The Dispersivity of Multi-Walled Carbon Nanotubes (NMWTs) and Pressure-Sensitive Property of NMWTs Reinforced Cement Composite

2009 ◽  
Vol 60-61 ◽  
pp. 475-479 ◽  
Author(s):  
Jian Lin Luo ◽  
Zhong Dong Duan
Keyword(s):  
Carbon Nanotubes ◽  
Applied Pressure ◽  
Wheatstone Bridge ◽  
Cement Composite ◽  
Cement Matrix ◽  
Ultrasonic Dispersion ◽  
Multi Wall Carbon Nanotubes ◽  
Pressure Sensitive ◽  
Reinforced Cement ◽  
The Individual

The individual and/or combinatory impacts of two surfactants (polyoxyethylene nonyl phenyl ether 10 (Tx-100), Arabic gum powder (AG)) on the dispersivity of multi-wall carbon nanotubes (NMWTs) were firstly investigated and evaluated through naked and microstructures observation; hereafter, NMWTs with 1.0% loading were firstly dispersed in aqueous solution with surfactant ultrasonic dispersion process, and cast-mixed into cement matrix to fabricate 2 groups NMWTs reinforced cement composites (NMTRCs), associated with the plain reference. Wheatstone bridge configurations were simultaneously employed to obtain the resistances and the monoaxial stresses, to investigate the pressure-sensitive properties of these nanocomposites. Results with naked observation reveal that either Tx-100 or AG at some concentration has good dispersion effect on NMWTs, the blackness homogeneity and stability of NMWTs suspended solution could retain more than 15 d; yet microstructures results show that NMTRC with AG has more homogeneous dispersion impact and more compatible with cement hydration than that with Tx-100. Results related on the pressure-sensitive properties of NMTRCs demonstrate that, the fractional change in resistivity of NMTRC with AG linearly falls down by increment of applied pressure within elastic range, this good pressure-sensitive traits mainly contribute to the increasing chance of physical contacts, the denser of current chargers between NMWTs, and the shortened trend of the potential barrier widths between NMWTs and matrix by increment of pressure, after efficient dispersion with AG. Yet that of NMTRC with Tx-100 has not good linearity descending trend, but some exaggerate fluctuations, and that of the reference has also no any regular descending trend.

scholarly journals Reinforcing Effect of Carbon Nanotubes/Surfactant Dispersions in Portland Cement Pastes

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Oscar A. Mendoza Reales ◽  
Caterin Ocampo ◽  
Yhan Paul Arias Jaramillo ◽  
Juan Carlos Ochoa Botero ◽  
Jorge Hernán Quintero ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cement Matrix ◽  
Multiwalled Carbon ◽  
Element Analysis ◽  
Cement Pastes ◽  
Reinforcing Effect ◽  
Linear Elastic ◽  
Crack Propagation Process ◽  
Negative Effect ◽  
The Individual

Decoupling the individual effects of multiwalled carbon nanotubes (MWCNTs) and surfactants when used as reinforcement materials in cement-based composites is aimed in this study. Powder MWCNTs were dispersed in deionized water using different types of surfactants as chemical dispersing agents and an ultrasonic tip processor. Cement pastes with carbon nanotubes additions of 0.15% by mass of cement were produced in two steps: first, the MWCNT/surfactant dispersions were combined with the mixing water, and then, cement was added and mixed until a homogeneous paste was obtained. Mechanical properties of the pastes cured at 7 days were measured, and their fracture behavior was characterized using the linear elastic finite element analysis. It was found that the reinforcing effect of MWCNT was masked by the negative effect of surfactants in the cement matrix; nevertheless, nanotubes were capable of increasing both stress and strain capacity of the composite by controlling the crack propagation process at the tip of the crack.

Research Progress on Carbon Nanotubes Reinforced Cement-Based Materials

2014 ◽  
Vol 629-630 ◽  
pp. 487-493
Author(s):  
Bao Min Wang ◽  
Shuai Liu ◽  
Yu Han
Keyword(s):  
Carbon Nanotubes ◽  
High Performance ◽  
Weight Fraction ◽  
Research Field ◽  
Research Progress ◽  
Cement Matrix ◽  
Cement Composites ◽  
Mechanical Stirring ◽  
Cement Based Materials ◽  
Reinforced Cement

For their remarkable properties, carbon nanotubes (CNTs) are considered as promising candidate for next generation of high performance and functional cement-based composites in 21st century. The paper focuses on the dispersibility, mechanical property, durability, conductivity and piezoresistivity properties of CNTs reinforced cement-based materials. A homogenous CNTs-suspension was obtained using the method which combined ultrasonic processing with mechanical stirring, electric-field introduction and surfactant decoration. The low weight fraction of CNTs improved the mechanical properties of CNTs/cement composites. The compressive strength and toughness were correspondingly improved. The added CNTs improved the sulfate attack resistance and impermeability properties of the prepared CNTs/cement mixes. Meanwhile, the added CNTs improved the pressure-sensitive, conductivity and electromagnetic absorption properties of the prepared mixes, which laid a foundation of multi-functional concrete and structure. It concludes that the key issue for CNTs/cement composites is the dispersibility and the compatibility of CNTs in cement matrix. The solving solutions are put forward. In the meantime, the further research prospects in this research field are forecasted.

The I-V Characteristics and Percolation Threshold of the Cement-Based Materials Filled with Multi-Walled Carbon Nanotubes

2009 ◽  
Vol 60-61 ◽  
pp. 36-39
Author(s):  
Jian Lin Luo ◽  
Zhong Dong Duan
Keyword(s):  
Carbon Nanotubes ◽  
Percolation Threshold ◽  
Near Field ◽  
Cement Matrix ◽  
Ultrasonic Dispersion ◽  
Integrated Network ◽  
Cement Based Materials ◽  
Multi Walled Carbon Nanotubes ◽  
Electrode Method ◽  
Walled Carbon Nanotubes

Some multi-walled carbon nanotubes (NMWTs) were firstly dispersed in aqueous solution with surfactant ultrasonic dispersion process, then mixed into cement matrix, casting six groups cement-based materials filled with varying NMWTs additions (nwt) (NFCMs), and as comparison, the plain referential cement paste was fabricated. The ampere-volt (I-V) characteristics and percolation threshold of this type of nanocomposites were focused by four-electrode method. Results show that, the I-V features of the reference has obvious nonlinearity due to polarized reaction within cement hydrated electrolytes after being induced by passing 0~±30 V voltages, those of the NFCMs with six different nwt still have somewhat nonlinear traits, which mainly attribute to the double-layer coatings between NMWTs and out-encapsulated cement hydration isolation. The resistivity (ρ) of the NFCM nanocomposite steadily decreases with the increment of nwt, which contributes to superior capabilities of charge transporter and near-field emission of NMWTs, and the overlapped chance of physical contacts between conducting aggregates of NMWTs and bulk matrix increases by nwt enhancing; although there is still some fluctuation on ρ, but it becomes weaker and weaker by nwt increasing. The percolation threshold of the NFCMs is nwt being 2.0%, and the integrated network pathways at micro-scale form between NMWTs each other through the correspondent NFCM, also revealed in microstructure.

Effect and Microscopic Mechanisms of Slag Micropowder on the Reinforcement of CaCO3 Whisker in Cement Composites

2011 ◽  
Vol 675-677 ◽  
pp. 529-535 ◽  
Author(s):  
Jian Qiang Wei ◽  
Ming Li Cao
Keyword(s):  
Cement Composite ◽  
Cement Matrix ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Slag Powder ◽  
Pull Out ◽  
Reinforced Cement ◽  
Powder Content

Whisker pull-out, which indicates that the interfacial bond strength of whiskers/cement is not high enough, is dominant in the microstructure of whisker-reinforced cement fractured surfaces. The weak interfacial bond of whiskers in cement matrix severely restrained the further improvement of properties. Superfine slag powder was used to modify and improve the strength and bond behavior of whisker-reinforced cement. Crystal structures, microcosmic appearances and characterizations of Slag Micro powder and the composite were studied by X-ray diffraction (XRD), and scan electron microscope (SEM/EDS), etc. Effect and mechanisms of different Slag powder content on the micro-structure and macro-properties of cement composite were investigated. The results show that Slag Micropowder can modify and improve the microstructure, interfacial and mechanical properties of whisker-reinforced cement.

Compressive Strength and Microstructure of Multi-Wall Carbon Nanotubes Reinforced Cement Composites

2012 ◽  
Vol 450-451 ◽  
pp. 594-599
Author(s):  
Jin Tao Liu ◽  
Dong Ming Yan ◽  
Shi Lang Xu
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Carbon Nanotube ◽  
Microscopic Analysis ◽  
Cement Composites ◽  
Cement Pastes ◽  
Multi Wall Carbon Nanotubes ◽  
Multi Walled Carbon Nanotubes ◽  
Reinforced Cement ◽  
Walled Carbon Nanotubes

Advancement in the study of carbon nanotube has enabled its application in civil engineering as constitutive materials or additives. In this study, the availability of applying multi-walled carbon nanotube to improve the characteristics of cement composites was investigated with experiments on more than 30 specimens. The multi-walled carbon nanotubes (MWCNTs) were effectively dispersed in the water with surfactant, which can keep stable for over 3 months. Specimens with MWCNTs of 0.025%, 0.05% and 0.1% of cement (by weight) were tested with a loading machine and then analyzed with a SEM. It was found that the compressive strength of the samples increased with the increasing MWCNTs, it can improve the 7-day compressive strength by 22% . Microscopic analysis (SEM) revealed that carbon nanotubes were surrounded with hydration products. The bridging and debonding of carbon nanotubes in cement pastes was observed as well.

scholarly journals Durability of Alkali-Resistant Glass Fibers Reinforced Cement Composite: Microstructural Observations of Degradation

2018 ◽  
Author(s):  
Nourredine Arabi ◽  
Laurent Molez ◽  
Damien Rangeard
Keyword(s):  
Glass Fibers ◽  
Energy Dispersive Spectrometer ◽  
Cement Composite ◽  
Cement Matrix ◽  
Test Results ◽  
X Ray Diffraction ◽  
Curing Conditions ◽  
Humid Environment ◽  
Phase Development ◽  
Reinforced Cement

Usually, glass fibers in concrete permit the increase of the flexural strength. But the fibers in contact with cement are quickly degraded by alkali reactions due to the presence of portlandite. This article presents the results of investigations carried out to study the influence of curing conditions on the durability of alkali-resistant glass fibers in a cement matrix. Test results showed that alkali resistant fibers treated with zirconium oxide, present the same degradation phenomenon. The used cement nature has a large influence on the protection of the fibers. In addition, the degradation is weakened when silica fumes are added, owing to the pozzolanic effect that decreases the portlandite quantity. In spite of those different ameliorations, the use of such materials in humid environment is proving to be risky. The used techniques to study those phenomena are SEM equipped with energy dispersive spectrometer (EDX) to observe the attack microstructures of the fibers and X-ray diffraction to quantify the portlandite and other phase development.

Studies of Carboxyl-Functionalized Multi-Wall Carbon Nanotubes and Mechanical Properties of its MWCNTs-OPC Cement Composites

2013 ◽  
Vol 774-776 ◽  
pp. 499-502
Author(s):  
Jing Xin Yang ◽  
Yong Zhi Xu
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Cement Matrix ◽  
Acid Oxidation ◽  
Cement Composites ◽  
Multiwalled Carbon ◽  
Multi Wall Carbon Nanotubes ◽  
Pristine Mwcnts ◽  
Uniform Dispersion ◽  
Nitric Acid Oxidation

This study successfully grafted multiwalled carbon nanotubes (MWCNTs) with carboxyl group (MWCNTs-COOH) via concentrated nitric acid oxidation reaction. The morphologies of MWCNTs oxidized under various conditions and the extent of dispersion of the MWCNTs in the cement matrix were characterized using fourier transform infrared spectroscopy (FTIR). This investigation also optimized the mechanical properties of MWCNTs-OPC cement composites by utilizing pristine MWCNTs (P-MWCNTs) and modified MWCNTs (MWCNTs-COOH) through a combination of dispersion method. Micrographs of MWCNTs incorporated cement samples revealed uniform dispersion of MWCNTs in cement, good interfacial adhesion between MWCNTs and cement, and improved interfacial bonding between MWCNTs-OPC cement at 0.4 wt.% loading. An improved dispersion and hence an improved crosslink interaction between MWCNTs-COOH and cement lead to the stronger shift of the mechanical properties of the cement composites.

scholarly journals Electrical, Piezoresistive and Electromagnetic Properties of Graphene Reinforced Cement Composites: A Review

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3220
Author(s):  
Shengchang Mu ◽  
Jianguang Yue ◽  
Yu Wang ◽  
Chuang Feng
Keyword(s):  
Material Properties ◽  
High Performance ◽  
Cement Composite ◽  
Electromagnetic Properties ◽  
Cement Matrix ◽  
Future Research ◽  
Cement Composites ◽  
Preparation Methods ◽  
Reinforced Cement ◽  
Filler Dispersion

Due to their excellent combination of mechanical and physical properties, graphene and its derivatives as reinforcements have been drawing tremendous attention to the development of high-performance and multifunctional cement-based composites. This paper is mainly focused on reviewing existing studies on the three material properties (electrical, piezoresistive and electromagnetic) correlated to the multifunction of graphene reinforced cement composite materials (GRCCMs). Graphene fillers have demonstrated better reinforcing effects on the three material properties involved when compared to the other fillers, such as carbon fiber (CF), carbon nanotube (CNT) and glass fiber (GF). This can be attributed to the large specific surface area of graphene fillers, leading to improved hydration process, microstructures and interactions between the fillers and the cement matrix in the composites. Therefore, studies on using some widely adopted methods/techniques to characterize and investigate the hydration and microstructures of GRCCMs are reviewed and discussed. Since the types of graphene fillers and cement matrices and the preparation methods affect the filler dispersion and material properties, studies on these aspects are also briefly summarized and discussed. Based on the review, some challenges and research gaps for future research are identified. This review is envisaged to provide a comprehensive literature review and more insightful perspectives for research on developing multifunctional GRCCMs.

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