Table of Contents - Volume 20 Number 3

In this study, porous zeolite spheres were produced at a low temperature by a facile and economical method, sol-gel, using a natural zeolite from the Gördes region of Türkiye and waste soda glass powder. Waste glass powder was achieved by milling the recyclable waste soda glass bottles to be used as a source of silica. Elemental analysis of the waste glass was carried out by using X-ray fluorescence spectrometry. It was determined that Si (57.3 wt. %), Ca (20.9 wt. %), Na (13.9 wt. %), Mg (2.64 wt. %), and Al (1.64 wt. %) were the major constituents of the waste glass. Three different sphere compositions were designed containing 1:1, 3:2, and 7:3 zeolite:waste glass ratio. When the zeolite:waste glass ratio was 1:1 oval-shaped green spheres were achieved. For the compositions containing 3:2, and 7:3 zeolite:waste glass ratio spherical green samples were achieved.  Prepared spheres were sintered at 300°, 400°, and 500°C for 1 h. It was observed that the samples could not maintain their spherical form when the sintering temperature was lower than 500°C. Scanning electron microscopy investigation of the spheres sintered at 500°C revealed that highly porous zeolite spheres, containing pores from ~20 µm to nanometre sizes, were achieved. Image J software was used to determine effect of composition on the size and size distribution of the sintered spheres.

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The high specific properties of aluminium based nanostructured alloys have attracted significant attention due to their promise for structural applications especially at elevated temperatures such as pistons for internal combustion engines. Several types of aluminium-based nanostructured alloys have been developed with microstructures of nanometre-sized particles embedded in the aluminium matrix. In this work a newly developed aluminium based nanostructured alloy is studied to understand its microstructure formation, stability and mechanical properties at elevated temperatures. The microstructure was characterised by means of X-ray diffraction, light and scanning electron microscopies. Heat treatments were carried out to determine the T6 condition properties and the microstructural stability at elevated temperatures for long periods of exposure. The hardness of the new alloy at T6 was 30% higher than the corresponding to Al-4032 which is the commonly used alloy for piston application. The work also compared the mechanical properties of the new alloy with two conventional aluminium alloys used in piston applications. The new alloy has 1.3–4.7 times higher strengths than Al-4032.

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Currently, lithium-ion batteries have the highest energy density; hence naturally, this chemistry is the most promising solution for high-density energy storage. This means the commercially used anode material, that is, graphite with a theoretical capacity of 372 mAh/g, needs to be improved; hence the implementation of more capacity material is needed. In regard, silicon is the best alternative available for this with ~4200 mAh/g theoretical capacity. In this work an industrially scalable procedure using ultrasonication followed shear mixer to synthesize a composite of ball-milled silicon with exfoliated graphite for the anode material in lithium-ion batteries. The material is characterized using X-ray diffraction for crystallite information, and scanning electron microscopy shows the composite visuals with X-ray photoelectron spectroscopy to indicate bonding details in the composite, along with half coin-cell tested for18 cycles with a capacity of 222.48 mAh/g and columbic efficiency of 97.86%. Hence the silicon/exfoliated graphite composite using 2 step ultrasonic and shear process can be economical and scalable.

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India uses more than 100 million cubic meters of concrete annually, making it the most common building material. It is common knowledge that traditional concrete constructed using compressive strength does not meet many functional requirements, including impermeability and frost resistance. By emitting a significant amount of CO₂, the manufacture of Portland cement, a key component of concrete, has had disastrous effects on our ecosystem. When one tonne of cement materials is produced, one tonne of CO₂ and other greenhouse gases are emitted. Additional cementitious materials must be used to efficiently substitute cement without compromising the required qualities of concrete. The samples were tested for durability properties like water and chloride permeability and mechanical properties for lengths of 7, 28, and 56 days. Mix M7 exhibits outstanding compressive strength progression, showcasing impressive results of 30.72 N/mm² at 14 days, followed by significant enhancement to 43.18 N/mm² at 28 days, and a robust 48.91 N/mm² at 56 days, making it a highly durable and high-performance concrete mix. In the study comparing the conventional mix and study mix (M1 to M8), the M7 mix exhibited a 28-day split tensile strength of 4.28 N/mm² and flexural strength of 9.657 N/mm². A significant amount of fly ash produced by the coal-based power station is recovered via huge ponds and dykes. It was revealed that 30% GGBS and 20% pond ash replacement of cement yielded the best results. According to research, there are industrial wastes that can replace up to 40% and 20% of the cement and fine aggregate in concrete by GGBS and Pond Ash, respectively.

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The coarse aggregate replacement in part with crushed waste ceramic tiles was explored at varying percentages, ranging from 10% to 50%. Simultaneously, granite powder and ceramic tile powder were employed as substitutes for fine aggregate, each at a 10% replacement rate alongside the ceramic coarse tiles. As a result of continuous innovations and advancements in the construction industry, there has been a significant rise in the utilization of natural aggregates. The generation of solid waste from construction demolitions has also witnessed a substantial increase. Research indicates that approximately from 20% to 30% of materials produced in manufacturing plants end up as waste. To address the constraints of natural aggregate resources and mitigate construction waste, there is a pressing need to repurpose this waste material. Concrete of M₂₅ grade was designed and subjected to testing. Mix designs for different combinations were formulated by altering the percentages of crushed tiles and granite powder in both coarse and fine aggregates. Experiments were conducted on several concrete mixes using variable volumes of discarded shattered tiles and granite powder during seven, fourteen, and 28 days of curing. These examinations included “workability assessments, compressive strength tests, split tensile strength tests, and flexural strength tests”. The results show that larger replacement percentages of granite powder and crumbled tiles boost workability. Additionally, the strength of the concrete exhibited an improvement, particularly with a 30% replacement of ceramic coarse tile aggregate. Explore the use of advanced ceramic composites with improved mechanical properties and durability for enhanced performance in concrete. Investigate the potential use of recycled ceramics or explore novel production methods that reduce energy consumption and greenhouse gas emissions, aligning with sustainable construction practices.

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