Percentage Of Carbon Nanotubes Research Articles

Nanomaterials in concrete: Enhancing strength and durability

Carbon nanotubes (CNTs) have received great attention for their applications in concrete due to their unique properties such as high strength, flexibility, and electrical conductivity. This study aims to investigate the effect of adding carbon nanotubes on the energy combination of the material. Concrete samples were prepared with different concentrations of carbon nanotubes and their mechanical properties were measured and compared with control samples without carbon nanotubes. The results show that the addition of carbon nanotubes increases the compressive and flexural strength of concrete. The findings suggest that incorporating carbon nanotubes into concrete could be a good way to improve concrete's mechanical properties and improve its performance in construction. Compared with white cement M20 samples aged 7, 14 and 28 days. The 28day maximum strength is stated below for 0.0045 wt.% SWCNT and MWCNT and 0.0030 wt.% SWCNT and MWCNT. It was determined that nanocomposites containing a lower proportion of long MWCNTs had properties comparable to nanocomposites containing a higher proportion of short MWCNTs. Many of the walls of the carbon nanotubes reach microcracks, indicating that the carbon nanotubes are cracked and pulled out. Besides the compression test, we also calculated the slit tensile strength by adding different percentages of carbon nanotubes. The usage percentage increased for 0.0015% MWCNTs and 0.0030% and 0.0045% SWNTs.

Analysis of static and dynamic mechanical properties of carbon black/carbon nanotubes hybrid filled natural rubber nanocomposites using coarse‐grained molecular dynamics

AbstractNanoparticle (NP)‐filled natural rubber (NR) has attracted much attention owing to their prominent mechanical strength, stiffness, and wear resistance. In this study, the static and dynamic mechanical properties of carbon black (CB)/carbon nanotubes (CNTs) hybrid filled NR nanocomposites are investigated using coarse‐grained molecular dynamics (CGMD) simulations. The non‐bonded coarse‐grained force fields for the CB/CNTs hybrid filled NR nanocomposites are constructed by combining several methods (i.e., effective force coarse‐graining, iterative Boltzmann inversion, and energy matching methods). The uniaxial tensile results indicate that the gradual replacement of CB by the same weight percentage of CNTs significantly improves the mechanical performances of the nanocomposites and increases the heterogeneity of the stress and strain distributions in the nanocomposites, which can be ascribed to the high mechanical strength of CNTs and the formation of the rigid interface networks between CNTs and the NR matrix due to the wrapping behavior of NR molecular chains on the surface of CNTs. Furthermore, the dynamic shear results demonstrate that the introduction of NPs significantly enhances the Payne effect of the nanocomposites, and the higher the CNT loading in hybrid NPs, the stronger the Payne effect. It is also found that the breakup of NP networks plays a dominant role for the Payne effect of filled rubber as compared to the interfacial separation between NPs and the rubber matrix. The present multiscale computational framework can be further extended to other polymer nanocomposites, and sheds new light on the design and exploration of polymer nanocomposites through bottom‐up prediction.

Nonlinear flutter response and reliability of supersonic smart hybrid nanocomposite rupture trapezoidal plates subjected to yawed flow using DQHFEM

In the realm of aerospace engineering, the analysis of flutter under supersonic flight conditions is of paramount importance. Hybrid nanocomposite materials, known for their lightweight and high-strength properties, are increasingly being employed in aerospace engineering. This article examines the supersonic flutter behavior and reliability of smart hybrid nanocomposite trapezoidal plates, considering various practical factors. The structure is subjected to yawed flow conditions, a scenario often encountered during supersonic flight. The importance of the hybrid nanocomposite in various applications such as aerospace, public security tools, and so on, therefore the hybrid nanocomposite core layer reinforced by carbon nanotubes (CNTs) and carbon fibers incorporates real-world material complexities such as agglomeration, waviness, and random orientation of fibers into the analysis. The complexities and the accurate characterization of the hybrid nanocomposite properties are determined by using the Halpin-Tsai model. Going beyond the current field of application, the core layer is integrated with actuators and sensors, respectively at the top and bottom layers. The structure is controlled by a Proportional-Derivative (PD) controller, simulating real-world control mechanisms used in aerospace systems for flight safety. The structure is modeled by the nonlinear Refined Zigzag Plate (RZP) theory. The advanced numerical technique of the Differential Quadrature Hierarchical Finite Element Method (DQHFEM) for the solution of the motion equations provides a robust framework for studying the intricate flutter and aerodynamic behavior of the smart hybrid nanocomposite trapezoidal plates. The examination of the reliability of the structure employs the three-term conjugate finite-step length (TCFS) method. This technique is constructed through the utilization of the conjugate gradient method, incorporating a controlled scalar parameter to ensure numerical stability. The results of this article have been validated against existing experimental and numerical studies, demonstrating the validity of the presented model and the numerical technique used. The effects of various parameters, such as the smart controller, applied output voltage to the actuator layer, volume percentage of CNTs, agglomeration, and waviness of carbon fibers, geometric parameters, the skew angle of the plate, rupture, and yawed angle flow are examined on the flutter behavior, critical aerodynamic pressure, nonlinear frequency, and reliability index. The results indicate that the controlled system exhibits an approximately 18% increase in the flutter critical aerodynamic pressure compared to the uncontrolled system, along with a significant 50% rise in flutter frequency. Additionally, the structure with rupture displays approximately 20% lower flutter aerodynamic pressure and a 25% lower flutter frequency compared to a healthy plate. In the absence of carbon nanotubes and under positive external voltage, a damage parameter exceeding 0.35 leads to a reliability index below 0.931, indicating a risk of structural failure. Two solutions involve switching to negative voltage or increasing the volumetric percentage of carbon nanotubes, resulting in a 43% or 118% increase in reliability, respectively.

Improve the Hot Corrosion Behaviors of the Inconel 738LC Coating with Nano YSZ–CNTs

In this work, Inconel 738LC is coated with coatings with nano Yttria Stabilized Zirconia (YSZ) with different percentages of Carbon Nano Tubes (CNTs) which were done by using the technique of the plasma thermal spray. YSZ coating with different percentages of CNTs (100% nano YSZ, 96% nano YSZ + 4% CNTs, 94% nano YSZ + 6% CNTs, and 92% nano YSZ + 8% CNTs), adopting the plasma spray technique. The behavior of the Inconel 738LC alloy with and without artificial ash (67% wt. H2SO4 and 33% wt. V2O5) at different temperatures (650 oC, 750 oC, 850 oC, and 950 oC) was investigated. The cycles of hot corrosion and oxidation were achieved in an electric furnace for 10 cycles of 5 h each. At the completion of each cycle, the weight changes were measured and recorded. The Search Engine Marketing (SEM) and X-RayDiffraction (XRD) achieved for all the specimens were noted, prior and post the corrosion.

Effect of CNT filler and temperature on fracture toughness of epoxy composites reinforced with carbon fabric

AbstractIn present research the fracture behavior of carbon fabric‐epoxy composites (CE composites) was evaluated with the addition of 0.1, 0.2, 0.5, and 0.75 weight percentages of carbon nano tubes (CNTs) at different temperatures. The CE composites with different wt.% of CNT were fabricated using land layup method and cured by hot pressing. The fracture toughness of fabricated composites was evaluated in mode–I condition at different temperature. From the results it was shown that the highest fracture toughness was observed at 0.75 wt.% of reinforcement of CNT functional fillers. The fracture toughness of 0.75 wt.% CNT filled CE composites was increased by 19.73% compared to unfilled CE composites. The fracture toughness of CNT filled CE composites diminishes with increase in temperature and the composite filled with 0.75 wt.% CNT exhibits better fracture toughness than the unfilled CE composite at all the temperatures. The fracture toughness was improved by 57.76% and 71.65% at 40 and 60°C, respectively, at 0.75 wt.% reinforcement of CNT fillers. The fractured surfaces of composites were analyzed using Scanning Electron Microscope (SEM) to study the filler contribution to enhance the fracture toughness and failure mechanism of composites.

Effect of CNT on the Physical and Electrical Properties of CNT/UHMWPE Nanocomposite Sensor

Nano Composites Polymer represents a class of multifunctional sensors that can effectively respond to changes in electrical properties when subjected to external forces acting on their physical characteristics. The research aims to develop nanocomposite polymer sensors that can respond well and be easily molded. The experimental process involved mixing Ultra-high-molecular-weight polyethylene (UHMWPE) with 1%, 4%, and 7wt% of carbon nanotubes (CNT) using the hot pressing method, leading to remarkable improvements in the electrical and mechanical properties of the composite polymers. The distribution patterns of CNT at different weight ratios showed that 4 wt% exhibited a more desirable and uniform distribution. However, at 1 wt%, the amount of CNT was insufficient, resulting in scattering and disconnection. On the other hand, at 7 wt%, the CNT distribution appeared to be densely bundled in some areas, leading to detrimental effects on the mechanical and electrical properties, as well as the electrical percolation threshold of the composites. Regarding the mechanical properties test, significant improvements were found at 4 wt% for the tensile strength, but when the filler content exceeded 4 wt%, there was a reduction in the tensile strength of the CNT/UHMWPE composites. Additionally, the change in electrical resistance based on the physical characteristics was examined by varying the percentage of CNT added to UHMWPE through compression and bending tests. The compression tests were conducted using weights ranging from 0 to 10 kg, and the bending tests were performed with angles from 0° to 40° degrees. In terms of the test results, however, with 4% and 7% wt% CNT filler, the electrical resistance values could be successfully measured by a multimeter. The electrical percolation threshold was found to be very good at 4 wt%. For the compression testing results, the resistance values ranged from approximately 27.329 to 32.389 KΩ for the 4 wt% filler and from 0.504 to 0.552 KΩ for the 7 wt% filler. As for the bending testing, the resistance values ranged from approximately 4.019 to 4.044 KΩ for the 4 wt% filler and from 0.427 to 0.432 KΩ for the 7 wt% filler.

Durability Behaviours of Engineered Cementitious Composites Blended with Carbon Nanotubes against Sulphate and Acid Attacks by Applying RSM Modelling and Optimization

Chemical deterioration, including sulphate and acid attacks, is a major issue affecting the long-term durability of engineered cementitious composite (ECC) constructions that contact water from various sources, including groundwater, seawater, sewer water, and drinking water. This research enhances ECCs’ strength and resilience against chemical attack by combining cementitious composites with multiwalled carbon nanotubes (CNTs) and polyvinyl alcohol (PVA) fibre volume fractions using multiobjective optimization. The central composite design (CCD) of RSM was applied to generate thirteen mixes of different potential combinations of factors (multiwalled CNTs: 0.05% to 0.08%, PVA: 1–2%) and eight outcome responses were studied, although eight response models—six quadratic and two linear—were successfully designed and assessed using analysis of variance. The coefficients associated with R2 for all the models were exceptionally high, with values varying from 84 to 99 percent. The multiobjective optimization predicted the best outcomes and developed optimal values for both variables (CNTs: 0.05% and PVA: 1%). The results showed that, at 0.05% of CNTs in ECCs, an ultimate improvement of 23% in compressive strength was seen. Additionally, when CNTs are used to grow in the ECC matrix, the expansion owing to sulphate resistance and length change due to acid attack are both reduced. In addition, when the percentage of CNTs increases in ECCs, the weight loss and pH value owing to acid attack, as well as the rate of chloride permeability test results, are reduced. Furthermore, CNTs and PVA fibres with 0.05% and 1–1.5% concentrations offer optimal construction sector outcomes.

Effects of Carbon Nanotubes on Thermal Behavior of Epoxy Resin Composites

Human society’s need to build low-weight, high-strength and durable structures has increased the demand for composite materials. In this case, composites are used where high mechanical strength, low weight, sound and thermal insulation properties are required. One of the most important issues now is designing materials and coatings aimed at reducing heat loss and resisting high temperatures. One way to address this problem is to develop a technique for preparing and applying composite materials that slow down their heating applied to a surface. In this study, carbon nanotubes (CNTs) reinforced composites were fabricated using silicone molding to be applied to honeycomb sandwich structures. To determine the effect of CNTs on the thermal behavior of the sandwich panels, different weight percentages of this material (0.025, 0.05. 0.075 wt.%) were added to the epoxy resin. The results showed that the thermal stability of the epoxy composites was directly related to the increase in the percentage of CNTs as the CNT content increased to 0.075 wt.%, and the thermal degradation temperature of the epoxy composites increased by 14 °C. In addition, the energy absorption increased by 4.6% with an increase in CNTs up to 0.075 wt.%. Density measurements showed that the density of the nanocomposite samples increased by adding CNTs to pure epoxy resin. The actual densities of the samples reinforced with 0.025, 0.05, and 0.075 wt.% CNTs are 0.925, 0.926, and 0.927 of the theoretical density, respectively. Since the CNT dispersion uniformity in the epoxy matrix can significantly affect the properties of the composites, in this study, a new method of dispersing CNTs in the epoxy resin matrix resulted in higher thermal conductivity while using lower amounts of CNTs compared to other studies. The storage modulus of the epoxy matrix composites reinforced with 0.05 wt.% in this study was 25.9% and 6.9% higher than that from the previous study reinforced with 0.1 wt.% and 0.25 wt.% CNTs, respectively. Furthermore, the tanδ and loss modulus of the composite reinforced with 0.05 wt.% CNTs in this study were 52% and 54.5% higher than that from the previous study with 0.1 wt.% CNTs, respectively. This study provided an optimal approach for designers and engineers who want to effectively design their composite honeycomb sandwich structure with better thermal properties.

Railway ballast track hanging sleeper defect detection using a smart CNT self-sensing concrete railway sleeper

Health monitoring of railway tracks has become an increasingly valuable aspect of railway track maintenance and is taking on a leading role. Considering the current limitations in monitoring of railway components such as ballast and sleepers, a new method of self-sensing smart railway sleeper has been proposed in this research. Carbon nanotubes (CNT) as a functional filler can provide intrinsic self-sensing properties to railway sleepers to detect hanging sleeper defects. Therefore, to analysis the effectiveness of the proposed idea to detect hanging sleeper defect the self-sensing behavior of CNT-cement composite specimens and real scale railway sleepers are studied with three different percentages of CNT as 0.5%, 0.75%, and 1% by cement weight under different support conditions of disturbed and full ballast supports, and different electrode distances. Experimental results show that CNT generates sensitivity for the specimens corresponding to applied loads. This sensitivity is the highest for 0.75 %CNT and 0.5 %CNT and inner electrode distances by 0.043 and 0.036 10-6.N−1. Considering the mechanical performance and sensitivity coefficient (kx), 0.5 %CNT and inner electrodes are the optimal combination of electrode distance and CNT content. FE modeling study shows that hanging defect highly enlarges the dynamic response of hanged sleepers than full support railway sleepers. This increase in dynamic loads due to hanging defect results in hanged sleeper detection using distinguishable sensitivity coefficient values. The kx response in 150 kN axle load is highly relied on train speed as the difference percentage of kx increases by 7% for speed of 100 km/h to 300 km/h.

To Improve the Strength of Concrete by Using Carbon Nanotubes (CNTs)

Abstract: The use of carbon nanotubes (CNTs) in concrete has been gaining attention due to their unique properties, such as high strength, flexibility, and electrical conductivity. This study focuses on investigating the effect of adding CNTs to concrete mixtures on the strength of the resulting material. The concrete specimens were prepared with different percentages of CNTs, and their mechanical properties were measured and compared to those of control specimens without CNTs. The results showed that the addition of CNTs significantly improved the compressive and flexural strength of the concrete. The findings suggest that the incorporation of CNTs in concrete mixtures could be an effective way to enhance the mechanical properties of concrete and improve its performance in construction applications. Compared to the plain cement sample at 28 days. The highest increase in strength at 28 days for the 0.0045 wt.% MWCNTs and the 0.0030 wt.% MWCNTs was 43.4% and 37.79% respectively. It is concluded that nano composites with low concentration of long MWCNTs give comparable mechanical performance to the nano composites with higher concentration of short MWCNTs. Many of the MWCNIs were stretching across the micro-cracks showing CNT's breakage and pull-out. In addition to the compression test we had calculated the split tensile strength by adding the multi-walled carbon nano tubes by increasing the proportion as per the percentage. For 0.0015% MWCNT's, 0.0030% and 0.0045% the percentage of strength increased by 25.6%, 44.63% and 51.21% respectively.

Influence of carbon nanotube on the mechanical and electrical characteristics of concrete – A review

Conventional concrete, which is composed of cement, coarse aggregate, fine aggregate, water, and superplasticizer, has the disadvantages of low maximum split tensile strength and low ductility, which can lead to sudden failure. However, the use of carbon nanotubes (CNT) can improve the binding to detect cracks in the structure before it collapses, as well as increase the maximum split tensile strength and ductility. The CNT is utilized to improve the mechanical characteristics of concrete, including its compressive strength, split tensile strength, and flexural strength. In addition to self-sensing, researchers examined the impact of carbon fiber and CNT particles on the mechanical characteristics of beam specimens with the suggested reinforcement arrangement. In this review, mechanical tests such as compressive strength, split tensile strength, and flexural strength are examined to determine the impact percentage of CNT that is beneficial for enhancing the strength of concrete. The study also further reviewed the resistivity of self-sensing CNT concrete. The review explored that CNT also improves electrical properties, such as resistivity and conductivity, and thermal conductivity of cement composites. To increase the electrical conductivity of beams, CNT and chopped carbon fibers (CF) were utilized. As a Nano-material, CNT may be widely distributed in the concrete through a proper mixing strategy. Due to their high modulus of elasticity, tensile strength, and yield strain, CNTs are an appealing material for concrete reinforcement. Using ultrasonication and a superplasticizer, a solution of dispersed CNTs with exceptional workability in concrete was made because the accumulation of CNTs significantly decreased the electrical resistance. The purpose of adding CNT to concrete for the Structure Health Monitoring technique is to detect building fractures using self-sensing concrete (SHM). The research finally concludes that CNT is highly beneficial to enhance compressive strength, flexure strength, and split tensile strength.

Experimental and numerical study of tensile behavior of carbon nanotube reinforced glass-epoxy composite: The multiscale approach

In this paper, a multiscale approach is presented for strength and tensile modulus prediction of carbon nanotube (CNT) reinforced glass-epoxy composite. At the micro-scale, the three-dimensional representative volume element is obtained by randomly orienting the carbon nanotube in the resin according to the weight percentage. The interphase of the nanotube and resin is modeled using a cohesive element method. The behavior of the resin is accounted with a quasi-brittle non-local damage model. At the Mesoscale, the representative volume element is estimated by using the weight percentage of glass fiber and resin generalized with nanotubes. Finite element analyses were conducted to estimate the effective mechanical properties through numerical homogenization. The effect of different percentages of carbon nanotubes on tensile behavior was investigated experimentally and numerically. The results show that adding carbon nanotubes improves the tensile modulus by about 25% and the tensile strength by about 53%. In the numerical study, the strength of the composite is predicted with good accuracy by modeling the damage of resin, glass fibers, and fracture toughness mechanisms of carbon nanotubes such as bridging and pull-out of carbon nanotubes. A good agreement was observed between the simulation results and the experimental results at different percentages of carbon nanotubes.

OPTIMIZATION OF NANO FILLERS CONTENT TO FABRICATE ELECTRICALLY CONDUCTIVE CARBON FIBER REINFORCED POLYMER FOR SPACE USE

Carbon fiber reinforced polymer (CFRP) composites are used in aerospace sector due to their high specific stiffness and light weight, and are a better alternative for aluminum, Invar, and Kovar alloys. However, lower electrical and thermal conductivity of CFRP was the main restriction for extensive use in aerospace sector as compared to aluminum alloys. High aspect ratio, high mechanical stability, high electrical as well as thermal conductivity of carbon nanotubes (CNTs) makes them excellent filler material in CFRP to enhance its electrical, mechanical, and thermal properties. CNTs add synergetic effect to CFRP giving improved CNT-CFRP composites in terms of electrical and mechanical properties. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are used as filler for fabricating conductive CFRP. Selection of type of CNT (SW/MW-CNT), percentage of CNTs to be used as filler, extent of dispersion in thermosetting resin and carbon fiber layers, governs the properties of CNT-CFRP composites. Objective of the current study was to find optimum percentage of SWCNT and MWCNT to get highly electrically conductive CNT-CFRP composites with ease of manufacturing.

Investigation of Tensile Behavior of Carbon Nanotube/Coir Fiber/Fly Ash Reinforced Epoxy Polymer Matrix Composite

ABSTRACT Fiber-reinforced composite materials are lightweight and can withstand heavy loading conditions. Reinforcement augments the strength of the composite material, which is assessed by its elastic modulus. An attempt is made to reinforce epoxy with Coir Fiber, Carbon Nanotube (CNT) and Fly-ash. Central Composite Design (CCD), a Response Surface Methodology (RSM) tool, which is a Design of Experiment (DOE) technique, is used to fabricate the experimental samples to study their tensile behavior. Analysis of variance (ANOVA) is employed to investigate the effect of reinforcement percentage of CNT, coir-fiber, and fly-ash on tensile behavior of composite. The ANOVA results follow the trend of the experimental values with a deviation of less than 10% in yield strength, tensile strength, and Young’s modulus. Two models (Artificial Neural Network and Multiple Linear Regression Model) originated resting on the regression equation to speculate the elastic modulus for various reinforcement parameters using the experimental data. The main objective is to optimize reinforcement parameters using both the models having a maximum elastic modulus of 2.602 GPa and 2.682 GPa, respectively, which is achieved by the teaching learning-based optimization technique. Furthermore, confirmation experiments validate the optimization process with an error of less than 4%.

Mixing carbon nanotubes with asphalt binder through a foaming process toward high-performance warm mix asphalt (WMA)

ABSTRACT This paper investigates mixing carbon nanotubes (CNTs) with asphalt binder through a foaming process to produce high-performance warm mix asphalt (WMA). Two different solvents of ethanol and a water-based surfactant are used to disperse the multi-walled CNTs. Initial morphological assessment of the two CNT solutions showed that a more homogenous dispersion of the CNTs was achieved using the water surfactant solution. The foaming performance, thermal, and rheological properties of the foamed asphalt mixed with different percentages of CNTs are further investigated. The test results showed that a very small amount of CNTs (0.06% ∼ 0.1% in weight of the binder) can effectively enhance the foaming performance for bubble stability without tangibly increasing the rheological properties of the foamed asphalt. The specific heat capacity of the foamed samples was smaller than the neat binder, whereas the glass transition temperature of the foamed samples shifted to a lower temperature as compared to that of the neat binder. The thermal conductivity of the 6% CNTs sample (0.24% wt. in asphalt binder) was improved by two-fold compared with the foamed unmodified asphalt, which indicates the potential of using CNTs in the binder for enhancement of thermal properties in asphalt pavements.

PANI/CFO@CNTs ternary composite system for EMI shielding applications

With the advancement of modern communication technologies and the internet of things (IoT), the manufacturing of light, flexible, and high-performance electromagnetic interference (EMI) shields is imperative to minimize harmful effects of radiation on humans and electronic devices. Lightweight ferrites/carbon allotropes/polymer-based ternary composites with abundant interfaces are potential candidates for excellent absorption materials due to their high attenuation capability and impedance matching. We report EMI shielding properties of composites made of carbon nanotubes (CNTs) decorated with cobalt ferrite (CFO) nanoparticles and coated with polyaniline (PANI). The electromagnetic properties of the CFO@CNTs binary composite have been fine-tuned by varying the weight percentage of CNTs. The formation of CFO, CNTs and emeraldine form of PANI was confirmed by XRD and Raman spectroscopy. Transmission electron microscopy (TEM) revealed uniform attachment of CFO nanoparticles to the walls of CNTs, formation of 3D networks in the CFO@CNTs binary composite and its effective encapsulation by PANI. Benefiting from the controllable composition, 3D networking, porous structure of PANI, and strong complementary effect between CFO and CNTs (source of magnetic and dielectric losses), the PANI/CFO@CNTs ternary composite exhibited superior EMI shielding characteristics with a total shielding effectiveness of 16.80 dB corresponding to 97.90 % attenuation at a thickness of 2 mm. Considering the excellent EMI shielding properties, PANI/CFO@CNTs ternary composites can be employed as high-performance EMI shields.

Experimental investigation of nano materials applicability in Hot Mix Asphalt (HMA)

• The efficacy of using Nano materials in Hot Mix Asphalt (HMA) was examined. • The effect of CNT and NC, loading frequency and temperature on dynamic modulus and resilient modulus were investigated. • Nano materials (CNT and NC) led to higher stiffness improved Dynamic stability rutting resistance and moisture resistance of HMA. • The optimized percentage of CNT and 1.5% CNT with NC in HMA was determined to be 1.5% and 6%, respectively. • MEP and regression techniques was developed in predicting the dynamic modulus of the nano material modified HMA. Nanotechnology for asphalt modification and incorporating nanomaterials into Hot Mix Asphalt (HMA) to deal with road failure have gained popularity recently. Researchers have reported the improved performance of asphalt modified by nanomaterials but most of the study is limited to binder modification using nanomaterials. The utilization of Nanomaterials in HMA can significantly improve the performance indicators in the form of extension in pavement service life and decrease pavement distresses. The Nanomaterials reinforcement of HMA can enhance pavement performance indicators, including low and high-temperature dynamic modulus and stability and enhancement in rut resistance and stiffness modulus. Nano Materials modified is a suitable solution to improve the mechanical properties of HMA. The current study objectives focus on the experimental investigation of Nano Materials such as Carbon Nano Tubes (CNT) and Nano Clay (NC) applicability in HMA. CNT and NC percentages used in HMA to the weight of bitumen are 0.5%, 1.5%, 2.5% and 2%, 4%, 6%, 8%. Conventional and Nanomaterial modified asphalt mixes were subjected to performance tests such as Simple Performance Tester (SPT), Dynamic Stability and Rutting, Tensile Strength Ratio (TSR), and Resilient Modulus ( M R ) using UTM-25. The present study further aimed to predicting dynamic modulus of nanomaterial modified HMA through Artificial intelligence (AI) modeling using Multi Expression Programming (MEPX) and Regression modelling with validation. Results have indicated that the addition of CNT and NC has improved HMA properties such as enhancement in dynamic modulus and dynamic stability and improves stiffness, rut resistance, and moisture resistance. It has been observed that 1.5% CNT with 6% NC content by weight of bitumen in asphalt mixtures outperformed other CNT and NC percentages. Moreover, Dynamic stability and Rut resistance have been improved by 820% and 64.7%, respectively, while resilient modulus increased by 309% and moisture susceptibility has been reduced by 22.26%. Overall, the asphalt mixtures with 1.5% CNT with 6% NC content has the best results.

Utilization of carbon nanotubes and steel fibers to improve the mechanical properties of concrete pavement

BackgroundRigid pavements have become an urgent demand in recent years, as these pavements need less maintenance and renovation than other types. However, traditional rigid pavement faces various challenges and difficulties over its lifetime. It has a much higher initial erection cost than asphalt pavements, a greater sensitivity to dynamic stresses, and a highly susceptible to temperature variations causing cracking. Previous works dealt with these drawbacks by using effective materials as alternatives to cement and/or aggregates in pavements mixtures. In the last few years, much interest has been carried out in nanomaterial applications to improve the mechanical performance of construction materials, which can also be used for rigid pavement constructions. This improvement is due to nanomaterials' role in concrete as nanoreinforcements and nanofillers. On the other hand, various types of fibers have been used to improve the performance of concrete constructions. This study investigates the effect of adding carbon nanotubes (CNTs) and steel fibers (SFs) to concrete mixtures. A series of experiments on concrete mixes with various weight percentages of CNTs (0%, 0.025%, 0.050%, and 0.075%) were added to the mixtures to determine the best cost and amount of CNTs to add to a concrete mix. Compressive, tensile, and flexure strength characteristics are investigated. In the second experimental stage of this work, the effect of adding steel fibers to the mixture was investigated.ResultsAccording to the results, the optimal carbon nanotube content in concrete is 0.05%. Compared to other concrete combinations with varying proportions of CNTs, this quantity offers the maximum compressive, tensile, and flexural strength. Additionally, SFs can improve the mechanical properties of the mix as well as enhance its post-cracking and fatigue behavior. Adding both CNTs with SFs increased compressive, tensile, and flexural strength by 22.7%, 29.3%, and 70.8%, respectively, more than the traditional pavement.ConclusionThis work found that combining SFs with CNTs improves the mechanical properties of the concrete mortar, resulting in a stronger mortar that can withstand more loads than the traditional one.

Influence of discontinuities on the fracture behaviour of CNT reinforced composites subjected to thermo-mechanical load using XIGA

This paper is aimed to investigate the fracture behaviour of carbon nanotube (CNT) reinforced composite exposed to the thermo-mechanical environment in the presence of discontinuities using the extended isogeometric analysis (XIGA) method. The study focuses on finding the effects of discontinuities present in a finite plate with a pre-existing crack, on the stress intensity factors (SIFs). The mandatory equivalent mechanical and thermal properties are assessed with the help of various micromechanics models. Two types of CNTs are assumed to be reinforced in the epoxy-matrix: single-walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT). The CNT reinforced composite is examined for varying volume percentages of CNTs reinforcement. A comparative study is provided to see the influence of mechanical and coupled thermo-mechanical load on SIFs. Adiabatic crack is taken into account for the computational simulation for thermal loading condition. The interaction integral method is used for the extraction of SIFs. The findings of the test reveal that with the rise in the volume percentage of CNTs, the properties such as fracture energy and fracture toughness also rise. Moreover, the fracture of CNT reinforced composites is delayed with the increased content of CNT. The results establish the profound influence of holes on SIFs than the inclusions.

Microstructural and mechanical properties of CNT-reinforced ZrO2-Y2O3 coated boiler tube steel T-91

The main purpose of this study was to fabricate carbon nanotubes (CNTs) reinforced zircon­nium yttrium coatings on boiler tube steel and to investigate the microstructural and mechanical properties of these coatings. Plasma sprayed conventional ZrO2-Y2O3, ZrO2-Y2O3 and 1 wt.% CNT and ZrO2-Y2O3 and 4 wt.% CNT were prepared and deposited successfully on boiler tube steel material T-91 (ASTM SA-213) by plasma thermal spray technology. Microhardness, porosity, XRD (X-ray diffraction), SEM/EDAX (scanning elec­tron microscopy/energy dispersive X-ray spectroscopy), X-ray mapping and cross-sectional analyses were used to analyse the specimens. The hardness of CNT reinforced ZrO2-Y2O3 increased with the increase in the percentage of CNT, whereas the porosity of the composite coatings decreased with the increase in the CNT percentage. The observed increase in hardness may be attributed to the content of CNT in the composite coating. The present research gives important information related to the fabrication and physical characteristics of CNT-reinforced ZrO2-Y2O3 coatings deposited on T-91 boiler tube steel.