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1 – 10 of 23Tuba Kavas Akarca, Merve Karayol and Isinay E. Yuzay
The purpose of this study is to develop a multifunctional coating layer based on nitrocellulose (NC)/acrylic resins containing precipitated silica and kaolin and investigate its…
Abstract
Purpose
The purpose of this study is to develop a multifunctional coating layer based on nitrocellulose (NC)/acrylic resins containing precipitated silica and kaolin and investigate its suitability for use in packaging applications.
Design/methodology/approach
Different loading levels (1 and 5 Wt.%) of precipitated silica or kaolin particles were incorporated into NC/acrylic-based coating formulations and applied on low-density polyethylene (LDPE) films. The coatings and coated LDPE films were characterized in terms of structural, physical, mechanical, thermal, optical, surface, morphological and water vapor barrier properties.
Findings
The glossiness of the coating formulations decreased by increasing the precipitated silica and kaolin content. The incorporation of kaolin (1 and 5 Wt.%) and precipitated silica (1 Wt.%) had no significant effect on the melting temperature of LDPE film; however, with the addition of 5 Wt.% precipitated silica, the melting and crystallization temperatures were significantly changed. The incorporation of 5 Wt.% precipitated silica and kaolin also enhanced the water vapor barrier properties of LDPE films. The light transmittance declined with the precipitated silica and kaolin addition, especially in the ultraviolet (UV)-A/UV-B spectrum regions indicating an excellent UV light protection.
Originality/value
It was concluded that NC/acrylic resins coatings containing precipitated silica and kaolin exhibit improved thermal stability, UV and water vapor barrier properties and have the potential for use in packaging applications.
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Md. Ikramul Hoque, Muzamir Hasan and Shuvo Dip Datta
The stone dust column was used to strengthen the sample and had a significant effect on improving the shear strength of the kaolin clay. The application of stone columns, which…
Abstract
Purpose
The stone dust column was used to strengthen the sample and had a significant effect on improving the shear strength of the kaolin clay. The application of stone columns, which can improve the overall carrying capacity of soft clay as well as lessen the settlement of buildings built on it, is among the most widespread ground improvement techniques throughout the globe. The performance of foundation beds is enhanced by their stiffness values and higher strength, which could withstand more of the load applied. Stone dust is a wonderful source containing micronutrients for soil, particularly those derived from basalt, volcanic rock, granite and other related rocks. The aim of this paper is to evaluate the properties of soft clay reinforced with encapsulated stone dust columns to remediate problematic soil and obtain a more affordable and environmentally friendly way than using other materials.
Design/methodology/approach
In this study, the treated kaolin sample's shear strength was measured using the unconfined compression test (UCT). 28 batches of soil samples total, 12 batches of single stone dust columns measuring 10 mm in diameter and 12 batches of single stone dust columns measuring 16 mm in diameter. Four batches of control samples are also included. At heights of 60 mm, 80 mm and 100 mm, respectively, various stone dust column diameters were assessed. The real soil sample has a diameter of 50 mm and a height of 100 mm.
Findings
Test results show when kaolin is implanted with a single encased stone dust column that has an area replacement ratio of 10.24% and penetration ratios of 0.6, 0.8 and 1.0, the shear strength increase is 51.75%, 74.5% and 49.20%. The equivalent shear strength increases are 48.50%, 68.50% and 43.50% for soft soil treated with a 12.00% area replacement ratio and 0.6, 0.8 and 1.0 penetration ratios.
Originality/value
This study shows a comparison of how sample types affect shear strength. Also, this article provides argumentation behind the variation of soil strength obtained from different test types and gives recommendations for appropriate test methods for soft soil.
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Seda Aygül, Serkan Yılmazsönmez, Arzu Soyalp and Ayse Aytac
Titanium dioxide (TiO2) has high opacity, high brightness and whiteness, owing to its high refractive index value. It is mainly used in the coating industry and continuous efforts…
Abstract
Purpose
Titanium dioxide (TiO2) has high opacity, high brightness and whiteness, owing to its high refractive index value. It is mainly used in the coating industry and continuous efforts have been made to replace some of the TiO2 in paint with new pigments. This study aims to replace part of TiO2 pigment with various percentages of BaSO4, CaCO3 and kaolin in styrene butyl acrylate-based paint formulations, without changing the properties of paints using only titanium dioxide.
Design/methodology/approach
To determine the optimum use rate of new pigment mixing, opacity, gloss, scrub resistance and weather resistance properties have been investigated in the water-based paint formulation. The morphological properties of these samples were examined by scanning electron microscopy analysis.
Findings
In the total color change (ΔE) measurements, it was observed that the sample coded 85Ti/15Ba produced extremely similar results to the situation when TiO2 was used alone. It was seen that the best results were obtained when 85Ti/15Ba was used instead of TiO2.
Originality/value
Comparison research on the impact of replacing TiO2 with BaSO4, CaCO3 and kaolin on the performance characteristics of water-based styrene butyl acrylate-based paint formulations has not been done in the literature, according to the literature search.
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İpek Aytaç, Yosef Badali and Azim Doğuş Tuncer
Heat exchangers (HEs) which provide heat transfer and transfer energy through direct or indirect contact between fluids have an essential role in many processes as a part of…
Abstract
Purpose
Heat exchangers (HEs) which provide heat transfer and transfer energy through direct or indirect contact between fluids have an essential role in many processes as a part of various industries from pharmaceutical production to electronic devices. Using nanofluid as working fluid and integrating different types of turbulators could be used to upgrade the thermal effectiveness of HEs. Recently, to obtain more increment in thermal effectiveness, hybrid nanofluids are used that are prepared by mixing two or more various nanoparticles. The purpose of this experimental and numerical study is investigating different scenarios for improving the effectiveness of a concentric U-tube type HE.
Design/methodology/approach
In the numerical section of this study, different turbulator modifications, including circular and quarter circular rings, were modeled to determine the effect of adding turbulator on thermal performance. In addition, Al2O3/water and SiO2/water single and Al2O3–SiO2/water hybrid nanofluids were experimentally tested in an unmodified concentric U-tube HE in two different modes, including counter flow and parallel flow. Al2O3–SiO2/water hybrid nanofluid was prepared at 2% (wt./wt.) particle ratio and compared with Al2O3/water and SiO2/water single type nanofluids at same particle ratios and with distilled water.
Findings
Numerical modeling findings exhibited that integrating turbulators to the concentric tube type HE caused to raise in the effectiveness by improving heat transfer area. Also, experimental results indicated that using both hybrid and single type nanofluids notably upgraded the thermal performance of the concentric U-tube HE. Integrating turbulators cannot be an effective alternative in a concentric U-tube type HE with lower diameter because of raise in pressure drop. Numerically achieved findings exhibited that using quarter circular turbulators decreased pressure drop in comparison with circular turbulators. According to the experimental outcomes, using hybrid Al2O3–SiO2/water nanofluid leads to obtain more thermal performance in comparison with single type nanofluids. The highest increment in overall heat transfer coefficient of HE by using Al2O3–SiO2/water nanofluid achieved as 58.97% experimentally.
Originality/value
The overall outcomes of the current research exhibited the positive impacts of using hybrid nanofluid and integrating turbulators. In this empirical and numerical survey, numerical simulations were performed to specify the impact of applying different turbulators and hybrid nanofluid on the flow and thermal characteristics in a concentric U-tube HE. The achieved outcomes exhibited that using hybrid nanofluid can notably increase the thermal performance with negligible pressure drop in comparison with two different turbulator modifications.
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Mohamed Nabil Houhou, Tamir Amari and Abderahim Belounar
This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on…
Abstract
Purpose
This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on the additional single pile responses in terms of bending moment, lateral deflection, axial force, shaft resistance and pile settlement. Subsequently, a series of parametric studies were carried out to better understand the responses of single piles induced by tunneling. To give further understanding regarding the pile groups, a 2 × 2 pile group with two different pile head conditions, namely, free and capped, was considered.
Design/methodology/approach
Using the PLAXIS three-dimensional (3D) software, a full 3D numerical modeling is performed to investigate the effects of ground movements caused by tunneling on adjacent pile foundations. The numerical model was validated using centrifuge test data found in the literature. The relevance of the 3D model is also judged by comparison with the 2D plane strain model using the PLAXIS 2D code.
Findings
The numerical test results reveal that tunneling induces significant displacements and internal forces in nearby piles. The magnitude and distribution of internal forces depend mainly on the position of the pile toe relative to the tunnel depth and the distance between the pile and the vertical axis of the tunnel. As the volume loss increases from 1% to 3%, the apparent loss of pile capacity increases from 11% to 20%. By increasing the pile length from 0.5 to 1.5 times, the tunnel depth, the maximum pile settlement and lateral deflection decrease by about 63% and 18%, respectively. On the other hand, the maximum bending moment and axial load increase by about 7 and 13 times, respectively. When the pile is located at a distance of 2.5 times the tunnel diameter (Dt), the additional pile responses become insignificant. It was found that an increase in tunnel depth from 1.5Dt to 2.5Dt (with a pile length of 3Dt) increases the maximum lateral deflection by about 420%. Regarding the interaction between tunneling and group of piles, a positive group effect was observed with a significant reduction of the internal forces in rear piles. The maximum bending moment of the front piles was found to be higher than that of the rear piles by about 47%.
Originality/value
Soil is a complex material that shows differently in primary loading, unloading and reloading with stress-dependent stiffness. This general behavior was not possibly being accounted for in simple elastic perfectly plastic Mohr–Coulomb model which is often used to predict the behavior of soils. Thus, in the present study, the more advanced hardening soil model with small-strain stiffness (HSsmall) is used to model the non-linear stress–strain soil behavior. Moreover, unlike previous studies THAT are usually based on the assumption that the soil is homogeneous and using numerical methods by decoupled loadings under plane strain conditions; in this study, the pile responses have been exhaustively investigated in a two-layered soil system using a fully coupled 3D numerical analysis that takes into account the real interactions between tunneling and pile foundations. The paper presents a distinctive set of findings and insights that provide valuable guidance for the design and construction of shield tunnels passing through pile foundations.
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Lan Chu, Chao Guo, Qing Zhang, Qing Wang, Yiwen Ge, Mingyang Hao and Jungang Lv
This study aims to using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscope/energy dispersive Xray spectrometer to identify…
Abstract
Purpose
This study aims to using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscope/energy dispersive Xray spectrometer to identify different automotive coatings for forensic purpose.
Design/methodology/approach
Two four-layered samples in a hit-and-run case were compared layer by layer with three different methods. FTIR spectroscopy was used to primarily identify the organic and inorganic compositions. Raman spectrum and scanning electron microscope/energy dispersive Xray spectrometer (SEM-EDS) were further used to complement the FTIR results.
Findings
Two weak and tiny peaks in one layer found between two samples by FTIR, Raman microscope and SEM-EDS verified the result of differences. The study used the three instruments in combination and found it’s effective in sensing coatings, especially in the inorganic additives.
Research limitations/implications
Using these three instruments in combination is more accurate than individually in multilayered coating analysis for forensic purpose.
Practical implications
The three different instruments all present unique information on the composition, and provided similar and mutually verifiable results on the two samples.
Originality/value
With this method, scientists could identify and discriminate important coating evidences with tiny but characteristic differences.
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Nilesh R. Parmar, Sanjay R. Salla, Hariom P. Khungar and B. Kondraivendhan
This study aims to characterize the behavior of blended concrete, including metakaolin (MK) and quarry dust (QD), as supplementary cementing materials. The study focuses on…
Abstract
Purpose
This study aims to characterize the behavior of blended concrete, including metakaolin (MK) and quarry dust (QD), as supplementary cementing materials. The study focuses on evaluating the effects of these materials on the fresh and hardened properties of concrete.
Design/methodology/approach
MK, a pozzolanic material, and QD, a fine aggregate by-product, are potentially sustainable alternatives for enhancing concrete performance and reducing environmental impact. The addition of different percentages of MK enhances the pozzolanic reaction, resulting in improved strength development. Furthermore, the optimum dosage of MK, mixed with QD, and mechanical properties like compressive, flexural and split tensile strength of concrete were evaluated to investigate the synergetic effect of MK and quarry dust for M20-grade concrete.
Findings
The results reveal the influence of metakaolin and QD on the overall performance of blended concrete. Cost analysis showed that the optimum mix can reduce the 7%–8% overall cost of the materials for M20-grade concrete. Energy analysis showed that the optimum mix can reduce 7%–8% energy consumption.
Originality/value
The effective utilization is determined with the help of the analytical hierarchy process method to find an optimal solution among the selected criteria. According to the AHP analysis, the optimum content of MK and quarry dust is 12% and 16%, respectively, performing best among all other trial mixes.
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Maryam Khashij, Mohammad Hossein Salmani, Arash Dalvand, Hossien Fallahzadeh, Fatemeh Haghirosadat and Mehdi Mokhtari
This paper aims to investigation of processes for Pb2+ elimination from water/wastewater as a significant public health issue in many parts of world. The removal of Pb2+ ions by…
Abstract
Purpose
This paper aims to investigation of processes for Pb2+ elimination from water/wastewater as a significant public health issue in many parts of world. The removal of Pb2+ ions by various nanocomposites has been explained from water/wastewaters. ZnO-based nanocomposites, as eco-friendly nanoparticles with unique physicochemical properties, have received increased attention to remove Pb2+ ions from water/wastewaters.
Design/methodology/approach
In this review, different ZnO-based nanocomposites were reviewed for their application in the removal of Pb2+ ions from the aqueous solution, typically for wastewater treatment using methodology, such as adsorption. This review focused on the ZnO-based nanocomposites for removing Pb2+ ions from water and wastewaters systems.
Findings
The ZnO-based nanocomposite was prepared by different methods, such as electrospinning, hydrothermal/alkali hydrothermal, direct precipitation and polymerization. Depending on the preparation method, various types of ZnO-based nanocomposites like ZnO-metal (Cu/ZnO, ZnO/ZnS, ZnO/Fe), ZnO-nonmetal (PVA/ZnO, Talc/ZnO) and ZnO-metal/nonmetal (ZnO/Na-Y zeolite) were obtained with different morphologies. The effects of operational parameters and adsorption mechanisms were discussed in the review.
Research limitations/implications
The findings may be greatly useful in the application of the ZnO-based nanocomposite in the fields of organic and inorganic pollutants adsorption.
Practical implications
The present study is novel, because it investigated the morphological and structural properties of the synthesized ZnO-based nanocomposite using different methods and studied the capability of green-synthesized ZnO-based nanocomposite to remove Pb2+ ions as water contaminants.
Social implications
The current review can be used for the development of environmental pollution control measures.
Originality/value
This paper reviews the rapidly developing field of nanocomposite technology.
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Fatimah De'nan, Megat Azmi Megat Johari, Shaneez Christie Anak Nyandau and Nor Salwani Hashim
The purpose of this study is to know the influence of palm oil fuel ash and metakaolin on the strength of concrete and crack resistance of reinforced concrete beam. An ordinary…
Abstract
Purpose
The purpose of this study is to know the influence of palm oil fuel ash and metakaolin on the strength of concrete and crack resistance of reinforced concrete beam. An ordinary portland cement has been used in the concretes production where it is an important material to be considered due to its nature that reacts with every substance present. During the cement production, a significant amount of carbon dioxide is emitted from the clinker in rotary kiln and lot of energy is required in the production processes. Such an event can be prevented by replacing the part of cement with metakaolin (MK) and palm oil fuel ash (POFA). Aside from being a cementitious alternative, the materials can also contribute to a greener environment and more sustainable building, as POFA is available in Malaysia and may be used to substitute cement and minimize pollution.
Design/methodology/approach
This study assesses the effect of MK and POFA on the concrete in terms of compressive strength and cracks pattern of the reinforced concrete beam based on the relevant previous studies.
Findings
From this study, the compressive strength of concrete containing MK and POFA was higher than the control mix with the percentage of improvement in the range of 0.8%–78.2% for MK and 0.5%–14%, respectively. The optimum content of MK and POFA is between the range of 10% and 15% and 10% and 20%, respectively, to achieve high strength of concrete. Other than that, the inclusion of MK to the concrete mix improves the strength of reinforced concrete beams and reduces cracks on the surface of reinforced concrete beams, whereas the inclusion of POFA to the concrete mix increases the cracks on reinforced concrete beams. The cracks appeared within the flexure zone of every beam containing the MK and POFA.
Originality/value
It was found that the fineness of MK and POFA has a significant influence on the mechanical properties of concrete.
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Nivin M. Ahmed, Mostafa G. Mohamed and Walaa M. Abd El-Gawad
Long time ago, multistructured materials showed great interest being considered as the bridge between bulk and atomic materials. Core-shell particles are kind of composite…
Abstract
Purpose
Long time ago, multistructured materials showed great interest being considered as the bridge between bulk and atomic materials. Core-shell particles are kind of composite materials that refer to multilayered structures with a core totally surrounded by shell(s) (onion-like structure). These new structures can offer an advantage of applying new adjustable parameters like shape, stoichiometry and chemical ordering, in addition to the opportunity of tailoring more complexed structures for different applications. Recently it was found that these structures can be tuned and taken for more advanced path with novel structures formed of core surrounded by multishells. The purpose of this study is to study the effect of the new anticorrosive pigments with its mutual shells and how each shell affects the performance of the pigment in protecting the metal and which shell will be more relevant in its effect.
Design/methodology/approach
The prepared pigments were characterized using X-ray fluorescence, X-ray diffraction, TEM and SEM/EDX to prove their core-shell structure, and then they were integrated in coating formulations to evaluate their anticorrosive activity using immersion test and electrochemical impedance spectroscopy (EIS).
Findings
The results showed that the prepared core-shell pigments possess a lot of unique characteristics and can offer improved anticorrosive performance in the generated coatings.
Originality/value
Core-mutual shells structured pigments were prepared for improving the corrosion resistivity of the organic coatings as a new trend in anticorrosive pigments.
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