Key Engineering Materials Vol. 908

Abstract: Surface functionalization has diverse applications from tropicalization, superhydrophobicity to chemical bonding and biomolecular applications. Tropical climate adaptability is necessary in order to successfully carry out the equipment’s functionality in extreme climate. Temperature gradient can lead to internal damage and humidity also leads to the surface’s degradation, thus lead to circuits’ shortcuts. Hence this research aimed to fabricate and characterize polydimethylsiloxane (PDMS) based biomimicry and surface functionalization for hydrophobic, fungus free and stable layer against tropical climate. Another nanoparticle that needs to be used to optimize the required criteria is polytetrafluoroethylene (PTFE). Varying the ratio of PDMS/PTFE mixture affects the resulting performance. The composite was layered onto taro leaves using soft-lithography technique. Several of the conventional method limitations were addressed such as water contact angle (WCA) and light transmittance. The overall average WCA of a PDMS/PTFE template obtained was between 92° until 108° whereas for a negatively replicated PDMS/PTFE template was between 121° until 131°. The plain PDMS template shows the average transmittance of 62.28% whereas the PDMS/PTFE template shows the average of less than 7.49% transmittance. The negatively replicated leaf PDMS/PTFE template shows the average transmittance percentage of 15.772% and a minimum of less than 2%. The obtained WCA results had proven that the soft-lithography technique is able to increase the surface wettability of equipment.

Abstract: The challenge of self-healing coating is the mechanical integrity of the coating system embedded with microcapsules. This paper emphasis the mechanical integrity of self-healing coating embedded with microencapsulated vegetable oil (waste sunflower oil). The mechanical integrity of the coating system was determined by the bending and Vickers test. The microencapsulation of waste sunflower oil was successfully produced microcapsules with a mean diameter of 1 μm and a rough shell structure that matchable to embedded in coating matrix. The embedment of microcapsules into the coating matrix has generated self-healing performance with ability to self-heal after 5 days. The mechanical integrity of coating system was increased and demonstrated higher maximum stress (654.25 N/mm2) and higher hardness value (4.40 HV) as compared to the reference sample. It can be concluded that, the microencapsulated waste sunflower oil as an alternative natural vegetable oil to be embedded in the coating system to generate self-healing performance and induce higher mechanical integrity. This finding was able to contribute to the advancement of the future of metal coating industries.

Abstract: Owing to the inability of waste concrete to be recycled, unlike aluminium or glass, it is one of the most harmful substances to the environment. Thus, most of the waste concrete was poured in every available space, resulting in environmental contamination due to the chemical content of the waste concrete. This involves the fabrication and characterization of cement bricks’ compressive strength made from concrete sludge waste in order to investigate the feasibility of re using waste concrete. The concrete waste was to substitute the cement composition within the bricks. The composition of cement and waste concrete is varied to investigate effect of its compressive strength and its microstructure. In general, the optimal formulation is 100 wt % cement and 0 wt % waste, with a compressive strength of up to 12 MPa on average. Increasing the waste composition by 50% reduces the compressive strength of the concrete bricks to 2MPa which limiting the range of application suitable with its properties.

Abstract: Palm oil fuel ash (POFA) is produced and disposed of by the palm oil industries as waste after burning palm fiber, husk, kernel, and shell as fuel to general electricity in-house. The aim of this research is to investigate the influence of modified chemical compositions on POFA on the physico-mechanical properties of porcelain. POFA was washed with 1, 2, and 3 Molar of HCl acid and heat treated. The powder was partially replaced with quartz at 15 wt.% and mixed in a ball mill machine for 12 hours. Modified POFA (admixture of CaO, Al₂O₃, MgO, P₂O₅, SiO₂, and Fe₂O₃) was added to the porcelain composition at 1, 2, 3, 4, 5, 10, and 15 wt.% to measure its influence on physico-mechanical properties of porcelain. The mixture was homogeneously mixed and dry pressed into a pellet at mould pressure 91 MPa and sintered at 1150 °C for 2 hours soaking time. The result of this research shows that these chemical compounds influenced physico-mechanical properties of porcelain, the optimum bulk density, compressive strength, and Vickers micro hardness values were obtained by the addition of modified POFA (admixture of CaO, Al₂O₃, MgO, P₂O₅, SiO₂, and Fe₂O₃).

Abstract: Mortar is another construction medium made of cement, which is mixed with sands and water, and lime is applied to increase the product's longevity. The gypsum renders workability to make mortar or concrete by keeping the cement in plastic state at early age of hydration. The gypsum is called the retarding agent of cement because the gypsum which is mainly used for regulating the setting time of cement. To get the optimal setting time for optimum compressive strength, gypsum in the cement needs to be control. Cement setting time when it hydrates and renders cement paste when combined with water. The objective of this research is to analyze the effect of different amount in Ordinary Portland Cement (OPC). Vicat apparatus was used to analyze the initial setting time of cement paste. Gypsum and clinker were used in production of mortar with the size 50 mm x 50 mm x 50 mm. This research deals with observation of the cement setting time to point out some differences that would effect to strength of mortar. The results reveal that control gypsum with 4% of gypsum has the highest strength as compared to 0% of gypsum and 8% of gypsum. The setting time of cement paste are discussed with respect to their influence on the strength of mortar.

Abstract: Concrete is unquestionably the most desirable construction material, but, like any coin, italso has a negative side. In one way or another, the raw materials used in the production of concretehave a negative impact on the environment. Cement production releases carbon dioxide into theatmosphere, while aggregate production releases dust. The geology of the region where coarseaggregates were mined is also influenced by their extraction. Natural fine aggregates were replacedwith polyethylene terephthalate (PET) bottles in this analysis. PET Plastic aggregates wereproduced by little cutting of waste plastic bottle. Plastic is the most serious environmental problem,and it is having a rapid effect. Shredded waste plastic was used in concrete as a partial substitute fortraditional fine aggregate at 0%, 5%, 10%, 15%, and 20% by weight. The aim of this research wasto determine the compressive strength, microstructure of concrete, and the interfacial transition zoneof concrete (ITZ). The concrete with 5% fine aggregate replacement showed a possible outcome of21 MPa compressive strength, the control mix had the lowest percentage of 1.3 percent, and theconcrete with 20% PET plastic had the highest percentage of 9.8 percent. It can be concluded thatrecycled plastic aggregates can be used to replace fine aggregate in concrete up to 5% of thereplacement and can be used in non-load bearing structures where lightweight materials arepreferred

Abstract: The ability to improve the tendency of hardened concrete in compression at elevated temperature was studied. Five mixes of fly ash were cast with a replacement amount of 0%, 10%, 20%, 30%, and 40% by cement mass. They were exposed to 400°C and held for 2 hours after water curing. The specimens have been cooled down to room temperature and then undergo a compressive test. This research aims to study the physical and mechanical properties of fly ash concrete after being exposed to elevated temperatures. A digital microscope was used to analyse the formation mechanism of microstructure in concrete. Fly ash was used to produce high fire resistance concrete with 100 mm x 100 mm x 100 mm concrete cube. Sample 4 with 30% fly ash has the highest compressive strength with 26 MPa after 28 days and 21 MPa after exposed to 400°C. The results show that concrete containing a high amount of fly ash has several improvements when exposed to elevated temperature. The concrete specimens were used to validate an interfacial transition zone (ITZ) in concrete. The microstructure features were discussed concerning their influence on the strength development of concrete.

Abstract: The application of nanocellulose has been adapted as fillers in composite bricks. Raw kenaf and oil palm empty fruit bunch were treated through chemical treatment and high intensity ultrasonication process to produce cellulose nanofibrils (CNF). One control brick without CNF and ten CNF composite bricks were fabricated. The composite bricks used different amount of CNF which were 40 - 200 ml mixed with filtered sand, portland cement and pebbles. Physical and mechanical characterization was done by using field emission scanning electron microscopy (FESEM) and universal testing machine (UTM) on CNF and composite bricks. FESEM showed the fibril diameter were ranges from 30 - 80 nm for kenaf and 20 - 60 nm for oil palm. The compression tests showed that control brick, 40 ml kenaf CNF composite brick and 40 ml oil palm CNF composite brick were cracked at force 39.01 kN, 50.46 kN and 42.16 kN respectively. Kenaf CNF composite brick has the highest value of Young’s Modulus which is 28.92 N/mm², followed by oil palm CNF composite brick with 27.8 N/mm² and control brick (Malaysia Standard) with 25.8 N/mm². Kenaf and oil palm CNF can increase the strength of the bricks because of enhancement in their mechanical properties.

Abstract: Geopolymer is an alternative cementitious material produced by rich aluminosilicate mineral materials (Si-Al) combine with an alkaline activator. The objectives of this study are to study the effect of adding hydrogen peroxide (H₂O₂) and sodium dodecyl sulphate (SDS) as foaming and stabilizing agents, respectively to the fly ash (FA)-based geopolymer mortar properties. The geopolymer mortars were synthesized with a mixture of FA, alkaline activator and SDS with different H₂O₂ content. The geopolymer mortars were analyzed using compressive strength test, porosity test and Scanning Electron Microscopy (SEM) analysis. Geopolymer mortar with 1 wt% H₂O₂ content and 0.5 wt% SDS has the lowest compressive strength (8.67 N) compare to the other geopolymer mortar composition. As H₂O₂ content increase with presence of SDS, the formation of the pores also increased hence resulting in the low compressive strength of geopolymer mortar.

Abstract: The issue related to disposing the waste material from the industries becomes one of a major problem to the environmental, economic, and social issue. However, natural resources consume worldwide, while at the same time increased amount and type of waste material has resulted in a waste disposal crisis with a growing consumer population. In this project, Municipal Solid Waste Incineration (MSWI) by-product which is bottom ash and rice husk ash were used as blended cement. This research paper is prepared to investigate the utilization of municipal solid waste incineration bottom ash in blended cement and designed for the strength of 15 MPa at 28 days will be evaluated for its early-stage properties. Rice husk ash is used to reduce the amount of cement in mortar and it helps to increase the durability of mortar while keeping up consistent workability. The percentage of replacement in cement is by 0% (control), (5% rice husk ash + 10% bottom ash), (10% rice husk ash + 10% bottom ash), and (15% rice husk ash + 10% bottom ash) The result of this research indicates that 5% of replacement of rice husk ash with 10% of bottom ash shows highest compressive strength with 17.79 MPa with density 2080 kg/mɜ and water absorption of 5.18% at 28 days. This study proved that the addition of bottom ash can increase the durability, workability, and strength of mortar containing rice husk ash as a replacement for cement.