Search results for: recycling of materials

Authors: Ichrak Hamrouni, Tariq Ouahbi, Natalija Lhuissier, Saïd Taibi, Mehrez Jemai, Olivier Crumeyrolle, Hatem Zenzri

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Raw earth is the oldest building technique used for over 11 centuries, thanks to its various benefits. The most known raw earth construction technics are compressed earth blocks, rammed earth, raw earth concrete, and daub. The raw earth can be stabilized with hydraulic binders, mixed by fibers, or hyper-compacted in order to improve its mechanical behaviour. Moreover, raw earth is characterized by a low thermal conductivity what make it a good thermal insulator, and it has a very important capacity to condense and evaporate relative humidity. In this context, many researches have been developed. They have shown that the mechanical characteristics of earth materials increase with the hyper-compaction and adding fibers or hydraulic binders. Besides, other researches have been determined the thermal and hygroscopic properties of raw earth. They have shown that this material able to contribute to moisture and heat control in constructions. Its hygrothermal properties are better than fired earth bricks and concrete. The aim of this study is to evaluate the thermal and hygrometric behavior of raw earth material using experimental tests allows to determine the main Hygrothermal properties such as the water Vapour permeability and thermal conductivity and compare the results with those of other building materials such as fired clay bricks and cement concrete is presented.

Keywords: raw earth material, hygro-thermal, thermal conductivity, water vapour permeability, building materials, building materials

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Authors: Mohamed Saad Gad Eloghby

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Nanomaterials are widely used nowadays for the consolidation of degraded archaeological limestone. It’s one of the most predominant stones in monumental buildings and statuary works. Exposure to different weathering processes caused degradation and the presence of deterioration pattern as cracks, fissures, and granular disintegration. Nanomaterials have been applied to limestone consolidation. Among these nanomaterials are nanolimes, i.e., dispersions of lime nanoparticles in alcohols and nanosilica, i.e., dispersions of silica nanoparticles in water promising consolidating products for limestone. It was investigated and applied to overcome the disadvantages of traditional consolidation materials such as lime water, water glass and paraliod. So, researchers investigated and tested the effectiveness of nanomaterials as consolidation materials for limestone. The present study includes the evaluation of some nano materials in consolidation limestone stone in comparison with traditional consolidantes. These consolidation materials are nano calcium hydroxide nanolime and nanosilica. The latter is known commercially as Nano Estel and the former is known as Nanorestore compared to traditional consolidantes Wacker OH (ethyl silicate) and Paraloid B72 (a copolymer of ethyl methacrylate and methyl acrylate). The study evaluated the consolidation effectiveness of nanomaterials and traditional consolidantes by using followed methods, Characterization of physical properties of stone, Scanning electron microscopy (SEM), X-ray diffractometry, Fourier transform infrared spectroscopy and Mechanical properties. The study confirmed that nanomaterials were better in the distribution and encapsulation of calcite grains in limestone, and traditional materials were better in improving the physical properties of limestone. It demonstrated that good results can be achieved through mixtures of nanomaterials and traditional consolidants.

Keywords: nanomaterials, limestone, consolidation, evaluation, weathering, nanolime, nanosilica, scanning electron microscope

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Authors: Mohamed Ahmed Abd El Kader

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This paper describes the conservation processes of an Ancient Egyptian wooden coffin dating back to the Middle Kingdom, ancient Egypt, using several scientific and analytical methods in order to provide a deeper understanding of the deterioration status and a greater awareness of how well preserved the object is. Visual observation and 2D Programs, as well as Optical Microscopy (OM), Environmental scanning Electron Microscopy (ESEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were used in our study. The identification of wood species and the composition of the pigments and previous restoration materials were made. The coffin was previously conserved and stored in improper conditions, which led to its further deterioration; the surface of the lid dust, which obscured the decorations as well as all necessary restoration work was promptly carried out as soon as the coffin was transferred from the display hall from the Egyptian Museum to the Wood Conservation Laboratory of the Grand Egyptian Museum-Conservation Center (GEM-CC). The analyses provided detailed information concerning the original materials and the materials added during the previous treatment interventions, which was considered when applying the conservation plan. Conservation procedures have been applied with high accuracy to conserve the coffin including cleaning, consolidation of fragile painted layers, and the wooden boards forming the sides of the coffin were reassembled in their original positions. The materials and methods that were applied were extremely effective in stability and reinforcement of the coffin without harmfulness to the original materials and the coffin was successfully conserved and ready to display in the Grand Egyptian Museum (GEM).

Keywords: coffin, middle kingdom, deterioration, 2d program

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Authors: Sónia Ribeiro, Diana Farinha, Hélia Sales, Rita Pontes, João Nunes

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The demand and commitment to sustainability in the agrifood sector introduce news opportunities for new composite materials. Composite materials are emerging as a vital entity for the sustainable development. Polylactic acid (PLA) has been recognized as a potential polymer with attractive characteristics for agrifood sector applications. PLA that can be beneficial for the development of composites, biocomposites, films, porous gels, and so on. The production of PLA from lignocellulosic biomass residues matrix is a key option towards a sustainable and circular bioeconomy and a non-competitive application with feed and food sector. The Flui and BeirInov projects presents news developments in the production of PLA composites to value the Portuguese forest ecosystem, with high amount of lignocellulosic biomass residues and available. A performance production of lactic acid from lignocellulosic biomass undergoes a process of autohydrolysis, saccharification and fermentation, originating a lactic acid fermentation medium with a 72.27g.L-1 was obtained and a final purification of 72%. The high purification PLA from multi lignocellulosic residues representing one economic expensive process, and a new materials and application for the polymers and a combination with others types of composites matrix characteristic is the drive-up for this green market.

Keywords: polylactic acid, lignocellulosic biomass, agrifood, composite materials

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Authors: Young Cheol Choi, Eun-Jin Moon, Sung-Won Yoo, Sang-Hwa Jung, In-Hwan Yang

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Stainless steel slag (STS) is a by-product generated from the stainless steel refining process. The recycling of STS produced in Korea for construction applications is limited due to its poor hydraulic properties. On the other hand, STS has high carbonation reactivity to CO2 as it contains gamma-C2S content. This material is ideal for mineral carbonation which is one of the techniques proposed for carbon emission reduction. The objective of this study is to investigate the feasibility of developing a zero-cement STS binder activated by carbonation as alternative cementitious material. The quantitative analyses for CO2 uptake of STS powder and STS blended cement were investigated using thermogravimetric analysis (TGA), X-ray diffraction (XRD). In addition, the compressive strength and microstructure of STS pastes after CO2 curing were evaluated. Test results showed that STS can be activated by carbonation to gain a sufficient strength as alternative cementitious material.

Keywords: gamma-C2S, CO2 uptake, carbonation, stainless steel slag

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Authors: Igor Medved, Anton Trnik, Libor Vozar

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Phase-change materials (PCMs) are of great interest in the applications where a temperature level needs to be maintained and/or where there is demand for thermal energy storage. Examples are storage of solar energy, cold, and space heating/cooling of buildings. During a phase change, the enthalpy vs. temperature plot of PCMs shows a jump and there is a distinct peak in the heat capacity plot. We present a theoretical description from which these jumps and peaks can be obtained. We apply our theoretical results to fit experimental data with very good accuracy for selected materials and changes between two phases. The development is based on the observation that PCMs are polycrystalline; i.e., composed of many single-crystalline grains. The enthalpy and heat capacity are thus interpreted as averages of the contributions from the individual grains. We also show how to determine the baseline and excess part of the heat capacity and thus the latent heat corresponding to the phase change.

Keywords: averaging, enthalpy jump, heat capacity peak, phase change

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Authors: Lim Kar Sing, Siti Nur Afifah Azraai, Norhazilan Md Noor, Nordin Yahaya

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Polymeric composites are being increasingly used as repair material for repairing critical infrastructures such as building, bridge, pressure vessel, piping and pipeline. Technique in repairing damaged pipes is one of the major concerns of pipeline owners. Considerable researches have been carried out on the repair of corroded pipes using composite materials. This article attempts a short review of the subject matter to provide insight into various techniques used in repairing corroded pipes, focusing on a wide range of composite repair systems. These systems including pre-cured layered, flexible wet lay-up, pre-impregnated, split composite sleeve and flexible tape systems. Both advantages and limitations of these repair systems were highlighted. Critical technical aspects have been discussed through the current standards and practices. Research gaps and future study scopes in achieving more effective design philosophy are also presented.

Keywords: composite materials, pipeline, repair technique, polymers

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Authors: Astrid de Leeuw, Pierre Valois

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Environmental education is the key to enhancing or changing students’ ways of thinking and acting in order to create an environmentally robust future for all. The present study investigates the beliefs of 812 primary school students, which merit consideration when developing educational interventions. Results of multiple regression analyses reveal that educational interventions should focus on promoting students’ feelings of control over pro-environmental behaviors (PEB). For example, schools could provide recycling bins on the premises. Furthermore, it is critical to develop positive attitudes in students by stressing the various benefits of PEB for keeping our planet clean and protecting wildlife. Unfortunately, our results indicate that students believe that PEB is boring and annoying. Suggestions are offered for making PEB more interesting and relevant. Further research is needed to test the effectiveness of interventions based on the present results.

Keywords: pro-environmental behavior, primary school students, theory of planned behavior, beliefs, educational interventions

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Authors: Cherief Houria, Fouka Mourad

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In this work, the simulation of the radiation attenuation is carried out in a photon detector consisting of different common shielding material using a Monte Carlo program called PTM. The aim of the study is to investigate the effect of atomic weight and the thickness of shielding materials on the gamma radiation attenuation ability. The linear attenuation coefficients of Aluminum (Al), Iron (Fe), and lead (Pb) elements were evaluated at photons energy of 661:7KeV that are considered to be emitted from a standard radioactive point source Cs 137. The experimental measurements have been performed for three materials to obtain these linear attenuation coefficients, using a Gamma NaI(Tl) scintillation detector. Our results have been compared with the simulation results of the linear attenuation coefficient using the XCOM database and Geant4 codes and reveal that they are well agreed with both simulation data.

Keywords: gamma photon, Monte Carlo program, radiation attenuation, shielding material, the linear attenuation coefficient

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Authors: S. Ghosh, L. Ramos, A. N. Kouamé, A.-L. Teillout, H. Remita

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Catalytic materials have attracted continuous attention due to their promising applications in a variety of energy and environmental applications including clean energy, energy conversion and storage, purification and separation, degradation of pollutants and electrochemical reactions etc. With the advanced synthetic technologies, polymer nanostructures and nanocomposites can be directly synthesized through soft template mediated approach using swollen hexagonal mesophases and modulate the size, morphology, and structure of polymer nanostructures. As an alternative to conventional catalytic materials, one-dimensional PDPB polymer nanostructures shows high photocatalytic activity under visible light for the degradation of pollutants. These photocatalysts are very stable with cycling. Transmission electron microscopy (TEM), and AFM-IR characterizations reveal that the morphology and structure of the polymer nanostructures do not change after photocatalysis. These stable and cheap polymer nanofibers and metal polymer nanocomposites are easy to process and can be reused without appreciable loss of activity. The polymer nanocomposites formed via one pot chemical redox reaction with 3.4 nm Pd nanoparticles on poly(diphenylbutadiyne) (PDPB) nanofibers (30 nm). The reduction of Pd (II) ions is accompanied by oxidative polymerization leading to composites materials. Hybrid Pd/PDPB nanocomposites used as electrode materials for the electrocatalytic oxidation of ethanol without using support of proton exchange Nafion membrane. Hence, these conducting polymer nanofibers and nanocomposites offer the perspective of developing a new generation of efficient photocatalysts for environmental protection and in electrocatalysis for fuel cell applications.

Keywords: conducting polymer, swollen hexagonal mesophases, solar photocatalysis, electrocatalysis, water depollution

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Authors: Ergin Kosa, Ali Göksenli

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Erosion and abrasion are wear mechanisms reducing the lifetime of machine elements like valves, pump and pipe systems. Both wear mechanisms are acting at the same time, causing a “Synergy” effect, which leads to a rapid damage of the surface. Different parameters are effective on erosive abrasive wear rate. In this study effect of particle impact angle on wear rate and wear mechanism of ductile and brittle materials was investigated. A new slurry pot was designed for experimental investigation. As abrasive particle, silica sand was used. Particle size was ranking between 200-500 µm. All tests were carried out in a sand-water mixture of 20% concentration for four hours. Impact velocities of the particles were 4,76 m/s. As ductile material steel St 37 with Brinell Hardness Number (BHN) of 245 and quenched St 37 with 510 BHN was used as brittle material. After wear tests, morphology of the eroded surfaces were investigated for better understanding of the wear mechanisms acting at different impact angles by using optical microscopy and Scanning Electron Microscope. The results indicated that wear rate of ductile material was higher than brittle material. Maximum wear was observed by ductile material at a particle impact angle of 300. On the contrary wear rate increased by brittle materials by an increase in impact angle and reached maximum value at 450. High amount of craters were detected after observation on ductile material surface Also plastic deformation zones were detected, which are typical failure modes for ductile materials. Craters formed by particles were deeper according to brittle material worn surface. Amount of craters decreased on brittle material surface. Microcracks around craters were detected which are typical failure modes of brittle materials. Deformation wear was the dominant wear mechanism on brittle material. At the end it is concluded that wear rate could not be directly related to impact angle of the hard particle due to the different responses of ductile and brittle materials.

Keywords: erosive wear, particle impact angle, silica sand, wear rate, ductile-brittle material

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Authors: P. P. Woyciechowski

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Calculation of the carbon footprint of cement concrete is a complex process including consideration of the phase of primary life (components and concrete production processes, transportation, construction works, maintenance of concrete structures) and secondary life, including demolition and recycling. Taking into consideration the effect of concrete carbonation can lead to a reduction in the calculated carbon footprint of concrete. In this paper, an example of CO₂ balance for small bridge elements made of Portland cement reinforced concrete was done. The results include the effect of carbonation of concrete in a structure and of concrete rubble after demolition. It was shown that important impact of carbonation on the balance is possible only when rubble carbonation is possible. It was related to the fact that only the sequestration potential in the secondary phase of concrete life has significant value.

Keywords: carbon footprint, balance of carbon dioxide in nature, concrete carbonation, the sequestration potential of concrete

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Authors: Joanna Rybicka-Łada, Magda Kosmal, Anna Kuśnierz

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One of the main problems of the glass industry is the still high consumption of energy needed to produce glass mass, as well as the increase in prices, fuels, and raw materials. Therefore, comprehensive actions are taken to improve the entire production process. The key element of these activities, starting from filling the set to receiving the finished product, is the melting process, whose task is, among others, dissolving the components of the set, removing bubbles from the resulting melt, and obtaining a chemically homogeneous glass melt. This solution avoids dust formation during filling and is available on the market. This process consumes over 90% of the total energy needed in the production process. The processes occurring in the set during its conversion have a significant impact on the further stages and speed of the melting process and, thus, on its overall effectiveness. The speed of the reactions occurring and their course depend on the chemical nature of the raw materials, the degree of their fragmentation, thermal treatment as well as the form of the introduced set. An opportunity to minimize segregation and accelerate the conversion of glass sets may be the development of new technologies for preparing and dosing sets. The previously preferred traditional method of melting the set, based on mixing all glass raw materials together in loose form, can be replaced with a set in a thickened form. The aim of the project was to develop a glass set in a selectively or completely densified form and to examine the influence of set processing on the melting process and the properties of the glass.

Keywords: glass, melting process, glass set, raw materials

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Authors: Nazlina Shaari

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Sustainability is economic, social and environmental systems that make up the community in providing a healthy, productive, meaningful life for all community residents, present and future. The environmental profile of goods and services that satisfy our individual and societal needs were shaped by design activities. The integration of environmental aspect of product design, especially in textiles present much confusion surrounds the incorporation of environmental objectives into the design process. This paper explores the effective use of waste materials that can contribute to the development of more environmentally responsible practice in textile sector. It introduces key elements of the ecological approach and innovative ideas from waste to wealth. The paper focuses on the potential methods of utilizing sago residue as a natural colour enhancer in natural dyeing process. It will discover the potential of waste materials to be fully utilized to attempt to make the production of that textile more environmentally friendly.

Keywords: sustainability, textiles, waste materials, environmentally friendly

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Authors: Sofia Figueroa, Efrain Bernal, Silvia Del Pilar Forero, Humberto Ramirez

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This work shows a detailed review of the scope of global research on the road infrastructure using materials from Construction and Demolition Waste (C&DW), also called RCD. In the first phase of this research, a segment of road was designed using recycled materials such as Reclaimed Asphalt Pavement (RAP) on the top, the natural coarse base including 30% of RAP and recycled concrete blocks. The second part of this segment was designed using regular materials for each layer of the pavement. Both structures were built next to each other in order to analyze and measure the material properties as well as performance and environmental factors in the pavement under real traffic and weather conditions. Different monitoring devices were installed among the structure, based on the literature revision, such as soil cells, linear potentiometer, moisture sensors, and strain gauges that help us to know the C&DW as a part of the pavement structure. This research includes not only the physical characterization but also the measured parameters in a field such as an asphalt mixture (RAP) strain (ετ), vertical strain (εᵥ) and moisture control in coarse layers (%w), and the applied loads and strain in the subgrade (εᵥ). The results will show us what is happening with these materials in order to obtain not only a sustainable solution but also to know its behavior and lifecycle.

Keywords: sustainable pavements, construction & demolition waste-C&DW, recycled rigid concrete, reclaimed asphalt pavement-rap

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Authors: A. Mudau, T. R. Stacey, R. A. Govender

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This paper reports for the first time the findings on the dynamic compressive strength data of Bushveld Complex brittle rock materials. These rocks were subjected to both quasi-static and impact loading tests to help understand their behaviour both under quasi-static and dynamic loading conditions. Unlike quasi-static tests, characterization of dynamic behaviour of materials is challenging, in particularly brittle rock materials. The split Hopkinson pressure bar (SHPB) results reported for anorthosite and norite showed relatively low values for dynamic compressive strength compared to the quasi-static uniaxial compressive strength data. It was noticed that the dynamic stress conditions were not fully attained during testing, as well as constant strain rate.

Keywords: Bushveld Complex, dynamic comperession, rock brittleness, stress equilibrium

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Authors: J. T. Johnson, R. A. Atule, E. Gbodo

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The widespread problem of infant malnutrition in developing countries has stirred efforts in research, development and extension by both local and international organizations. As a result, the formulation and development of nutritious weaning foods from local and readily available raw materials which are cost effective has become imperative in many developing countries. Thus, local and readily available raw materials where used to compound and develop nutritious new infant formulae. The materials used for this study include maize, millet, cowpea, pumpkin, fingerlings, and fish bone. The materials where dried and blended to powder. The powders were weighed in the ratio of 4:4:4:3:1:1 respectively and were then mixed properly. Analysis of nutritive value was conducted on the formulae and compared with NAN-2 standard and results reveals that the formulae had reasonable amount of moisture, lipids, carbohydrate, protein, and fibre. Although NAN-2 was superior in both carbohydrate and protein, the new infant formula was higher in mineral elements, vitamins, fibre, and lipids. All the essentials vitamins and both macro and micro minerals where found in appreciable quantity capable of meeting the biochemical and physiological demand of the body while the anti-nutrients composition were significantly below FAO and WHO safe limits. Finally, the compounded infant formulae was feed to a set of albino Wistar rats while some other set of rats was feed with NAN-2 for the period of twenty seven (27) days and body weight was measure at three days intervals. The results of body weight changes was spectacular as their body weight over shot or almost double that of those animals that were feed with NAN-2 at each point of measurement. The results suggest that the widespread problem of infant malnutrition in the developing world especially among the low income segment of the society can now be reduced if not totally eradicated since nutritive and cost effective weaning formulae can be prepared locally from common readily available materials.

Keywords: formulation, nutritive value, local, materials

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Authors: Mohsin Talib Mohammed, Zahid A. Khan, Arshad N. Siddiquee

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Biometallic materials are the most important materials for use in biomedical applications especially in manufacturing a variety of biological artificial replacements in a modern worlds, e.g. hip, knee or shoulder joints, due to their advanced characteristics. Titanium (Ti) and its alloys are used extensively in biomedical applications based on their high specific strength and excellent corrosion resistance. Beta-Ti alloys containing completely biocompatible elements are exceptionally prospective materials for manufacturing of bioimplants. They have superior mechanical, chemical and electrochemical properties for use as biomaterials. These biomaterials have the ability to introduce the most important property of biochemical compatibility which is low elastic modulus. This review examines current information on the recent developments in alloying elements leading to improvements of beta Ti alloys for use as biomaterials. Moreover, this paper focuses mainly on the evolution, evaluation and development of the modulus of elasticity as an effective factor on the performance of beta alloys.

Keywords: beta alloys, biomedical applications, titanium alloys, Young's modulus

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Authors: Y. S. Lee, F. Malek, E. M. Cheng, W. W. Liu, F. H. Wee, M. N. Iqbal, Z. Liyana, B. S. Yew, F. S. Abdullah

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This paper presents the electromagnetic interference (EMI) shielding effectiveness of rice husk and carbon nanotubes (RHCNTs) composites in the X-band region (8.2-12.4 GHz). The difference weight ratio of carbon nanotubes (CNTs) were mix with the rice husk. The rectangular wave guide technique was used to measure the complex permittivity of the RHCNTs composites materials. The complex permittivity is represented in terms of both the real and imaginary parts of permittivity in X-band frequency. The conductivity of RHCNTs shows increasing when the ratio of CNTs mixture increases. The composites materials were simulated using Computer Simulation Technology (CST) Microwave Studio simulation software. The shielding effectiveness of RHCNTs and pure rice husk was compared. The highest EMI SE of 30 dB is obtained for RHCNTs composites of 10 wt % CNTs with 10 mm thick.

Keywords: EMI shielding effectiveness, carbon nanotube, composite materials wave guide, x-band

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Authors: A. Saurabh Singh, B. Raghvendra, C. Prabhakar Singh

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Solid Oxide Fuel Cells (SOFCs) are one of the most attractive electrochemical energy conversion systems, as these devices present a clean energy production, thus promising high efficiencies and low environmental impact. The electrodes are the main components that decisively control the performance of a SOFC. Conventional, anode materials (like Ni-YSZ) are operates at very high temperature. Therefore, cost-effective materials which operate at relatively lower temperatures are still required. In present study, we have synthesized La doped Strontium Titanate via solid state reaction route. The structural, microstructural and density of the pellet have been investigated employing XRD, SEM and Archimedes Principle, respectively. The electrical conductivity of the systems has been determined by impedance spectroscopy techniques. The electrical conductivity of the Lanthanum Strontium Titanate (LST) has been found to be higher than the composite Ni-YSZ system at 700 °C.

Keywords: IT-SOFC, LST, Lanthanum Strontium Titanate, electrical conductivity

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Authors: Afsheen Aman, Zainab Bibi, Shah Ali Ul Qader

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Introduction: Xylan is a heteropolysaccharide composed of xylose monomers linked together through 1,4 linkages within a complex xylan network. Owing to wide applications of xylan hydrolytic products (xylose, xylobiose and xylooligosaccharide) the researchers are focusing towards the development of various strategies for efficient xylan degradation. One of the most important strategies focused is the use of heat tolerant biocatalysts which acts as strong and specific cleaving agents. Therefore, the exploration of microbial pool from extremely diversified ecosystem is considerably vital. Microbial populations from extreme habitats are keenly explored for the isolation of thermophilic entities. These thermozymes usually demonstrate fast hydrolytic rate, can produce high yields of product and are less prone to microbial contamination. Another possibility of degrading xylan continuously is the use of immobilization technique. The current work is an effort to merge both the positive aspects of thermozyme and immobilization technique. Methodology: Geobacillus stearothermophilus was isolated from soil sample collected near the blast furnace site. This thermophile is capable of producing thermostable endo-β-1,4-xylanase which cleaves xylan effectively. In the current study, this thermozyme was immobilized within a synthetic and a non-synthetic matrice for continuous production of metabolites using entrapment technique. The kinetic parameters of the free and immobilized enzyme were studied. For this purpose calcium alginate and polyacrylamide beads were prepared. Results: For the synthesis of immobilized beads, sodium alginate (40.0 gL-1) and calcium chloride (0.4 M) was used amalgamated. The temperature (50°C) and pH (7.0) optima of immobilized enzyme remained same for xylan hydrolysis however, the enzyme-substrate catalytic reaction time raised from 5.0 to 30.0 minutes as compared to free counterpart. Diffusion limit of high molecular weight xylan (corncob) caused a decline in Vmax of immobilized enzyme from 4773 to 203.7 U min-1 whereas, Km value increased from 0.5074 to 0.5722 mg ml-1 with reference to free enzyme. Immobilized endo-β-1,4-xylanase showed its stability at high temperatures as compared to free enzyme. It retained 18% and 9% residual activity at 70°C and 80°C, respectively whereas; free enzyme completely lost its activity at both temperatures. The Immobilized thermozyme displayed sufficient recycling efficiency and can be reused up to five reaction cycles, indicating that this enzyme can be a plausible candidate in paper processing industry. Conclusion: This thermozyme showed better immobilization yield and operational stability with the purpose of hydrolyzing the high molecular weight xylan. However, the enzyme immobilization properties can be improved further by immobilizing it on different supports for industrial purpose.

Keywords: immobilization, reusability, thermozymes, xylanase

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Authors: Maryam Meftahi, Yashar Hamidzadeh

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In recent decades, the amount of solid waste production has been rising. In the meantime, plastic waste is one of the major parts of urban solid waste, so, recycling plastic waste from water bottles has become a serious challenge in the whole world. The experimental program includes the study of the effect of waste plastic fibers on maximum dry density (MDD), optimum moisture content (OMC) with different sizes and contents. Also, one dimensional consolidation tests were carried out to evaluate the benefit of utilizing randomly distributed waste plastics fiber to improve the engineering behavior of a tested soils. Silty soil specimens were prepared and tested at five different percentages of plastic waste content (i.e. 0.25%, 0.50%, 0.75%, 1% and 1.25% by weight of the parent soil). The size of plastic chips used, are 4 mm, 8 mm and 12 mm long and 4 mm in width. The results show that with the addition of waste plastic fibers, the MDD and OMC and also the compressibility of soil decrease significantly.

Keywords: silty soil, waste plastic, compaction, consolidation, reinforcement

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Authors: Venkatesan Sundaramoorthy

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The field of ceramics has undergone a remarkable transformation with the advent of additive manufacturing technologies. This comprehensive review explores the mechanical properties of additively manufactured ceramic components, focusing on key materials such as Alumina, Zirconia, and Silicon Carbide. The study delves into various authors' review technology into the various additive manufacturing techniques, including Stereolithography, Powder Bed Fusion, and Binder Jetting, highlighting their advantages and challenges. It provides a detailed analysis of the mechanical properties of these ceramics, offering insights into their hardness, strength, fracture toughness, and thermal conductivity. Factors affecting mechanical properties, such as microstructure and post-processing, are thoroughly examined. Recent advancements and future directions in 3D-printed ceramics are discussed, showcasing the potential for further optimization and innovation. This review underscores the profound implications of additive manufacturing for ceramics in industries such as aerospace, healthcare, and electronics, ushering in a new era of engineering and design possibilities for ceramic components.

Keywords: mechanical properties, additive manufacturing, ceramic materials, PBF

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Authors: Arturo Reyes Roman, Daniza Castillo Godoy, Francisca Balarezo Olivares, Francisco Arriagada Castro, Miguel Maulen Tapia

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Mining waste–based geopolymers are a sustainable alternative to conventional cement materials due to their contribution to the valorization of mining wastes as well as to the new construction materials with reduced fingerprints. The objective of this study was to determine the potential of leaching gravel (LG) from hydrometallurgical copper processing to be used as a raw material in the manufacture of geopolymer. NaOH, Na2SiO3 (modulus 1.5), and LG were mixed and then wetted with an appropriate amount of tap water, then stirred until a homogenous paste was obtained. A liquid/solid ratio of 0.3 was used for preparing mixtures. The paste was then cast in cubic moulds of 50 mm for the determination of compressive strengths. The samples were left to dry for 24h at room temperature, then unmoulded before analysis after 28 days of curing time. The compressive test was conducted in a compression machine (15/300 kN). According to the laser diffraction spectroscopy (LDS) analysis, 90% of LG particles were below 500 μm. The X-ray diffraction (XRD) analysis identified crystalline phases of albite (30 %), Quartz (16%), Anorthite (16 %), and Phillipsite (14%). The X-ray fluorescence (XRF) determinations showed mainly 55% of SiO2, 13 % of Al2O3, and 9% of CaO. ICP (OES) concentrations of Fe, Ca, Cu, Al, As, V, Zn, Mo, and Ni were 49.545; 24.735; 6.172; 14.152, 239,5; 129,6; 41,1;15,1, and 13,1 mg kg-1, respectively. The geopolymer samples showed resistance ranging between 2 and 10 MPa. In comparison with the raw material composition, the amorphous percentage of materials in the geopolymer was 35 %, whereas the crystalline percentage of main mineral phases decreased. Further studies are needed to find the optimal combinations of materials to produce a more resistant and environmentally safe geopolymer. Particularly are necessary compressive resistance higher than 15 MPa are necessary to be used as construction unit such as bricks.

Keywords: mining waste, geopolymer, construction material, alkaline activation

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Authors: Sisaynew Tesfaw Admassu

Abstract:

The strengthening of timber beams can be necessary for several reasons including the increase of live loads (possible in a historical building for a change of destination of use or upgrading to meet new requirements), the reduction of the resistant cross-sections following deterioration (attacks of biological agents such as fungi, and insects) or traumatic events (fires) and the excess of deflection in the members. The main purpose of strengthening an element is not merely to repair it, but also to prevent and minimize the appearance of future problems. This study did an experimental investigation on the behavior of reference and strengthened solid timber beams. The strengthening materials used in this study were CSM-450 glass fiber and steel materials for both flexural and shear strengthening techniques. Twenty-two solid timber beams of Juniperus procera (TID) species with the dimensions of 60 x 90 x 780 mm were used in the present study. The binding material to bond the strengthening materials with timber was general-purpose resin with Luperox® K10 MEKP catalyst. Three beams were used as control beams (unstrengthen beams) while the remaining nineteen beams were strengthened using the strengthening materials for flexure and shear. All the beams were tested for three points loading to failure by using a Universal Testing Machine, UTM-600kN machine. The experimental results showed that the strengthened beams performed better than the unstrengthen beams. The experimental result of flexural strengthened beams showed that the load-bearing capacity of strengthened beams increased between 16.34 – 42.55%. Four layers of Glass Fiber Reinforced polymer on the tension side of the beams was shown to be the most effective way to enhance load-bearing capacity. The strengthened beams also have an enhancement in their flexural stiffness. The stiffness of flexural strengthened beams was increased between 1.18 – 65.53% as compared to the control beams. The highest increment in stiffness has occurred on beams strengthened using 2x60 mm steel plates. The shear-strengthened beams showed a relatively small amount of performance as compared to flexural-strengthened beams; the reason is that the beams are sufficient for shear. The polyester resin used in the experimental work showed good performance in bonding agents between materials. The resin showed more effectiveness in GFRP materials than steel materials.

Keywords: heritage structures, strengthening, stiffness, adhesive, polyester resin, steel plates

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Authors: Woo Young Jung, Min Ho Kwon, Bu Seog Ju

Abstract:

A failure of the non-structural component can cause significant damages in critical facilities such as nuclear power plants and hospitals. Historically, it was reported that the damage from the leakage of sprinkler systems, resulted in the shutdown of hospitals for several weeks by the 1971 San Fernando and 1994 North Ridge earthquakes. In most cases, water leakages were observed at the cross joints, sprinkler heads, and T-joint connections in piping systems during and after the seismic events. Hence, the primary objective of this study was to understand the seismic performance of T-joint connections and to develop an analytical Finite Element (FE) model for the T-joint systems of 2-inch fire protection piping system in hospitals subjected to seismic ground motions. In order to evaluate the FE models of the piping systems using OpenSees, two types of materials were used: 1) Steel 02 materials and 2) Pinching 4 materials. Results of the current study revealed that the nonlinear moment-rotation FE models for the threaded T-joint reconciled well with the experimental results in both FE material models. However, the system-level fragility determined from multiple nonlinear time history analyses at the threaded T-joint was slightly different. The system-level fragility at the T-joint, determined by Pinching 4 material was more conservative than that of using Steel 02 material in the piping system.

Keywords: fragility, t-joint, piping, leakage, sprinkler

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Authors: Kivilcim Ersoy, Cansu Yazganarikan

Abstract:

In recent years, composite materials are more frequently utilized not only in aviation but also in automotive industry due to its high strength to weight ratio, fatigue and corrosion resistances as well as better performances in specific environments. The market demand also favors lightweight design for wheeled and tracked armored vehicles due to the increased demand for land and amphibious mobility features. This study represents the current application areas and trends in automotive, bus and armored land vehicles industries. In addition, potential utilization areas of fiber composite and hybrid material concepts are being addressed. This work starts with a survey of current applications and patent trends of composite materials in automotive and land vehicle industries. An intensive investigation is conducted to determine the potential of these materials for application in land vehicle industry, where small series production dominates and challenging requirements are concerned. In the end, potential utilization areas for combat land vehicle systems are offered. By implementing these light weight solutions with alternative materials and design concepts, it is possible to achieve drastic weight reduction, which will enable both land and amphibious mobility without unyielding stiffness and survivability capabilities.

Keywords: land vehicle, composite, light-weight design, armored vehicle

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Authors: Girish Sambhaji Gund

Abstract:

The controlled nanostructure growth and its strong coupling with the current collector are key factors to achieve good electrochemical performance of faradaic-dominant electroactive materials. We employed binder-less and additive-free hydrothermal and physical vapor doping methods for the synthesis of nickel (Ni) and cobalt (Co) based compounds nanostructures (NiO, NiCo2O4, NiCo2S4) deposited on different conductive substrates such as carbon nanotube (CNT) on stainless steel, and reduced graphene oxide (rGO) and N-doped rGO on nickel foam (NF). The size and density of Ni- and Co-based compound nanostructures are controlled through the strong coupling with carbon allotropes on stainless steel and NF substrates. This controlled nanostructure of Ni- and Co-based compounds with carbon allotropes leads to stable faradaic electrochemical reactions at the material/current collector interface and within the electrode, which is consequence of strong coupling of nanostructure with functionalized carbon surface as a buffer layer. Thus, it is believed that the results provide the synergistic approaches to stabilize electrode materials physically and chemically, and hence overall electrochemical activity of faradaic dominating battery-type electrode materials through buffer layer engineering.

Keywords: metal compounds, carbon allotropes, doping, electrochemicstry, hybrid supercapacitor

Procedia PDF Downloads 76

Authors: D. S. Vardar, A. S. Kipcak, F. T. Senberber, E. M. Derun, S. Piskin, N. Tugrul

Abstract:

Zinc borate is an important inorganic hydrate borate material, which can be use as a flame retardant agent and corrosion resistance material. This compound can loss its structural water content at higher than 290°C. Due to thermal stability; Zinc Borate can be used as flame reterdant at high temperature process of plastic and gum. In this study, the ultrasonic reaction of zinc borates were studied using hydrozincite (Zn5(CO3)2•(OH)6) and boric acid (H3BO3) raw materials. Before the synthesis raw materials were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Ultrasonic method is a new application on the zinc borate synthesis. The synthesis parameters were set to 90°C reaction temperature and 55 minutes of reaction time, with 1:1, 1:2, 1:3, 1:4 and 1:5 molar ratio of starting materials (Zn5(CO3)2•(OH)6 : H3BO3). After the zinc borate synthesis, the products analyzed by XRD and FT-IR. As a result, optimum molar ratio of 1:5 (Zn5(CO3)2•(OH)6:H3BO3) is determined for the synthesis of zinc borates with ultrasonic method.

Keywords: borate, ultrasonic method, zinc borate, zinc borate synthesis

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Authors: Sung-mo Seo, Chang-u Chae

Abstract:

The Product Carbon Footprint Labeling has been run for more than four years by the Ministry of Environment and there are number of products labeled by KEITI, as for declaring products with their carbon emission during life cycle stages. There are several categories for certifying products by the characteristics of usage. Building products which are applied to a building as combined components. In this paper, current status of PCF labeling has been compared with LCI DB for data composition. By this comparative analysis, we suggest carbon labeling development.

Keywords: carbon labeling, LCI DB, building materials, life cycle assessment

Procedia PDF Downloads 419