Zarina Yahya
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Preferred name
Zarina Yahya
Official Name
Zarina, Yahya
Alternative Name
Yahya, Zarina
Zarina, Y.
Zarina, Yahya
Main Affiliation
Scopus Author ID
51162069600
Researcher ID
DXZ-6436-2022

Research Output
Now showing 1 - 8 of 8
  • Publication
    Optimization of NaOH Molarity, LUSI Mud/Alkaline Activator, and Na2SiO3/NaOH Ratio to produce lightweight aggregate-based geopolymer
    ( 2015)
    Rafiza Razak
    ;
    Mohd Abdullah
    ;
    Kamarudin Hussin
    ;
    Khairul Ismail
    ;
    Djwantoro Hardjito
    ;
    Zarina Yahya
    This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced.
  • Publication
    The effects of various concentrations of NaOH on the Inter-Particle Gelation of a Fly Ash Geopolymer Aggregate
    ( 2021)
    Alida Abdullah
    ;
    Kamarudin Hussin
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Zarina Yahya
    ;
    Wojciech Sochacki
    ;
    Rafiza Abdul Razak
    ;
    Katarzyna BÅ‚och
    ;
    Hamzah Fansuri
    Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na2SiO3 used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m3. The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels.
  • Publication
    The Effects of Various Concentrations of NaOH on the Inter-Particle Gelation of a Fly Ash Geopolymer Aggregate
    ( 2021)
    Alida Abdullah
    ;
    Kamarudin Hussin
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Zarina Yahya
    ;
    Wojciech Sochacki
    ;
    Katarzyna BÅ‚och
    ;
    Hamzah Fansuri
    ;
    Rafiza Abdul Razak
    Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na2SiO3 used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m3. The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels.
  • Publication
    Fly ash-based geopolymer lightweight concrete using foaming agent
    ( 2012)
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Kamarudin Hussin
    ;
    Mohamed Bnhussain
    ;
    Khairul Nizar Ismail
    ;
    Zarina Yahya
    ;
    Rafiza Abdul Razak
    In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.
  • Publication
    Optimization of NaOH molarity, LUSI mud/alkaline activator, and Na₂SiO₃/NaOH ratio to produce lightweight aggregate-based geopolymer
    ( 2015)
    Rafiza Abd Razak
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Djwantoro Hardjito
    ;
    Kamarudin Hussin
    ;
    Khairul Azwan Ismail
    ;
    Zarina Yahya
    This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na₂SiO₃/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced.
  • Publication
    Utilization of palm oil boiler ash (POBA) as geopolymer material for Industrialized Building System (IBS) application
    ( 2015)
    Zarina Yahya
    The increment of palm oil waste from palm oil extraction increased every year in Malaysia. Palm oil boiler ash (POBA) or bottom ash is one of the waste material from the palm oil industry where it was obtained from the burning process of solid waste such as empty fruit bunch, shell and fiber. The production of POBA was estimated about 4 million tonnes/year where it was usually used as fertilizer. Geopolymer or alkali-activated binder is produced by synthesizing aluminosilicate source materials with an alkaline activator solution. This study has been conducted to produce POBA geopolymer paste and brick and IBS brick by using geopolimerization process. The parameters for the geopolymer paste production included the NaOH concentration, ratios of S/L as well as Na2SiO3/NaOH and curing temperature. Then, the effect of each parameter towards production of geopolymer paste was evaluated using compressive strength, XRD, FTIR, and SEM. Meanwhile, for mix design of geopolymer brick and IBS brick, the optimum ratio (NaOH concentration, ratio of S/L and Na2SiO3/NaOH and curing temperature) from the geopolymer paste production has been used to produce the bricks. The ratio of POBA-to-sand for geopolymer brick and IBS brick for this study was 1:3. The performance of geopolymer brick and IBS brick were analyzed in term of compressive strength, water absorption and density at different aging period, which is 1st, 3rd, 7th, 28th and 60th days.
  • Publication
    Artificial lightweight aggregates made from pozzolanic material: A review on the method, physical and mechanical properties, thermal and microstructure
    ( 2022)
    Dickson Ling Chuan Hao
    ;
    Rafiza Abd Razak
    ;
    Marwan Kheimi
    ;
    Zarina Yahya
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Dumitru Doru Burduhos Nergis
    ;
    Hamzah Fansuri
    ;
    Ratna Ediati
    ;
    Rosnita Mohamed
    ;
    Alida Abdullah
    As the demand for nonrenewable natural resources, such as aggregate, is increasing worldwide, new production of artificial aggregate should be developed. Artificial lightweight aggregate can bring advantages to the construction field due to its lower density, thus reducing the dead load applied to the structural elements. In addition, application of artificial lightweight aggregate in lightweight concrete will produce lower thermal conductivity. However, the production of artificial lightweight aggregate is still limited. Production of artificial lightweight aggregate incorporating waste materials or pozzolanic materials is advantageous and beneficial in terms of being environmentally friendly, as well as lowering carbon dioxide emissions. Moreover, additives, such as geopolymer, have been introduced as one of the alternative construction materials that have been proven to have excellent properties. Thus, this paper will review the production of artificial lightweight aggregate through various methods, including sintering, cold bonding, and autoclaving. The significant properties of artificial lightweight aggregate, including physical and mechanical properties, such as water absorption, crushing strength, and impact value, are reviewed. The properties of concrete, including thermal properties, that utilized artificial lightweight aggregate were also briefly reviewed to highlight the advantages of artificial lightweight aggregate.
  • Publication
    Properties and morphology of fly ash based Alkali Activated Material (AAM) paste under steam curing condition
    ( 2022)
    Rafiza Abd Razak
    ;
    Sh. Nur Syamimi Sy. Izman
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Zarina Yahya
    ;
    Alida Abdullah
    ;
    Rosnita Mohamed
    This paper details the properties, microstructures, and morphologies of the fly ash-based alkali-activated material (AAM), also known as geopolymers, under various steam curing temperatures. The steam curing temperature result in subsequent high strengths relative to average curing temperatures. However, detailed studies involving the use of steam curing for AAM remain scarce. The AAM paste was prepared by mixing fly ash with an alkali activator consisting of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH). The sample was steam cured at 50°C, 60°C, 70°C, and 80°C, and the fresh paste was tested for its setting time. The sample also prepared for compressive strength, density, and water absorption testings. It was observed that the fastest time for the fly ash geopolymer to start hardening was at 80°C at only 10 minutes due to the elevated temperature quickening the hydration of the paste. The compressive strength of the AAM increased with increasing curing time from 3 days to 28 days. The AAM’s highest compressive strength was 61 MPa when the sample was steam cured at 50°C for 28 days. The density of AAM was determined to be ~2122 2187 kg/m3 , while its water absorption was ~6.72-8.82%. The phase analyses showed the presence of quartz, srebrodolskite, fayalite, and hematite, which indirectly confirms Fe and Ca’s role in the hydration of AAM. The morphology of AAM steam-cured at 50°C showed small amounts of unreacted fly ash and a denser matrix, which resulted in high compressive strength.