Alida Abdullah
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Preferred name
Alida Abdullah
Official Name
Alida, Abdullah
Alternative Name
Abdullah, Alida
Abdullah, A.
Abdullah, A. C.
Main Affiliation
Scopus Author ID
54979598300

Research Output
Now showing 1 - 5 of 5
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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 Błoch , 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.

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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.

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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 Błoch , 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.

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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.

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Fly ash based geopolymer as lightweight aggregate with low processing temperature for structural insulating concrete application.

2019 , Alida Abdullah

The lightweight aggregate in concrete has been broadly used nowadays due to its low density with great mechanical properties. These lightweight aggregates can be produced by thermal treatment from either naturally resource or from industrial by-product. However, the current production methods usually involving high energy due to high sintering temperature used despite of giving a great mechanical properties. Hence, there is a clear need of searching and replacing for more competent and proficient methods beyond the limitations of the current methods. Geopolymer becomes an attractive research due to its improving concrete properties and preserves the environment by using industrial waste such as fly ash. This research focuses on producing a fly ash geopolymer lightweight aggregate with good thermal insulation properties for structural concrete application with minimal sintering temperature by using geopolymerization methods. The 1effects of geopolymeric synthesis parameters such as the NaOH concentration (6 M, 8 M, 10 M, 12 M and 14 M), ratio of fly ash/alkali activator (2.0, 2.5, 3.0 and 3.5), and sintering temperature (400 °C to 1200 °C) to the fly ash geopolymer lightweight aggregate on mechanical and microstructure properties were studied. The optimum aggregate properties in term of highest impact strength with low density and water absorption then tested its thermal insulation properties through the effects of thermal conductivity, thermal diffusivity and specific heat capacity of aggregates. The results indicated that the fly ash geopolymer aggregate have an optimum NaOH concentration of 12 M with AIV of 22.43 % and an optimum ratio fly ash/alkali activator of 3.0 with AIV of 21.43 %. For the effect of sintering temperature, the results showed aggregate with sintering temperature of 900 °C gives the lowest AIV value (14.77 %) indicating highest impact strength with lightweight density (1730 kg/m3) and lowest water absorption (4.50 %). For thermal properties, at the aggregate of 900 °C shows the lowest thermal conductivity and diffusivity of 0.585 W/mK and 0.358 mm2/s, respectively. The performance of fly ash geopolymer lightweight aggregate in OPC concrete were tested for its mechanical and thermal properties and compared with the concrete of commercial lightweight aggregate. The results of concrete with fly ash geopolymer lightweight aggregate has shown better properties in term of strength with 43.71 MPa of compressive strength at 28 days, water absorption of 8.36 % and density of 1735 kg/m3 which can be classified as structural lightweight aggregate concrete according to ACI 213R. Concrete with fly ash geopolymer lightweight aggregate presented good thermal insulation properties through thermal conductivity results as low as 0.28 W/mK which makes it suitable for use as a good thermal insulation material. This work expands the findings contribution of microspheres in fly ash and the effect of iron (Fe) content to the geopolymerization process as well as produces a geopolymer lightweight aggregate with good thermal properties and high impact strength at low processing temperature.

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