Now showing 1 - 10 of 40
  • 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
    ;
    ;
    Ahmad Syauqi Sauffi
    ;
    ;
    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
    ;
    ;
    S. S. Majeed
    ;
    R. Omar
    ;
    ;
    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
    Phase analysis of different liquid ratio on Metakaolin/Dolomite geopolymer
    ( 2021)
    Ahmad Syauqi Sauffi
    ;
    ; ;
    Masdiyana Ibrahim
    ;
    ;
    Fakhryna Ahmad Zaidi
    Geopolymer is widely studied nowadays in various scope of studies. Some of the ongoing studies are the study of the various materials towards the geopolymer strength produced. Meanwhile, some of the studies focus on the mixing of the geopolymer itself. This paper discussed the phase analysis of metakaolin/dolomite geopolymer for different solid to the liquid ratio which was, 0.4, 0.6, 0.8, and 1.0, and the properties that affected the geopolymer based on the phases. The constant parameters in this study were the percentage of metakaolin and dolomite used. The metakaolin used was 80% meanwhile dolomite usage was 20%. Besides that, the molarity of NaOH used is 10M and the alkaline activator ratio used is 2.0. All the samples were tested at 28 days of curing. The results show that the 0.8 solid to the liquid ratio used gave better properties compare to other solid to liquid ratio. The phases analyzed were quartz, sillimanite, mullite, and faujasite. The 0.8 S/L ratio shows the better properties compared to others by the test of phase analysis, compressive strength morphology analysis, and functional group analysis.
      21  6
  • Publication
    Geopolymer Ceramic as Piezoelectric Materials: A Review
    ( 2020-07-09)
    Ahmad R.
    ;
    ; ; ;
    Victor Sandhu A.
    ;
    ;
    Waried Wazien Ahmad Zailani
    Diverse application for geopolymer so called inorganic polymer have been expanded as potential to continue growing at a realistic rate where the properties, processing tolerance and economical are comparable with the existing materials. An aluminosilicate inorganic polymer can be produced at low temperature under highly alkali conditions from a solid aluminosilicate and an alkali silicate solution. The conversion of amorphous to semi-crystalline behaviour of geopolymer into crystalline phases upon heating make the method be an alternate way in producing ceramic materials. For another application related to high temperature packaging and enclosure of electronical devices, piezoelectric behavior turn out to be important properties to the geopolymer ceramic materials. This paper summarize the review on the important research findings on the basic geopolymer systems, current knowledge of geopolymer ceramic, and outline potential piezoelectric effect on ceramic materials.
      5  31
  • Publication
    Correlation between Thermal Insulation Properties with Compressive Strength and Density of Lightweight Geopolymer
    This paper reports the results of an experimental work conducted to investigate the correlation between thermal insulation properties with compressive strength and density of lightweight geopolymer prepared by using fly ash as source material and combination of sodium hydroxide and sodium silicate as alkaline activator. The experiments were conducted by varying the ageing time of 3, 7, 28, 60 and 90 days, respectively. The specimens cured for a period of 90 days have presented the highest compressive strength and lowest density accompanied with satisfied value of thermal conductivity. From the results obtained, it was evident that the thermal conductivity had a high correlation coefficient with compressive strength and density.
      2  24
  • Publication
    Effect of sintering mechanism towards crystallization of geopolymer ceramic - a review
    (MDPI, 2023-05-31)
    Nur Bahijah Mustapa
    ;
    ; ; ;
    Nuttawit Wattanasakulpong
    ;
    Ovidiu Nemeș
    ;
    Andrei Victor Sandu
    ;
    Petrica Vizureanu
    ;
    Ioan Gabriel Sandu
    ;
    Christina W. Kartikowati
    ;
    Puput Risdanareni
    Globally, there is an increasing need for ceramic materials that have a variety of applications in the environment, for precision tools, and for the biomedical, electronics, and environmental industries. However, in order to obtain remarkable mechanical qualities, ceramics have to be manufactured at a high temperature of up to 1600 °C over a long heating period. Furthermore, the conventional approach presents issues with agglomeration, irregular grain growth, and furnace pollution. Many researchers have developed an interest in using geopolymer to produce ceramic materials, focusing on improving the performances of geopolymer ceramics. In addition to helping to lower the sintering temperature, it also improves the strength and other properties of the ceramics. Geopolymer is a product of polymerization involving aluminosilicate sources such as fly ash, metakaolin, kaolin, and slag through activation using an alkaline solution. The sources of the raw materials, the ratio of the alkaline solution, the sintering time, the calcining temperature, the mixing time, and the curing time may have significant impacts on the qualities. Therefore, this review aims to study the effects of sintering mechanisms on the crystallization of geopolymer ceramics, concerning the strength achieved. A future research opportunity is also presented in this review.
      8  22
  • Publication
    Effect of the sintering mechanism on the crystallization kinetics of Geopolymer-Based ceramics
    ( 2023)
    Nur Bahijah Mustapa
    ;
    ; ; ;
    Andrei Victor Sandu
    ;
    Ovidiu Nemes
    ;
    Petrica Vizureanu
    ;
    Christina W. 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.
      3  22