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

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Influence of Polyformaldehyde Monofilament fiber on the engineering properties of foamed concrete

2022 , Md Azree Othuman Mydin , Mohd. Mustafa Al Bakri Abdullah , Mohd Nasrun Mohd Nawi , Zarina Yahya , Liyana Ahmad Sofri , Madalina Simona Baltatu , Andrei Victor Sandu , Petrica Vizureanu

Foamed concrete is considered a green building material, which is porous in nature. As a result, it poses benefits such as being light in self-weight, and also has excellent thermal insulation properties, environmental safeguards, good fire resistance performance, and low cost. Nevertheless, foamed concrete has several disadvantages such as low strength, a large amount of entrained air, poor toughness, and being a brittle material, all of which has restricted its usage in engineering and building construction. Hence, this study intends to assess the potential utilization of polypropylene fibrillated fiber (PFF) in foamed concrete to enhance its engineering properties. A total of 10 mixes of 600 and 1200 kg/m3 densities were produced by the insertion of four varying percentages of PFF (1%, 2%, 3%, and 4%). The properties assessed were splitting tensile, compressive and flexural strengths, workability, porosity, water absorption, and density. Furthermore, the correlations between the properties considered were also evaluated. The outcomes reveal that the foamed concrete mix with 4% PFF attained the highest porosity, with approximately 13.9% and 15.9% for 600 and 1200 kg/m3 densities in comparison to the control specimen. Besides, the mechanical properties (splitting tensile, compressive and flexural strengths) increased steadily with the increase in the PFF percentages up to the optimum level of 3%. Beyond 3%, the strengths reduced significantly due to poor PFF dispersal in the matrix, leading to a balling effect which causes a degraded impact of scattering the stress from the foamed concrete vicinity to another area of the PFF surface. This exploratory investigation will result in a greater comprehension of the possible applications of PFF in LFC. It is crucial to promote the sustainable development and implementation of LFC materials and infrastructures.

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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.

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Influence of salinity of mixing water towards physical and mechanical properties of high strength concrete

2023 , Rafiza Abd Razak , Khai Yen Ng , Mohd. Mustafa Al Bakri Abdullah , Zarina Yahya , M. Nabiałek , K. Muthusamy , W.A.W. Jusoh , B. Jeż , R. Mohamed

Dramatic population and economic growth result in increasing demand for concrete infrastructure, which leads to an increment of freshwater demand and a reduction of freshwater resources. However, freshwater is a finite resource, which means that freshwater will be used up someday in the future when freshwater demand keeps increasing while freshwater resources are limited. Therefore, replacing freshwater with seawater in concrete blending seems potentially beneficial for maintaining the freshwater resources as well as advantageous alternatives to the construction work near the sea. There have been few experimental research on the effect of blending water salt content on the mechanical and physical characteristics of concrete, particularly high-strength concrete. Therefore, a research study on the influence of salt concentration of blending water on the physical and mechanical properties of high-strength concrete is necessary. This study covered the blending water salinity, which varied from 17.5 g/L to 52.5 g/L and was determined on the physical and mechanical properties, including workability, density, compressive strength, and flexural strength. The test results indicate that the use of sea salt in blending water had a slight negative influence on both the workability and the density of high strength concrete. It also indicates that the use of sea salt in blending water had a positive influence on both the compressive strength and the flexural strength of high-strength concrete in an earlystage.

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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.

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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.

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Bahan binaan : asas kayu

2011 , Mohd. Mustafa Al Bakri Abdullah , Zarina Yahya , Rafiza Abd Razak , Sharizam Saad , Che Mohd Ruzaidi Ghazali

Buku Bahan Binaan: Asas Kayu merupakan sebuah buku yang membincangkan beberapa perkara asas yang penting mengenai kayu. Buku ini menghuraikan beberapa topik seperti Pengenalan Kepada Kayu, Pengelasan Kayu, Sifat-Sifat Kayu, Air dan Kayu, Pengeringan Kayu, Kemasan Terakhir dan Perlindungan Kayu dan Penggunaan Bahan-Bahan Kayu. Kayu mempunyai nilai estetik untuk digunakan sebagai kemasan untuk industri pembinaan. Buku ini memberikan pemahaman tentang sifat-sifat kayu apabila beban dikenakan ke atasnya dan juga aplikasi kayu sebagai bahan binaan seperti papan lapis, papan partikel dan sebagainya.

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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.

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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.

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Bahan geopolimer : Pemprosesan, Pencirian dan Aplikasi

2015 , Mohd. Mustafa Al Bakri Abdullah , Zarina Yahya , Alida Abdullah , Rafiza Abd Razak , Kamarudin Hussin , Liyana Jamaludin , Muhammad Faheem Mohd. Tahir

Buku Bahan Geopolimer: Pemprosesan, Pencirian dan Aplikasi adalah sebuah buku yang membincangkan beberapa aspek penting mengenai bahan geopolimer seperti pemprosesan, perincian, aplikasi dan sifat bahan geopolimer dalam teknologi konkrit. Buku ini juga menerangkan secara terperinci tentang bahan geopolimer dari aspek teori, pemprosesan, pencirian dan aplikasi yang sesuai dijadikan sebagai bahan rujukan dan panduan kepada pelajar, penyelidik dan pengamal industri.

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Mechanical performance, microstructure, and porosity evolution of fly ash geopolymer after ten years of curing age

2023 , Ikmal Hakem A. Aziz , Mohd. Mustafa Al Bakri Abdullah , Rafiza Abd Razak , Zarina Yahya , Mohd Arif Anuar Mohd Salleh , Jitrin Chaiprapa , Catleya Rojviriya , Petrica Vizureanu , Andrei Victor Sandu , Muhammad Faheem Mohd. Tahir , Alida Abdullah , Liyana Jamaludin

This paper elucidates the mechanical performance, microstructure, and porosity evolution of fly ash geopolymer after 10 years of curing age. Given their wide range of applications, understanding the microstructure of geopolymers is critical for their long-term use. The outcome of fly ash geopolymer on mechanical performance and microstructural characteristics was compared between 28 days of curing (FA28D) and after 10 years of curing age (FA10Y) at similar mixing designs. The results of this work reveal that the FA10Y has a beneficial effect on strength development and denser microstructure compared to FA28D. The total porosity of FA10Y was also lower than FA28D due to the anorthite formation resulting in the compacted matrix. After 10 years of curing age, the 3D pore distribution showed a considerable decrease in the range of 5–30 µm with the formation of isolated and intergranular holes.

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