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FTIR spectra of carbon nanofiber's: (a) pristine; (b) oxidized; and (c) further acid/microwave-treated.
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Graphite nanomaterials can play multi-faceted roles towards enhancing the mechanical, physical and functional attributes of cementitious materials. Graphite nanoplatelets and carbon nanofibers, when compared with carbon nanotubes, offer desired mechanical and physical characteristics at reduced cost. However thorough dispersion of nanomaterials in...
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... dispersion of CNFs in aqueous media. When compared with CNTs, CNFs have surfaces with relatively high density of defect sites which are more prone to acid oxidation for introducing a relatively high concentration of COOH groups on their surfaces. The CNFs further functionalized through acid oxidation were characterized by FTIR spectroscopy. Fig. 5 shows the FTIR spectra of pristine CNFs, oxidized CNFs (supplied by the manufacturer), and nanofibers after further acid oxida- tion. In Fig. 5a through 5c, the peak at 1580 cm À1 is assigned to the C@C stretching mode associated with nanofiber surface defects. The peak at 1710 cm À1 is assigned to the C@O stretch- ing mode of ...
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... prone to acid oxidation for introducing a relatively high concentration of COOH groups on their surfaces. The CNFs further functionalized through acid oxidation were characterized by FTIR spectroscopy. Fig. 5 shows the FTIR spectra of pristine CNFs, oxidized CNFs (supplied by the manufacturer), and nanofibers after further acid oxida- tion. In Fig. 5a through 5c, the peak at 1580 cm À1 is assigned to the C@C stretching mode associated with nanofiber surface defects. The peak at 1710 cm À1 is assigned to the C@O stretch- ing mode of acid-treated CNFs, and points at success of the functionalization process in generating -COOH groups on CNF surfaces (Fig. ...
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... after further acid oxida- tion. In Fig. 5a through 5c, the peak at 1580 cm À1 is assigned to the C@C stretching mode associated with nanofiber surface defects. The peak at 1710 cm À1 is assigned to the C@O stretch- ing mode of acid-treated CNFs, and points at success of the functionalization process in generating -COOH groups on CNF surfaces (Fig. ...
Citations
... According to the aforementioned review, research on carbon nanofibers (CNFs) and GNPs has primarily concentrated on two concerns: (1) how to make nanomaterials evenly dispersed in a cementitious matrix [46,47]; and (2) whether using nanomaterials significantly improves the performance of cementitious matrixes and the dosage of nanomaterials needed [48,49]. The incorporation of nanomaterials has been demonstrated to improve the compressive, tensile, and flexural properties of ultra-high-performance concrete (UHPC) [50]. ...
In recent decades, there have been initiatives to incorporate carbon nanomaterials (CNMs) into cement composites, particularly graphene oxide (GO), carbon nanotubes, graphite (GP), and mild carbon (MC). Nevertheless, little is known about how these CNMs interact with the cement matrix itself. In this research, the impact of CNM incorporation at high temperatures (250, 500, 750, and 1,000°C) on cement’s mechanical characteristics and microstructure was investigated. Nine mixes were created with the CNM content (0.1 and 0.3%) being taken into consideration. The microstructure of the CNM composites was further investigated using X-ray diffractometry, thermogravimetry, derivative thermogravimetry, digital microscopy, and micro-computed tomography (micro-CT). Based on research observations, the study demonstrated that the mechanical properties of most specimens could be enhanced through the introduction of CNMs. The recommended proportions of GP-0.1, GO-0.1, and MC-0.1, in accordance with the weight of the binder, and the impact of the CNMs on the elastic modulus were also assessed. As a consequence, the CNM’s porous structure and apparent crack pattern were identified using microstructure analysis.
... The effectiveness of MWCNT can be attributed to the formation of nucleation sites, which in turn enriches the medium with various activation sites for the growth of the hydration phase [39]. However, an overdose of MWCNT exceeding 0.10% has a negative impact due to increased agglomeration, resulting in increased porosity and deformation of the matrix. ...
The main purpose of this paper is to carry out a comparative investigation into the performance of multiwall carbon nanotube (MWCNT) and carbon wastes that are derived from the production of aluminum in the creation of thermally stable cementitious mortar. In Egypt, carbon waste is produced as a by-product of the aluminum industry and it is identified by its nano-scale dimensions. The cement mortar is produced by using a combination of blended cement (CEMIII) and sand that passes through a 1 mm sieve, with different ratios of both MWCNT and C-waste ranging from 0.1% to 0.7%. The addition of MWCNT and c-waste leads to an enhancement in compressive strength values up to 0.1%, resulting in values of approximately 70MPa and 75 MPa at 90 days, respectively. The findings validate the superior physical and mechanical properties of c-waste as compared to MWCNT, in addition to its lower production cost in comparison to precious MWCNT. The cement mortar demonstrates increased resistance to high temperatures when exposed to firing temperatures up to 700 degrees, achieving measurements of about 60 MPa and 63 MPa for MWCNT and carbon waste, respectively. The results also confirm the higher thermal stability of carbon waste when compared to MWCNT, despite both exceeding the limits specified for thermal resistance in mortar, which is 60 MPa.
... 23,24 To achieve a new breakthrough in radar absorbing materials, it is necessary to explore new ways to develop new radar absorbing materials with the characteristics of "thin," "wide," "light," and "strong." [25][26][27] Graphite is a type of carbon nanomaterial with unique properties, such as high mechanical strength and electrical conductivity, which makes them have a much range of potential applications in various fields, one of which is absorbing materials. [28][29][30][31] Graphene-based absorbing materials have received wide attention because of their excellent absorbing performance and tunability. ...
The graphite/Al2O3 composite was prepared using plasma spray technology, the material design, experimental methods, and process flow are introduced. The microstructure, chemical composition, and complex permittivity of the composite are investigated, and its performance to absorb electromagnetic waves is studied. The mechanism of interaction between chemical composition, microstructure, complex permittivity, and absorption performance is analyzed. Furthermore, a microwave absorber composed of graphite/Al2O3 and sheet resistance, and performance is discussed. The reflectivity of the composite coating with different periods and sizes and resistances is analyzed. The impedance and reflectivity of the designed absorber that contains sheet resistance are discussed, and its absorption mechanism is explained in detail. The results demonstrate that the microwave absorption performance of graphite/Al2O3 coating is enhanced by electromagnetic resonance of the sheet resistance. The designed absorber exhibits good wave‐absorbing performance and stability at the frequency of the 8.2–18 GHz range. When the sample thickness is 2.3 mm, the absorber achieves a reflection loss (RL) value of −16.8 dB at 9.8 GHz and a wide effective absorption bandwidth (EAB) of 9.8 GHz. It means that the RL below −10 dB can be obtained in the whole X band and Ku bands. These results proved that the EAB can be tuned and enhanced by manipulating sheet resistance.
... In particular, it was shown that the compressive strength improved by a factor of 1.44, while the flexural strength showed an improvement that was 2.16 times greater when GNPs were utilised. Peyvandi et al. [44], made the discovery that multiple graphite nanoparticles may function well as reinforcements in cementitious paste. There was a variety of increases in the flexural strength of cement that came from the integration of several kinds of graphene nano-platelets (GNPs) and their associated oxides at a concentration of 0.13 wt percent. ...
... Additionally, carboxylate-based superplasticizers contain the hydrophilic groups (-COOH) which make covalence-modified CNTs to enhance the interfacial contacts in AAM composites. The Caþ ions from AAM mortars make strong bonding with -COOH groups in the AAM matrix, which improves the formation of three-dimensional AAM-hydrated products [103]. This results in improvement of compaction and microstructure homogeneity [82]. ...
Alkali-activated material (AAM) is a potential sustainable substitute for normal Portland cement-based concrete, but the composition of the material and the design of the mixture have a significant impact on fresh and hardened properties. This research describes the formulation and mechanical behavior of a multi-walled carbon nanotube-reinforced-based alkali-activated nanocomposite. Multiwall carbon nanotubes (MWCNTs) were incorporated into the FA/hydrated lime-based alkali-activated material at concentrations of 0.1%, 0.2%, 0.3%, and 0.35% by weight of the binder. The significant dispersion of MWCNTs within the matrix was achieved in an aqueous solution of surfactant and superplasticizer by employing both magnetic stirring and sonication procedures. The fresh-state characteristics of the MWCNT-based AAM were evaluated in terms of setting time and rheology parameters. Notably, samples containing 0.3% and 0.35% MWCNTs exhibited setting times of 26 and 25 minutes, respectively. The rheological behavior of the nanocomposite adhered to Modified Bingham's model, displaying shear-thinning properties. Moreover, an increase in MWCNT content led to an augmentation in yield stress, with the highest enhancement of 11.1% and 13.1% in yield stress and plastic viscosity, respectively, observed for mortar samples with 0.3% MWCNTs. Mechanical assessments were performed at 7, 14, and 28 days to investigate the compressive and flexural strengths of the specimens. The addition of approximately 0.3% MWCNTs resulted in an impressive boost of up to 14% in compressive strength and an even more remarkable increase of 28% in flexural strength. Furthermore, after exposure to acid and sulfate attacks, the ACN3 samples (0.3% wt. of MWCNTs) exhibited minimal strength loss, with only 5.1% and 3.9% decrease in compressive strength after acid and sulfate attacks, respectively. According to these results, the MWCNTs can function as effective bridges to reduce and limit the progression of microcracks through the AAM-based nanocomposite under the circumstances of homogeneous distribution and good adhesion between both the MWCNTs and the adjacent AAM paste.
... 6 wt.%, and 9 wt.%, respectively. The contents of carbon nanotubes and graphene in CNT/PI and GNS/PI are set at 0.5 wt.%, 1 wt.%, and 1.5 wt.%, which took into account the fact that carbon nanomaterials are extremely easy to aggregate, leading to the degradation of mechanical properties [22][23][24]. ...
The thermal conductivity, mechanical, and tribological properties of polyimide (PI) composites filled by copper (Cu), carbon nanotube (CNT), graphene nanosheet (GNS), or combination were investigated by molecular dynamics simulation (MD). The simulated results suggested that Cu can improve thermal stability and thermal conductivity, but it reduces mechanical properties and tribological properties. CNT and GNS significantly improved the thermal and tribological properties at low content, but they decreased the properties at high content. In this study, the modification mechanism, friction, and wear mechanism of different fillers on polyimide were revealed by observing the frictional interface evolution process from the atomic scale, extracting the atomic relative concentration, the temperature and velocity distribution at the friction interface, and other microscopic information.
... To facilitate the dispersion of GO in the aqueous medium, mechanical methods such as Ultrasonication, high-speed mixing, and stirring are performed using minimum surfactants, such as Polycarboxylate Superplasticizer (PCE). In addition, these methods potentially break the GO layers [39][40][41]. GO in cement composites adversely affects workability by absorbing excess water due to its large surface area and hydrophilic functional groups [42]. Currently, few theories and observations state that the seeding effect of GO accelerates the hydration process and densifies the cement matrix leading to a modification in its microstructure [43][44][45][46]. ...
The introduction of Graphene Oxide (GO), a nanomaterial, has shown considerable promise in improving the mechanical properties of cement composites. However, the reasons for this improvement are not yet fully understood and demand further research. This study aims to understand the effect of laboratory-produced GO, using Tour’s method, on the mechanical properties and morphology of cement mortar containing GO. The GO was characterized using Fourier-transform infrared spectroscopy, X-ray Photoelectron Spectroscopy (XRD), X-ray powder diffraction, and Raman spectroscopy alongside Scanning electron microscopy (SEM). This study adopted a cement mortar with GO percentages of 0.02, 0.025, 0.03, 0.035, and 0.04 with respect to the weight of the cement. The presence of GO in cement mortar increased the density and decreased the consistency and setting times. At the optimum of 0.03% GO viscous suspension, the mechanical properties such as the 28-day compressive strength, splitting tensile strength, and flexural strength were enhanced by 41%, 83%, and 43%, respectively. In addition, Brunauer–Emmett–Teller analysis indicates an increase in surface area and volume of micropores of GO cement mortar, resulting in a decreased volume of mesopores. The improvement in properties was due to increased nucleation sites, calcium silicate hydrate (CSH) density, and a decreased volume of mesopores.
... However, due to the emergence of porosity and cracks, the durability and performance of the cement decreases. This situation has been overcome with the introduction of nanomaterials within the cement paste structure, making it possible to produce more durable and crack-free cementitious materials [1][2][3]. In this sense, CNTs show excellent mechanical properties and chemical stability, promoting the enhancement of concrete performance. ...
Over the last few years, the addition of small amounts of carbon nanotubes (CNTs) to construction materials has become of great interest, since it enhances some of the mechanical, electrical and thermal properties of the cement. In this sense, single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively) can be incorporated into cement to achieve the above-mentioned improved features. Thus, the current study presents the results of the addition of SWCNTs and MWCNTs on the microstructure and the physical properties of the cement paste. Density was measured through He pycnometry and the mass change was studied by thermogravimetric analysis (TGA). The microstructure and the phases were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Finally, the electrical conductivity for different CNT concentrations was measured, and an exponential increase of the conductivity with concentration was observed. This last result opens the possibility for these materials to be used in a high variety of fields, such as space intelligent systems with novel electrical and electronic applications.
... For this reason, the application of the ultrasonication method is a useful technique to minimize the agglomeration of nanomaterials and to provide more homogeneous distribution of nanomaterials in the slurry mixture. 18,19 The w/b is known as one of the most important parameters affecting the mechanical and fluidity features of grout mixtures. For this reason, choosing the most appropriate w/b for grout injection applications is an important step that should be considered as the priority in the design of grout mixtures. ...
... 16,17 Usually, the ultrasonication method is applied to control agglomeration and to ensure a more homogeneous distribution of nanopowders in the grout mixture. 18,19 For this reason, to minimize n-Al 2 O 3 precipitation in free water and to provide homogeneous dispersion in water by removing these adhering nanopowders from each other, the ultrasonication method was applied in this study. The ultrasonication method with ultrasonicator was applied to the aqueous medium for 180 minutes as soon as preparing all the fresh grout mixtures with mixing n-Al 2 O 3 into 200 mL free water volume. ...
In this experimental study, the workability and bleeding properties
of cement-based grout mixtures combined with fly ash (FA)
and colloidal nanopowder (n-Al2O3) were investigated, and some
prediction models were developed with an artificial neural network
(ANN). Marsh cone flow time, mini-slump spreading diameter, and
Lombardi plate cohesion of the grout samples were measured based
on the workability test. Test results showed that the use of FA as
mineral additive in the grout samples positively contributed to an
increase of the fluidity of the grout samples as expected. Considerable
effects were observed on workability features of grout mixtures
with the addition of nano alumina because of having a large specific
surface area. In addition, the use of nano alumina together with
FA in grout mixtures contributes to the stability of these mixtures
by looking at changes in bleeding values. Using the experimental
data obtained, an ANN model was developed to predict the values
of Marsh cone flow time, mini-slump spreading diameter, and
plate cohesion. The developed ANN model can predict mini-slump
spreading diameter with an error rate of –0.04%, Marsh cone flow
time value with an error rate of –0.23%, and plate cohesion value
with an error rate of –1.07%.
... Over the last few years, the photocatalytic oxidation technique has swiftly become a significant portion of the water treatment procedure, and multiple semiconductor photocatalysts have emerged to treat water phase contaminants. Some typical semiconductor photocatalysts comprise ZnO [14], TiO 2 [15], g-C 3 N 4 [16], Fe 2 O 3 [17], CdS [18], MoS 2 [19], etc. Nevertheless, these photocatalysts still possess explicit restrictions in practical largescale application. ...
Designing and simulating an effective photocatalytic material having a suitable bandgap to degrade organic pollutants is essential for environmental remediation. This paper describes the development of a class of nanostructure, La2Cu2O5, for photocatalytic decomposition of various types of organic pollutants under UV and visible lights. La2Cu2O5 nanostructures were synthesized by a rapid and environmentally friendly sonochemical technique for the first time. The impacts of molar ratio of precursors, calcination temperature, power, and time of sonication were scrutinized for the synthesis of La2Cu2O5 nanostructures with relevant attributes in terms of purity, particle size, and morphology. The bandgap of these nanostructures was calculated at 3.25 eV, making them profitable for contaminant degradation in the UV region. The photocatalytic activity of the desired La2Cu2O5 was examined for photodegradation of multiple pollutants, such as thymol blue, acid black, methyl violet, rhodamine B, phenol red, malachite green, acid Yellow, and erythrosine for the first time. The La2Cu2O5 nanocatalyst revealed premium performance over the degradation of the mentioned pollutants. La2Cu2O5 was capable of degrading the acid black contaminant better (80.1%). The highest photocatalytic efficiency was obtained at a greater rate constant reaction (k = 0.01332 min⁻¹).
