Optimum Percentage Research Articles

Enhancement of n-butanol sensing performance of porous ZnO flakes by decorating Ag nanoparticles

This study designs to investigate a high-performance n-butanol gas sensor with a porous morphology. Porous ZnO flakes modified with Ag particles are prepared in two steps using hydrothermal and precipitation methods. Morphological analysis of the samples shows that the ZnO flakes were covered with mesopores with high porosity, and their edge lengths ranged from 3 μm to 6 μm, with a minimum thickness of 11.3 nm. Through rigorous gas sensing testing, we find that the optimal mass percentage Ag-ZnO sensor provided significantly better sensing behavior, with a 100.8 response for 100 ppm n-butanol, compared to 14.5 for the pure ZnO sensor, a 5.95-fold improvement. In addition, the sensor's optimal operating temperature is reduced from 290 °C to 190 °C, increasing its adaptability and versatility in practical applications. In subsequent tests, it is found that this Ag-ZnO sensor not only shows excellent selectivity to n-butanol but also favorable stability, with no significant degradation during 30 days of continuous testing. The experimental analysis shows that the formation of porous flake structure and the modification of Ag particles are effective approaches to improve the ZnO gas sensor.

Porous hierarchical sphere g-C3N4 with coordinated Co-ions as an efficient and stable self-Fenton photocatalyst for the removal of antibiotic

Photocatalysis-self-Fenton reaction is a promising antibiotics-contaminated wastewater treatment method, but it is still limited by the leakage and sluggish cycling of metal-ions activating sites. Herein, a novel porous hierarchical sphere g-C3N4 with coordinated Co-ions (HCN-Co) was successfully synthesized by a supramolecular modified calcination strategy. The hierarchical sphere structure and coordinated Co-ions of HCN-Co exhibited a synergistic effect on enhancing visible-light absorption, stabilization of Co-ions, charge transfer and surface reaction, which leaded to increased H2O2 generation and activation under visible-light irradiation. Consequently, HCN-Co displayed remarkable and stable photocatalysis-self-Fenton degradation of ciprofloxacin (CIP) with an optimal removal percentage of 99.9 % under visible-light irradiation for 50 min. In this photocatalysis-self-Fenton reaction, H2O2 was generated from 2-step single-e− oxygen reduction reaction and activated to hydroxyl radical (OH) by Co2+ refreshing from interface charge transfer (IFCT) excitation. This work presents a viable approach and provides valuable insights for developing efficient photocatalysis-self-Fenton system for wastewater remediation.

Recycling of Waste Granodiorite Powder as a Partial Cement Replacement Material in Ordinary Concrete

Abstract In this study, the effect of using waste granodiorite powder (WGP) as a cement replacement material in percentages ranging from 1 to 9% on various physical and mechanical properties of ordinary concrete was investigated. The resistance of produced concretes with WGP to the high temperature effects on the 28 days compressive strength were studied as well. Granodiorite is one of the well-known igneous rocks that have been used in previous research as a replacement for coarse or fine aggregates due to the hardness of its grains. However, rare studies have investigated its powder as a partial cement replacement material. Results showed the ability of investigated WGP with high surface area to act as a supplementary cementitious material that contributed to enhance the results of mechanical and physical properties of concrete. At traditional room temperature, the optimal replacement percentage was 7%, where the 28 days compressive and tensile strengths were improved by 28.3% and 17.3%, respectively. The optimal replacement ratio varied between 7 and 9% in the case of high temperatures, according to exposure time and temperature degree. Statistical and sensitivity analysis was conducted on 66 available compressive strength value represents all variables before and after elevated temperature exposure. While the regression equation showed good R2 value of 85.3%, sensitivity analysis indicated that compressive strength value is most sensitive to temperature, followed by WGP ratio and exposure time, with importance values of 56, 26, and 18 %, respectively. Results showed also that the setting times and consistency was decreased with increasing the replacement ratio with WGP, while the workability was slightly improved up to 5% replacement ratio. Furthermore, microstructure analysis showed that WGP can help to densify the concrete matrix due to its small size and ability to fill the interstitial voids in the concrete matrix.

Zn2-xGeO4-GeO2:(x)Mn2+ films with long persistence, intense brightness and high quantum efficiency, deposited by ultrasonic spray pyrolysis

This work shows the synthesis and characterization of the Zn2-xGeO4-GeO2:(x)Mn2+ (x = 0.10, 0.25, and 0.50 at.%) films using the Ultrasonic Spray Pyrolysis (USP) technique. These films were deposited at 500 °C and heat treated at 800 °C for 13 h. X-ray diffraction (XRD) measurements showed the rhombohedral and hexagonal phases of Zn2-xGeO4 (78.8 %) and GeO2 (21.2 %), respectively. SEM micrographs exhibited the surface morphology of these films. The STEM and HAADF show Ge, Zn, and O atomic layers. In addition, XPS was carried out to observe the oxidation states of Mn2+ (75.4 %) and Mn3+ (24.6 %) for the films doped with Mn ions (0.10 at.%). Incorporating manganese ions into the Zn2-xGeO4-GeO2 host lattice generated an extremely green emission, exciting at 250 nm. The photoluminescence and persistence luminescence properties were studied in accordance with the manganese doping concentration. For photoluminescence, it was found that the optimal doping percentage was 0.25 at.%, and for persistence luminescence, it was 0.10 at.% Mn with λex = 250 nm. Quantum efficiency measurements gave a result of 100 %. In addition, preliminary CL measurements were exhibited.

Influence of heating elements layout on temperature uniformity in a large size heat treatment furnace

Computational Fluid Dynamics simulations were used to optimize heating elements placement on the walls of a large size electrical heat treatment furnace in order to reduce temperature gradients within the furnace and uneven temperatures on different faces of the blocks which could result in variabilities in final mechanical properties. Initial evaluations of different layouts highlighted the effectiveness of equipping two side walls. Subsequently, an optimal percentage of side wall coverage was identified through simulations and multi-objective evolutionary optimization. Genetic and pareto search algorithms yielded 10 % and 14.2 % as optimum values, respectively. Implementing an optimal coverage demonstrated significant reductions in surface temperature non-uniformity, surface-to-center temperature differential, and temperature differences between loaded blocks. These improvements suggest a potential for enhanced uniformity in mechanical properties across a batch of products. This approach presents a promising strategy for obtaining consistent and efficient heat treatment cycles in industrial heat treatment furnaces resulting in energy saving and improved product quality.

What Degree of Radiological Compression Predicts Cauda Equina Syndrome: A Retrospective Study at a National Tertiary Center

ObjectiveCauda Equina Syndrome (CES) is diagnosed both clinically and radiologically. However, it's unclear if a specific degree of cauda equina compression (CEC) on imaging can confirm the diagnosis. This study aimed to identify an optimal percentage of prolapse to canal ratio (PCR) on MRI that correlates with CEC, facilitating reliable decision-making for CES symptoms. MethodsA single-center retrospective case series analysis was conducted from 2020 to 2021. Sixty-one patients who underwent emergency lumbar discectomy within 48 hours of presentation were included, divided into a CES group and a disc prolapse (DP) group. CES cases were identified using ICD-10 code G83.4. PCR was calculated by dividing the width of the disc herniation by the total width of the spinal canal at the level of the herniation on single mid-sagittal T2 MRI scans, using the IC Measure software on Windows. ResultsCES most frequently occurred at the L4/5 level (37/61). The median PCR in CES cases was 76.19% (66.67 – 85.71), significantly higher than in DP cases, 48.08% (31.33 – 55.56) (p<0.001). A PCR threshold of 40% maximized sensitivity at 100% but had a specificity of 45%. Conversely, a threshold of 75% maximized specificity at 100% with a sensitivity of 50%. The optimal PCR, determined by the Youden index, was 66%, yielding a sensitivity of 75% and specificity of 97%, with an area under the curve (AUC) of 0.923. ConclusionsSimple radiological measurements of PCR can potentially triage CES patients and guide their management. Future studies should correlate PCR with clinical signs and symptoms for a comprehensive assessment.

Experimental Study on Concrete Strength Behavior Using Plastic Waste as a Partial Replacement of Fine Aggregate

Waste from plastic materials is outstripped due to the growth of industrialization and urbanization. Plastic materials are non-biodegradable; decomposition is not possible all the time. The recycling of plastic materials by using them in concrete will be a great deal for plastic management. This research investigation aims to measure the optimum percentage of plastic in concrete without a reduction in concrete strength and shear behavior of reinforced concrete. Using the provision of Mix Design ACI 211.1-91, the M28 concrete grade was created. Plastic materials have been collected and passed through a No-4 sieve (4.76mm). The combination of fine aggregates and ground plastic materials (RPET, PP) in the weight fraction of fine aggregate mix (0%, 2%, 4%, 6%, 8%, 10%) was used in the concrete. Concrete beams (750´150´150 mm) are reinforced with two 12 mm longitudinal steel bars in the tension zone, with proper clear cover for testing the shear capacity. In order to conduct the compressive and tensile splitting test, concrete specimens with a diameter of 100 mm and a height of 200 mm were used. The experimental findings demonstrate guidelines for using plastic as a partial replacement within 2% to 4% of fine aggregate to produce the best outcomes.

The Effect of Iron Sand (Wale) On The Compressive Strength of Quality ConcreteF'c 26.4 Mpa

Concrete is the most widely used building material in construction, both building and bridge construction. This is supported by the ease of the concrete making process that can be made by various groups, both those who understand concrete mix design and those who have no understanding of concrete at all. The difference between the two is only in the quality and quality of the concrete made. The effect of iron sand on normal concrete constituent materials is carried out using percentages of 0.5%, 5% and 20% of the total volume of natural sand used. In this study, iron sand additives were used to determine the most optimal percentage that affects the compressive strength of concrete with the addition of iron sand material of 0.5%, 5% and 20% of the total volume of natural sand. The review of the analysis of this study is compressive strength with a cylindrical test piece with a diameter of 15 cm and a height of 30 cm. From this study, it can be known that the strength of the concrete produced by the use of iron sand mixture is 0.5%, 5% and 20% of the total volume of natural sand.

Investigation of Strength Concrete Materials Using Pozzolanic Additives

In the study, pozzolanic materials serve as replacements for additives, namely Palm Shell Ash (PSA), Coal Fly Ash (CFA), and Rice Husk Ash (RHA). The purpose of the study is to determine the optimum proportion of additives used in high-performance concrete. The addition of 15% PSA resulted in a strength of 69.227 MPa over a test period of 56 days, while the addition of 15% CFA yielded a strength of 69.369 MPa, and the addition of 5% RHA resulted in a strength of 59.984 MPa. The maximum concrete strength is achieved by adding 15% PSA. Correlation analysis between stress-strain indicates that aggregates exhibit higher strength compared to cement paste, mortar, and concrete, highlighting the relationship between the aggregate, cement paste, mortar components, and concrete as a composite material. Aggregate strength values found to be the highest among concrete, cement paste, and mortar, indicating that cement paste contributes the least to the strength of concrete, followed by mortar as concrete reinforcement. The results suggest that aggregates remain the primary strength component supporting concrete. The finding indicates that the relationship between the basic substances in this study aligns closely with existing theory. Moreover, it suggests that all concrete materials with pozzolan variants can classified as high-quality concrete. The optimum percentage is obtained by adding 15% palm shell ash, resulting in the highest compressive strength compared to counterparts and test objects with other types of pozzolan additions. The relationships between the constituents of concrete demonstrate that aggregates continue to be important contributors to concrete strength, with the cement paste contributing the least. Concrete strength values fall between those of aggregates and those of cement and mortar pastes.

A study on the synthesis and performance evaluation of fly ash and alccofine as sustainable cementitious materials

Construction and global infrastructure depend on cement production. It is one of the biggest carbon emitters, making it an aspect of environmental sustainability and climate change mitigation. Each stage of cement production releases CO2 and other greenhouse gasses. About 8% of worldwide CO2 emissions come from the cement sector, making it a major contributor. Different supplementary cementitious materials (SCMs) like fly ash (FA), silica fume (SF), and slag are used to partially replace traditional raw materials like limestone, reducing the environmental impact. This study investigated the use of supplementary cementitious materials, specifically FA and alccofine (AF), as partial replacements for cement in concrete to reduce environmental impact. The study first identified an optimal replacement percentage for FA (20%, 30%, and 40%) by weight of cement. Subsequently, using the optimal FA percentage, AF was added at varying percentages (5%, 10%, and 15%) by weight of cement. The study evaluated the mechanical properties of the concrete mixtures, including workability, compressive strength, split tensile strength, and flexural strength. Durability, measured by water sorptivity and rapid chloride penetrability tests, was also assessed. The microstructural properties of the concrete were analyzed to understand their influence on performance. As a result of the significant environmental implications of producing and using concrete for all activities, an in-depth life cycle assessment (LCA) was conducted. Additionally, artificial neural networks were employed to predict the compressive strength of the concrete. The study concluded that incorporating FA and AF in concrete mixtures is a promising approach to producing more environmentally friendly concrete.

Design and characterisation of activated magnetic zeolite 4A from naturally occurring kaolin clay of Cameroonian origin for optimised dye removal by Fenton-like degradation

ABSTRACT The transformation of local clay material of Cameroonian origin into magnetic zeolite (Fe@Zeo-4A) for the degradation of acid-blue 90 in solution was investigate herein. The insertion of magnetic iron oxide particles into the zeolitic framework of Zeo-4A was achieved via hydrothermal synthesis. FT-IR spectroscopy, XRD and SEM confirmed the transformation of the clay into zeolite while EDX analysis and elemental mappings confirmed the presence of iron in the magnetic zeolite. Fe@Zeo-4A was strongly attracted to an external magnetic field. N2 adsorption-desorption studies revealed a considerable decrease in specific surface area and pore volume from the zeolite to the magnetic zeolite, suggesting the occupation of the pores of the zeolite by magnetite. The central composite design of the response surface methodology was used as optimisation approach for four parameters affecting the efficiency of degradation: solution pH, H2O2 concentration, initial dye concentration and time of stirring. ANOVA results revealed good correlation between the experimental and predicted results as well as the suitability of the linear regression model for describing the dye degradation process. An adjusted correlation coefficient of 85.17% was obtained for the dye degradation model. An optimal degradation percentage of 95.2% was obtained experimentally under optimal conditions of 7.6 for pH, 20 mg/L for dye concentration, 15.0 mol/L for [H2O2] and 15 min for time, in close agreement with a theoretical response of 96.6% predicted by the model. The magnetic zeolite was found to exhibit good stability over a wide pH range and lost only about 18% of its catalytic efficiency after five cycles of degradation experiments. Therefore, the novel magnetic zeolite-based material is an efficient Fenton catalyst for treating dye-contaminated wastewater.

Ecological mortars produced from sustainable hydrated lime obtained from biomass ash

Sustainable hydrated lime is produced from biomass ash rich in calcium carbonate, with properties similar to industrial hydrated lime. However, there is a lack of current and relevant research on sustainability related to the use of alternative limestone, derived from waste such as biomass ash. In this sense, the present research aims to study the behavior of cementitious coating mortars with partial and total replacement of industrial hydrated lime by sustainable hydrated lime, through microstructural, macrostructural, physical and chemical tests. Microstructural analyses performed by SEM demonstrated the presence of cement hydration products (CSH and ettringite) in all mortars evaluated. Chemical analyses through XRF and XRD showed similarity in chemical composition and crystallographic phases between the mortar with industrial hydrated lime and the ecological mortars. The FTIR showed chemical bonds characteristic of cement mortars in all ecological mortars, ratified by TG/DTG, which shows the decomposition of products such as CSH, ettringite, portlandite and calcite in all ecological mortars. Through the results found, the viability of replacing sustainable hydrated lime with industrial hydrated lime in the preparation of ecological mortars stands out, at the optimum percentage of 50 %, with possible total replacement (100 %) without significant losses in resistance.

Physicochemical, mechanical and thermal analysis of unfired clay bricks: Kaolinite-PEG 6000 composite

This study aims to evaluate the potential of polyethylene glycol (PEG 6000), a recycled material, as an additive to improve unfired clay bricks. By proposing a sustainable alternative to traditional methods potentially linked to medical waste. This research explores the physicochemical, mechanical and thermal properties of unfired clay bricks modified by different contents of PEG 6000 (0%, 1%, 3%, 7%, 15% and 20% by weight) according to the standard NM 13.1 0.0442005. The testing methods comply with recognized building sector standards (Belgian NBN EN 771-3+A1 and American ASTM C675-17). The clay used was extracted from Berrechid city and it is identified as kaolinite and some trace of illite, which has non-swelling properties. The incorporation of PEG 6000 into the unfired clay bricks has notably reduced the porosity rate from 3.91 % to 1.21 %, an improvement of 69 % compared to the reference sample, leading to a decrease in the rate of capillary water absorption. The bulk density of the bricks has slightly decreased to 1670.07 kg/m3, which still allowed them to be classified as light bricks. The incorporation of 7% of PEG 6000 increased compressive strength and flexural strength up to 15.98 MPa and 0.959 KN respectively, an improvement of 63.23 % compared to the reference sample, making them suitable for the construction of interior and exterior walls according to the standard NBN EN 771-3+A1. However, thermal conductivity and specific heat capacity have been improved by 42.22 % compared to the reference sample, reaching 0.26 W/m.K and 0.89 kJ/kg.K respectively. Optimization showed that 7% of PEG 6000 is the optimal percentage for manufacturing high-performance bricks, taking into account all properties studied previously. Moreover, the simulations carried out by the TRANSYS software suggest significant energy gains in terms of insulation, achieving up to 58.33% energy savings. In essence, this research demonstrates the potential of PEG 6000 as a sustainable additive for unfired clay bricks, offering improved properties and promising energy efficiency benefits.

Sustainable quick quantitative screening for the physiology of chitinases production by Bacillus thuriengiensis gallariae and detection of Aedes aegypti biopesticide activity

Background Chitin is considered the world’s first and most abundant amino-carbon substrate. Objective The proposed method aims to speed up the detection and measuring of microbial chitinase production. Materials and methods Solid-state fermentation, plates, viscosity, and spectrophotometric methods were used to detect microbial chitinase activity. Analysis of variance was used for statistical analysis. Results and conclusion The trailed Bacillus thuriengiensis gallariae strain was differentiated from other tested strains of Bacillus thuriengiensis in terms of mosquito resistance, besides being superior to other studied Bacillus sphaericus. As anticipated, results from the clear zone plates method were not clear compared with the viscosity method where the strain exhibited the best. Worthy, the same result was reached in the color methods. The superlative incubation period for the physiological properties of chitinase production from Bacillus thuriengiensis gallariae was attained after 5 days. Results indicated that the best size of chitin particles was 1 mm, the best percentage of humidity of the growth was 67%, the best inoculum volume was 10 ml, and the best carbon source for the production of crude chitinases was glucose. The optimal concentration for the production of chitinases was 20% of the weight of the growth medium, yet 5% of the weight of the growth medium was the optimal percentage of glucose as a carbon source for the production of other protein metabolites. The proposed colorimetric method seemed to be an effective and rapid method to survey the aptitude of huge quantities of microorganisms to produce chitinases.

THE MECHANICAL PROPERTIES OF CRUMB RUBBER STEEL FIBER CONCRETE (CRSFC)

Waste materials can be used in concrete as part of replacement material. Currently, 4 billion tires are abandoned in landfills, with 1 billion generated annually and 1.2 billion dumped without treatment by 2030. The number of waste tires is continually increasing, because of the growing use of transport vehicles. Therefore, effectively reusing waste tires as crumb rubber in the mix of concrete can save energy and protect the environment, while the use of steel fiber in the concrete will help enhance its properties. The aim this research to producing the steel fiber crumb rubber concrete (CRSFC) and to balance the issues of strength loss and sustainability. Crumb rubber is used as sand replacement in the mix concrete in the following proportions: 0%, 5%, 10%, 15%, and 20%, while steel fiber is added in the following proportions: 0.5% by volume. Slump, compressive strength, dry density, water absorption, ultrasonic pulse velocity, and rebound hammer tests are performed on the concrete after curing. As the percentage of CRSFC increased, the slump value and dry density decreased while the water absorption increased. Steel fiber helps increase compressive strength by 33 % over normal concrete. The optimum percentage of crumb rubber in CRSFC as a sand replacement is approximately 5% to 10% by volume. In summary, incorporating crumb rubber and steel fibers into concrete can result in a more eco-friendly and resilient construction material.

A Review on Experimental Study of Design of Rigid Pavement by using Recycled Coarse Aggregate with M30 Mix Design

Concrete, a fundamental construction material, boasts attributes like durability, versatility, and cost- effectiveness. However, the depletion of natural resources and the escalating concrete waste production necessitate innovative solutions. In this rapidly industrializing world, recycling construction materials plays a pivotal role in preserving our finite resources. Concrete pavements, widely practiced in developed countries, are relatively new in India. Selecting the right pavement type is crucial, but equally important is determining the optimal pavement thickness based on traffic levels, subgrade conditions, and environmental factors. Unfortunately, many existing methodologies overlook critical factors (such as vehicle loads, support loss, thermal gradients, and environmental stress), leading to inaccurate thickness calculations. In this context, rigid pavement construction using recycled coarse aggregate (RCA) emerges as an eco-friendly and cost- effective solution. In a recent research endeavour, Recycled Coarse Aggregates (RCAs) sourced from demolished material took center stage. These demolished materials are meticulously crushed to a suitable size and repurposed as recycled coarse aggregate. Meanwhile, natural sand continues to serve as the fine aggregate. Notably, the concrete industry consumes a staggering 12.6 billion tons of raw materials annually, making it the world’s largest natural resource consumer. The environmental impact of concrete production—especially the extraction of raw ingredients such as cement, coarse aggregates, and fine aggregates—is considerable. To address this, the study employed a trial-and-error approach for mix design, adhering to relevant standards (such as IS code and IRC: 44-2008). For M30 grade cement concrete, varying percentages (0%, 25%, 50%, 75%, and 100%) of recycled coarse aggregates replaced conventional coarse aggregates. Casting used cube and beam models to obtain laboratory test results for rigid pavement to determine how much optimal percentage of RCA can be substituted in place of NCA. By integrating RCAs, we not only mitigate environmental impact but also contribute to sustainable rigid pavement structures. Key Words: Rigid Pavement Design, Recycled Coarse Aggregate, RCA Concrete, Natural Coarse Aggregate, NCA Concrete, Mix Proportion, Pavement Thickness, Life Cycle Cost, And Environmental Benefits etc.

Use of pumice stone and silica fume as precursor material for the design of a geopolymer.

Geopolymers are alternative materials to cement because they require less energy in their production process; hence, they contribute to the reduction in CO 2 emissions. This study aims to evaluate the possibility of using industrial residues such as silica fume (SF) to improve the physical and mechanical properties of a pumice stone (PS)-based geopolymer. Through an experimental methodology, the process starts with the extraction, grinding, and sieving of the raw material to carry out the physical and chemical characterization of the resulting material, followed by the dosage of the geopolymer mixture considering the factors that influence the resistance mechanical strength. Finally, the physical and mechanical properties of the geopolymer were characterized. This research was carried out in four stages: characterization of the pumice stone, design of the geopolymer through laboratory tests, application according to the dosage of the concrete, and analysis of the data through a multi-criteria analysis. It was determined that the optimal percentage of SF replacement is 10%, which to improves the properties of the geopolymer allowing to reach a maximum resistance to compression and flexion of 14.10 MPa and 4.78 MPa respectively, showing that there is a direct relationship between the percentage of SF and the resistance. Geopolymer preparation involves the use of PS powder with a composition rich in silicon and aluminum. The factors influencing strength include the ratio of sodium silicate to sodium hydroxide, water content, temperature, curing time, molarity of sodium hydroxide, and binder ratio. The results showed an increase in the compression and flexural strength with 10% SF replacement. The geopolymer's maximum compressive strength indicates its non-structural use, but it can be improved by reducing the PS powder size.

Gallium Nitride Electrodeposition at Indium Tin Oxide and Fluorine Tin Oxide Electrodes in Ammonium Nitrate and Gallium Nitrate Aqueous Solution

The potential of gallium nitride thin films in semiconductor technology and devices has garnered interest. This study aims to develop an effective GaN electrodeposition technique that will function on both Earth and microgravity situations and may be applied to any kind of needed application, such as in photovoltaic devices. To determine the optimal electrodeposition conditions, e.g. applied potential, cyclic voltammetry (CV) was done on a boron-doped diamond electrode at 0.01 mV/s potential scan rate and at 0.8 V vs. Ag/AgCl (Saturated KCl) constant applied potential. In the CV study, a well-defined peak formed at -1.75 V vs. Ag/AgCl (Saturated KCl). To start examining all the features of the electrodeposition of a thin film on Indium Tin Oxide (ITO) and Fluorine Tin Oxide (FTO) Electrodes, chronoamperometry (CA) measurements were done at different time scales, ranging from 3600s to 14400s and at a constant applied potential of -1.7 V vs. Ag/AgCl (Saturated KCl). The characterization methods used to examine the materials' topography, elemental contrast, crystal structure, and electrodeposition weight percentages included scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). Longer electrodeposition times produced the best grain formation, promoting dendritic structure at the electrode surface. Furthermore, the optimal weight electrodeposition percentage of Ga and N was 10% and 35 % at 3600s, respectively, although the electrodeposited electrode surface was heterogeneous. The surface topographies at 3600s showed less grains definition and dendritic structures. At higher electrodeposition times, e.g. 14400s, more grain definitions and dendritic structures were found. For the 3600s electrodeposition time, XRD peaks were found at 33o, 37o and 46o, which are characteristics of GaN wurtzite structure according to literature.

Analisis Pengaruh Serbuk Besi Sebagai Substitusi Agregat Halus pada Lataston Lapis Aus (HRS-WC) Terhadap Kinerja Jalan Beraspal

Damage to flexible pavements is still commonly found in Indonesia. As technology develops, there is some research regarding using iron powder as an alternative replacement material for asphalt mixtures. This research used iron powder waste as a substitute for fine aggregate in Hot Rolled Sheet–Wearing Course with levels of 0%,15%,30%, and 45%. The purpose of this research to determine the Optimum Asphalt Content (OAC) and optimum percentage of iron powder waste addition as a substitute for fine aggregate to the indicator of Marshall test based on The General Specification of Bina Marga 2018 (Revision 2). Based on Marshall testing that has been carried out, the OAC values are 7,5% with an average of stability 2040,46 kg, flow 3,40 mm, MQ 600,24 kg/mm, voids in mix 4,69%, voids in mineral aggregate 18,30%, and voids filled with asphalt 74,39%. While the optimum percentage of iron powder value is 13% with an average of stability 2091,90 kg, flow 3,17 mm, MQ 662,79 kg/mm, voids in mix 3,92%, voids in mineral aggregate 17,59%, and voids filled with asphalt 77,72%. The result met the General Specification of Bina Marga 2018 (Revision 2). The addition of iron powder as a substitute for fine aggregate in HRS-WC is can increase stability but reduce air voids in the asphalt mixture. This result makes the asphalt mixture more impermeable and plastic.

Improving landfill liner performance with bentonite-slag blend permeated with ammonia for a Municipal solid waste landfill

Leachate emanating from landfills contains ammonia which may cause serious health effects on living things. An effectively designed clay barrier should not allow the contaminant to infiltrate the soil and groundwater systems. The utilization of certain industrial by-products in engineered landfill barriers, not only reduces the need for conventional liner materials but also helps in sustainable waste management. This study investigated the hydraulic conductivity, unconfined compressive strength, compaction, and adsorption characteristics of lithomargic clay blended with an optimum percentage of bentonite (10%) and granulated blast furnace slag (15%) permeated with ammonia. The results revealed that increasing the content of granulated blast furnace slag decreased the maximum dry density while increasing the optimum moisture content. In comparison to lithomargic clay, the hydraulic conductivity of the amended soil liner permeated with ammonia decreased from a value of 3 × 10−8 m/s to 5 × 10−10 m/s. The unconfined compressive strength of the amended soil specimens showed an increasing trend with curing times (i.e., 0, 14, 28, and 56 days). The batch adsorption results revealed that Freundlich and Langmuir's isotherm fits the equilibrium adsorption data and the adsorption of ammonia on clay liner follows non-linear behaviour. Overall, the experimental results implied that lithomargic clay blended with 10% bentonite and 15% granulated blast furnace slag can be used as an impermeable soil reactive barrier in engineered landfills.