scholarly journals Study of the mechanical-electrical-magnetic properties and the microstructure of three-layered cement-based absorbing boards

2020 ◽  
Vol 59 (1) ◽  
pp. 160-169
Author(s):  
Yafei Sun ◽  
Yueyue Peng ◽  
Tianshu Zhou ◽  
Hongwei Liu ◽  
Peiwei Gao
Keyword(s):  
Mechanical Properties ◽  
Magnetic Properties ◽  
Carbon Fiber ◽  
Carbon Black ◽  
Mechanical Strength ◽  
Cement Hydration ◽  
Hydration Products ◽  
Frequency Range ◽  
Cement Slurry ◽  
Nano Graphene

AbstractIn this paper, a three-layered cement-based wave-absorbing board is designed and prepared by mixing wave-absorbing fillers such as nano-Si3N4, multi-layer nano graphene platelets (NGPs), nano-Ni, carbon fiber (CF) and carbon black (CB) into cement slurry. The effect of the amount of wave-absorbing fillers on the mechanical properties, resistivity and wave-absorbing reflectivity of cement slurry is studies. The microstructure of NGPs, nano-Si3N4 and the wave-absorbing board are characterized by TEM and SEM. Research shows that low content of NGPs and other wave-absorbing fillers can significantly reduce the resistivity of cement slurry and improve its mechanical strength, and dense massive crystals are precipitated in the cement hydration products. The reflectivity test reveals that in the frequency range of 2~18 GHz, the minimum reflectivity of the three-layered cement-based wave absorbing board reaches −18.8 dB, and the maximum bandwidth less than −10 dB reaches 15.3 GHz. This study can serve as reference for the preparation of new three-layered cement-based wave absorbing boards.

scholarly journals Comparative study on mechanisms for improving mechanical properties and microstructure of cement paste modified by different types of nanomaterials

2021 ◽  
Vol 10 (1) ◽  
pp. 370-384
Author(s):  
Tao Meng ◽  
Kanjun Ying ◽  
Xiufen Yang ◽  
Yongpeng Hong
Keyword(s):  
Mechanical Properties ◽  
Cement Paste ◽  
Cement Hydration ◽  
Inhibitory Effect ◽  
Test Methods ◽  
Cement Clinker ◽  
Hydration Products ◽  
Nucleation Effect ◽  
Nano Graphene ◽  
Nano Titanium Dioxide

Abstract Filling and nucleation are the mechanisms of modifying cement paste with nanomaterials, as investigated by previous studies, and are difficult to reflect the different effects of nanomaterials, especially on the changes of cement clinker and hydration products in the cement hydration process. In this study, the mechanisms of modifying cement paste with nano-calcium carbonate (NC), nano-graphene oxide (NG), nano-silica (NS), and nano-titanium dioxide (NT) were investigated by determining the mechanical properties of cement paste treated with nanomaterials and analysing the changes in the cement clinker (tricalcium silicate and dicalcium silicate), hydration products (portlandite and ettringite), and microstructure through many micro-test methods. The results indicate that the incorporation of nanomaterials could improve the early strength of cement paste specimens due to more consumption of cement clinker. Meanwhile, different nanomaterials promote the formation of different hydration products at early ages. C–A–S–H gel, flower-like ettringite, and C–S–H seeds are widely distributed in the cement paste with the incorporation of NC, NG, and NS, respectively. NT exhibits insignificant nucleation effect and has inhibitory effect on portlandite precipitation. This study provides key insights into the mechanism of nanomaterials from the perspective of cement hydration, which may promote the further research and application of nanomaterials in the cement and concrete industries.

scholarly journals Electromagnetic Interference Shielding and Physical-Mechanical Characteristics of Rubber Composites Filled with Manganese-Zinc Ferrite and Carbon Black

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 616
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Klaudia Hložeková ◽  
Rastislav Dosoudil ◽  
Marek Gořalík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Zinc Ferrite ◽  
Mechanical Characteristics ◽  
Hybrid Composites ◽  
Rubber Matrix ◽  
Butadiene Rubber ◽  
Frequency Range ◽  
Manganese Zinc ◽  
Manganese Zinc Ferrite

In the present work, composite materials were prepared by incorporation of manganese-zinc ferrite, carbon black and combination of ferrite and carbon black into acrylonitrile-butadiene rubber (NBR). For cross-linking of composites, standard sulfur-based curing system was applied. The main goal was to investigate the influence of the fillers on the physical-mechanical properties of composites. Then, the electromagnetic absorption shielding ability was investigated in the frequency range 1 MHz–3 GHz. The results revealed that composites filled with ferrite provide sufficient absorption shielding performance in the tested frequency range. On the other hand, ferrite behaves as an inactive filler and deteriorates the physical-mechanical characteristics of composites. Carbon black reinforces the rubber matrix and contributes to the improvement of physical-mechanical properties. However, composites filled with carbon black are not able to absorb electromagnetic radiation in the given frequency range. Finally, the combination of carbon black and ferrite resulted in the modification of both physical-mechanical characteristics and absorption shielding ability of hybrid composites.

Evaluating the Effect of Carbon Black—A Short Carbon Fiber Hybrid Filler on the Electro-Activated Shape Memory Cyanate Ester/Epoxy Composites

2020 ◽  
Vol 12 (5) ◽  
pp. 652-658 ◽  
Author(s):  
Yong-Kun Wang ◽  
Liang-Chao Wang ◽  
Yu-Ting Zhang ◽  
Jun-Jie Ye ◽  
Yang Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Carbon Black ◽  
Shape Memory ◽  
Storage Modulus ◽  
Synergistic Effects ◽  
Cyanate Ester ◽  
Short Carbon Fiber ◽  
And Storage ◽  
Short Carbon

An electro-activated type shape memory cyanate ester-epoxy (CE-EP) composites containing short carbon fiber (SCF) and carbon black (CB) were fabricated, where SCF linked among CB particles to make the superior conductivity network in compositions. In the compositions, the content of CB was fixed at 5 wt%, while the amount of SCF was ranged from 0 to 0.9 wt%. The synergistic effects of SCF and CB on the mechanical properties test, electrical properties, SEM, DMA and the electro-activated type shape memory experiment was reviewed. The outcomes showed that when the parts of SCF is less than 0.9%, the mechanical properties and storage modulus of required compositions expand with the content of the SCF growth. But, when the SCF content reaches 0.9 wt%, the flexural strength and storage modulus of the compositions decrease slightly. With the growth of SCF content, the glass transformation temperature increases from 89 °C to 103 °C and the resistivity of the composites decreases gradually. The resistivity of the composites is only 7.37 Ω/cm with 0.9 wt% of SCF. Further, the thermal response speed and shape convalescence rate of the compositions increase greatly with the growth of SCF content.

scholarly journals Mechanical Properties of Aramid/Carbon Hybrid Fiber-Reinforced Concrete

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5881
Author(s):  
Yeou-Fong Li ◽  
Hsin-Fu Wang ◽  
Jin-Yuan Syu ◽  
Gobinathan Kadagathur Ramanathan ◽  
Ying-Kuan Tsai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Mechanical Strength ◽  
Carbon Fibers ◽  
Coupling Agent ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
The Impact

In this study, aramid fiber (Kevlar® 29 fiber) and carbon fiber were added into concrete in a hybrid manner to enhance the static and impact mechanical properties. The coupling agent presence on the surface of carbon fibers was spotted in Scanning Electron Microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) graphs. The carbon fiber with a coupling agent affected the mechanical strength of the reinforced concrete. At 1% fiber/cement weight percentage, the hybrid fiber-reinforced concrete (HFRC) prepared using Kevlar fiber and carbon fiber of 12 and 24 mm in length under different mix proportions was investigated to determine the maximum mechanical strengths. From the test results, the mechanical strength of the HFRC attained better performance than that of the concrete with only Kevlar or carbon fibers. Foremost, the mix proportion of Kevlar/carbon fiber (50–50%) significantly improved the compressive, flexural, and splitting tensile strengths. Under different impact energies, the impact resistance of the HFRC specimen was much higher than that of the benchmark specimen, and the damage of the HFRC specimens was examined with an optical microscope to identify slippage or rupture failure of the fiber in concrete.

Electrical and Mechanical Properties of Conducive Carbon Black/Polyolefin Composites Mixed With Carbon Fiber

2006 ◽  
Vol 3 (10) ◽  
pp. 100431 ◽  
Author(s):  
SW Dean ◽  
A Farshidfar ◽  
V Haddadi-Asl ◽  
H Nazokdast
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Carbon Black

scholarly journals Hybrid Effect of Wollastonite Fiber and Carbon Fiber on the Mechanical Properties of Oil Well Cement Pastes

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianglin Zhu ◽  
Jiangxiong Wei ◽  
Qijun Yu ◽  
Mingbiao Xu ◽  
Yuwei Luo
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Carbon Fiber ◽  
Impact Strength ◽  
Flexural Strength ◽  
Cement Stone ◽  
Oil Well ◽  
Cement Slurry ◽  
Oil Well Cement ◽  
Well Cement

Oil well cement is a type of natural brittle material that cannot be used directly in cementing operations. Fiber is a type of material that can effectively improve the strength and toughness of cement stone, and hybrid fiber materials can more effectively improve the performance of a cement sample. To overcome the natural defects of oil well cement, the new mineral fiber, i.e., wollastonite fiber, and common carbon fiber were used in oil well cement, and the micromorphology, mechanical properties, and stress-strain behavior of the cement were evaluated. The experimental results show that carbon fiber and wollastonite fiber are randomly distributed in the cement paste. The mechanical properties of the cement paste are improved by bridging and pulling out. The compressive strength, flexural strength, and impact strength of cement stone containing only carbon fiber or wollastonite fiber are higher than those of the pure cement, but too many fibers are not conducive to the development of mechanical properties. A mixture of 0.3% carbon fiber with 6% wollastonite fiber in oil well cement slurry results in a greater increase in compressive strength, flexural strength, and impact strength. In addition, compared with blank cement stone, the strain of the mixed cement stone increases substantially, and the elastic modulus decreases by 37.8%. The experimental results supply technical support for the design of a high-performance cement slurry system.

scholarly journals Effect of Delaminated MXene (Ti3C2) on the Performance of Cement Paste

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jianping Zhu ◽  
Genshen Li ◽  
Chunhua Feng ◽  
Libo Wang ◽  
Wenyan Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Paste ◽  
Cement Hydration ◽  
Hydration Heat ◽  
Hydration Process ◽  
Cement Matrix ◽  
Cement Composites ◽  
Hydrated Cement ◽  
Hydration Products

Delaminated MXene was incorporated into cement to improve the properties of cement composites, and its effects on the hydration process, microstructures, and mechanical properties were investigated, respectively. The investigation results showed that delaminated MXene was well-dispersed in the cement matrix and significantly reinforced the compressive strength of cement, especially when the addition is 0.01 wt%. Meanwhile, the total hydration heat of cement hydration and the quantity of hydration products were increased with the addition of delaminated MXene. In addition, the formation of HD C-S-H gel was promoted, and the microstructure of hydrated cement became more compact.

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