Experimental study of the behaviour of cement pastes in the presence of carbon nanotubes

One of the methods recently applied for the noticeably improvement of properties of cementitious materials is the use of the single or multi-walled carbon nanotubes (CNTs) as nano-reinforcements in cementitious materials. The positive action of CNTs highly depends not only on its nature, length and amount, but also on previous treatment of CNTs and quality of CNTs dispersion. It is important to obtain the effects of multi-walled CNTs, dispersed only in carboxyl-methyl cellulose – commercially available pellets without the use of any commercially available surfactants or plasticizers. The influence of dispersed CNTs on the rheological properties of fresh cement pastes and physical and mechanical properties of hardened specimens was analyzed in this work. Compared to the dynamic viscosity of pure distilled water smaller amounts of CNTs (0.00005–0.005%) reduce the dynamic viscosity down to the 15% whereas higher amounts of CNTs (0.05–0.5%) increase the dynamic viscosity from 1.3 to 4.7 times. Mechanical tests of hardened for 28 days cement paste specimens showed that smaller amounts of CNTs (0.00005–0.005%) increase the compressive and flexural strengths by 38.07– 42.3% and 40.1– 44.6%, whereas higher amounts of CNTs (0.05–0.5%) increase these strengths just by 21.11–18.82% and 18.33–6.6% respectively.

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Stabilizing effect of methylcellulose on the dispersion of multi-walled carbon nanotubes in cementitious composites

Nanotechnology Reviews ◽

10.1515/ntrev-2020-0009 ◽

2020 ◽

Vol 9 (1) ◽

pp. 93-104

Author(s):

Mingrui Du ◽

Yuan Gao ◽

Guansheng Han ◽

Luan Li ◽

Hongwen Jing

Keyword(s):

Carbon Nanotubes ◽

Pore Solution ◽

Cementitious Materials ◽

High Ionic Strength ◽

Cementitious Composites ◽

Uniform Distributions ◽

Stabilizing Effect ◽

Multi Walled Carbon Nanotubes ◽

The Stability ◽

Walled Carbon Nanotubes

AbstractMulti-walled carbon nanotubes (MWCNTs) have been added in the plain cementitious materials to manufacture composites with the higher mechanical properties and smart behavior. The uniform distributions of MWCNTs is critical to obtain the desired enhancing effect, which, however, is challenged by the high ionic strength of the cement pore solution. Here, the effects of methylcellulose (MC) on stabilizing the dispersion of MWCNTs in the simulated cement pore solution and the viscosity of MWCNT suspensions werestudied. Further observations on the distributions of MWCNTs in the ternary cementitious composites were conducted. The results showed that MC forms a membranous envelope surrounding MWCNTs, which inhibits the adsorption of cations and maintains the steric repulsion between MWCNTs; thus, the stability of MWCNT dispersion in cement-based composites is improved. MC can also work as a viscosity adjuster that retards the Brownian mobility of MWCNTs, reducing their re-agglomerate within a period. MC with an addition ratio of 0.018 wt.% is suggested to achieve the optimum dispersion stabilizing effect. The findings here provide a way for stabilizing the other dispersed nano-additives in the cementitious composites.

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Using of Untreated Carbon Nanotubes in Cement Compositions

Materials Science Forum ◽

10.4028/www.scientific.net/msf.865.6 ◽

2016 ◽

Vol 865 ◽

pp. 6-11 ◽

Cited By ~ 2

Author(s):

Kateryna Pushkarova ◽

Maryna Sukhanevych ◽

Artur Martsikh

Keyword(s):

Carbon Nanotubes ◽

Cement Paste ◽

Cementitious Materials ◽

Positive Influence ◽

Mechanical Tests ◽

Strength Characteristics ◽

Concrete Durability ◽

Cement Mortars ◽

Optimum Decision ◽

Cement System

One of the most important problem of concrete durability is increasing of waterproofing. Researches are devoted studying of cement mortars modified by carbon nanotubes, dispersed in plasticizers solutions. Were investigated physico-mechanical properties of cement paste, cement-sand mortar into which structure entered untreated carbon nanotubes (production of plant TM "Spetsmash" Kyiv, Ukraine) in various quantity. Were used as plasticizers in cement compositions additives substances of the various chemical nature – naphtaleneformaldehyde, melamineformaldehyde and polycarboxylate. Quantity of untreated nanotubes varied from 0,5%; 1,0% and to 1,5%. Concentration of additives was accepted taking into account recommendations of producers and made about 1% from the weight of cement. Were studied some technological processes of introduction untreated carbon nanotubes in cement system and is shown that the way of introduction of nanomodifiers has essential impact on strength characteristics of cementitious materials. Optimum decision introduction of untreated carbon nanotubes is using its in dispersion plasticizer of the working concentration prepared in an ultrasonic dispergator is established. Results of physico-mechanical tests of cement paste and cement-sand mortar showed positive influence at introduction of untreated carbon nanotubes as cement modifiers on strength characteristics of samples. Resalts is shown that the nanomodifier, used quantity about 1% in solution of lignosulfonate with polycarboxylate and melamineformaldehyde plasticizer has great impact on strength characteristics.

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Compression Moulding of Thermoplastic Nanocomposites Filled with MWCNT

Polymers and Polymer Composites ◽

10.1177/096739111702500806 ◽

2017 ◽

Vol 25 (8) ◽

pp. 611-620 ◽

Cited By ~ 1

Author(s):

Fabrizio Quadrini ◽

Denise Bellisario ◽

Loredana Santo ◽

Felicia Stan ◽

Fetecau Catalin

Keyword(s):

Carbon Nanotubes ◽

Differential Scanning Calorimetry ◽

Filler Content ◽

Thermoplastic Polyurethane ◽

Mechanical Tests ◽

Compression Moulding ◽

Scanning Calorimetry ◽

Melt Mixing ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Multi-walled carbon-nanotubes (MWCNTs) were melt-mixed with three different thermoplastic matrices (polypropylene, PP, polycarbonate, PC, and thermoplastic polyurethane, TPU) to produce nanocomposites with three different filler contents (1, 3, and 5 wt.%). Initial nanocomposite blends (in the shape of pellets) were tested under differential scanning calorimetry to evaluate the effect of the melt mixing stage. Nanocomposite samples were produced by compression moulding in a laboratory-scale system, and were tested with quasi-static (bending, indentation), and dynamic mechanical tests as well as with friction tests. The results showed the effect of the filler content on the mechanical and functional properties of the nanocomposites. Compression moulding appeared to be a valuable solution to manufacture thermoplastic nanocomposites when injection moulding leads to loss of performance. MWCNT-filled thermoplastics could be used also for structural and functional uses despite, the present predominance of electrical applications.

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Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

Biomimetics ◽

10.3390/biomimetics5030043 ◽

2020 ◽

Vol 5 (3) ◽

pp. 43

Author(s):

Athanasios Kotrotsos ◽

Prokopis Yiallouros ◽

Vassilis Kostopoulos

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Polylactic Acid ◽

Physical And Mechanical Properties ◽

Polymeric Materials ◽

Cost Effective ◽

Electrospinning Process ◽

Wide Range ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

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Dispersion of Carbon Nanotubes with Different Types of Superplasticizer as a Dispersing Agent for Self-Sensing Cementitious Materials

Applied Sciences ◽

10.3390/app11188452 ◽

2021 ◽

Vol 11 (18) ◽

pp. 8452

Author(s):

Pedro de Almeida Carísio ◽

Yasmim Gabriela dos Santos Mendonça ◽

Carlos Fernando Teodósio Soares ◽

Oscar Aurelio Mendoza Reales ◽

Eduardo de Moraes Rego Fairbairn ◽

...

Keyword(s):

Carbon Nanotubes ◽

Cementitious Materials ◽

Cement Matrix ◽

Cement Pastes ◽

Sensing Applications ◽

Dispersing Agent ◽

Vis Spectroscopy ◽

Different Types ◽

Conductive Fillers ◽

Dispersing Agents

Due to their exceptional electrical properties, carbon nanotubes (CNTs) can be applied as conductive fillers to develop self-sensing cement-based matrices. In order to obtain an adequate self-sensing response, CNTs must be evenly dispersed through the cement matrix in a volume sufficient enough to create an electric percolation network. This is challenged by the difficulty of dispersing CNTs; therefore, there is a demand for an efficient dispersing agent that can be filled by superplasticiezers, which are products of known compatibility with cement and high availability. This research explores the use of four commercial superplasticizers available in Brazil, both naphthalene and ether polycarboxylate-based, as dispersing agents for CNTs in water. Ultrasonic energy was applied to aqueous solutions containing CNTs and superplasticizers. UV–Vis spectroscopy and ξ-potential measurements were used to investigate which superplasticizer was more effective to disperse the CNTs. Cement pastes were produced with the CNT dispersions and their electrical resistivity was measured. It was found that only superplasticizers without aliphatic groups in their structure were capable of dispersing CNTs in water. It was concluded that second-generation naphthalene-based superplasticizers were more efficient dispersing agents for CNTs than third-generation ether polycarboxylate-based ones for self-sensing applications.

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Structure and Mechanical Properties of Multi-Walled Carbon Nanotubes-Filled Isotactic Polypropylene Composites Treated by Pressurization at Different Rates

Polymers ◽

10.3390/polym11081294 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1294 ◽

Cited By ~ 1

Author(s):

Xiaoting Li ◽

Wenxia Jia ◽

Beibei Dong ◽

Huan Yuan ◽

Fengmei Su ◽

...

Keyword(s):

Carbon Nanotubes ◽

Isotactic Polypropylene ◽

Mechanical Tests ◽

High Yield ◽

Scanning Calorimetry ◽

X Ray ◽

Polypropylene Composites ◽

Pressurization Rate ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Isotactic polypropylene filled with 1 wt.% multi-walled carbon nanotubes (iPP/MWCNTs) were prepared, and their crystallization behavior induced by pressurizing to 2.0 GPa with adjustable rates from 2.5 to 1.3 × 104 MPa/s was studied. The obtained samples were characterized by combining wide angle X-ray diffraction, small angle X-ray scattering, differential scanning calorimetry, transmission electron microscopy and atomic force microscopy techniques. It was found that pressurization is a simple way to prepare iPP/MWCNTs composites in mesophase, γ-phase, or their blends. Two threshold pressurization rates marked as R1 and R2 were identified, while R1 corresponds to the onset of mesomorphic iPP formation. When the pressurization rate is lower than R1 only γ-phase generates, with its increasing mesophase begins to generate and coexist with γ-phase, and if it exceeds R2 only mesophase can generate. When iPP/MWCNTs crystallized in γ-phase, compared with the neat iPP, the existence of MWCNTs can promote the nucleation of γ-phase, leading to the formation of γ-crystal with thicker lamellae. If iPP/MWCNTs solidified in mesophase, MWCNTs can decrease the growth rate of the nodular structure, leading to the formation of mesophase with smaller nodular domains (about 9.4 nm). Mechanical tests reveal that, γ-iPP/MWCNTs composites prepared by slow pressurization display high Young’s modulus, high yield strength and high elongation at break, and meso-iPP/MWCNTs samples have excellent deformability because of the existence of nodular morphology. In this sense, the pressurization method is proved to be an efficient approach to regulate the crystalline structure and the properties of iPP/MWCNTs composites.

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Vacuum Casting and Mechanical Characterization of Nanocomposites from Epoxy and Oxidized Multi-Walled Carbon Nanotubes

Molecules ◽

10.3390/molecules24030510 ◽

2019 ◽

Vol 24 (3) ◽

pp. 510

Author(s):

Gerald Singer ◽

Philipp Siedlaczek ◽

Gerhard Sinn ◽

Patrick Kirner ◽

Reinhard Schuller ◽

...

Keyword(s):

Carbon Nanotubes ◽

Mechanical Tests ◽

Image Correlation ◽

Sem Images ◽

Vacuum Casting ◽

Multi Walled Carbon Nanotubes ◽

Properties Of Materials ◽

Walled Carbon Nanotubes

Sample preparation is an important step when testing the mechanical properties of materials. Especially, when carbon nanotubes (CNT) are added to epoxy resin, the increase in viscosity complicates the casting of testing specimens. We present a vacuum casting approach for different geometries in order to produce specimens from functional nanocomposites that consist of epoxy matrix and oxidized multi-walled carbon nanotubes (MWCNTs). The nanocomposites were characterized with various mechanical tests that showed improved fracture toughness, bending and tensile properties performance by addition of oxidized MWCNTs. Strengthening mechanisms were analyzed by SEM images of fracture surfaces and in-situ imaging by digital image correlation (DIC).

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The effect of multi-walled carbon nanotubes on the rheological properties and hydration process of cement pastes

Construction and Building Materials ◽

10.1016/j.conbuildmat.2018.09.082 ◽

2018 ◽

Vol 189 ◽

pp. 947-954 ◽

Cited By ~ 8

Author(s):

Dainius Leonavičius ◽

Ina Pundienė ◽

Giedrius Girskas ◽

Jolanta Pranckevičienė ◽

Modestas Kligys ◽

...

Keyword(s):

Carbon Nanotubes ◽

Rheological Properties ◽

Hydration Process ◽

Cement Pastes ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.450-451.594 ◽

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.

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