Romisuhani Ahmad
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Romisuhani Ahmad
Official Name
Romisuhani, Ahmad
Alternative Name
Ahmad, Romisuhani
Romisuhani, Ahmad
Romisuhani, A.
Ahmad, R.
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Scopus Author ID
56354732400
Researcher ID
AAA-1058-2021

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Characterization and properties of palm kernel shell filled low density polyethylene biocomposites

2011 , Romisuhani Ahmad

Biocomposites based on palm kernel shell (PKS) and low density polyethylene (LDPE) was investigated. The biocomposites were prepared by using Z-Blade mixer at processing temperature 180 oC and rotor speed 50 rpm. The effect of filler loading of PKS as filler in LDPE on mechanical properties, water absorption, morphology, thermal properties and fourier tranformation infrared spectroscopy (FTIR) were studied. The results show that the increasing of filler loading have decreased the tensile strength and elongation at break but increased the Young’s modulus and water absorption. The morphology study using scanning electron microscopy (SEM) shows poor interfacial interaction between PKS and LDPE with increasing of the filler loading. The crystallinity of the biocomposites increased with increasing of PKS loading. To improve the mechanical properties, compatibilizer, Polyethylene co-acrylic acid (PEAA) was used. The effect of chemical modification of biocomposites with polyethylene co-acrylic acid (PEAA), acrylic acid (AA) and coconut coupling agent (COCA) enhanced the tensile strength, Young’s modulus and crystallinity of the biocomposites but reduced the elongation at break and water absorption. The morphology study (SEM) shows that the filler-matrix interaction was improved with incorporation of PEAA, AA and COCA. The FTIR results show that the wave number of hydroxyl group for all biocomposites shifted to lower wave number which indicates that interaction between the hydroxyl groups from PKS with compatibilizer and coupling agent.

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Densification behavior and mechanical performance of Nepheline geopolymer ceramics: preliminary study

2023 , Nur Bahijah Mustapa , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Wan Mastura Wan Ibrahim , Andrei Victor Sandu , Christina Wahyu Kartikowati , Puput Risdanareni , Wan Hasnida Wan Mohamed Saimi

Nepheline geopolymer ceramics have emerged as a promising sustainable alternative to traditional cementitious materials in various applications. As the sintering mechanism plays a crucial role in the densification and mechanical performance of ceramics, therefore, in this paper, a preliminary study was conducted to examine the effects of densification towards mechanical properties of geopolymer-based nepheline ceramics upon sintering. The said innovative geopolymer technology can convert raw materials of aluminosilicate activating with alkaline activator into ceramic-like materials requiring low temperatures. The experimental procedure includes the synthesis of nepheline geopolymer ceramics through the geopolymerization method, then sintered at different temperatures to explore the sintering behavior and its impact on the materials’ microstructure and mechanical performance. The densification behavior of nepheline geopolymer ceramics during sintering was analyzed by evaluating the changes in density, shrinkage, and porosity. The microstructural evolution and are determined by using SEM. The relationships between sintering conditions, microstructure, and mechanical performance were investigated to understand the underlying mechanisms affecting the material’s strength and durability. The geopolymer exhibited its highest flexural strength of 54.93 MPa when sintered at 1200 ℃, while the lowest strength of 6.07 MPa was observed at a sintering temperature of 200 ℃. The findings demonstrate a positive correlation between the sintering temperature and the flexural strength of the geopolymer ceramics, indicating that higher temperatures lead to increased strength. Ultimately, this knowledge can facilitate the broader utilization of nepheline geopolymer ceramics as sustainable materials in various engineering and construction applications.

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Role of sintering temperature in production of nepheline Ceramics-Based geopolymer with addition of ultra-high molecular weight polyethylene

2021 , Romisuhani Ahmad , Fakhryna Hannanee Ahmad Zaidi , Mohd. Mustafa Al Bakri Abdullah , Wan Mastura Wan Ibrahim , Jitrin Chaiprapa , Kamarudin Hussin , Jerzy J. Wysłocki , Katarzyna Błoch , Marcin Nabiałek

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm−1 becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

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Comparison Study on Microstructure Properties of Kaolin Based Geopolymer Ceramics with Addition of UHMWPE under Different Sintering Condition

2020-07-17 , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Ibrahim W.M.W. , Sandu A.V. , Vizureanu P. , Tengah M.S.

To better understand the structure-mechanical properties relation of additively fabrication of kaolin geopolymer ceramics with sintering method, a comparison study was performed. Kaolin based geopolymer ceramics were synthesized starting from the powders of kaolin based geopolymer, using powder metallurgy method. Typically, the sintering method used are one step (1200 °C - 5 min) and novel two step sintering processes (600 °C-5 min and 1200 °C - 5 min) for both kaolin based geopolymer ceramics with and without ultra high molecular weight polyethylene were applied and compared. The outcome revealed that there is no phase changes on the both sintering method pattern and the two step sintering method giving a smooth surface owing to the densification process during the preheat treatment.

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Effect of the sintering mechanism on the crystallization kinetics of geopolymer-based ceramics

2023 , Nur Bahijah Mustapa , Romisuhani Ahmad , Andrei Victor Sandu , Mohd. Mustafa Al Bakri Abdullah , Ovidiu Nemes , Wan Mastura Wan Ibrahim , Petrica Vizureanu , Christina Wahyu Kartikowati , Puput Risdanareni

This research aims to study the effects of the sintering mechanism on the crystallization kinetics when the geopolymer is sintered at different temperatures: 200 °C, 400 °C, 600 °C, 800 °C, 1000 °C, and 1200 °C for a 3 h soaking time with a heating rate of 5 °C/min. The geopolymer is made up of kaolin and sodium silicate as the precursor and an alkali activator, respectively. Characterization of the nepheline produced was carried out using XRF to observe the chemical composition of the geopolymer ceramics. The microstructures and the phase characterization were determined by using SEM and XRD, respectively. The SEM micrograph showed the microstructural development of the geopolymer ceramics as well as identifying reacted/unreacted regions, porosity, and cracks. The maximum flexural strength of 78.92 MPa was achieved by geopolymer sintered at 1200 °C while the minimum was at 200 °C; 7.18 MPa. The result indicates that the flexural strength increased alongside the increment in the sintering temperature of the geopolymer ceramics. This result is supported by the data from the SEM micrograph, where at the temperature of 1000 °C, the matrix structure of geopolymer-based ceramics starts to become dense with the appearance of pores.

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The properties of crumb rubber loading on fly ash based geopolymer mortar

2023 , Reshikesan Ravi , Ahmad Azrem Azmi , Mohd. Mustafa Al Bakri Abdullah , Lokman Hakim Ibrahim , Romisuhani Ahmad , Che Mohd Ruzaidi Ghazali

By replacing traditional Portland cement (OPC) with crumb rubber in fly ash-based geopolymer mortar, waste tyre disposal and natural mineral aggregate use can be reduced, resulting in lower CO2 emissions. Crumb rubber geopolymer mortar is formed when sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) are mixed with fly ash (class F) to make aluminosilicate gel. All of the fly ash geopolymer preparations followed the same ratio of solid to liquid (2:1) and the same ratio of NaOH solution (12M) to Na2SiO3 solution (2.5). Different amounts of crumb rubber (0%, 5%, 10%, 15%, and 20% by weight of solid) were added to the mixture. The results show that the compressive strength of the geopolymer mortar decreased with increasing crumb rubber loading. The results of the analysis show that the compressive strengths of CR-0%, CR-5%, CR-10%, CR-15%, and CR-20% are 25,59,14,31,11.19,10.38, and 8.16 MPa. The strength is diminished because of inadequate interfacial adhesion between the crumb rubber and geopolymer paste. As the sample weight fell, the percentage of crumb rubber in the geopolymer mortar in-creased, but the density decreased.

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Role of sintering temperature in production of nepheline ceramics-based geopolymer with addition of ultra-high molecular weight polyethylene

2021 , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Jitrin Chaiprapa , Kamarudin Hussin , Wan Mastura Wan Ibrahim , Fakhryna Hannanee Ahmad Zaidi , Jerzy J. Wysłocki , Katarzyna Błoch , Marcin Nabiałek

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm−1 becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

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Development of geopolymer ceramic as a potential reinforcing material in solder alloy: short review

2020 , Nadiah ‘Izzati Zulkifli , Mohd. Mustafa Al Bakri Abdullah , Mohd Arif Anuar Mohd Salleh , Andrei Victor Sandu , Romisuhani Ahmad , Nurul Aida Mohd Mortar

Nowadays, the consumption of lead-free solder has been widely used around the world since the utilization of SnPb solder has been banned and restricted by European Union. Variety of studies have been conducted by the researchers to find an alternative to replace the usage of SnPb such as SnCu, SAC, SnAg and etc. However, the development of plain lead-free solder was declared to provide low mechanical, thermal, and electrical properties in terms of interfacial intermetallic compound and wettability towards its solder joint compare to the traditionally monolithic SnPb solder alloy. Mostly, previous studies stated that addition of some additives such as ceramic particles (Si 3 N 4, TiO 2, SiC, NiO and etc) may improves the solder joint reliability. At the same time, no major studies were done using geopolymer ceramic as reinforcing agent in plain matrix alloy. Therefore, this paper reviews the fabrication process of multiple geopolymer-based ceramic such as fly ash, kaolin, and slag as reinforcement in solder alloy. The development process includes the processing method of geopolymer ceramic and the characterization of geopolymer ceramic as reinforcing material consist of; i) chemical composition, and ii) phase identification.

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Investigation of mechanical, physical and durability properties of metakaolin-based geopolymer

2023 , Wan Mastura Wan Ibrahim , Masdiyana Ibrahim , M.Z.A. Azis , Mohd. Mustafa Al Bakri Abdullah , Ahmad Syauqi Sauffi , Romisuhani Ahmad , Suraya Hani Adnan

Due to their potential to lower CO2 emissions linked with the cement and concrete industries, geopolymer binders are a desirable alternative for Portland cement binders. However, if they are to become a viable alternative to conventional Portland cement materials, their resilience in harsh conditions has to be further investigated. This paper presented mechanical and short-term durability properties of metakaolin based geopolymer concrete at sulphuric acid (H2SO4) solutions exposed with the concentrations of 2%, 3%, 4% and 5% for 14 days. (0%) or unexposed sample also prepared as referral and comparison. The geopolymer concretes were synthesized using an alkali activation of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The main objective of the study was to examine the durability and deterioration mechanism parameters like different acid percentages, changes in weight, compressive strength, density and water absorption. Morphology analysis also performed in this study. The results indicated that metakaolin geopolymer experienced some strength deterioration with increasing sulphuric concentration solutions which are from 32.58 MPa, 20.67 MPa and 4.25 MPa at unexposed (0%), 2% and 5% sulphuric acid immersion respectively. Furthermore, change in weight or mass loss and water absorption after the chemical attack resulted directly proportional to sulphuric acid concentration due to increment of crack on the sample. Among that, the metakaolin geopolymer submerged in 2% acid gives the optimum results in terms of durability, mechanical and physical qualities.

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Assessment of geopolymer concrete for underwater concreting properties

2021 , Fakhryna Hannanee Ahmad Zaidi , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Wan Mastura Wan Ibrahim , Ikmal Hakem Aziz , Subaer Junaidi , Salmabanu Luhar

For ages, concrete has been used to construct underwater structures. Concrete laying underwater is a very complex procedure important to the success or failure of underwater projects. This paper elucidates the influence of alkali activator ratios on geopolymers for underwater concreting; focusing on the geopolymer concrete synthesized from fly ash and kaolin activated using sodium hydroxide and sodium silicate solutions. The geopolymer mixtures were designed to incorporate multiple alkali activator ratios to evaluate their effects on the resulting geopolymers’ properties. The fresh concrete was molded into 50 mm cubes in seawater using the tremie method and tested for its engineering properties at 7 and 28 days (curing). The control geopolymer and underwater geopolymers’ mechanical properties, such as compressive strength, water absorption density, and setting time were also determined. The differences between the control geopolymer and underwater geopolymer were determined using phase analysis and functional group analysis. The results show that the geopolymer samples were optimally strengthened at a 2.5 alkali activator ratio, and the mechanical properties of the control geopolymer exceeded that of the underwater geopolymer. However, the underwater geopolymer was determined to be suitable for use as underwater concreting material as it retains 70% strength of the control geopolymer.

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