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The Effect of Admixtures on Electrical Conductance of CFRC

MAO Qizhao,YANG Yuanxia,LI Zhuoqiu,SHEN Darong,

无机材料学报 , 1997,
Abstract: The effects of various specially made admixtures on properties of CFRC were studied. Theresults reveal that by using MKC, together with proper manufacturing technologyt the electricalconductivity, dispersion of fibre in cement and compression sensibility of CFRC are much improved,compared to the corresponding plAlN CFRC values. In addition, CKH can improve the electricalconductance of CFRC evidently.
Self-adjustment of Carrying Capacity of Concrete Embedded with CFRC

材料科学技术学报 , 2006,
Abstract: By heating up the embedded carbon fiber reinforced cement based material (CFRC), the carrying capacity and deformation of concrete member could be adjusted. The relationship between temperature difference and expansion strain of CFRC was demonstrated, and the temperature-deformation-load effect of concrete embedded with CFRC was studied. Heating the CFRC up to different temperatures resulted in different degree of inner pre-stress in concrete. Thus, the load capacity of concrete could be regulated owing to counteracting the pre-stress.
cfrc电热特性的研究  [PDF]
武汉理工大学学报 , 1997,
Abstract: ?通过对特制碳纤维水泥基复合材料(cfrc)试样的系统研究,发现了其焦耳效应,并对其稳定温升与表面负荷的关系、升温和降温时温度随时问变化的关系以及电阻温度特性等电热特性进行了较系统的研究。这一研究对扩充碳纤维水泥基复合材料的功能和应用具有重要的意义。
利用cfrc的导电性评估混凝土结构修补质量  [PDF]
武汉理工大学学报 , 2008,
Abstract: ?研究了利用碳纤维增强混凝土(cfrc)的导电性对混凝土结构修补质量进行在线评估的可行性,根据敷在服役混凝土结构上cfrc导电性能的变化,判断新旧混凝土界面的粘结质量,并通过cfrc导热性能的差异进行了验证。文中的研究在对修补混凝土结构的同时,为混凝土结构修补质量的监测和在线评估提供了新的方法。?
Experimental study of mechanical properties of CFRC composite beams

- , 2017, DOI: 10.7511/dllgxb201706008
Abstract: 碳纤维混凝土(CFRC)复合梁是在普通混凝土梁中掺入短切碳纤维,以此改善混凝土的性能.碳纤维弹性模量高,将其掺入混凝土中能改善混凝土的韧性并起到增强阻裂的效果.通过四点加载试验,研究普通混凝土梁与不同纤维层厚度、不同纤维长度的复合梁的弯曲破坏机理、荷载挠度行为、裂缝形态等.试验结果表明,在混凝土梁的受拉区掺入短切碳纤维可以有效改善其变形能力;碳纤维对混凝土裂缝扩展的抑制、裂缝形态的改善效果较好;纤维层厚75 mm、纤维长度10 mm的复合梁性能最优.最后提出了CFRC弯曲构件极限承载力的计算公式.
Carbon fiber reinforced concrete (CFRC) composite beam is a kind of concrete beam which is reinforced with short carbon fiber to improve the performance of concrete. CFRC toughness and crack resistance ability can be enhanced by high elastic modulus carbon fiber. The failure mechanism, load deflection behaviors, crack pattern of concrete beams and composite beams with different fiber layer thickness and fiber length are studied by four-point bending test. The results show that the deformation ability of concrete beams can be effectively improved by the short carbon fiber in the tension zone. The carbon fiber shows positive effect on restraining crack propagation and changing crack distribution in concrete matrix. Composite beam with 75 mm fiber layer thickness and 10 mm fiber length shows the best performance. Finally, the design formula for ultimate bearing capacity of CFRC bending member is proposed.
Study on the Electromagnetic Interference of CFRC Composites by Reflectivity

Kezhi LI,Chuang WANG,Hejun LI,Gengsheng JIAO,Jian WEI,

材料科学技术学报 , 2008,
Abstract: The influence of dispersion of carbon fibers in carbon-fiber-reinforced cement-based composites (CFRC) on the mechanical properties of the composites was discussed. The microstructure of the fracture surface of the CFRC samples was observed with a scanning electron microscope (SEM). The electromagnetic interference (EMI) was evaluated indirectly by reflectivity in the Naval Research Laboratory (NRL) testing system. The reflectivity of the electromagnetic radiation by the composites was measured in the frequency range of 8.0-18.2 GHz for different carbon fiber contents of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% (in wt pct), respectively. The results showed that the reflectivity decreased with the growing fiber content till the percentage of 0.6%.The minimum reflectivity was -23 dB, far less than -10 dB, and the composites were strong wave absorbers.After this percentage, the curve increased abruptly as the fiber content proceeded. The electromagnetic waves were gradually reflected. When the fiber content reached 1.0% finally, the maximum reflectivity -7.5 dB appeared and there was stronger reflection. The shielding mechanism includes mainly reflection, absorption,and multiple reflections.
CVD Treatment of Carbon Fibers and Evaluation of Their Dispersion in CFRC  [PDF]
Chuang Wang, Bingliang Li, Lei Peng, Wenmin He, Liping Zhao, Kezhi Li
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.88046
Abstract: Carbon-fiber-reinforced cement-based (CFRC) composites is a promising functional material which can be used both in the military and civil fields against electromagnetic interference. However, it is essential to make carbon fibers dispersed uniformly during the preparation of CFRC. In this work, short carbon fibers were treated through Chemical Vapor Deposition (CVD) process at high temperature between 900°C and 1200°C under the protection of diluted nitrogen gas N2 to modify the surface of carbon fibers to further strengthen the bonding between carbon fibers and cement matrix. Natural gas (98% CH4) was used as a precursor. It was decomposed to produce an uneven layer of pyrocarbon that was deposited on the surface of carbon fibers. CVD-treated carbon fibers were pre-dispersed by using ultrasonic wave. Both hydroxyethyl cellulose (HEC) and silicon fume were used as dispersants and as admixtures. They helped CVD-treated carbon fibers distribute uniformly. The mass fraction of HEC was around 1.78% in the aqueous solution. Four methods, namely, the simulation experiment (SE) method, the scanning electron microscopy (SEM) method, the fresh mixture (FM) method, and the electrical resistivity measurement (ERM) method were, respectively, applied to evaluate fiber dispersion degree. Each method indicated its own advantages and disadvantages and it therefore catered for different conditions. Of the four evaluation methods, the SE method was the most convenient way to determine the pre-dispersion state prior to the preparation of CFRC composites. This method was helpful for predicting the subsequent dispersion state of carbon fibers in the cement matrix because it economized a large quantity of raw materials and time.
cfrc中碳纤维长度分布规律研究  [PDF]
武汉理工大学学报 , 2010,
Abstract: ?以羧甲基纤维素钠(cmc)和硅灰为碳纤维分散剂配制了碳纤维水泥基复合材料(cfrc),通过酸洗、多次过滤等从新拌cfrc料浆中将碳纤维分离出来,以分析碳纤维在cfrc中的长度分布规律。研究表明,碳纤维完全以单根纤维形式分散在水泥基体中,碳纤维在cfrc中以2mm以下的短小纤维数量最多,而且在全部碳纤维中所占的体积分数为45%。这些短小碳纤维的长度低于纤维从水泥中拔出的临界长度,使得cfrc的电阻随载荷而变化。cmc的表面润滑作用、分散剂体系的粘性、硅灰填充效应和特别的湿拌?干湿拌?湿拌工艺有利于碳纤维在水泥基体中的分散。
极化效应对碳纤维增强水泥(cfrc)导电性的影响  [PDF]
材料研究学报 , 1997,
Abstract: ?研究了碳纤维增强水泥(cfrc)导电时的极化效应.实验表明:极化效应对cfrc导电性有不可忽视的影响.调整碳纤维含量,可以控制极化效应,随着养护龄期延长,极化效应明显减小.因此,可以用直流电流法测量cfrc的电阻.
cfrc路面材料的温敏性研究  [PDF]
武汉理工大学学报 , 2001,
Abstract: ?研究了按特定配比和工艺条件制作的碳纤维混凝土(cfrc)路面材料的电阻率与温度之间的关系,表明碳纤维混凝土路面材料具有温敏性和温度自诊断特性,其电阻率随温度的升高而减小,随温度的降低而增大;分析了cfrc路面材料温敏效应的机理;利用这一性质,可将碳纤维混凝土制作成温度传感器,用于特殊混凝土路面结构的温度自诊断检测。
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