Romisuhani Ahmad
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Preferred name
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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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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Geopolymer-based nepheline ceramics: effect of sintering profile on morphological characteristics and flexural strength

2022 , Romisuhani Ahmad , Wan Mastura Wan Ibrahim , Mohd. Mustafa Al Bakri Abdullah , Phakkhananan Pakawanit , Petrica Vizureanu , Arman Shah Abdullah , Andrei Victor Sandu , Fakhryna Hannanee Ahmad Zaidi

The focus of this study is the fabrication of innovative and sustainable ceramic-based geopolymer with improved low temperatures performances. Kaolin was mixed with liquid sodium silicate (Na₂SiO₃) and 12M of sodium hydroxide (NaOH) solution using alkali activator ratio of 0.24 and solid-to-liquid ratio of 1:1 to synthesize kaolin geopolymer. The effect of the sintering profile on the microstructure, pore evolution and flexural strength were investigated. The heating exposure aided consolidation and created a fairly uniform microstructure, resulting in a smooth surface texture. In comparison to the unheated geopolymer, 3D pore distribution showed a significant increase in the range size of ~30 µm with the appearance of isolated and intergranular pores. The flexural strength at 1200 °C with a heating rate of 5 °C/min and was increased by 146.4% to 85.4 MPa, as compared to the heating rate of 2 °C/min. The sintering process has an impact on the final microstructure formation thus improving the characteristic of geopolymer-based nepheline ceramic.

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

2022 , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Wan Mastura Wan Ibrahim , Kamarudin Hussin , Jitrin Chaiprapa , Jerzy J. Wysłocki , Katarzyna Błoch , Fakhryna Hannanee Ahmad Zaidi , 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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Publication

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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Geopolymer as underwater concreting material: A review

2021-07-12 , Fakhryna Hannanee Ahmad Zaidi , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Shayfull Zamree Abd. Rahim , Zarina Yahya , Li L.Y. , Ediati R.

Underwater concrete is one of the special types of high-performance concrete in the current industry which is commonly used to construct bridges, dams and structures whose foundation is built underwater. In contrast with typical concrete, the implementation of concrete underwater requires different techniques due to the different concrete properties in order to ensure successful implementation. A new material called geopolymer is now widely promoted for its ability to replace ordinary Portland cement (OPC) as a binder due to its green technology. Numerous researches have established that the geopolymer has comparable strength and chemical resistivity compared to OPC. However, to date, only limited researches had been conducted to examine the use of geopolymer as an underwater concreting material. From the review that has been done, it can be concluded that the requirements for underwater concreting material should include washout resistivity, workability and durability in addition to high strength. This review highlights that the geopolymers are proven to provide excellent strength, durability and workability in accordance with the EFNARC standard. Finally, future research opportunities are also presented in this review with regards to the potential of geopolymer in replacing OPC as underwater concreting material.

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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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The effect of seawater on the strength, microstructure and elemental distribution of fly ash/kaolin based underwater geopolymer

2020 , Fakhryna Hannanee Ahmad Zaidi , Romisuhani Ahmad , Mohd. Mustafa Al Bakri Abdullah , Ahmad Syauqi , Wan Mastura Wan Ibrahim

Concrete in seawater is subjected to various aggressive constituents in seawater commonly sulphate, chloride and carbonate. This paper investigates the potential effects towards mechanical and physical properties of geopolymer when used as underwater concreting material. Besides identifying the microstructure using Scanning Electron Microscopy (SEM), the sample is also characterized using Synchrotron based micro X-Ray Fluorescence (µ-XRF) to identify the elemental distribution that had occurred in the underwater geopolymer. Other essential properties for concrete such as compressive strength, water absorption and density were also determined. The compressive strength result indicates a slightly lower strength for underwater geopolymer (31.40 MPa) compared to normal geopolymer (35.91 MPa). Relevant to the strength, the water absorption and density also shows a slight difference between the geopolymer samples. The µ-XRF analysis shows the presence of chlorine (Cl) element only for underwater geopolymer which indicates that the are chloride penetration for underwater geopolymer. Additionally, other element distribution such as Silica (Si), Aluminum (Al) and Calcium (Ca) shows a different value when comparing normal geopolymer and underwater geopolymer. Despite the difference in elemental distribution between sample, geopolymer is proven to have the potential to be used as underwater material since it is able to retain at least 70% strength of the control sample.

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