scholarly journals The Effect of the Addition of Graphene Nanoplatelets on the Selected Properties of Cementitious Composites

2021 ◽  
Vol 7 ◽  
Author(s):  
Zhi Ge ◽  
Jin Qin ◽  
Renjuan Sun ◽  
Yanhua Guan ◽  
Hongzhi Zhang ◽  
...  
Keyword(s):  
Setting Time ◽  
Graphene Nanoplatelets ◽  
Cementitious Composites ◽  
Treatment Procedure ◽  
Resistance Change ◽  
Change Rate ◽  
Future Developments ◽  
Cyclical Loading ◽  
Binder Material ◽  
Pre Treatment

The aim of the current study is to investigate the properties of graphene nanoplatelets-cementitious composites in a consistent sense. The influence of the addition of 2D graphene nanoplatelets (GNPs) on the workability, setting time, flowability, strengths and piezoresistive properties were studied. The dosage of the GNPs is 0 0.05, 0.1, 0.3, 0.5, 0.7, and 1.0 wt% of the binder material. PVP type surfactant was used to disperse GNPs. The experimental results showed that the addition of GNPs increases the water requirement for normal consistency and decreases the flowability. A small amount of GNPs (0.05 wt%) can facilitate the setting. When the dosage of GNPs is above 0.1 wt%, it leads to the delay of the setting time. In terms of the strengths, the addition of GNPs can considerably promote the flexural strength, while the compressive strength is slightly decreased until 28 days. A pre-treatment procedure consisting of drying specimens at 105°C for 1 day can be regarded as a proper way to enhance the piezoresistive properties of the GNPs-mortar. Piezoresistive properties under two different cyclical loading schemes were measured using the GNPs-mortar with 1 wt% GNPs. It has been shown that the average resistance change rate increases with the amplitude increasing and a reduction is observed for the sustained cyclical loading condition. In the end, the influence of the microcracks on the piezoresistive properties was investigated. This study will contribute to future developments of cementitious composites incorporating GNPs for a variety of applications.

Wet oxidation: a pre-treatment procedure for sludge

2002 ◽  
Vol 22 (6) ◽  
pp. 611-616 ◽  
Author(s):  
Nevim Genç ◽  
Şems Yonsel ◽  
Levent Dağaşan ◽  
A.Nur Onar
Keyword(s):  
Wet Oxidation ◽  
Treatment Procedure ◽  
Pre Treatment

Effect of Kaolin on the Properties of Flue Gas Desulphurization Gypsum-Steel Slag Cementitious Materials

2011 ◽  
Vol 306-307 ◽  
pp. 1553-1556
Author(s):  
Lei Zhang ◽  
Zhi Wang ◽  
Li Ying Fan ◽  
Guo Pu Shi
Keyword(s):  
Flue Gas ◽  
Setting Time ◽  
Steel Slag ◽  
Cementitious Materials ◽  
Cementitious Composites ◽  
Excitation Mechanism ◽  
Final Setting Time ◽  
Micro Morphology ◽  
Scanning Electron ◽  
Flue Gas Desulphurization

The effects of kaolin on the properties of flue gas desulphurization gypsum-based steel slag composites were analyzed in this article and the influence rules of setting time, final setting time on the flexural strength and compressive strength of cementitious composites were also discussed. The micro-morphology of the composite was observed by scanning electron microscope. At the same time, the excitation mechanism of kaolin on gas desulphurization gypsum-based steel slag was put forward. It was demonstrated that kaolin with content of 3% in the composites can better stimulate the activity of steel slag and improve the mechanical properties of cementitious composites.

scholarly journals Resistance behaviour of carbon fibre-reinforced polymers subjected to lightning strikes: Experimental investigation and application

2019 ◽  
Vol 28 ◽  
pp. 2633366X1989227 ◽  
Author(s):  
Jian Chen ◽  
Zhengcai Fu ◽  
Yang Zhao
Keyword(s):  
Carbon Fibre ◽  
Surface Resistance ◽  
Inflection Point ◽  
Front Surface ◽  
Resistance Change ◽  
Reinforced Polymers ◽  
Change Rate ◽  
Lightning Strikes ◽  
Inflection Points ◽  
Carbon Fibre Reinforced Polymers

It is difficult to monitor lightning damage to carbon fibre-reinforced polymers (CFRPs) online. This work experimentally investigates the changes associated with the electrical resistance of CFRPs subjected to lightning strikes. Two kinds of simulated lightning currents with different amplitudes in the range of 10–80 kA were injected into the CFRP samples. By measuring and comparing the changes in the struck-side (front) surface resistance, the surface resistance of the side opposite to the struck-side (back) and the oblique resistance of each sample before and after the lightning strike, it was observed that inflection points exist in the curve of the resistance change rate. The resistance decreases with increasing peak currents before the inflection point and increases when the peak current goes beyond the inflection point. The change rate of the front surface resistance is more sensitive to the lightning damage than are those of the back surface resistance and the oblique resistance. Different simulated lightning currents have approximately the same action integrals at the inflection points of resistance change rate. The characteristics indicate that resistance change detection could be a possible method for the online monitoring of CFRP lightning damage.

Feasibility Study of Using Desulphurization Slag as Binder Material for Concrete Mixing

2012 ◽  
Vol 476-478 ◽  
pp. 1665-1668
Author(s):  
Her Yung Wang ◽  
Tung Tsan Chen
Keyword(s):  
Compressive Strength ◽  
Feasibility Study ◽  
Setting Time ◽  
Binder Material ◽  
And Performance

This study investigated the feasibility of using desulphurization slag as binder material for concrete mixing. Results show that the amount of water required in mortar preparation increased with increasing fineness and proportion of desulphurization slag used. The greater the amount of desulphurization slag, the longer the setting time and the lower the compressive strength are. Moreover, the durability showed a decreasing trend with increase in desulphurization slag used. After 28-day curing, better compressive strength could be achieved with desulphurization slag added. In particular, mortar mixed with almost any proportion of desulphurization slag used, except for 20% and 30%, showed increase in compressive strength exceeding 21 MPa. Durability was also enhanced with desulphurization slag added. In sum, mortar prepared with 5% of cement replaced by desulphurization slag of #200 fineness showed good properties and performance, proving that desulphurization slag can be an ideal binder material for concrete mixing.

scholarly journals Temperature Characteristics of a Pressure Sensor Based on BN/Graphene/BN Heterostructure

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2223 ◽  
Author(s):  
Mengwei Li ◽  
Teng Zhang ◽  
Pengcheng Wang ◽  
Minghao Li ◽  
Junqiang Wang ◽  
...  
Keyword(s):  
Temperature Coefficient ◽  
Pressure Sensor ◽  
High Performance ◽  
Pressure Sensors ◽  
Resistance Change ◽  
Change Rate ◽  
Influence Of Temperature ◽  
Temperature Characteristics ◽  
Device Resistance ◽  
Influence Of Temperature On

Temperature is a significant factor in the application of graphene-based pressure sensors. The influence of temperature on graphene pressure sensors is twofold: an increase in temperature causes the substrates of graphene pressure sensors to thermally expand, and thus, the graphene membrane is stretched, leading to an increase in the device resistance; an increase in temperature also causes a change in the graphene electrophonon coupling, resulting in a decrease in device resistance. To investigate which effect dominates the influence of temperature on the pressure sensor based on the graphene–boron nitride (BN) heterostructure proposed in our previous work, the temperature characteristics of two BN/graphene/BN heterostructures with and without a microcavity beneath them were analyzed in the temperature range 30–150 °C. Experimental results showed that the resistance of the BN/graphene/BN heterostructure with a microcavity increased with the increase in temperature, and the temperature coefficient was up to 0.25%°C−1, indicating the considerable influence of thermal expansion in such devices. In contrast, with an increase in temperature, the resistance of the BN/graphene/BN heterostructure without a microcavity decreased with a temperature coefficient of −0.16%°C−1. The linearity of the resistance change rate (ΔR/R)–temperature curve of the BN/graphene/BN heterostructure without a microcavity was better than that of the BN/graphene/BN heterostructure with a microcavity. These results indicate that the influence of temperature on the pressure sensors based on BN/graphene/BN heterostructures should be considered, especially for devices with pressure microcavities. BN/graphene/BN heterostructures without microcavities can be used as high-performance temperature sensors.

A simple and rapid method for blood plasma separation driven by capillary force with an application in protein detection

2020 ◽  
Vol 12 (20) ◽  
pp. 2560-2570 ◽  
Author(s):  
Qingxue Gao ◽  
Yongjia Chang ◽  
Qingmei Deng ◽  
Hui You
Keyword(s):  
Blood Plasma ◽  
Rapid Method ◽  
Capillary Force ◽  
Protein Detection ◽  
Microfluidic Devices ◽  
Treatment Procedure ◽  
Plasma Separation ◽  
Pre Treatment ◽  
Blood Plasma Separation

Blood plasma separation is a vital sample pre-treatment procedure for microfluidic devices in blood diagnostics, and it requires reliability and speediness.

A Controlled Comparison of Simulated and Real ECT

1978 ◽  
Vol 133 (6) ◽  
pp. 514-519 ◽  
Author(s):  
J. Lambourn ◽  
D. Gill
Keyword(s):  
Rating Scale ◽  
Muscle Relaxation ◽  
Control Treatment ◽  
Treatment Procedure ◽  
Double Blind ◽  
Convulsive Therapy ◽  
Pre Treatment ◽  
Controlled Evaluation ◽  
Electro Convulsive Therapy ◽  
Hamilton Rating Scale

SummaryTwo groups of 16 patients with depressive psychosis took part in a controlled evaluation of electro-convulsive therapy (ECT). One group received six brief pulse unilateral shocks under conventional anaesthesia and muscle relaxation; the second group underwent the same procedure without receiving shocks. Outcome was assessed by a separate investigator using the Hamilton Rating Scale for Depression under double-blind conditions. The results showed that this form of ECT was only superior to the control treatment for one item in the scale, a finding which could have occurred by chance. The results suggest that the ECT pre-treatment procedure has an important therapeutic effect. This casts some doubt on current views of the effectiveness of electro-convulsive therapy in general, and of brief pulse unilateral ECT in particular.

scholarly journals Electrical Characterization of a Double-Layered Conductive Pattern with Different Crack Configurations for Durable E-Textiles

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 977
Author(s):  
Tomoya Koshi ◽  
Ken-ichi Nomura ◽  
Manabu Yoshida
Keyword(s):  
Crack Growth ◽  
Tensile Deformation ◽  
Elongation Rate ◽  
Double Layers ◽  
Single Crack ◽  
Multiple Crack ◽  
Resistance Change ◽  
Change Rate ◽  
Electrical Failure ◽  
Silver Ink

For the conductive patterns of electronic textiles (e-textiles), it is still challenging to maintain low electrical resistance, even under large or cyclic tensile deformation. This study investigated a double-layered pattern with different crack configurations as a possible solution. Patterns with single crack growth exhibit a low initial resistance and resistance change rate. In contrast, patterns with multiple crack growth maintain their conductivity under deformation, where electrical failure occurs in those with single crack growth. We considered that a double-layered structure could combine the electrical characteristics of patterns with single and multiple crack growths. In this study, each layer was theoretically designed to control the crack configuration. Then, meandering copper patterns, silver ink patterns, and their double layers were fabricated on textiles as patterns with single and multiple crack growths and double-layered patterns, respectively. Their resistance changes under the single (large) and cyclic tensile deformations were characterized. The results confirmed that the double-layered patterns maintained the lowest resistance at the high elongation rate and cycle. The resistance change rates of the meandering copper and silver ink patterns were constant, and changed monotonically against the elongation rate/cycle, respectively. In contrast, the change rate of the double-layered patterns varied considerably when electrical failure occurred in the copper layer. The change rate after the failure was much higher than that before the failure, and on the same order as that of the silver ink patterns.

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