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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  • Publication
    Behavior of alkali-activated fly ash through underwater placement
    ( 2021-11-01)
    Zarina Yahya
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Li Long-Yuan
    ;
    Nergis D.D.B.
    ;
    Muhammad Aiman Asyraf Zainal Hakimi
    ;
    Sandu A.V.
    ;
    Vizureanu P.
    ;
    Rafiza Abd Razak
    Underwater concrete is a cohesive self-consolidated concrete used for concreting underwater structures such as bridge piers. Conventional concrete used anti-washout admixture (AWA) to form a high-viscosity underwater concrete to minimise the dispersion of concrete material into the surrounding water. The reduction of quality for conventional concrete is mainly due to the washing out of cement and fine particles upon casting in the water. This research focused on the detailed investigations into the setting time, washout effect, compressive strength, and chemical composition analysis of alkali-activated fly ash (AAFA) paste through underwater placement in seawater and freshwater. Class C fly ash as source materials, sodium silicate, and sodium hydroxide solution as alkaline activator were used for this study. Specimens produced through underwater placement in seawater showed impressive performance with strength 71.10 MPa on 28 days. According to the Standard of the Japan Society of Civil Engineers (JSCE), the strength of specimens for underwater placement must not be lower than 80% of the specimen’s strength prepared in dry conditions. As result, the AAFA specimens only showed 12.11% reduction in strength compared to the specimen prepared in dry conditions, thus proving that AAFA paste has high potential to be applied in seawater and freshwater applications.
      2
  • Publication
    Influence of ZnO Nanoparticles on Mechanical Properties and Photocatalytic Activity of Self-cleaning ZnO-Based Geopolymer Paste
    ( 2020-06-01)
    Siti Norsaffirah Zailan
    ;
    Bouaissi, Aissa
    ;
    Norsuria Mahmed
    ;
    Mohd. Mustafa Al Bakri Abdullah
    Abstract: The influence of zinc oxide (ZnO) nanoparticles on the mechanical properties and photocatalytic degradation of methylene blue (MB) of ZnO-based geopolymer material was investigated under the illumination of ultraviolet (UV) radiations. In this work, ZnO-based geopolymer paste was manufactured using class F fly ash (FA) and ZnO nanoparticles powders with different mass percentages (0, 2.5, 5.0, 7.5 and 10 wt%). The FA-ZnO dry mix was activated by alkaline activator solution made from sodium silicate and sodium hydroxide with a ratio of 2.5. The mechanical properties were investigated by performing a compressive strength test at 28 days. The photocatalytic activity of ZnO nanoparticles was evaluated by measuring the photodegradation level of methylene blue under sunlight rays. The results showed a substantial influence of ZnO on the compressive strength, which decreased with the increase of ZnO amounts ranging from 2.5 to 7.5 wt% then a slightly increased at 10 wt% of ZnO. The addition of ZnO nanoparticles to a geopolymeric material showed a satisfactory efficiency of photocatalytic degradation of methylene blue after 150 min of exposure to sunlight. Phase analysis revealed that the addition of ZnO nanoparticles in the geopolymeric system develops a new ZnO crystalline phases. Graphic Abstract: [Figure not available: see fulltext.].
      3  38
  • Publication
    Seawater Exposure Effect on Fly Ash based Geopolymer Concrete with Inclusion of Steel Fiber
    ( 2020-03-18)
    Zarina Yahya
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Jing L.Y.
    ;
    Li L.Y.
    ;
    Rafiza Abd Razak
    Concrete is widely used in construction offshore such as concrete floating bridges and sea tank. This research is providing an alternative construction material to replace ordinary Portland cement (OPC) concrete known as geopolymer. The geopolymer concrete was produced by mixing fly ash with alkaline activator and 3% of steel fibre in order to improve the properties of fiber reinforced geopolymer concrete (FRGPC). The effects of aging period in term of strength, changes in weight and carbonation of FRGPC in seawater is investigated and compared with the fiber reinforced concrete (FROPC). The compressive strength obtained for FRGPC were higher than FROPC. The highest compressive strength obtained by FRGPC is 76.87 MPa at 28 days and 45.63 MPa at 28 days for FROPC concrete. The compressive strength was decreased as the period of immersing the concrete in seawater is increased. During the immersion process of both samples in seawater up to 120 days, the carbonation was not detected even though with the existence of steel fibres.
      3  21
  • Publication
    Bonding strength characteristics of FA-based geopolymer paste as a repair material when applied on OPC substrate
    ( 2020)
    Warid Wazien Ahmad Zailani
    ;
    Aissa Bouaissi
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Rafiza Abd Razak
    ;
    Sorachon Yoriya
    ;
    Mohd Arif Anuar Mohd Salleh
    ;
    Mohd Remy Rozainy M. A. Z.
    ;
    Hamzah Fansuri
    This investigative study aims to study the mechanical and morphological properties of fly ash (FA)-based geopolymer paste as a repair material when applied on ordinary Portland cement (OPC) overlay concrete. The first part of this study investigates the optimal mix design of FA-based geopolymer paste with various NaOH concentrations of 8, 10, 12, and 14 M, which were used later as a repair material. The second part studies the bonding strength using a slant shear test between the geopolymer repair material and OPC substrate concrete. The results showed that a shorter setting time corresponds to the higher NaOH molarity, within the range of 53 and 30 min at 8 and 14 M, respectively. The compressive strength of FA-based geopolymer paste was found to reach 92.5 MPa at 60 days. Also, from the slant shear test results, prism specimens with 125 mm length and 50 mm wide have a large bond strength of 11 MPa at 12 M. The scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis showed that the OPC substrate has a significant effect on slant shear bond strength, where the presence of free cations of Ca2+ on the OPC substrate surface contributed to the formation of calcium alumina-silicate hydrate gel (C-A-S-H) by building various cross-links of Ca-O-Si.
      2  14