Now showing 1 - 10 of 41
  • Publication
    Effect of the sintering mechanism on the crystallization kinetics of geopolymer-based ceramics
    (MDPI, 2023)
    Nur Bahijah Mustapa
    ;
    ;
    Andrei Victor Sandu
    ;
    ;
    Ovidiu Nemes
    ;
    ;
    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.
  • Publication
    Densification behavior and mechanical performance of Nepheline geopolymer ceramics: preliminary study
    (Springer, 2023)
    Nur Bahijah Mustapa
    ;
    ; ; ;
    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.
  • Publication
    Investigation of mechanical, physical and durability properties of metakaolin-based geopolymer
    (Polish Academy of Sciences, 2023) ;
    Masdiyana Ibrahim
    ;
    M.Z.A. Azis
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    ;
    Ahmad Syauqi Sauffi
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    ;
    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.
  • Publication
    Buffalo reef mesothermal gold mineralization mineralogy and geochemistry in Kuala Lipis, Pahang, Malaysia
    (Springer, 2023)
    Siti Hasanah Osman
    ;
    Afikah Rahim
    ;
    In Pahang, the East Coast of Peninsular Malaysia, Buffalo Reef remains active as a gold mine among the main gold deposits at the North of Selinsing Gold Mine. Mineralization of gold is possible when stibnite occurs in quartz veins. The main purpose of this study is to examine the geological condition governing the mineralization of ore and the origin of gold mineralization of Buffalo Reef. The XRD result shows the quartz stage (SiO2) while quartz, sillimanite and stibnite are identified. Ten samples were tested with XRF geochemical studies showing SiO2 contents of 24.98–70.67 wt%, and the overall Na2O + K2O diagram versus SiO2 alkaline diagram showed varies basaltic andesite, andesite and dacite series with favourable and random distribution. The deposits region consists of the thick Permian rock sequences especially tuff volcanic rock that is intertwined by clay (argillite, phyllite) and carbonate rocks. Mineralization of volcanic rock and pyroclastic tuff supporting and regulating the orogenic gold deposit under the Raub–Bentong framework. The region epizoic and mesonic with a mesothermal deposit characterized by the presence of gold, stibnite and arsenopyrite with the grade of gold is 4.01 g/t Au from AAS.
  • Publication
    Foamed concrete durability properties reinforced with agave cantala-based fibre
    (Polish Academy of Sciences, 2025)
    M. A. O. Mydin
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    ;
    S. S. Majeed
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    R. Omar
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    ;
    S. Ishak
    The construction industry across the world recognizes the need for green, lightweight, and self-compacting materials that are also ecologically benign. Considering this requirement, a recent discovery has indicated that a novel form of concrete, known as foamed concrete (FC), has the potential to reduce structural self-weight. Natural fibres are an excellent option to be added in FC for durability properties improvement and are viewed as a great way to contribute to sustainability. The purpose of this study is to examine the possible utilization of agave cantala-based fibre (AF) in the fabrication of foamed concrete (FC) with the objective of enhancing their durability properties. Low densities FC are prone to serious durability performance degradation hence in this experiment FC of low density of 650 kg/m3 was fabricated and evaluated. Varying weight fractions of AF between 0% to 5% were considered as an additive in FC. The durability parameters that were evaluated included apparent porosity, shrinkage, water absorption and UPV. The experimental findings indicate that incorporating a weight fraction of 3% of AF in FC resulted in the optimal durability characteristics across all the durability measures examined in this study. The inclusion of AF in the combination resulted in a significant decrease in the permeability porosity and water absorption of FC. The presence of FC-AF composites with 4% fibre led to the highest drying shrinkage and UPV value and it performed better than the remaining mixtures.
  • Publication
    Role of sintering temperature in production of nepheline Ceramics-Based geopolymer with addition of ultra-high molecular weight polyethylene
    ( 2021) ;
    Fakhryna Hannanee Ahmad Zaidi
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    ; ;
    Jitrin Chaiprapa
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    ;
    Jerzy J. Wysłocki
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    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.
      8  10
  • Publication
    Role of sintering temperature in production of nepheline ceramics-based geopolymer with addition of ultra-high molecular weight polyethylene
    (MDPI, 2021) ; ;
    Jitrin Chaiprapa
    ;
    ; ;
    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.
      3  19
  • Publication
    Assessment of geopolymer concrete for underwater concreting properties
    ( 2021)
    Fakhryna Hannanee Ahmad Zaidi
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    ; ; ;
    Ikmal Hakem Aziz
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    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.
      4  17
  • Publication
    Production of fly ash-based geopolymer bricks through geopolymerization process
    Utilization of fly ash as a raw material for geopolymer brick production seems to be a logical solution that allows for the conservation of natural resources, abates further pollution and preserves the environment. Fly ash-based geopolymer have been studied by several researchers worldwide for several decades due to their excellent mechanical properties. Geopolymer is a type of amorphous alumino-silicate material which can be synthesized by polycondensation reaction of geopolymeric materials, and alkali solutions. This study has been conducted to produce fly ash-based geopolymer bricks by means of pressure forming without firing procedure and low energy consumptions. The experiments were conducted on fly ash-based geopolymer bricks by varying the ratio of fly ash-to-sand (1:2 - 1:5, by mass of ratio), curing time (1 - 24 hours) and curing temperature (room temperature - 80°C). Compressive strength, water absorption, dimensional test and density analysis was set as the mechanical properties to be tested on the fly ash-based geopolymer bricks. The compression test and water absorption test were measured at 1, 3, 7, 28 and 60 days. Results of the investigation indicated that there was decrease in compressive strength when the ratio of fly ash-to-sand increase. However, the strength was increased with increase in curing time and curing temperature. Compressive strength up to 20.3 MPa was obtained with curing at 70 °C for a period of 24 hours at 60 days of ageing. The density of geopolymer bricks ranged between 1800 Kg/m3 to 1950 Kg/m3. The microstructural properties of fly ash-based geopolymer bricks were investigated by using XRD and SEM analysis.
      1  44
  • Publication
    Kaolin-based geopolymer as a heavy metal removal: Short review
    ( 2023)
    Ikmal Hakem AZIZ
    ;
    Nurul Ain MAZLAN
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    ;
    Noor Fifinatasha SHAHEDAN
    ;
    Ratna EDIATI
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    ;
    Hamzah FANSURI
    Adsorption procedure have been studies and found to be an effective, easy, and low-cost approach for removing heavy metals from aqueous solution when compared to other methods and technologies. Porous geopolymer will be made by combining aluminosilicate mineral with an alkaline activation solution to be utilized as an adsorbent. This review focuses on the current development in heavy metal removal material. This work also summarize the crucial factors (such as solid-to-liquid ratio, foaming agent ratio, sintering temperatures, and adsorbent dosage) influenced the properties (pore formation, microstructure, chemical bonding, and phase analysis) of kaolin-based geopolymer were highlighted. This review manifests the remarkable potential of kaolin-based geopolymer in high-added value applications.
      22  2