsorption of Na + by alkali-silica reaction gel under Microwave Curing reduced the adverse effect of Na + on the late hydration of cement and the compressive strength. But the total porosity of mortar under Microwave Curing was increased by the increase of pores in the range of 50–100 nm, which goes against the improvement of compressive strength.
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sem analysis of the interfacial transition zone between cement glass powder paste and aggregate of mortar under Microwave Curing
Materials, 2016Co-Authors: Yaning Kong, Peiming Wang, Shuhua Liu, Guorong Zhao, Yu PengAbstract:In order to investigate the effects of Microwave Curing on the microstructure of the interfacial transition zone of mortar prepared with a composite binder containing glass powder and to explain the mechanism of Microwave Curing on the improvement of compressive strength, in this study, the compressive strength of mortar under Microwave Curing was compared against mortar cured using (a) normal Curing at 20 ± 1 °C with relative humidity (RH) > 90%; (b) steam Curing at 40 °C for 10 h; and (c) steam Curing at 80 °C for 4 h. The microstructure of the interfacial transition zone of mortar under the four Curing regimes was analyzed by Scanning electron microscopy (SEM). The results showed that the improvement of the compressive strength of mortar under Microwave Curing can be attributed to the amelioration of the microstructure of the interfacial transition zone. The hydration degree of cement is accelerated by the thermal effect of Microwave Curing and Na+ partially dissolved from the fine glass powder to form more reticular calcium silicate hydrate, which connects the aggregate, calcium hydroxide, and non-hydrated cement and glass powder into a denser integral structure. In addition, a more stable triangular structure of calcium hydroxide contributes to the improvement of compressive strength.
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Hydration and microstructure of cement-based materials under Microwave Curing
Construction and Building Materials, 2016Co-Authors: Yaning Kong, Peiming Wang, Shuhua Liu, Zhiyang GaoAbstract:Abstract By reducing the Curing time, Microwave Curing can enhance the productivity, save the capital and decrease the plant areas for precast concrete when compared with the steam Curing. Based on the results of 6-h and 24-h compressive strength tests the optimum Curing regime was selected. The sample Microwave cured using the selected Curing regime was then compared against samples cured using (a) normal Curing (b) steam Curing at 40 °C for 10 h and (c) steam Curing at 80 °C for 4 h by performing the compressive strength, XRD, TG-DSC, SEM-EDS and MIP. The results indicate that, compared with the steam Curing at 80 °C, Microwave Curing improves the compressive strength of mortar before the age of 28 days, increases the porosity of mortar slightly, while reduces the pores in the range of >100 nm greatly, forms short-rod AFt and smaller particle size of calcium hydroxide, and increases the adsorption of K, S and Mg by C-S-H gel.
