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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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.

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Thermal Insulation and Mechanical Properties in the Presence of Glas Bubble in Fly Ash Geopolymer Paste

2022-01-01 , Shahedan N.F. , Mohd. Mustafa Al Bakri Abdullah , Norsuria Mahmed , Liew Yun Ming , Shayfull Zamree Abd. Rahim , Aziz I.H.A. , Kadir A.A. , Sandu A.V. , Mohd Fathullah Ghazli@Ghazali

The density, compressive strength, and thermal insulation properties of fly ash geopolymer paste are reported. Novel insulation material of glass bubble was used as a replacement of fly ash binder to significantly enhance the mechanical and thermal properties compared to the geopolymer paste. The results showed that the density and compressive strength of 50% glass bubble was 1.45 g/ cm3 and 42.5 MPa, respectively, meeting the standard requirement for structural concrete. Meanwhile, the compatibility of 50% glass bubbles tested showed that the thermal conductivity (0.898 W/mK), specific heat (2.141 MJ/m3K), and thermal diffusivity (0.572 mm2/s) in meeting the same requirement. The improvement of thermal insulation properties revealed the potential use of glass bubbles as an insulation material in construction material.

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Thermal Exposure of Fly Ash-Metakaolin Blend Geopolymer with Addition of Monoaluminum Phosphate (MAP)

2020-07-09 , Zulkifly K. , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Hussin K.

Recent research reveals that formulation of blended geopolymers based on the association of two aluminosilicate precursors had a better performance than one precursor geopolymers. This study presents a facile method to enhance the compressive strength of fly ash-metakaolin blend geopolymer by incorporating monoaluminum phosphate (MAP) during the geopolymerization reaction. The effect of the thermal exposure on the microstructure and compressive strength of the geopolymer are investigated. Results show that the MAP is transformed to granule structures, bonded and surrounded by geopolymer gel. The unique microstructure increases the compressive strength of the room temperature curing geopolymer from 54.7 MPa to 64.21 MPa (14.8%) with an optimum addition of 1.0 wt% MAP. This enhancement in compressive strength was ensured by the formation of an amorphous structure of aluminosilicophosphate (SiO2.Al2O3.P2O5.nH2O) phase. At higher temperatures, the formation of stable crystalline phase of berlinite and nepheline contribute to strength retention of the geopolymer. Hereby, it can be concluded that the addition of 1.0wt% MAP in the geopolymer reinforced the structure.

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Thermal insulation and mechanical properties in the presence of glass bubble in fly ash geopolymer paste

2022-01-01 , Noor Fifinatasha Shahedan , Mohd. Mustafa Al Bakri Abdullah , Norsuria Mahmed , Liew Yun Ming , Shayfull Zamree Abd. Rahim , Ikmal Hakem Abdul Aziz , Kadir A.A. , Sandu A.V. , Mohd Fathullah Ghazli@Ghazali

The density, compressive strength, and thermal insulation properties of fly ash geopolymer paste are reported. Novel insulation material of glass bubble was used as a replacement of fly ash binder to significantly enhance the mechanical and thermal properties compared to the geopolymer paste. The results showed that the density and compressive strength of 50% glass bubble was 1.45 g/ cm3 and 42.5 MPa, respectively, meeting the standard requirement for structural concrete. Meanwhile, the compatibility of 50% glass bubbles tested showed that the thermal conductivity (0.898 W/mK), specific heat (2.141 MJ/m3K), and thermal diffusivity (0.572 mm2/s) in meeting the same requirement. The improvement of thermal insulation properties revealed the potential use of glass bubbles as an insulation material in construction material.

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Compressive strength and thermal conductivity of metakaolin geopolymers with anisotropic insulations

2020-03-18 , Jaya N.A. , Liew Yun Ming , Mohd. Mustafa Al Bakri Abdullah , Kamarudin Hussin , Heah Cheng Yong , Bayuaji R. , Muhammad Faheem Mohd. Tahir

This research investigated the properties of thermally insulating geopolymer prepared using waste filler (fibreboard and rubber) to act as anisotropic pore/insulation. The geopolymer matrix was synthesised using metakaolin and an alkaline solution consists of sodium hydroxide solution and sodium silicate mixture. Geopolymers with varying content (0, 3, 5 and 7 layers) of coin-shaped fibreboard and expanded polystyrene are produced to examine the anisotropic insulation effect on the material characteristics. The compressive strength and thermal conductivity were determined experimentally. From the results, it is proved that the use of anisotropic insulations can improve the thermal conductivity and minimizing the reduction of compressive strength. Geopolymer incorporated with fibreboard had better performance in terms of strength while geopolymer incorporated with rubber had better thermal conductivity.

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Correlation between pore structure, compressive strength and thermal conductivity of porous metakaolin geopolymer

2020-06-30 , Jaya N.A. , Liew Yun Ming , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Kamarudin Hussin

This paper investigates the effect of mixing parameters (that are, alkali concentration, AA ratio, and MK/AA ratio) on the thermal conductivity of metakaolin geopolymers. The combination effect of foaming agent (H2O2) and surfactant (Tween 80) on the physical properties, compressive strength, and pore characteristic was also elucidated. Results showed that metakaolin geopolymer with maximum compressive strength of 33 MPa, bulk density of 1680 kg/m3, porosity of 18% and thermal conductivity of 0.40 W/mK were achieved with alkali concentration of 10 M, AA ratio of 1.0 and MK/AA ratio of 0.8. Gradation analysis demonstrated that AA ratio was the strength determining factor. Whilst, thermal conductivity was dependent on the MK/AA ratio. Adding H2O2 and surfactant produced geopolymer foam with acceptable compressive strength (0.4–6 MPa). The geopolymer foam had bulk density of 471–1212 kg/m3, porosity of 36–86% and thermal conductivity of 0.11–0.30 W/mK. Pore structure, size, and distribution were governed by H2O2 and surfactant dosages that have a great impact on the compressive strength. Narrower pore distribution and smaller pore diameter were achieved when both foaming agent and surfactant were used instead of foaming agent alone. The pore size and distribution varied to a greater extent with varying H2O2 contents. Surfactant illustrated distinct pore stabilizing effect at low H2O2 (<0.75 wt%) which diminished at high H2O2 content. In terms of thermal conductivity, even with increasing porosity at high H2O2 and surfactant content, the thermal conductivity did not show substantial reduction due to the interconnected pores as a result of pore coalescence.

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FINITE ELEMENT ANALYSIS ON STRUCTURAL BEHAVIOUR OF GEOPOLYMER REINFORCED CONCRETE BEAM USING JOHNSON-COOK DAMAGE IN ABAQUS

2022-01-01 , Nurul Aida Mohd Mortar , Mohd. Mustafa Al Bakri Abdullah , Kamarudin Hussin , Rafiza Abd Razak , Sanusi Hamat , Ahmad Humaizi Hilmi , Noorfifi Natasha Shahedan , Li L.Y. , Ikmal Hakem Abdul Aziz

This paper details a finite element analysis of the behaviour of Si-Al geopolymer concrete beam reinforced steel bar under an impulsive load and hyper velocity speed up to 1 km/s created by an air blast explosion. The initial torsion stiffness and ultimate torsion strength of the beam increased with increasing compressive strength and decreasing stirrup ratio. The study involves building a finite element model to detail the stress distribution and compute the level of damage, displacement, and cracks development on the geopolymer concrete reinforcement beam. This was done in ABAQUS, where a computational model of the finite element was used to determine the elasticity, plasticity, concrete tension damages, concrete damage plasticity, and the viability of the Johnson-Cook Damage method on the Si-Al geopolymer concrete. The results from the numerical simulation show that an increase in the load magnitude at the midspan of the beam leads to a percentage increase in the ultimate damage of the reinforced geopolymer beams failing in shear plastic deformation. The correlation between the numerical and experimental blasting results confirmed that the damage pattern accurately predicts the response of the steel reinforcement Si-Al geopolymer concrete beams, concluded that decreasing the scaled distance from 0.298 kg/m3 to 0.149 kg/m3 increased the deformation percentage.

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Thermal insulation and mechanical properties in the presence of glass bubble in fly ash geopolymer paste

2022-01-01 , Noor Fifinatasha Shahedan , Mohd. Mustafa Al Bakri Abdullah , Norsuria Mahmed , Liew Yun Ming , Shayfull Zamree Abd. Rahim , Ikmal Hakem Abdul Aziz , Kadir A.A. , Sandu A.V. , Mohd Fathullah Ghazli@Ghazali

The density, compressive strength, and thermal insulation properties of fly ash geopolymer paste are reported. Novel insulation material of glass bubble was used as a replacement of fly ash binder to significantly enhance the mechanical and thermal properties compared to the geopolymer paste. The results showed that the density and compressive strength of 50% glass bubble was 1.45 g/ cm3 and 42.5 MPa, respectively, meeting the standard requirement for structural concrete. Meanwhile, the compatibility of 50% glass bubbles tested showed that the thermal conductivity (0.898 W/mK), specific heat (2.141 MJ/m3K), and thermal diffusivity (0.572 mm2/s) in meeting the same requirement. The improvement of thermal insulation properties revealed the potential use of glass bubbles as an insulation material in construction material.

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Phase transformation of Kaolin-ground granulated blast furnace slag from geopolymerization to sintering process

2021-03-01 , Noorina Hidayu Jamil , Mohd. Mustafa Al Bakri Abdullah , Faizul Che Pa , Hasmaliza M. , Wan Mohd Arif W Ibrahim , Aziz I.H.A. , Jeż B. , Nabiałek M.

The main objective of this research was to investigate the influence of curing temperature on the phase transformation, mechanical properties, and microstructure of the as-cured and sintered kaolin-ground granulated blast furnace slag (GGBS) geopolymer. The curing temperature was varied, giving four different conditions; namely: Room temperature, 40, 60, and 80â—¦ C. The kaolin-GGBS geopolymer was prepared, with a mixture of NaOH (8 M) and sodium silicate. The samples were cured for 14 days and sintered afterwards using the same sintering profile for all of the samples. The sintered kaolin-GGBS geopolymer that underwent the curing process at the temperature of 60â—¦ C featured the highest strength value: 8.90 MPa, and a densified microstructure, compared with the other samples. The contribution of the Na2 O in the geopolymerization process was as a self-fluxing agent for the production of the geopolymer ceramic at low temperatures.

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Fly ash-metakaolin blend geopolymers under thermal exposures: Physical and mechanical performances

2020-11-02 , Zulkifly K. , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Kamarudin Hussin , Abdullah S.F.A.

In this paper, an experimental study on the thermo-mechanical properties of fly ash-metakaolin blend geopolymers is presented. Visual observations, density and mass loss and compression test were conducted on geopolymers heated in a furnace at 200 °C, 400 °C, 600 °C, 800 °C and 1000 °C with a heating rate of 10 °C/min and soaking time of 1 hours. Fly ash-metakaolin blend geopolymers possessed excellent strength of 54.7MPa at ambient temperature and degraded 23.4% to 41.9MPa when exposed 200?C. The tested result show that the geopolymer can perform good residual strength (up to 23.2MPa) after 600?C. The strength of geopolymers decreased to 5.8MPa with increasing temperature up to 800?C. Even so, the geopolymers could withstand high temperature and remained intact. The higher mass loss due to the liberation of water from the surface, led to significant strength degradation in fly ash-metakaolin blend geopolymers. However, geopolymer gels exhibited structural stability at 1000°C, since at this temperature it promotes the reaction of the residue fly ash and metakaolin in the geopolymer samples, leading to a strength increase to 9.1MPa Employing blend fly ash and metakaolin as a precursor in the geopolymers helped to minimize the disruption effect caused by high temperature exposures.

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