Heah Cheng Yong
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Preferred name
Heah Cheng Yong
Official Name
Heah, Cheng Yong
Alternative Name
Yong, Heah Cheng
Yong, H. C.
Heah, Cheng Yong
Heah, C. Y.
Cheng-Yong, Heah
Cheng Yong, Heah
Main Affiliation
Scopus Author ID
54402789500
Researcher ID
S-7139-2019

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  • Publication
    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.
      1
  • Publication
    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.
      1
  • Publication
    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.
      1
  • Publication
    Effect of Solid-to-Liquid Ratio on Thin Fly Ash Geopolymer
    ( 2020-03-18)
    Yong-Sing N.
    ;
    Liew Yun Ming
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Hui-Teng N.
    ;
    Kamarudin Hussin
    ;
    Heah Cheng Yong
    ;
    Nurul Aida Mohd Mortar
    ;
    Sandu A.V.
    The present work studies the effect of solid-to-liquid (S/L) ratio on the properties of thin fly ash-based geopolymer. The fly ash geopolymers with dimension of 160 mm × 40 mm × 10 mm were synthesised by using various S/L ratios (1.5, 2.0, 2.5, 3.0 and 3.2). The alkali activator was prepared by mixing 10M sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) with the Na2SiO3/NaOH ratio of 2.5. The samples were cured at 60°C for 6 hours. The performance of fly ash geopolymers was evaluated by testing the flexural strength after 28 days. Results showed that the S/L ratio had an effect on flexural strength. The optimum flexural strength of 5.12 MPa was achieved by the fly ash geopolymer with S/L ratio of 2.5. However, the flexural strength dropped with higher S/L ratio as the workability decreases. However, further experimental lab work should be carried out as there is less knowledge in the study on the flexural strength of thin fly ash geopolymer.
      1
  • Publication
    Silica Bonding Reaction on Fly Ash Based Geopolymer Repair Material System with Incorporation of Various Concrete Substrates
    ( 2022-01-01)
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ikmal Hakem A. Aziz
    ;
    Zailani W.W.A.
    ;
    Shayfull Zamree Abd. Rahim
    ;
    Heah Cheng Yong
    ;
    Sandu A.V.
    ;
    Loke Siu Peng
    This paper presents an experimental investigation on the mechanical properties and microstructure of geopolymer repair materials mixed using fly ash (FA) and concrete substrates. An optimal combination of FA and concrete substrate was determined using the compressive test of geopolymer mortar mixed with various concrete substrate classes. It was found that the contribution of (C35/45) concrete substrates with the FA geopolymer mortar increases the 28-day bonding strength by 25.74 MPa. The microstructure analysis of the samples using scanning electron microscopy showed the denser structure owing to the availability of high calcium and iron elements distribution. These metal cations (Ca2+ and Fe3+) are available at OPC concrete substrate as a result from the hydration process reacted with alumina-silica sources of FA and formed calcium aluminate silicate hydrate (C-A-S-H) gels and Fe-bonding linkages.
      3
  • Publication
    Geopolymer via Pressing Method: Aluminosilicates/Alkaline Solution Ratio as the Determining Factor
    ( 2020-07-09)
    Shee Ween O.
    ;
    Heah Cheng Yong
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ho Li Ngee
    ;
    Wan En O.
    Aluminosilicates/alkaline solution (FA/AA) ratio has a great influence on the morphology and mechanical properties of geopolymer fabricated via pressing method. The aim of this paper is to evaluate the effect of FA/AA ratio on the performance of pressed geopolymer. The geopolymer mixtures were prepared at FA/AA ratio of 4.5-7.0 and compacted with uniaxial hydraulic press. The resultant specimens were cured at room temperature (30°C) for 7 and 28 days. The physical properties of the specimens were measured by porosity and water absorption analysis. The microstructure and strength of pressed geopolymers were determined. The results revealed that the pressed geopolymer with FA/AA ratio of 5.5 had the lowest porosity and water absorption. Furthermore, SEM micrographs proved that FA/AA ratio of 5.5 yielded the formation of well-compacted structure. Maximum compressive strength of 78.54 MPa was achieved.
      2
  • Publication
    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.
      1
  • Publication
    Effect of phosphate addition on room-temperature-cured fly ash-metakaolin blend geopolymers
    ( 2021-02-08)
    Khairunnisa Zulkifly
    ;
    Heah Cheng Yong
    ;
    Liew Yun Ming
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ong Shee-Ween
    ;
    Khalid M.S.B.
    This paper details the influence of NaOH concentration, solid-to-liquid (S/L) and sodium silicate-to-sodium hydroxide (Naâ‚‚SiO3/NaOH) ratios, and the role of aluminum phosphate on the compressive strength development of the fly ash-metakaolin (FA-MK) blend geopolymer. The blended geopolymer was prepared with FA: MK at a ratio of 1:1, activated with a sodium-based alkali activator and then cured at room temperature. The optimum FA-MK blend geopolymer was formulated using a 10 M NaOH solution, a S/L ratio of 1.2, and a Naâ‚‚SiO3/NaOH ratio of 2.6. Monoaluminium phosphate (MAP) and aluminum dihydrogen triphosphate (ATP) were added as the source of aluminium phosphate. The FA-MK blend geopolymers have compressive strengths of 63.7 MPa and 55.5 MPa after being cured for 28 days with the addition of 1 wt% of MAP and ATP, respectively. The strength enhancement was assumed to be dictated by the formation of a matrix with a higher cross-linking geopolymer framework. The microstructure of blend geopolymer with MAP and ATP was smoother and compact compared to those without phosphate addition. In comparison, MAP addition in blend geopolymer yielded better physical and mechanical properties.
      1