Mohd. Mustafa Al Bakri Abdullah
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Preferred name
Mohd. Mustafa Al Bakri Abdullah
Official Name
Abdulah, Mohd. Mustafa Al Bakri
Alternative Name
Abdullah, M.M.A.
M.M.A. Abdullah
Mustafa Al Bakri, A. M.
Albakri Abdullah, M. M.
Main Affiliation
CeGeoGTech UniMAP
Scopus Author ID
53164519100

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Preparation of Fly Ash-Ladle Furnace Slag Blended Geopolymer Foam via Pre-Foaming Method with Polyoxyethylene Alkyether Sulphate Incorporation

2022-06-01 , Ng Hui Teng , Heah Cheng Yong , Liew Yun Ming , Mohd. Mustafa Al Bakri Abdullah , Rojviriya C. , Razi H.M. , Garus S. , Nabiałek M. , Sochacki W. , Abidin I.M.Z. , Ng Yong Sing , Śliwa A. , Sandu A.V.

This paper uses polyoxyethylene alkyether sulphate (PAS) to form foam via pre-foaming method, which is then incorporated into geopolymer based on fly ash and ladle furnace slag. In the literature, only PAS-geopolymer foams made with single precursor were studied. Therefore, the performance of fly ash-slag blended geopolymer with and without PAS foam was investigated at 29–1000 °C. Unfoamed geopolymer (G-0) was prepared by a combination of sodium alkali, fly ash and slag. The PAS foam-to-paste ratio was set at 1.0 and 2.0 to prepare geopolymer foam (G-1 and G-2). Foamed geopolymer showed decreased compressive strength (25.1–32.0 MPa for G-1 and 21.5–36.2 MPa for G-2) compared to G-0 (36.9–43.1 MPa) at 29–1000 °C. Nevertheless, when compared to unheated samples, heated G-0 lost compressive strength by 8.7% up to 1000 °C, while the foamed geopolymer gained compressive strength by 68.5% up to 1000 °C. The thermal stability of foamed geopolymer was greatly improved due to the increased porosity, lower thermal conductivity, and incompact microstructure, which helped to reduce pressure during moisture evaporation and resulted in lessened deterioration.

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Chemical Distributions of Different Sodium Hydroxide Molarities on Fly Ash/Dolomite-Based Geopolymer

2022-09-01 , Wan Mastura Wan Ibrahim , Mohd. Mustafa Al Bakri Abdullah , Romisuhani Ahmad , Sandu A.V. , Vizureanu P. , Benjeddou O. , Rahim A. , Ibrahim M. , Sauffi A.S.

Geopolymers are an inorganic material in an alkaline environment that is synthesized with alumina–silica gel. The structure of geopolymers consists of an inorganic chain of material and a covalent-bound molecular system. Currently, Ordinary Portland Cement (OPC) has caused carbon dioxide (CO2) emissions which causes greenhouse effects. This analysis investigates the impact on fly ash/dolomite-based-geopolymer with various molarities of sodium hydroxide solutions which are 6 M, 8 M, 10 M, 12 M and 14 M. The samples of fly ash/dolomite-based-geopolymer were prepared with the usage of solid to liquid of 2.0, by mass and alkaline activator ratio of 2.5, by mass. After that, the geopolymer was cast in 50 × 50 × 50 mm molds before testing after 7 days of curing. The samples were tested on compressive strength, density, water absorption, morphology, elemental distributions and phase analysis. From the results, the usage of 8 M of NaOH gave the optimum properties for the fly ash/dolomite-based geopolymer. The elemental distribution analysis exposes the Al, Si, Ca, Fe and Mg chemical distribution of the samples from the selected area. The distribution of the elements is related to the compressive strength and compared with the chemical composition of the fly ash and dolomite.

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Computer Simulations of End-Tapering Anchorages of EBR FRP-Strengthened Prestressed Concrete Slabs at Service Conditions

2023-01-01 , Wattanapanich C. , Imjai T. , Garcia R. , Nur Liza Rahim , Mohd. Mustafa Al Bakri Abdullah , Sandu A.V. , Vizureanu P. , Matasaru P.D. , Thomas B.S.

This article examines numerically the behavior of prestressed reinforced concrete slabs strengthened with externally bonded reinforcement (EBR) consisting of fiber-reinforced polymer (FRP) sheets. The non-linear finite element (FE) program Abaqus® is used to model EBR FRP-strengthened prestressed concrete slabs tested previously in four-point bending. After the calibration of the computational models, a parametric study is then conducted to assess the influence of the FRP axial stiffness (thickness and modulus of elasticity) on the interfacial normal and shear stresses. The numerical analysis results show that increasing the thickness or the elastic modulus of the FRP strengthening affects the efficiency of the FRP bonding and makes it susceptible to earlier debonding failures. A tapering technique is proposed in wet lay-up applications since multiple FRP layers are often required. It is shown that by gradually decreasing the thickness of the FRP strengthening, the concentration of stress along the plate end can be reduced, and thus, the overall strengthening performance is maximized. The tapering is successful in reducing the bond stress concentrations by up to 15%, which can be sufficient to prevent concrete rip-off and peel-off debonding failure modes. This article contributes towards a better understanding of the debonding phenomena in FRP-strengthened elements in flexure and towards the development of more efficient computational tools to analyze such structures.

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Influence of polyformaldehyde monofilament fiber on the engineering properties of foamed concrete

2022-12-01 , Mydin M.A.O. , Mohd. Mustafa Al Bakri Abdullah , Mohd Nawi M.N. , Zarina Yahya , Liyana Ahmad Sofri , Baltatu M.S. , Sandu A.V. , Vizureanu P.

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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Near-Infrared (NIR) Silver Sulfide (Ag₂S) Semiconductor Photocatalyst Film for Degradation of Methylene Blue Solution

2023-01-01 , Mubarokah Z.R. , Norsuria Mahmed , Mohd Natashah Norizan , Ili Salwani Mohamad , Mohd. Mustafa Al Bakri Abdullah , Błoch K. , Nabiałek M. , Baltatu M.S. , Sandu A.V. , Vizureanu P.

A silver sulfide (Ag2S) semiconductor photocatalyst film has been successfully synthesized using a solution casting method. To produce the photocatalyst films, two types of Ag2S powder were used: a commercialized and synthesized powder. For the commercialized powder (CF/comAg2S), the Ag2S underwent a rarefaction process to reduce its crystallite size from 52 nm to 10 nm, followed by incorporation into microcrystalline cellulose using a solution casting method under the presence of an alkaline/urea solution. A similar process was applied to the synthesized Ag2S powder (CF/syntAg2S), resulting from the co-precipitation process of silver nitrate (AgNO3) and thiourea. The prepared photocatalyst films and their photocatalytic efficiency were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy (UV-Vis). The results showed that the incorporation of the Ag2S powder into the cellulose films could reduce the peak intensity of the oxygen-containing functional group, which indicated the formation of a composite film. The study of the crystal structure confirmed that all of the as-prepared samples featured a monoclinic acanthite Ag2S structure with space group P21/C. It was found that the degradation rate of the methylene blue dye reached 100% within 2 h under sunlight exposure when using CF/comAg2S and 98.6% for the CF/syntAg2S photocatalyst film, and only 48.1% for the bare Ag2S powder. For the non-exposure sunlight samples, the degradation rate of only 33–35% indicated the importance of the semiconductor near-infrared (NIR) Ag2S photocatalyst used.

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Improvements of Flexural Properties and Thermal Performance in Thin Geopolymer Based on Fly Ash and Ladle Furnace Slag Using Borax Decahydrates

2022-06-01 , Ng Yong-Sing , Liew Yun Ming , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Pakawanit P. , Vizureanu P. , Khalid M.S. , Ng Hui-Teng , Yong-Jie H. , Nabiałek M. , Pietrusiewicz P. , Garus S. , Sochacki W. , Śliwa A.

This paper elucidates the influence of borax decahydrate addition on the flexural and thermal properties of 10 mm thin fly ash/ladle furnace slag (FAS) geopolymers. The borax decahydrate (2, 4, 6, and 8 wt.%) was incorporated to produce FAB geopolymers. Heat treatment was applied with temperature ranges of 300◦C, 600◦C, 900◦C, 1000◦C and 1100◦C. Unexposed FAB geopolymers experienced a drop in strength due to a looser matrix with higher porosity. However, borax decahydrate inclusion significantly enhanced the flexural performance of thin geopolymers after heating. FAB2 and FAB8 geopolymers reported higher flexural strength of 26.5 MPa and 47.8 MPa, respectively, at 1000◦C as compared to FAS geopolymers (24.1 MPa at 1100◦C). The molten B2O3 provided an adhesive medium to assemble the aluminosilicates, improving the interparticle connectivity which led to a drastic strength increment. Moreover, the borax addition reduced the glass transition temperature, forming more refractory crystalline phases at lower temperatures. This induced a significant strength increment in FAB geopolymers with a factor of 3.6 for FAB8 at 900◦C, and 4.0 factor for FAB2 at 1000◦C, respectively. Comparatively, FAS geopolymers only achieved 3.1 factor in strength increment at 1100◦C. This proved that borax decahydrate could be utilized in the high strength development of thin geopolymers.

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The Suitability of Photocatalyst Precursor Materials in Geopolymer Coating Applications: A Review

2022-09-01 , Liyana Jamaludin , Rafiza Abd Razak , Mohd. Mustafa Al Bakri Abdullah , Vizureanu P. , Bras A. , Imjai T. , Sandu A.V. , Shayfull Zamree Abd. Rahim , Heah Cheng Yong

Today, the building and construction sector demands environmentally friendly and sustainable protective coatings using inorganic coating materials for safe, non-hazardous, and great performance. Many researchers have been working on sustainable solutions to protect concrete and metal infrastructures against corrosion and surface deterioration with the intention of introducing green alternatives to conventional coatings. This article presents a review of developments of geopolymer pastes doped with different types of photocatalyst precursors including factors affecting geopolymer properties for enhancing coating with photocatalytic performance. Photodegradation using geopolymer photocatalyst has great potential for resolving harmless substances and removing pollutants when energized with ultraviolet (UV) light. Although geopolymer is a potentially new material with great properties, there has been less research focusing on the development of this coating. This study demonstrated that geopolymer binders are ideal precursor support materials for the synthesis of photocatalytic materials, with a significant potential for optimizing their distinctive properties.

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Improvements of Flexural Properties and Thermal Performance in Thin Geopolymer Based on Fly Ash and Ladle Furnace Slag Using Borax Decahydrates

2022-06-01 , Ng Yong-Sing , Liew Yun Ming , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Pakawanit P. , Vizureanu P. , Khalid M.S. , Ng Hui-Teng , Hanh Yong-Jie , Nabiałek M. , Pietrusiewicz P. , Garus S. , Sochacki W. , Śliwa A.

This paper elucidates the influence of borax decahydrate addition on the flexural and thermal properties of 10 mm thin fly ash/ladle furnace slag (FAS) geopolymers. The borax decahydrate (2, 4, 6, and 8 wt.%) was incorporated to produce FAB geopolymers. Heat treatment was applied with temperature ranges of 300◦C, 600◦C, 900◦C, 1000◦C and 1100◦C. Unexposed FAB geopolymers experienced a drop in strength due to a looser matrix with higher porosity. However, borax decahydrate inclusion significantly enhanced the flexural performance of thin geopolymers after heating. FAB2 and FAB8 geopolymers reported higher flexural strength of 26.5 MPa and 47.8 MPa, respectively, at 1000◦C as compared to FAS geopolymers (24.1 MPa at 1100◦C). The molten B2O3 provided an adhesive medium to assemble the aluminosilicates, improving the interparticle connectivity which led to a drastic strength increment. Moreover, the borax addition reduced the glass transition temperature, forming more refractory crystalline phases at lower temperatures. This induced a significant strength increment in FAB geopolymers with a factor of 3.6 for FAB8 at 900◦C, and 4.0 factor for FAB2 at 1000◦C, respectively. Comparatively, FAS geopolymers only achieved 3.1 factor in strength increment at 1100◦C. This proved that borax decahydrate could be utilized in the high strength development of thin geopolymers.

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Alkaline-Activation Technique to Produce Low-Temperature Sintering Activated-HAp Ceramic

2023-02-01 , Wan Mohd Arif W Ibrahim , Mohd. Mustafa Al Bakri Abdullah , Jamil N.H. , Mohamad H. , Mohd Arif Anuar Mohd Salleh , Sandu A.V. , Vizureanu P. , Baltatu M.S. , Sukmak P.

The fabrication of hydroxyapatite (HAp) ceramics prepared by existing conventional sintering requires high-temperature sintering of 1250 °C to 1300 °C. In this paper, the activated metakaolin (MK)/HAp specimens were prepared from varied mix design inputs, which were varied solid mixtures (different amounts of MK loading in HAp) and liquid-to-solid (L/S) ratios, before being pressed and sintered at 900 °C. Phase analysis, thermal analysis, surface morphology, and tensile strength of the specimens were investigated to study the influences of the Al, Si, Fe, Na, and K composition on the formation of the hydroxyapatite phase and its tensile strength. XRD analysis results show the formation of different phases was obtained from the different mix design inputs HAp (hexagonal and monoclinic), calcium phosphate, sodium calcium phosphate silicate and calcium hydrogen phosphate hydrate. Interestingly, the specimen with the addition of 30 g MK prepared at a 1.25 L/S ratio showed the formation of a monoclinic hydroxyapatite phase, resulting in the highest diametrical tensile strength of 12.52 MPa. Moreover, the increment in the MK amount in the specimens promotes better densification when sintered at 900 °C, which was highlighted in the microstructure study. This may be attributed to the Fe2O3, Na2O, and K2O contents in the MK and alkaline activator, which acted as a self-fluxing agent and contributed to the lower sintering temperature. Therefore, the research revealed that the addition of MK in the activated-HAp system could achieve a stable hydroxyapatite phase and better tensile strength at a low sintering temperature.

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Preparation of Carbon Nanotubes/Alumina Hybrid-Filled Phenolic Composite with Enhanced Wear Resistance

2023-04-01 , Siti Shuhadah Md Saleh , Mohd Firdaus Omar , Akil H.M. , Kudus M.H.A. , Mohd. Mustafa Al Bakri Abdullah , Sandu A.V. , Vizureanu P. , Khairul Anwar Abdul Halim , Mohamad Syahmie Mohamad Rasidi , Syarifah Nuraqmar Syed Mahamud , Sandu I. , Nosbi N.

Hybrid fillers can be produced via various methods, such as physical mixing and chemical modification. However, there is a limited number of studies on the effect of hybridisation on the mechanical performance of hybrid filler-reinforced polymer composites, especially in the context of wear performance. This study investigated the wear resistance of carbon nanotubes (CNTs)/alumina hybrid-filled phenolic composite, where two hybrid methods were used to produce the CNTs/alumina hybrid filler. The CNTs/alumina (CVD hybrid) was synthesised using the chemical vapour deposition (CVD) method, whereas the CNTs-/alumina (physically hybrid) was prepared using the ball milling method. The CNTs/alumina hybrid filler was then used as a filler in the phenolic composites. The composites were prepared using a hot mounting press and then subjected to a dry sliding wear test using a pin-on-disc (POD) tester. The results show that the composite filled with the CVD hybrid filler (HYB composite) had better wear resistance than the composite filled with physically hybrid filler (PHY composite) and pure phenolic. At 5 wt%, the HYB composite showed a 74.68% reduction in wear, while the PHY composite showed a 56.44% reduction in wear compared to pure phenolic. The HYB composite exhibited the lowest average coefficient of friction (COF) compared to the PHY composite and pure phenolic. The average COF decreased with increasing sliding speeds and applied loads. The phenolic composites’ wear and average COF are in the order HYB composite < PHY composite < pure phenolic under all sliding speeds and applied loads.

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