Presence Of Carbon Nanotubes Research Articles

Study on the fluidity, mechanical and fracture behavior of ABS/TPU/CNT nanocomposites

Acrylonitrile butadiene styrene has relatively good mechanical performances, but its low melt fluidity limits the production of thin parts. In this research, acrylonitrile butadiene styrene/thermoplastic polyurethane (ABS/TPU) blends and ABS/TPU/CNT nanocomposites were prepared by employing melt-mixing process. The melt fluidity, mechanical and fracture behavior of different samples were evaluated. The morphology of fracture surfaces was studied by scanning electron microscopy. The addition of TPU into ABS substantially elevated the melt flow index, but noticeably weakened the notched impact toughness. The presence of carbon nanotubes in ABS/TPU blend promoted the mechanical performances and developed a rough fracture surface morphology. The notched impact resistance and essential work of fracture in nanocomposite containing 0.1 wt.% CNT showed about 95 and 50% increases respectively as compared to ABS/TPU (90/10) blend. In the presence of 0.3 wt.% CNT, the plane stress condition favorably dominated the toughness behavior, enhancing the non-essential work of fracture and crack propagation energy. The appropriate dispersion of carbon nanotubes and their adhesion to ABS/TPU polymer matrix were considered as the prominent factors affecting the fracture resistance of ABS/TPU/CNT nanocomposites.

Water distribution in confined space of single-wall carbon nanotube

Since the discovery of carbon nanotubes (CNTs), they have attracted extensive attention from scholars in various fields because of their excellent properties. The hollow-structured CNTs are often regarded as conduits and containers, which can act as nano-channels for various molecular substances in the membrane structure. As a source of life, water is indispensable to any living organism. In the application of carbon nanotubes as nanochannels, the most important is the ability of carbon nanotubes to store and transport liquids, especially nanoscaled aqueous solutions. Water molecular clusters in confined spaces exhibit unusual structures and properties. The study of special water structures in carbon nanotubes is of great theoretical importance in chemistry, biology and materials science. There are great difficulties in making the experiment on a nanoscale, but molecular dynamic simulation enables us to better study and analyze the structure and properties of water in confined space of CNT on a nanoscale. One has also studied the influence of temperature on the structure of water, but there are few studies focusing on the effect of temperature on the structure of water in confined space. Therefore, molecular dynamics simulation is used to investigate the effects of CNT diameter, CNT chirality and temperature on the water structure and distribution in a confined space. The simulation calculation is completed by GROMACS, the SPE/C water model is used for water molecules, and GROMOS96 54a7 force field is used. Because of the presence of carbon nanotubes, water molecules tend to line up against the walls of the tubes, both inside and outside. In addition, water molecules tend to form highly ordered multi-ring structures in the carbon nanotubes with a size of 1.018–1.253 nm at a certain temperature. It is difficult to form the ordered structure of water in the outer carbon nanotubes. In the above range, with the increase of pipe diameter, the structure of multi-element ring water changes from three-element ring to six-element ring. On the one hand, the ordered structure depends on the diameter of the carbon nanotube, but the chirality of the carbon nanotube does not have a great influence on it. On the other hand, the stability of the ordered structure is temperature-dependent, and the ordered structure of multiple ring water in the carbon nanotube with a larger diameter is more likely to disappear with the increase of temperature. The van der Waals potential distribution is calculated by Multiwfn, and it is concluded that the van der Waals potential inside the tube is extremely low, resulting in a very large dispersion effect, and molecules can spontaneously move from the outer area to the tube. The van der Waals potential can also be negative outside the tube. This explains why water molecules tend to line up against the wall of the tube.

INFLUENCE OF CARBON NANOTUBES REINFORCEMENT ON CHARACTERISTICS OF THERMALLY SPRAYED CERAMIC COATINGS

The influence of reinforcement of carbon nanotubes (CNTs) on microstructural features and mechanical properties of thermally sprayed Al2O3–3[Formula: see text]wt.%TiO2and WC–20[Formula: see text]wt.%Co coatings was investigated. Alumina–Titania coatings were deposited by Air Plasma Spraying (APS) and Tungsten Carbide–Cobalt coatings were deposited by High-Velocity Oxy-Fuel (HVOF) spraying process. The coatings obtained with reinforcement of CNTs were characterized to interpret the microstructural changes and also to evaluate the variation in their mechanical properties. The percentage composition of CNTs in both APS and HVOF coatings systems were varied in the order of 2, 4, and 6[Formula: see text]wt.%. It has been found that homogenous dispersion of carbon nanotubes in the coating systems results in increased microhardness and reduced surface roughness. Also, the microstructural features of the coating systems clearly showed that the coatings are denser with fewer pores due to the presence of CNTs.

Preparation of Hybrid Polyaniline/Nanoparticle Membranes for Water Treatment Using an Inverse Emulsion Polymerization Technique under Sonication

This manuscript describes a novel in situ interfacial dynamic inverse emulsion polymerization process under sonication of aniline in the presence of carbon nanotubes (CNT) and graphene nanoparticles in ethanol. This polymerization method is simple and very rapid (up to 10 min) compared to other techniques reported in the literature. During polymerization, the nanoparticles are coated with polyaniline (PANI), forming a core-shell structure, as confirmed by high-resolution scanning electron microscopy (HRSEM) and Fourier-Transform Infrared (FTIR) measurements. The membrane pore sizes range between 100–200 nm, with an average value of ~119 ± 28.3 nm. The film resistivity decreased when treated with alcohol, and this behavior was used for selection of the most efficient alcohol as a solvent for this polymerization technique. The membrane permeability of the PANI grafted CNT was lower than the CNT reference, thus demonstrating better membranal properties. As measured by water permeability, these are ultrafiltration membranes. An antimicrobial activity test showed that whereas the reference nanoparticle Bucky paper developed a large bacterial colony, the PANI grafted CNT sample had no bacterial activity. The thicker, 2.56 mm membranes exhibited high salt removal properties at a low pressure drop. Such active membranes comprise a novel approach for future water treatment applications.

Effect of Humidity on Gas Sensing Performance of Carbon Nanotube Gas Sensors Operated at Room Temperature

Carbon nanotubes (CNTs) have shown promising results for gas sensing due to their high surface area. Since humidity has a great impact on the electrical conductivity of resistive CNT gas sensors, we have investigated the change of humidity on their sensing properties. In this study, we fabricated vertically aligned CNT-based gas sensors for the detection of volatile organic compounds. The morphologies and phase structures of the fabricated samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR), confirming the presence of CNT with some surface impurities. It was found that a relative humidity increase from 10% to 80% can reduce the electrical conductivity of the sensor by around 4%. On the other hand, for a humidity above 80% the conductivity increased slightly. The fabricated device has been used as a gas sensor for volatile organic compounds, and the cross-sensitivity to humidity was investigated. It was found that in the fabricated sensors, a change in humidity up to 80% results in a 40% decrease in the response for the studied organic compounds.

Effect of carbon nanotubes grown temperature on the fracture behavior of carbon fiber reinforced magnesium matrix composites: Interlaminar shear strength and tensile strength

The design of an interfacial structure is particularly important for load transfer in composites. In this paper, different amounts of carbon nanotubes (CNTs) were grafted onto the carbon fiber (CF) surface by adjusting grown temperature using injection chemical vapor deposition (ICVD). The prepared CF preform grafted with CNTs (CNTs-CF) were used to reinforce magnesium alloy by squeeze casting process. The microstructures were analyzed by means of optical microscope (OM) and scanning electron microscope (SEM), and the interlaminar shear strength (ILSS) and tensile strength of the composites were determined by double-notch shear test and tensile test. The results indicated that moderate ILSS was more conducive to improving the tensile properties of carbon fiber reinforced magnesium matrix (Cf/Mg) composites. Compared with Cf/Mg, the tensile strength of composite with CNTs increased by about 80%. For Cf/Mg composites grafted with CNTs, CNTs had the effects of delaying crack propagation and increasing energy consumption by the pull-out and bridging mechanism, which were the main reasons for improving the strength. The analysis of shear fracture surface showed that the crack propagation path can be optimized by adjusting the amounts of grafted CNTs. The presence of CNTs affects the stress distribution and consequently the crack initiation as well as the crack propagation.

Enhanced Performance of Carbon Nanotube Immobilized Membrane for the Treatment of High Salinity Produced Water via Direct Contact Membrane Distillation

Membrane distillation (MD) is a promising desalination technology for the treatment of high salinity water. Here, we investigated the fouling characteristics of produced water obtained from hydraulic fracturing by implementing a carbon nanotube immobilized membrane (CNIM) via direct contact membrane distillation. The CNIM exhibited enhanced water vapor flux and antifouling characteristics compared to the pristine membrane. The normalized flux decline with the polytetrafluoroethylene (PTFE) membrane after 7 h of operation was found to be 18.2% more than the CNIM. The addition of 1-Hydroxy Ethylidene-1, 1-Diphosphonic acid (HEDP) antiscalant was found to be effective in reducing the membrane fouling. The salt deposition on the membrane surface was 77% less in the CNIM, which was further reduced with the addition of HEDP in the feed by up to 135.4% in comparison with the PTFE membrane. The presence of carbon nanotubes (CNTs) on the membrane surface also facilitated the regenerability of the membrane. The results indicated that the CNIM regained 90.9% of its initial water flux after washing, whereas the unmodified PTFE only regained 81.1% of its initial flux after five days of operation.

Evaluating the effect of carbon nanotubes (CNTs) and recycled glass powder (RGP) on the rheological and mechanical properties of bitumen and hot mix asphalt (HMA)

ABSTRACT By modifying the conventional and mechanical properties of bitumen and asphalt mixtures with recycled additives such as Recycled Glass Powder (RGP) as well as new additives such as Carbon Nanotubes (CNTs), in addition to improving the properties of bitumen and asphalt mixtures, it can also be environmentally friendly. For the first time, this article evaluated the rheological and mechanical properties of bitumen and Hot Mix Asphalt (HMA) with CNTs and RGP. For this purpose, a total of 17 types of asphalt mixes were made. CNTs and RGP were added to bitumen with aggregate at different percentages. Finally, an economic analysis was conducted for a 3-Line road. The results of the rheological properties of bitumen showed that adding additives reduced the thermal susceptibility of bitumen. Also, the results of the Marshall Test showed that the stability of samples containing RGP and CNTs increased due to the more effective presence of CNTs compared to the presence of RGP. Moreover, it was found that the Marshall ratio of the modified samples increased. Economically, the addition of RGP and CNTs led to an uneconomical design. Finally and considering all aspects, C1G25 asphalt mix is recommended due to technical-economical properties.

Hybrid effect of carbon nanotubes and polypropylene microfibers on fire resistance, thermal characteristics and microstructure of cementitious composites

The current study experimentally investigates the hybrid effect of carbon nanotubes (CNTs) and polypropylene (PP) microfibers on fire resistance and thermal characteristics of cementitious composites. Cement mortar with small dosages of CNTs and PP fibers are prepared and heated at 150 °C, 200 °C, 450 °C, and 600 °C. The residual mechanical properties, microstructure deterioration, and thermal properties of heated mortar are reported. The results shows the ability of the CNTs to enhance the residual compressive and flexural strengths of PP fiber-reinforced mortar exposed to elevated temperature up to 600 °C. Residual fracture energy is improved by adding small dosage of PP microfibers and CNTs. The improvement was less significant in the case of exposure temperatures greater than melting point of the fibers. Thermal conductivity of cement mortar is increased by the addition of the CNTs but not the PP fibers for all heating levels. According to the DSC and TGA analysis, presence of CNTs increased heat absorption needed for decomposition of the hydration products of cement mortar whereas the presence of the fibers has minor effect. SEM images show that the CNTs filled the pores and delayed the initiation of the cracks, whereas the PP fibers bridged these cracks and mitigated their propagation.

Preparation carbon nanotube-decorated carbon fibers under low pressure for epoxy-based unidirectional hierarchical composites with enhanced interlaminar shear strength

Multi-walled carbon nanotubes (CNTs) were grown in-situ on the surface of carbon fibers (CFs) at low pressure by a vertical chemical vapor deposition (CVD) reactor. The surface of CFs was modified by electrochemical anodization, and the growth morphology and other properties of CNTs were analyzed by detailed techniques. The CNT-grown CF reinforced unidirectional hierarchical composite material based on the epoxy resin was prepared. The interlaminar shear strength (ILSS) indicates that the maximum strength of the composites reaches 108 MPa after the CNTs are grown on the CF surface with a 25.2% increase than that of the desized CF composites. The fracture surface of composites was observed by scanning electron microscopy (SEM) to further understand the interfacial fracture behavior and enhancement mechanism of CNTs-CF/epoxy composites. The significant improvement in the overall performance of the hierarchical composites can be attributed to the increased adhesion of the interface between the fibers and the resin. The presence of CNTs can restrict the molecular movement of the resin and achieve a strong anchoring interaction, thereby increasing the strength and toughness of the composites and reducing the stress concentration between the layers.

Investigations on structural, morphological and electrochemical properties of Co(OH)2 nanosheets embedded carbon nanotubes for supercapacitor applications

The nanostructured cobalt hydroxide [Co(OH)2] embedded carbon nanotubes (CNT) have been synthesised by a simple chemical reflux method. The crystallinity of cobalt hydroxide has been confirmed by using powder X-ray diffraction data. The presence of CNT in the synthesised nanocomposite is also examined. Fourier transform infrared spectroscopy reveals the OH and CoO vibrations in the Co(OH)2/fCNT nanocomposite. SEM and TEM images expose the surface morphology of Co(OH)2 sheet that is embedded over carbon nanotube. The electrochemical performance of the Co(OH)2 embedded fCNT has been examined by the cyclic voltammetry in 6 M potassium hydroxide (KOH) electrolyte in room temperature. Co(OH)2 embedded fCNT nanocomposite exhibits higher specific capacitance up to 1006.8 F/g at 0.5 mV s−1 scan rate. The specific capacitance of Co(OH)2 embedded fCNT nanocomposite is calculated from the charge-discharge curve. The synthesised hybrid nanocomposite is used as a cathode, and the functionalized CNT is used as an anode. These are used to fabricate an asymmetrical supercapacitor device. The device is delivered to a high power density of 7000 W kg−1 and energy density of 17 W h kg−1 in the potential window from 0 V to 1.4 V. The results of hybrid Co(OH)2/fCNT||fCNT asymmetrical supercapacitor exhibit better cycle stability up to 5000 cycles. The usefulness of Co(OH)2/fCNT||fCNT asymmetrical supercapacitor is analysed for energy storage devices.

Dielectric investigations on carbon nanotubes doped polymer dispersed liquid crystal films

We obtained carbon nanotubes (CNTs) doped polymer dispersed liquid crystal (PDLC) films using the nematic E7 and polymethyl methacrylate, a composite that combines the benefic characteristic of the liquid crystals (LC) and carbon nanoparticles. The clearing temperatures recorded by differential scanning calorimetry for the PDLC blends were found to be lower than the value recorded for pure E7 LC mixture with no significant impact of the CNTs’ concentration. Broadband dielectric spectroscopy (DS) measurements were performed in the $$ (10^{ - 1} \div 10^{7} )\;{\text{Hz}} $$ frequency range, in the temperature domain (280–350) K. From the DS study, a two order magnitude variation of the conductivity over the entire temperature range was observed. The presence of CNTs results in an increase of electrical conductivity, with increasing concentration. Because the loss tangent spectra have complex shapes, they were fitted using the generalized Havriliak–Negami functions, and the characteristic relaxation times were extracted. The dependency of the characteristic relaxation time on temperature was modeled using the Vogel–Fulcher–Tammann function, and it showed a temperature variation according to the Arrhenius law. The increase of the CNT concentration increases the activation energy of the molecular electric dipoles of the LC. The interface LC-polymer interactions influence the nematic to isotropic phase transition of the LC.

Influence of CNTs addition on structural and superconducting properties of mechanically alloyed MgB<sub>2</sub>

The result of adding carbon nanotubes (CNTs) to the lattice parameters, critical temperature and electrical resistivity of the MgB2 superconductors is reported. Structurally, the addition of CNTs was found to decrease the a-lattice from 3.086 Ã… of CNTs free sample to 3.078 Ã… and 3.074 Ã… of 5% and 10% CNTs added samples due to a substitution of C at the B site which presence in the form of Mg(B1-xCx)2 main phase. The doping level x of CNTs added samples were 2.25 at% and 3.75 at% respectively. The unreacted CNTs presence as the second phase and further acting as the suppression agent for crystallite growth. The addition of CNTs is also to refine the grain size and improves the grain connectivity. Samples show a metallic behavior which observed only at temperatures above ~41 K, below which, a sharp transition of resistivity occurred toward zero resistivity, confirming the superconductivity behavior. This study concluded that the effect of CNTs addition affects the structural parameters and superconducting properties. The addition of the CNTs to 5% and 10% has changed the zero critical temperature of the sample material to respectively 39.20 and 38.02 K from 39.31 K of CNTs free sample.

Influence of CNTs addition on structural and superconducting properties of mechanically alloyed MgB 2

The result of adding carbon nanotubes (CNTs) to the lattice parameters, critical temperature and electrical resistivity of the MgB 2 superconductors is reported. Structurally, the addition of CNTs was found to decrease the a -lattice from 3.086 A of CNTs free sample to 3.078 A and 3.074 A of 5% and 10% CNTs added samples due to a substitution of C at the B site which presence in the form of Mg(B 1-x C x ) 2 main phase. The doping level x of CNTs added samples were 2.25 at% and 3.75 at% respectively. The unreacted CNTs presence as the second phase and further acting as the suppression agent for crystallite growth. The addition of CNTs is also to refine the grain size and improves the grain connectivity. Samples show a metallic behavior which observed only at temperatures above ~41 K, below which, a sharp transition of resistivity occurred toward zero resistivity, confirming the superconductivity behavior. This study concluded that the effect of CNTs addition affects the structural parameters and superconducting properties. The addition of the CNTs to 5% and 10% has changed the zero critical temperature of the sample material to respectively 39.20 and 38.02 K from 39.31 K of CNTs free sample.

Nanomechanics of graphene oxide-bacteriophage based self-assembled porous composites

Graphene oxide, integrated with the filamentous bacteriophage M13, forms a 3D large-scale multifunctional porous structure by self-assembly, with considerable potential for applications. We performed Raman spectroscopy under pressure on this porous composite to understand its fundamental mechanics. The results show that at low applied pressure, the sp^2 bonds of graphene oxide stiffen very little with increasing pressure, suggesting a complicated behaviour of water intercalated between the graphene layers. The key message of this paper is that water in a confined space can have a significant impact on the nanostructure that hosts it. We introduced carbon nanotubes during the self-assembly of graphene oxide and M13, and a similar porous macro-structure was observed. However, in the presence of carbon nanotubes, pressure is transmitted to the sp^2 bonds of graphene oxide straightforwardly as in graphite. The electrical conductivity of the composite containing carbon nanotubes is improved by about 30 times at a bias voltage of 10 V. This observation suggests that the porous structure has potential in applications where good electrical conductivity is desired, such as sensors and batteries.

Behaviour of ultra-high performance concretes incorporating carbon nanotubes under thermal load

Ultra High Performance Concretes (UHPC) are known for exceptional mechanical and durability properties due to optimized particle packing and a denser microstructure. However, the very tight packing of particles resulting in a dense microstructure can be a cause of problems in UHPCs when exposed to higher temperatures. The low porosity delays the movement of water vapour inside de concrete and a layer of condensed water is created, preventing water to escape the microstructure and increasing internal pressure, that may result in explosive spalling. In this research, carbon nanotubes (CNTs) were introduced in UHPCs to assess their influence on the properties after exposition to high temperatures. Specimens were subjected to slow and fast heating rates and occurrence of spalling was investigated. Mechanical tests, such as compressive strength (before heating and after heating) and splitting tensile strength were conducted to investigate the impact of CNTs on the mechanical properties. Gas permeability tests were performed to investigate alterations in porosity due to the presence of CNTs. Results show that the presence of CNTs can reduce the occurrence of spalling at additions of 0.05% and 0.10% by weight of cement. CNTs can also increase the residual strength at temperatures up to 300 °C at a slow heating rate. At the same time, the 28-day compressive and splitting tensile strengths remained unaltered and oxygen permeability coefficients were reduced when CNTs were added to the matrix.

4-Nitrobenzaldehyde removal by catalytic ozonation in the presence of CNT

4-nitrobenzaldehyde (4-NBA) degradation pathway was studied during single and catalytic ozonation processes. Multi-walled carbon nanotubes (CNT) were used as ozonation catalysts and different textural and chemical modifications were performed to obtain samples with enhanced catalytic activity (CNT(BM) and CNT-M(BM 4 h)). Single ozonation was capable of total pollutant degradation after 180 min of reaction; however, complete mineralization was not achieved, reaching nearly 40 % of total organic carbon (TOC) removal. Catalytic ozonation presented a faster pollutant removal rate, and a high content of organic matter was removed in the first 30 min of reaction. For this specific case, the incorporation of nitrogen heteroatoms in the CNT structure (sample CNT-M(BM 4 h)) did not actively contribute to increasing the performance of the material, achieving a mineralization degree very similar to that obtained with the commercial catalyst (CNT) at the end of the reaction. The most promising catalyst was the ball-milled sample, CNT(BM), attaining 60 % of mineralization degree after 180 min of reaction. The catalyst CNT(BM) proved to be stable even after several reuses, presenting a loss of efficiency of 15 % in terms of TOC from the first to the fifth cycle. Radical scavenger experiments revealed that there is a significant contribution of OH radicals during single ozonation, whereas for catalytic ozonation process the reaction mechanism is quite different with less involvement of OH radicals in solution and a large contribution of the pathway involving adsorption and surface reactions.

Influence of carbon nanotubes on heat transfer in MHD nanofluid flow over a stretchable rotating disk: A numerical study

AbstractThe transfer of heat is an important phenomenon in the several areas due to its numerous applications in industries. Several fluids like water, ethylene glycol and oil, and so on have very‐low thermal conductivities due to which the transfer of heat in these fluids become very low. To enhance heat transfer rate, carbon nanotubes (CNTs) including single‐walled CNTs and multi‐walled CNTs are suspended into base fluids, this mixture is known as nanofluid. The aim of this study is to examine the heat transfer rate of nanofluid in the presence of CNTs over a stretchable rotating disk. The mathematical model, developed by Tiwari and Das, is used and solved numerically by using the shooting method. The impacts of governing constraints on the dimensionless velocities, temperature, skin friction, and Nusselt number are investigated. It is noted that heat transfer rate increases by enhancing the concentration of CNTs into base fluids. The numerical results show that the solid volume fraction of the CNTs augment heat transfer rate more in ethylene glycol as compared with water.

Striking effect of carbon nanotubes on adjusting sc-CO2 foaming performance of PS/LLDPE blends and forming semi-open cellular structure

The effect of carbon nanotubes (CNTs) on the phase structure and foaming performance of PS/LLDPE blends during batch foaming of sc-CO2 was studied. It was found that the phase structure of PS/LLDPE = 50/50 blends with CNTs could be transformed from bi-continuous to sea-island morphology, when a sufficient quantity of CNTs nanofillers was added. As a result, the foaming ability of PS/LLDPE = 50/50 blends was improved effectively. Meanwhile, the critical value of CNTs for significantly improving the foaming ability of blends decreased slightly with the increase of foaming temperature. In contrast, for the PS/LLDPE blends with sea-island phase structure (such as 20/80), the addition of CNTs did not significantly change the morphology and foaming capacity of the blends. Very interestingly, the foam with semi-open cellular structure (meaning that there were small pores within the large cell wall) was obtained in the foamed PS/LLDPE blends after tetrahydrofuran (THF) etching PS phase. Benefiting from the interfacial channel effect formed by the presence of CNTs, the etching speed and efficiency of PS were significantly improved, and the size for the small pore on the cell wall could be adjusted by the content of PS dispersed phase in the PS/LLDPE/CNTs nanocomposites.

Pore and phase identification through nanoindentation mapping and micro-computed tomography in nanoenhanced cement

In this work, a methodology is presented in order to assess the microstructure of Portland Cement through advanced characterisation. Nanoindentation is used to determine reduced elastic modulus and hardness, which are involved in the design of construction materials. Elemental mapping and X-ray scanning microtomography were also used to establish structure-property relations through porosity distribution and morphology as well as phase identification by nanoindentation and image analysis. The variation of carbon nanotubes (CNTs) concentration between 0.02 and 1.0 wt% demonstrated alterations in phase composition, and thus the effect of CNTs reinforcement in hydration progress was clarified. Characterisation by all techniques identified 0.5 wt% concentration as promising due to the formation of higher density hydrated phases, even though total porosity was not minimized. This fact was explained by nanoindentation as enhanced Calcium-Silicate-Hydrates connectivity in the porous network was detected. The voids of cement were filled with low stiffness hydrated gel phases as a result of enhanced hydration in the presence of CNTs.