Conference Publications
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PublicationParameter effects and optimisation studies on ultrasound-assisted extraction of polyphenolics from mango peel wastes(AIP Publishing, 2024-04)In this study, the bioactive properties, such as the total phenolic content (TPC), total flavonoid compound (TFC), and the antioxidant activity of mango peel wastes (MPW) extract were evaluated. The extract was obtained through an ultrasound-assisted extraction (UAE) technique, where 70% ethanol was used as the extractive medium. The main effects of extraction parameters involving the solvent-to-sample ratio, sonication time, and extraction time were studied through a single-factor experiment. It was found that the highest TPC, TFC, and antioxidant activity can be obtained at conditions of 40 mL/g, 30 min, and 50 °C, respectively. Based on the conditions, the TPC was optimised by response surface methodology (RSM), where a significant quadratic regression model with R2 of 0.92 was acquired. The optimum conditions were obtained at 41.49:1 solvent-to-sample ratio, 31.15 min sonication time, and 46.87 °C extraction temperature with a maximum TPC of 25.58 mg GAE/g. Validation experiments were conducted at the optimum extraction condition and successfully yielded a higher TPC yield with an average value of 26.11±2.11 mg GAE/g.
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PublicationA review on the fly ash characteristics and geopolymerization reaction mechanism of fly ash based geopolymer(AIP Publishing, 2024-04-19)The application of Portland cement as a cementitious binder has been used widely in the construction industry. However, the application of geopolymer has equal popularity nowadays, especially for concrete repair works and rehabilitation. Research and development of high-performance geopolymer binders or known as alkali-activated materials is increasing worldwide. There are various precursors that have been investigated to optimize the performance of the geopolymer binders such as kaolin, slag, and many others. The application of fly ash is popularly being tested and proved to be the most efficient precursor owing to its excellent properties and performance. The performance of this precursor is being reviewed and presented in this paper and the high calcium fly ash is notably the most suitable precursor for fast setting and high early strength geopolymer. This paper presents an overview of fly ash, in terms of its properties, reaction, and mechanism. Several significant properties affecting the performances of fly ash-based geopolymer were discussed. It is being highlighted in this paper that fly ash has various microstructures which produced different geopolymerization reaction mechanisms.
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PublicationCorrelation study of compressive strength with water absorption and density for fly ash based geopolymer concrete(AIP Publishing, 2024-04)Geopolymer Concrete (GPCs) is a novel type of concrete that uses an inorganic alumina silicate binder system rather than the hydrated calcium silicate binder system, which is activated by alkaline liquids. Fly ash is the primary ingredient used to activate the geopolymerization process, as well as to substitute traditional Portland cement. The sole difference between this concrete and standard Portland cement concrete is the binding agent. Sodium hydroxide and sodium silicate solutions were used to activate the substance in fly ash. The geopolymer has the advantages of rapid strength increase, no need for water curing, excellent mechanical and durability features, and is an environmentally safe and sustainable alternative to OPC-based concrete. The manufacture of Portland cement, in particular, results in the release of air pollutants, resulting in environmental pollution in the construction industry. It cuts CO2 emissions by 80-90 percent. This research is to consolidate on the study on characterization and strength of fly ash based geopolymer rigid pavement through compressive strength, water absorption and density. From the results, it is concluded that when the solid to liquid ratio increased, compressive strength and the density will be increased due to the characteristics and properties of the geopolymer concrete however decrease in water absorption.
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PublicationFeasibility study of welding wire for low carbon welding on heavy equipment components based on welding strength and microstructure analysis(AIP Publishing, 2024)In this article, the use of welding wire is examined in relation to the weld strength and microstructure of low carbon steel used in the construction of components for heavy machinery. The goal of this research was to compare the microstructure and mechanical properties of two types of welding wire (A and B) that conform to the Japanese Industrial Standard (JIS) Z 3312. A tensile test, a Vickers hardness test, and a metallographic test were carried out. Type B welding wire had a tensile strength of 472.5 MPA, while type A welding wire had a tensile strength of just 448.9 MPA. Average hardness was determined to be 165 HV for type B welding wire, which also requires the most heat input. Type A wire, with its 162 HV hardness and low heat generation, is an excellent example. These findings indicate that the welding heat input is strongly correlated with the tensile strength and hard-ness value. The metallographic analysis also revealed the presence of pearlite and ferrite. Type A welding metal welding wire had a maximum pearlite content of 16.40%, whereas type B welding metal welding wire peaked at 17.33%. The strength of a material can be affected by its pearlite content, with a positive correlation between the two.
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PublicationEffects of diameter on copper pillar with solder cap interconnections during reflow soldering process(Springer, 2023)Recently, the copper pillar with solder cap interconnection has been introduced as an alternative for the solder bump interconnection to tackle the limitations, such as the collapsing nature of the solder bump and larger pitch size. This paper presents an effective simulation tool to evaluate the effects of different diameters of the copper pillar with solder cap during the reflow soldering process. A three-dimensional numerical approach is used to investigate the thermal behavior of the copper pillar with solder caps with different diameters. The interconnection bump diameters are 150, 200, 250, 300, and 350 μm. The model is developed and meshed using the Computational Fluid Dynamics (CFD) software. The temperature distributions of the copper pillar with solder caps with different diameters during the reflow soldering process are predicted. The paper aims to provide an understanding of the effect of diameters on the temperature distribution of copper pillars with solder caps during reflow soldering.