Ho Li Ngee
Thumbnail Image
Preferred name
Ho Li Ngee
Official Name
Ho, Li Ngee
Alternative Name
Li Ngee, Ho
Ho, Li Ngee
Ngee, Ho Li
Ho, L. N.
Main Affiliation
Scopus Author ID
57219028372
Researcher ID
DDY-6348-2022

Research Output

Filters

3
3
3
Reset filters

Settings
Now showing 1 - 3 of 3
  • Publication
    Towards greener one-part geopolymers through solid sodium activators modification
    ( 2022-12-10)
    Ooi Wan-En
    ;
    Liew Yun Ming
    ;
    Heah Cheng Yong
    ;
    Ho Li Ngee
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Bin Khalid M.S.
    ;
    Foo Kai Loong
    ;
    Ong Shee-Ween
    ;
    Pei Seng T.
    ;
    Hang Yong Jie
    ;
    Khairunnisa Zulkifly
    This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.
  • Publication
    Towards greener one-part geopolymers through solid sodium activators modification
    ( 2022-12-10)
    Ooi Wan En
    ;
    Liew Yun Ming
    ;
    Heah Cheng Yong
    ;
    Ho Li Ngee
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Bin Khalid M.S.
    ;
    Foo Kai Loong
    ;
    Ong Shee Ween
    ;
    Pei Seng T.
    ;
    Hang Yong Jie
    ;
    Khairunnisa Zulkifly
    This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.
  • Publication
    Acid-resistance of one-part geopolymers: Sodium aluminate and carbonate as alternative activators to conventional sodium metasilicate and hydroxide
    ( 2023-11-10)
    Wan-En O.
    ;
    Yun-Ming L.
    ;
    Cheng-Yong H.
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ho Li Ngee
    ;
    Pakawanit P.
    ;
    Wei Ken P.
    ;
    Khalid M.S.
    ;
    Md Razi H.
    ;
    Lee W.H.
    ;
    Soo Jin T.
    ;
    Shee-Ween O.
    ;
    Yong-Jie H.
    In this study, the durability of one-part geopolymers (OPGs) made from high calcium fly ash is assessed by investigating their resistance to acid attacks. The predominant use of less environmentally sustainable sodium metasilicate (Na2SiO3) and sodium hydroxide (NaOH) in OPG, along with the limited understanding about the influence of solid alkali activators on OPG's acid resistance propelled the investigation and comparison of acid resistance of OPGs activated using both conventional activators and potential alternatives like sodium aluminate (NaAlO2) and sodium carbonate (Na2CO3). The OPGs developed were exposed to sulphuric acid (H2SO4) solution for 28 days. The MH sample (activated with Na2SiO3 and NaOH) was vulnerable to acid attack, with a 66% compressive strength drop after 5% H2SO4 solution exposure, due to high sorptivity. In contrast, the MA sample (activated with Na2SiO3 and NaAlO2) demonstrated excellent acid resistance, with only a 32% strength reduction, attributed to its Al-rich hydrated gel. The MC sample (activated with Na2SiO3 and Na2CO3) exhibited a 41% strength reduction, where the formation of calcite reduced extensive ion exchange, gradually mitigated deterioration. The residual compressive strength of MA and MC samples increased by 7% and 9% from 7 to 28 days of immersion in 5% H2SO4 solution, respectively. The NaAlO2 and Na2CO3 are potential activators for OPG, serving as alternative construction materials to OPC and traditional geopolymers in acidic environments.